Proceedings of the Autumn Meeting Chester April 2006 ENIGMAS OF THE CANINE ELBOW. BVOA: Proceedings Autumn Scientific Meeting November

Transcription

1 Proceedings of the Autumn Meeting Chester April 2006 ENIGMAS OF THE CANINE ELBOW BVOA: Proceedings Autumn Scientific Meeting November

2 CONTENTS ELBOW DYSPLASIA 1: BACKGROUND What do we know about normal elbow development in dogs? Claudia Wolschrijn......No abstract What is required for breeding programmes or molecular technologies to make a positive impact on the prevalence and incidence of elbow dysplasia in dogs? Jeff Sampson Gene expression in normal and diseased elbows Dylan Clements Protein expression in elbow development and dysplasia Mathew Pead ELBOW DYSPLASIA 2 CLINICAL ISSUES Is elbow dysplasia a syndrome? John Innes Optimising imaging in elbow dysplasia Ian Holsworth The pathogenesis of FMCP and related lesions: current concepts Claudia Wolschrijn......No abstract Treatment options for FMCP The role of conservative care Mark Glyde The role of surgical or arthroscopic debridement Bernadette Van Ryssen......No abstract The role of proximal ulnar osteotomy Malcolm Ness The role of coronoidectomy Noel Fitzpatrick The role of sub-total arthroscopic partial coronoidectomy and concurrent distal ulnar ostoetomy Ian Holsworth Does the primary treatment method change the long-term outcome in FMCP? Angus Anderson Salvaging the canine elbow Arthroscopy, ulnar and humeral osteotomy, replacement arthroplasty Ian Holsworth Humeral slide osteotomy clinical case series Noel Fitzpatrick Salvaging the human elbow: a brief history of elbow replacement arthroplasty John Stanley FRCS......No abstract... BVOA: Proceedings Autumn Scientific Meeting November

3 ÿ INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE The pathogenesis of IOHC Mark Glyde The diagnosis and current treatment of IOHC Imaging, arthroscopy and basic fixation Ian Holsworth ABCD graft and self-canulating screw fixation Noel Fitzpatrick Should IOHC lesions be treated aggressively? John Ferguson Fractures associated with IOHC: Current concepts in the management of condylar fractures of the humerus Malcolm McKee External skeletal fixation for the management of Y fractures John Ferguson The BVOA would like to thanks our sponsors for their kind generosity in supporting this meeting: Veterinary Instrumentation Schering-Plough Animal Health Pfizer Animal Health Orthomed Iddex Hills Merial Freelance Surgical Boehringer Ingelheim BVOA: Proceedings Autumn Scientific Meeting November

4 ELBOW DYSPLASIA 1: BACKGROUND WHAT IS REQUIRED FOR BREEDING PROGRAMMES OR MOLECULAR TECHNOLOGIES TO MAKE IMPACT ON THE PREVALENCE AND INCIDENCE OF ELBOW DYSPLASIA IN DOGS? Jeff Sampson The Kennel Club Canine elbow dysplasia appears to be a complex, multifactorial condition. Estimates of its heritability vary from report to report and from breed to breed, but lie somewhere between 20% and 30%, which, although on the low side, suggests that, with appropriate genetic selection, the prevalence of the condition can be reduced. What is required is a suitable screening scheme that breeders can use to predict the genotype of individual dogs. At the moment, the BVA/KC Elbow Scoring Scheme assesses and grades the elbow phenotype from radiographs of an individual dog s elbows. Can such elbow scores be used for genetic selection? Evidence from other clinical screening programmes suggest that the answer should be yes. The Boxer suffers from aortic stenosis, an inherited condition that probably is genetically complex, and Boxer breeders have for some time now been screening their potential breeding stock using auscultation to detect and grade any heart murmurs that are present. This information has then been used as one of the many criteria to determine mating pairs within the breed. The graph below shows that taking note of dogs murmur grades will allow progress to be made toward reducing this problem in the breed: It is possible that the heritability of aortic stenosis in the Boxer is higher than that of elbow dysplasia, and so the effects of selection may be stronger in this case. However, heritability estimates of canine hip dysplasia are much closer to those derived for elbow dysplasia. Analysis of phenotypic hip data taken from Labrador Retrievers examined under the BVA/KC Hip Scoring Scheme suggest strongly that the hip score can be used for appropriate genetic selection and, if used responsibly, can allow breeders to begin to reduce the problem of hip dysplasia in the breed. The data demonstrate that parents with low hip scores are more likely BVOA: Proceedings Autumn Scientific Meeting November

5 ELBOW DYSPLASIA 1: BACKGROUND to produce puppies with low hip scores; conversely, parents with high hip scores are far more likely to produce puppies with high hip scores. One of the problems with the present Elbow Scoring Scheme is that it does not seem to have been taken up with the same enthusiasm by breeders as the Hip Scoring Scheme. Consequently, progress has been less obvious. It is not obvious why this is the case, but progress will not become apparent until more breeders actually have their breeding stock elbow graded and use the information as one of their selective criteria. It may be that progress on our molecular understanding of the genetics that underlie elbow dysplasia will advance rapidly, particularly because of the new technologies and approaches that the publication of the canine genome sequence has provided, and identify the specific mutations that are responsible for elbow dysplasia. DNA tests for these newly-identified mutations will quickly follow. Such DNA tests will provide the breeder with much more accurate methods of predicting an individual dog s genotype with respect to elbow dysplasia. Although this will be of great benefit, the use of DNA tests as a selection against elbow dysplasia will require the breeder to move to a new level of genetic evaluation if the prevelance of elbow dysplasia is to be reduced without accumulating collateral problems with the breed genetic population structure. The simple use of DNA tests for complex diseases in dogs will not completely solve the question of how to select against inherited disorders. The ideal approach will be to use estimated breeding values (EBVs), in conjunction with genotypic information provided by DNA testing. The breeding value is a measure of the genetic value of an animal, with the effects of the environment removed, and therefore offers a more accurate and potentially faster way to make genetic progress than if phenotypic measurements alone are considered. When marker information is available it is used, together with information on the observed disease among relatives, in the calculation of EBVs to yield more accurate predictions of the disease liability of future offspring. BVOA: Proceedings Autumn Scientific Meeting November

6 ELBOW DYSPLASIA 1: BACKGROUND GENE EXPRESSION IN NORMAL AND DISEASED ELBOWS Dylan Neil Clements BSc BVSc DSAS(Orth) DipECVS MRCVS Faculty of Veterinary Science, University of Liverpool Centre for Integrated Genomic Medical Research, University of Manchester Canine elbow dysplasia is a generic term encompassing a number of well defined conditions (phenotypes) of the elbow joint, such as fragmentation of the medial coronoid process (FCP), osteochondrosis dissecans (OCD) of the medial part of the humeral condyle and ununited anconeal process (UAP). Each of these conditions results in the development of osteoarthritis of the affected joint. In Labrador Retrievers the radiographic prevalence of canine elbow dysplasia has been reported to be between 2.9% and 17.8%, and the clinical prevalence has been between estimated between 4.0% and 5.0%. Heritability estimates for elbow dysplasia and strong breed predispositions with each of the associated conditions indicate that genetics contribute substantially to the development of elbow dysplasia. Pedigree studies have shown that FCP is inherited independently from OCD of the medial part of the humeral condyle and UAP which supports the view that the heritability of FCP alone cannot be ascertained from studies utilising a radiographic assessment of elbow dysplasia per se. Consequently, studies of canine elbow dysplasia, and their conclusions, should ideally be confined to the individual conditions. Pedigree analysis of canine elbow dysplasia also suggests that the component conditions of elbow dysplasia are polygenic in their nature (i.e. that they are caused by genetic changes to multiple genes). Polygenic disorders are extremely difficult to elucidate with traditional pedigree analysis, as the number of genes involved may be high and the relative contribution of each to the disease small. Consequently, novel methods for determining which genes are responsible for the genetic basis of a disease are required. One technique which has proved useful in human osteoarthritis research, is gene expression profiling. Gene expression profiling is an assessment of mrna expression of multiple genes, i.e. an evaluation of which genes are expressed within a sample, and an estimation of their relative abundance. Gene expression profiles are performed using microarray technology (which allows assessment of all 30,000 genes present in the canine genome) or the quantitative polymerase chain reaction (qpcr) which has a much greater degree of accuracy, but a much lower throughput (thus only 10 s of genes can be evaluated). Comparison of diseased and normal samples allows the identification of genes which are differentially expressed in diseased conditions. Changes in these candidate genes are then identified in the genome (DNA) and the frequency with which these changes are present is subsequently compared in large numbers of cases and controls, and thus the association of a gene with the diseased phenotype measured. Additionally, the gene expression profile also provides further information on the molecular pathways which contribute to disease, and provide novel targets for therapeutic intervention. In humans, a number of interlinked molecular pathways contributing to the degenerative process have been identified in osteoarthritic cartilage, such as those of cytokines, degradative enzyme production and matrix synthesis. Significant associations have been reported between changes in the genome of genes differentially expressed in osteoarthritis components of and/or molecules affecting the extracellular matrix of articular cartilage, namely; the collagen proteins, other structural proteins, hormones, cytokines and growth factors. BVOA: Proceedings Autumn Scientific Meeting November

7 ELBOW DYSPLASIA 1: BACKGROUND For the purpose of investigating FCP tissues worthy of investigation would include articular cartilage and synovium (with regard to the development of osteoarthritis), bone (with regard to the development of fragmentation and remodelling of the coronoid process) and physeal cartilage (with regard to asynchronous growth). We have iwdentified differential expression of genes (collagens [COL], aggrecan, cathespins [CTSD], matrix metalloproteinases [MMPs] and inhibitors of MMPs [TIMPs]) in osteoarthritic articular cartilage from the femoral head of dogs undergoing total hip replacement, using both microarray techniques and qpcr. Subsequently, we have utilised the same genes for expression profiling of articular cartilage from the medial coronoid process of the ulna from dogs with FCP by qpcr. Changes in gene expression were identified in the cartilage from dogs with FCP were similar to those identified in the articular cartilage from dogs with hip dysplasia (up-regulation of COL1A2, COL3A1, MMP3, MMP9, MMP13 and the down-regulation of TIMP2) were identified, although differences (down regulation of Cathepsin D) were also identified. When the expression profile data was examined with the radiographic data, good correlations between the IEWG score and gene expression were also identified. The tenuous link between a crude radiographic score and cellular activity was not expected. We hope that expression profiling of genes involved in bone remodelling (such as fibronectin 1 and TIMP2) in the bone fragments of the medial coronoid process from the same cohorts of dogs will ultimately provide further information as to the mechanical basis to disease. Subsequent studies of gene polymorphisms in the MMP13 gene in cases of canine elbow dysplasia (FCP) have failed to identify a significant association between disease and this gene. We have identified significant associations between polymorphisms of the Inteleukin-12 gene and elbow dysplasia, which suggests that at least one of the genetic changes responsible for FCP is present on canine chromosome 4. Studies of association of the other genes we have identified as being differentially expressed in articular cartilage are ongoing and will provide further information as to the genomic basis to FCP. Ultimately, it will be the combination of molecular biological techniques with epidemiological data from surgeons and radiologists which will allow us to crack the enigma of elbow dysplasia. Clearly, one of the fundamental difficulties with addressing elbow dysplasia is the issue of identifying which dogs do and do not have disease (i.e. when is a dog free of disease?). Until a consensus is reached on the optimal method for phenotyping dogs for disease, we may struggle to completely determine the genetic basis to elbow dysplasia. BVOA: Proceedings Autumn Scientific Meeting November

8 ELBOW DYSPLASIA 1: BACKGROUND PROTEIN EXPRESSION IN ELBOW DEVELOPMENT AND DYSPLASIA Matthew Pead BVetMed PhD CertSAO MRCVS & Caroline Ruaux-Mason Dept of Veterinary Clinical Sciences, The Royal Veterinary College, Hatfield, UK The clinical management of Elbow Dysplasia (ED) has undergone a number of changes in the last 10 years. The advent of arthroscopy has changed the evaluation of the damage within the joint, giving us a far greater understanding of the range of damage to the articular surfaces that occurs in relation to the primary lesions. Arthroscopy has also increased the range of surgical treatment options, and complements other surgical therapy such as fixation of Ununited Anconeal Process (UAP). Computed Tomography (CT) has given further insight into the process of the disease, giving very accurate images of Fragmented Coronoid Process (FCP) lesions and normally and abnormally positioned OCD lesions. While this advancement allows the clinician opportunities to improve their treatment of the individual animal suffering from ED, the principal problem remains unresolved. As soon as a clinician recognises a primary osteochondrosis lesion, or a clinical problem attributable to one, the processes of cartilage degeneration and osteoarthritis (OA) are already engaged. However successful the ensuing treatment from a clinical perspective, the joint will always be imperfect, so any treatment is in a sense, a salvage. In the long term veterinary success in ED is dependent on accurately screening for the disease, and breeding it out, or being able to predict the onset of the disease and treat it before the changes in the joint become irretrievable. Improved accuracy in screening is most likely to be dealt with using some form of genomic analysis and that will be dealt with in another presentation. Earlier detection of the clinical disease depends on an improved understanding of the changes that precede the clinical effects of an osteochondrosis lesion. Although the histological changes in some osteochondrosis lesions such as OCD are well documented, others such as FCP are less well known. Moreover the histological changes are downstream of the cellular or molecular events that initiate the problem. So these changes, involved in the initiation of osteochondrosis lesions could lead to an opportunity to detect the disease earlier and might provide a focus for or a link with the investigation of the genetic basis of the problem. We have looked at a variety of markers of joint metabolism to understand the early changes in osteochondrosis. Although this work is made difficult by the confusion between the osteochondrosis and OA processes, there are some important target molecules that appear to be differently expressed in osteochondritic and normal joints. Although OA is not an inflammatory joint disease there are elements of inflammatory processes associated with OA, and inflammatory components of the disease are linked to the degradation of articular cartilage. The presence of proinflammatory factors including the prostanoids, free radicals (eg nitric oxide), proinflammatory cytokines and metalloproteinases (eg MMP-9) may all be associated with such inflammation in such processes. We have measured several components of joint inflammation to evaluate whether FCP and OCD exhibited an inflammatory phase, including nitric oxide (NO) or and the MMP profile. Another potential area for early change in Osteochondrosis lesions are defects in the Extracellular matrix (ECM). Biochemical changes in the ECM of the cartilage or underlying bone may lead to weakness or fragmentation that could contribute to the detachment of either BVOA: Proceedings Autumn Scientific Meeting November

9 ELBOW DYSPLASIA 1: BACKGROUND the FCP or the OCD lesion. We have evaluated the turnover of a number of factors involved in the normal formation of the ECM, particularly concentrating on molecules related to the formation of the structural proteins in bone and cartilage and the mineralisation of these tissues. We chose these molecules because the succession of cartilage to bone and the appropriate mineralisation of the ECM appears to be related to the early histological changes that are seen in osteochondrosis. Cartilage oligomeric matrix protein (COMP), aggrecan, type X collagen and bone sialoprotein (BSP) have al played a role in our investigations. Our studies have some synergism with those of others and indicate that these molecules do appear to be involved in the early changes in osteochondrosis. There also appear to be differences between some types of primary lesion and further support for the contentions that FCP and OCD may have a different aetiology. BVOA: Proceedings Autumn Scientific Meeting November

10 ELBOW DYSPLASIA 2 CLINICAL ISSUES IS ELBOW DYSPLASIA A SYNDROME? John F. Innes BVSc PhD CertVR DSAS(orth) MRCVS Small Animal teaching Hospital and Musculoskeletal Research Group University of Liverpool, UK WHAT IS A SYNDROME? In medicine, the term syndrome is the association of several clinically recognisable features, signs, symptoms, phenomena or characteristics which often occur together, so that the presence of one feature alerts the physician to the presence of the others. The term syndrome derives from the Greek and means literally "run together". It is most often used when the reason that the features occur together (the pathophysiology of the syndrome) has not yet been discovered. A familiar syndrome name often continues to be used even after an underlying cause has been found, or when there are a number of different primary causes that all give rise to the same combination of symptoms and signs. SYNDROMES AND ASSOCIATED CONDITIONS The description of a syndrome usually includes a number of essential characteristics, which when concurrent lead to the diagnosis of the condition. Frequently these are classified as a combination of typical major symptoms and signs essential to the diagnosis together with minor findings, some or all of which may be absent. A formal description may specify the minumum number of major and minor findings respectively, that are required for the diagnosis. In contrast to the major and minor findings which are typical of the syndrome, there may be an association with other conditions, meaning that in persons with the specified syndrome these associated conditions occur more frequently than would be expected by chance. While the syndrome and the associated conditions may be statistically related, they do not have a clear cause and effect relationship i.e. there is likely to be a separate underlying problem or risk factor that explains the association. A knowledge of associated conditions would dictate that they are specifically looked for in the management of the syndrome. CONSIDERATION OF ELBOW DYSPLASIA Elbow dysplasias (ED) can be separated into different pathologies including ununited anconeal process (UAP), fragmented coronoid process (FCP), osteochondritis dissecans (OCD) of the medial humeral condyle and incongruities of the elbow joint (INC) (the author would suggest that we still do not have a definition of elbow incongruity ). Depending on the specific sub-population and the method of investigation, ED is seen in 46-50% of Rottweilers (Swenson, Audell et al. 1997) (Beuing, Mues et al. 2000), 36-70% of Bernese Mountain Dogs (Lang, Busato et al. 1998), 12-18% of Labradors (Morgan, Wind et al. 1999), 20% of the Golden Retrievers, 30% of Newfoundlands, and 18-21% of German Shepherds but also in Great Danes, St Bernards, Irish Wolfhounds, Great Pyrenees, Bloodhounds, Bouviers, Chow Chows and chondrodystrophic breeds. The term elbow dysplasia has been adopted to group the variety of lesions that occur in the elbows of developing dogs. The International Elbow Working Group (IEWG) agrees that elbow arthrosis caused by FCP, UAP, OCD, articular cartilage anomaly, and/or joint BVOA: Proceedings Autumn Scientific Meeting November

11 ELBOW DYSPLASIA 2 CLINICAL ISSUES incongruity is the manifestation of inherited elbow dysplasia ( It is possible that the term elbow dysplasia is with us for reasons of simplicity, clarity, clinical decision-making, politics, public understanding, or scientific misunderstanding! However, one needs to consider the frequency with which these various lesions occur together to evaluate whether we can indeed consider elbow dysplasia a syndrome. In some breeds a combination of UAP plus FCP, FCP plus OCD, or FCP plus INC can be seen. Are these syndromes, or disease associations? A recent study of dogs with UAP indicated that 16% of dogs with UAP have FCP (Meyer-Lindenberg, Fehr et al. 2006). What percentage of dogs with FCP also have UAP? This is not reported presumably because these dogs get labelled as UAP cases, but it is likely to be small; in a study of 150 Labradors, no cases of UAP or INC were identified (Ubbink, Hazewinkel et al. 1998). Study of populations can perhaps give us a clue as to whether these diseases have a common genetic or share a common disease pathway. In one reported study (Ubbink, Hazewinkel et al. 1998), of a Dutch Labrador population, FCP and OCD occurred in two different groups of closely related dogs although in one related subgroup both entities were present. In the same study, but since published (Ubbink, Hazewinkel et al. 1999), on a dendrogram of the Dutch Bernese Mountain Dog population it became clear that INC and FCP originate from two different groups of non-related ancestors but are now seen in 80% of the Bernese Mountain Dogs with ED. These data suggest that there are different diseases (FCP, OCD, INC) which may occur in the same animal but are not necessarily linked by a common genetic or pathogenic pathway. SUMMARY In the author s opinion, there is little evidence to suggest we should think of elbow dysplasia as a syndrome. It is clinically helpful to be aware of disease associations but these appear to be breed dependent. References Beuing R., Mues C. H., Tellhelm B. and Erhardt G. (2000) Prevalence and inheritance of canine elbow dysplasia in German Rottweiler. Journal of Animal Breeding and Genetics-Zeitschrift Fur Tierzuchtung Und Zuchtungsbiologie 117(6): Lang J., Busato A., Baumgartner D., Fluckiger M. and Weber U. T. (1998) Comparison of two classification protocols in the evaluation of elbow dysplasia in the dog" Journal of Small Animal Practice 39(4): Meyer-Lindenberg A., Fehr M. and Nolte I. (2006) Co-existence of ununited anconeal process and fragmented medial coronoid process of the ulna in the dog. Journal Of Small Animal Practice 47(2): Morgan J. P., Wind A. and Davidson A. P. (1999) Bone dysplasias in the Labrador retriever: A radiographic study. Journal of the American Animal Hospital Association 35(4): Swenson L., Audell L. and Hedhammar A. (1997) Prevalence and inheritance of and selection for elbow arthrosis in Bernese Mountain Dogs and Rottweilers in Sweden and benefit:cost analysis of a screening and control program. Journal Of the American Veterinary Medical Association 210(2): 215 Ubbink G., Hazewinkel H., Dijkshoom N., Meij B. and Nap R. (1998) Elbow dysplasia in Dutch Bernese Mountain Dogs and Labrador Retrievers. IEWG, Bologna Ubbink G. J., Hazewinkel H. A. W, van de Broek J. and Rothuizen J. (1999) Familial clustering and risk analysis for fragmented coronoid process and elbow joint incongruity in Bernese Mountain Dogs in the Netherlands. American Journal of Veterinary Research 60(9): BVOA: Proceedings Autumn Scientific Meeting November

12 ELBOW DYSPLASIA 2 CLINICAL ISSUES OPTIMISING IMAGING IN ELBOW DYSPLASIA Ian Holsworth BVSc MACVSc (Surgery) Diplomate American College of Veterinary Surgeons Elbow disorders are a common and increasing cause of lameness in the dog. The incidence of elbow dysplasia and its associated conditions is high among many purebred dogs. Early identification of site and severity is very important in treatment, prognosis and recommendations regarding breeding of affected individuals and lines. Classification of canine elbow disorders according to their anatomic location enables a systematic physical and imaging examination to diagnose the definitive pathology present within the individual patient. Diagnostic imaging should be utilized to visually identify disorders. Radiography is the initial imaging modality of choice and the standard projections include neutral lateral, fully flexed lateral and cranial-caudal views. The x-ray exposure and processing of radiographs obtained must be optimised to allow subtle changes to be identified accurately. When identification of the medial coronoid process of the ulna is difficult a cranial-10 degrees-to-proximal-caudal, craniolateral-caudomedial oblique (Cr15L-CdMO), or distomedial-proximolateral oblique (Di35M-PrLO) may also be obtained. Although these oblique views may improve coronoid visualization the standard projections are often sufficient for diagnosis. The use of advanced imaging modalities may be necessary to accurately identify specific disorders and to allow the most appropriate treatment plan to be formulated. Elbow ultrasonography has been investigated and examination protocols refined and magnetic resonance imaging has been determined to be an accurate and sensitive diagnostic tool. Computer tomography allows accurate examination of the cubital joint for fragmented medial coronoid process, osteochondritis dissecans and radio-ulnar incongruity. All these imaging options improve diagnostic accuracy over radiographs alone. Diagnostic arthroscopy may be utilized to examine intra-articular pathology and allow accurate documentation and grading of the severity of cartilage pathology. Nuclear scintigraphy may be employed to confirm the presence of an active pathological process at the elbow area in stoic or hyperexcitable patients and allow screening of the rest of the patient for other sites of soft tissue or bone remodeling and deposition. References Carpenter LG, Schwarz PD, Lowry JE, Park RD, Steyn PF (1993). Comparison of radiologic imaging techniques for diagnosis of fragmented medial coronoid process of the cubital joint in dogs. J Am Vet Med Assoc 203(1): Wosar MA, Lewis DD, Neuwirth L, et al (1999). Radiographic evaluation of elbow joints before and after surgery in dogs with possible fragmented medial coronoid process. J Am Vet Med Assoc. 214(1):52-8. Haudiquet PR, Marcellin-Little DJ, Stebbins ME (2002). Use of the distomedial-proximolateral oblique radiographic view of the elbow joint for examination of the medial coronoid process in dogs. Am J Vet Res. 63(7): Knox VW 4th, Sehgal CM, Wood AK (2003).Correlation of ultrasonographic observations with anatomic features and radiography of the elbow joint in dogs. Am J Vet Res 64(6): Meyer-Lindenberg A, Langhann A, Fehr M, Nolte I. (2002) Prevalence of fragmented medial coronoid process of the ulna in lame adult dogs. Vet Rec 24;151(8): Snaps FR, Balligand MH, Saunders JH, Park RD, Dondelinger RF (1997). Comparison of radiography, magnetic resonance imaging, and surgical findings in dogs with elbow dysplasia. Am J Vet Res 58(12): BVOA: Proceedings Autumn Scientific Meeting November

13 ELBOW DYSPLASIA 2 CLINICAL ISSUES Snaps FR, Park RD, Saunders JH, Balligand MH, Dondelinger RF (1999). Magnetic resonance arthrography of the cubital joint in dogs affected with fragmented medial coronoid processes. Am J Vet Res 60(2): Janach KJ, Breit SM, Kunzel WW (2006).Assessment of the geometry of the cubital (elbow) joint of dogs by use of magnetic resonance imaging. Am J Vet Res 67(2): Murphy ST, Lewis DD, Shiroma JT, Neuwirth LA, Parker RB, Kubilis PS (1998). Effect of radiographic positioning on interpretation of cubital joint congruity in dogs. Am J Vet Res 59(11): Reichle JK, Park RD, Bahr AM (2000). Computed tomographic findings of dogs with cubital joint lameness. Vet Radiol Ultrasound 41(2): Holsworth IG, Wisner ER, et al (2005). Accuracy of computerized tomographic evaluation of canine radio-ulnar incongruence in vitro. Vet Surg 34(2): Kramer A, Holsworth IG, Wisner ER, Kass PH, Schulz KS (2006). Computed tomographic evaluation of canine radioulnar incongruence in vivo. Vet Surg 35(1):24-9. BVOA: Proceedings Autumn Scientific Meeting November

14 ELBOW DYSPLASIA 2 CLINICAL ISSUES TREATMENT OPTIONS FOR FMCP The role of conservative treatment in the management of FMCP Mark Glyde BVSc MACVSc MVS DipECVS HDipUT&L MRCVS RCVS Recognised Specialist in Small Animal Surgery School of Veterinary and Biomedical Sciences Murdoch University Many options are available for treatment of FMCP / medial compartment disease including conservative management and various surgical options. Clinical data providing clear evidence for efficacy of any of the treatment options or the superiority of one treatment method over another are lacking. Large variations in study protocols make comparison of clinical trials for medial compartment disease very difficult. Read et al (1990) in a prospective double-blinded study with a mean follow-up period of 66 weeks in 22 dogs with medial compartment disease comparing conservative and surgical management (via arthrotomy) found no difference in outcome in young dogs with mild lameness whereas dogs with more significant lameness had a better outcome with surgical management. Huibregtse et al (1994) compared surgical management of the coronoid process disease (via arthrotomy) with conservative management (comprising rest and aspirin) in 22 dogs assessing outcome up to ten weeks with owner survey and / or clinical, radiographic and force plate data. There was no significant difference between the two groups; the majority of dogs improved though all dogs had progressive signs of osteoarthritis as assessed radiographically. Bouck et al (1995) in a randomised prospective clinical trial compared surgical management (via arthrotomy) with conservative management (comprising only pentosan polysulphate Cartrophen Vet) in 19 dogs with clinical, radiographic and force plate follow-up to 9 months found no significant difference between the two groups. The majority of dogs had improved lameness scores with progression of osteoarthritis as measured by range of motion assessment and radiography. Further well controlled clinical studies are needed to attempt to clarify the benefit and indications of conservative and surgical management in medial compartment disease. Given the ranges in disease severity, severity of clinical disease manifestation, conservative management options, owner compliance and surgical options available coupled with the difficulties in objective outcome assessment, evidence-based treatment protocols present a great challenge. Regardless of the relative benefits of conservative vs surgical management conservative management is an essential component of balanced management of medial compartment disease and primarily involves management of osteoarthritis symptoms with weight control, exercise control, physical therapy and medical management. Prior to commencing conservative management of medial compartment disease it is important to obtain and document accurate information on disease severity / extent initially and accurate information on disease progress and response to treatment. Reported options for this include: BVOA: Proceedings Autumn Scientific Meeting November

15 ELBOW DYSPLASIA 2 CLINICAL ISSUES ÿ ÿ ÿ ÿ ÿ ÿ owner information on patient performance (objective measures of achievement where possible) physical examination documenting findings including ROM measurements radiographs advanced imaging CT or MRI arthroscopy digital archive system +/- pictorial or descriptive standardized grading system repeat arthroscopy. Given the low morbidity and high accuracy of elbow arthroscopy repeat arthroscopic examination as a component option for ongoing management and assessment of treatment of medial compartment disease is important. This needs to be communicated clearly to the owner prior to commencement of the initial treatment. Owners need to be given realistic outcome expectations to enable them to make an informed decision to buy in to ongoing management from a philosophical and financial point of view and be apprised of the managing veterinarian s approach to management of elbow disease. It is important to recognise that the correlation between the severity of joint disease as assessed radiographically, arthroscopically and clinically is poor. Gordon et al (2003) reported that there is no relationship between limb function and radiographic osteoarthrosis score in dogs with stifle osteoarthrosis. Accurate documentation of arthroscopic findings and thorough clinical follow up may offer improved correlation and allow more accurate prognostication though this remains to be proven. It is also important to recognise that many of our elbow disease patients may have significant levels of sub clinical arthritic disease that is not apparent to their owners or that is not apparent on lameness examination. In a study comparing visual observation of gait and force plate gait analysis in cruciate disease Evans et al (2005) found that visual observation of gait was unreliable in discriminating normal dogs from lame dogs. In this study 75% of dogs that had no observable gait abnormalities had a <42% probability of being sound on force platform gait analysis. Visual observation of lameness correlated well with lameness on force platform gait analysis. It is not unreasonable to assume that the findings for elbow disease would be similar. For this reason ongoing conservative management of FMCP-related elbow arthrosis, particularly the need for analgesic medication, should not be predicated solely on visual assessment of lameness. Determination of the need for ongoing conservative management should be made with consideration of owner assessment of patient performance, thorough repeat orthopaedic examination (particularly assessing muscle mass and presence of arthrosis joint range of motion, presence of periarticular fibrosis and effusion, pain) and the original arthroscopic classification of disease severity and extent (using an accepted grading system such as the Modified Outerbridge Grading System for Articular Cartilage. Table 1) +/- appropriate follow up arthroscopic assessment of disease progression. BVOA: Proceedings Autumn Scientific Meeting November

16 ELBOW DYSPLASIA 2 CLINICAL ISSUES Table 1: Modified outerbridge grading system for articular cartilage Grade Description 0 Normal cartilage I II III IV V Chondromalacia (softening and swelling) Fibrillation (velveting or cobblestone) Fissures to subchondral bone Erosions that do not reach subchondral bone Exposure of subchondral bone Eburnated bone ANALGESIA: PERIOPERATIVE AND LONGTERM NSAIDs remain the cornerstone of management of osteoarthritis (OA) providing analgesic and anti-inflammatory benefit. The last 15 years have seen tremendous advances in NSAID safety and availability. Meloxicam, Firocoxib, Carprofen, Deracoxib, Etodolac and Tepoxalin can all provide effective long-term therapy with a low incidence of side effects. It is important to advise owners of the risk and signs of NSAID side effects prior to commencement of treatment. Owners should also be advised to temporarily discontinue treatment and seek veterinary advice should signs of inappetance, lethargy, vomiting or diarrhea develop. Given the likely need for ongoing NSAID therapy it is very important that owners are fully informed regarding the low risk / high benefit of NSAIDs to their pet. Discussion of the possible occult nature of canine OA, the risk/benefit of NSAID therapy to their pet and the likely disease progression / prognosis should all be discussed. Tailoring of NSAID dosage to suit the owner /animal activity pattern (suits partners working and animals exercised primarily on weekends) is increasingly popular. This is a pragmatic cost effective solution but works counter to our understanding of the importance of regular exercise in the overall management of joint disease. Tailoring of dosage based on response is ideal but the difficulty of subjective assessment of response remains. Perioperative analgesia is an important component of initial adjunctive conservative management of surgically managed elbow disease. Perioperative NSAIDs, local anaesthetics and opiates in addition to perioperative physical therapy are recommended. Electrostimulated acupuncture (ESA) has been proposed to be of benefit in the management of OA associated with medial compartment disease in dogs. Kapatkin et al (2006) in a randomised controlled crossover clinical trial using force plate and subjective outcome assessment in nine dogs with elbow OA secondary to medial compartment disease found no significant effect of ESA. BVOA: Proceedings Autumn Scientific Meeting November

17 ELBOW DYSPLASIA 2 CLINICAL ISSUES SADMOAS (slow acting disease modifying osteoarthritis agents)/nutraceuticals These were originally termed chondroprotective drugs for their effect in preserving or restoring cartilage matrix. Abnormal cartilage loading (through a variety of mechanisms) is a key component in the development of OA. There is a net loss of cartilage proteoglycan in OA suggesting that the rate of matrix degradation exceeds the capacity of the metabolically hyperactive chondrocytes for matrix component production. The rationale for the use of these drugs is to perfuse cartilage with molecules that slow matrix degradation and support the biosynthetic functions of chondrocytes. Chondroprotective drugs would also ideally promote synthesis of hyaluronic acid, decrease synovial inflammation and relieve pain. Pentosan polysulphate (Cartrophen Vet, Pentosan Vet) is a heavily-sulphated polysaccharide composed of semi-synthetic polysuplhated xylan. PPS has been shown to modify the behaviour of chondrocytes in vitro by stimulating the synthesis of cartilage matrix and suppressing cartilage degradation. PPS also has been shown to stimulate hyaluronic acid synthesis in synovial fibroblasts in vitro. Other claimed beneficial effects of PPS include an anti-inflammatory activity (at much increased dose rates than approved for treating OA), fibrinolytic activity (through the release of plasminogen activator from the endothelium) and antilipidaemic effects. The last two benefits may improve subchondral blood flow, thereby reducing pain. PPS should theoretically not be administered concurrently with NSAID therapy. There is a huge range of human and veterinary SADMOAs / nutraceuticals available. Many of these products have the attraction of being readily available over the counter and of being a natural therapy. Many are composite products and there appears to be a wide variation in content with few legislative controls on content and quality. These nutritional supplements are not subject to the same degree of testing required for pharmaceutical products. The main components are glucosamine HCl / glucosamine SO4 and chondroitin sulphate. Nutraceuticals are widely used as adjunctive or primary therapy in OA. There are few reported adverse reactions. Beneficial effect is reported to require at least two months of therapy. Much anecdotal support exists for the use of nutraceuticals. Evidence exists for significant gastrointestinal absorption (Setnikar et al 1986, Conte et al 1995, Adebowale et al 2005) though Laverty et al 2005 questioned whether therapeutic concentrations were reached in synovial fluid after oral dosing in horses. In vitro benefit of nutraceuticals has been demonstrated with increased PG production by chondrocytes (Bassleer et al 1998) and partial block of IL-1 effects on PG synthesis (Dodge and Jiminez 2003). In vivo evidence of benefit is not clear. Moreau et al 2003 in a prospective, double-blinded force platform study of 71 dogs with OA with 60 day follow up found significant improvement in ground reaction forces with meloxicam and carprofen but not in the nutraceutical group. Bouck et al (1995) in a randomized prospective clinical trial compared surgical management (arthrotomy) with treatment with PPS in 19 dogs with clinical, radiographic and force plate follow-up to 9 months found no significant difference between the two groups. BVOA: Proceedings Autumn Scientific Meeting November

18 ELBOW DYSPLASIA 2 CLINICAL ISSUES Results of trials in humans are equivocal. In a double-blinded placebo controlled trial of 1258 patients with knee OA with follow-up to 24 weeks 64-67% of patients in the three nutraceutical groups achieved the defined treatment outcome compared to 70% of patients on Celecoxib. Achievement of the desired treatment outcome was 60% in the placebo group (Arth Rheum 52:9(suppl), p622, 2005). PHYSICAL THERAPY The aim of physical therapy is to improve blood flow to the disease area, relax muscles, improve mobility and relieve pain. An additional benefit with pet owners may be involving them in the lifelong management of a chronic condition and increasing their awareness of the need for long term and multi-modal care. Evidence from human studies supports that physical therapy is beneficial in OA management though depends on the type of therapy and particularly on the personality of the patient. The recognition of the importance of early mobilization and rapid return to weight bearing has revolutionized human joint surgery management. Passive mobilisation in the perioperative period has replaced immobilisation following joint surgery. Postoperative icing of joints significantly reduces post-surgical synovitis and maintaining joint ROM can avoid pain, delayed return to function and disuse atrophy. Well controlled studies assessing the benefit of physical therapy in dogs with elbow disease are currently lacking. Marsolais et al (2002) in a force plate study of 51 dogs with cruciate disease managed surgically with a lateral extracapsular method and meniscectomy found limb function to be significantly better in the physical therapy group compared to the no-physical therapy group at 6 months post surgery. LIFESTYLE CHANGE Controlled exercise programs are recommended for OA management as they are thought to contribute to mobility and build muscle strength. Swimming, underwater treadmills and other moderate energy low impact exercises such as walking over level grassed surfaces such as playing fields are ideal. Owners should be encouraged to undertake with their pets an appropriately tailored and progressively increasing exercise program under veterinary or physical therapy direction. This should ideally be combined with an ongoing weight control program. Where possible dogs with elbow OA should avoid steps, hard uneven ground and repetitive play with other dogs. Weight control provides significant benefit in the management of canine OA. Strong evidence exists for the benefit of decreased calorie intake in the management of OA (Kealy et al JAVMA 1992, 1997, 2002). Obesity may be pro-inflammatory with regard to OA. Strong evidence also exists for the benefit of omega-3 fatty acids as a component of a balanced diet (Curtis et al Proc Nutr Soc 2002). CONCLUSION Conservative management of secondary OA is an integral part of successful management of FMCP. Owners should be informed of the role of adjunctive conservative management in elbow disease / OA management and the likely need for both long term management and the importance of their involvement in the process. BVOA: Proceedings Autumn Scientific Meeting November

19 ELBOW DYSPLASIA 2 CLINICAL ISSUES Well controlled prospective clinical trials to defiwne evidence -based benefits of conservative &/or surgical management of medial compartment disease and to define the relative benefits of the specific components of conservative management remain a challenge for the veterinary profession. Bibliography Bouck GR, et al (1995). A comparison of surgical and medical treatment of fragmented coronoid process and osteochondritis dissecans of the canine elbow. VCOT 8, 177 Evans R, et al (2005): Accuracy and optimization of force platform gait analysis in Labradors with cranial cruciate disease evaluated at a walking gait. Vet Surg 34: Gordon WJ, Conzemius MG, Riedesel E, et al (2003): The relationship between limb function and radiographic osteoarthrosis in dogs with stifle osteoarthrosis. Vet Surg 32: Huibregtse BA, et al (1994). The effect of treatment of fragmented coronoid process on the development of osteoarthritis of the elbow. JAAHA 30 (2), Kapatkin AS, et al (2006). Effects of electrostimulated acupuncture on ground reaction forces and pain scores in dogs with chronic elbow joint arthritis. J Am Vet Med Assoc 228: Marsolais GS, Dvorak G &Conzemius MG (2002). Effects of postoperative rehabilitation on limb function after cranial cruciate ligament repair in dogs. J Am Vet Med Assoc 220: Moreau M, et al (2003). Clinical evaluation of a nutraceutical, carprofen and meloxicam for the treatment of dogs with osteoarthritis. The Veterinary Record 152: Read RA, et al (1990). Fragmentation of the medial coronoid process of the ulna in dogs: a study of 109 cases. JSAP 31, 330 BVOA: Proceedings Autumn Scientific Meeting November

20 ELBOW DYSPLASIA 2 CLINICAL ISSUES TREATMENT OPTIONS FOR FMCP The role of proximal ulna osteotomy in the management of canine elbow dysplasia Malcolm Ness BVetMed DipECVS CertSAO FRCVS Croft Veterinary Hospital, Blyth, Northumberland Canine elbow dysplasia was first described as a significant cause of elbow arthritis and lameness approximately 30 years ago. Subsequently a wide range of treatments have been described in the literature and an even wider range discussed by veterinary orthopaedic pundits: there are substantially more opinions than there is evidence. Documented treatment options include conservative/medical management; various assaults on the medial coronoid process/ridge either via arthrotomy or arthroscopically. Arthroscopic coronoidectomy can be partial, sub-total, total or extravagant. Despite being very widely practised and much talked about, there is remarkably little written in the peer reviewed veterinary literature to support elbow arthroscopy for ED. Finally, osteotomies of the distal humerus, the proximal ulnar or the distal ulnar have been proposed and some results reported. In defining the role of proximal ulnar osteotomy, a good starting point is to consider how we might justify any kind of surgery in the treatment of elbow dysplasia. It is widely agreed that elbow dysplasia associated with fragmentation of the medial coronoid process causes osteoarthritis. Guthrie (1989) demonstrated consistent osteoarthritis and attempted to quantify its progression. Because conservative-medical management will not modify the progression of osteoarthritis, ED starts to lok like a surgical disease. However, over the years a number of investigators have failed to demonstrate any benefit associated with elbow surgery. For example, Grondalen (1979) Surgical removal of the coronoid process often relieves pain but does little to alter the progression of arthritis or lameness in the long-term"; Bennet and colleagues (1981) "It is not certain that surgical treatment.. is justified"; Huibregtse and colleagues (1984) "There was no difference in limb function (based on force plate analysis) between treatment groups (conservative and surgical)"; Read and colleagues "There was no difference in the incidence of lameness following treatment". A recent literature search revealed no subsequent controlled long-term follow-up studies, no controlled studies on arthroscopic surgery, nor any controlled studies on the osteotomy techniques. It is obvious, therefore, that the evidence upon which to make a proper decision about whether any kind of surgery is justified is lacking. Embarking upon a discussion about which surgery is best seems premature. Because the various assaults on the coronoid process have not (??yet) been shown to be beneficial, a number of surgeons have considered treatment by osteotomy the rational being to restore normal loading of the elbow joint, specifically the relationship between humeroulnar and humero-radial loading. The author treated a small number (13) of young, active prospective working Labradors with elbow dysplasia treated by proximal ulnar osteotomy, using a technique described concurrently in France by Bardet(1995), and in Australia by Thomson and Robbins(1995). Outcome assessment was by subjective evaluation of lameness; ability to resume normal activity/work and independent radiographic assessment using a technique developed by Dr Sue Guthrie (1989). Clinically, all dogs did well and BVOA: Proceedings Autumn Scientific Meeting November

21 ELBOW DYSPLASIA 2 CLINICAL ISSUES radiographically there was some evidence that proximal ulnar osteotomy slowed (but did not stop) progression of osteoarthritis estimated by development of osteophytes. The advantages of proximal ulnar osteotomy for treatment of elbow dysplasia are that it appears to perform at least as well as any other reported treatment and, in addition, there is some evidence for disease modification. Bardet (1996) and Snelling and Lavelle (2004) have reported beneficial effects associated with this surgery and Preston, Schultz and colleagues (2001) demonstrated in vitro that proximal ulnar ostectomy can restore normal elbow joint contact patterns. This work represents important proof of concept. However, the evidence is not robust and, in common with all other currently proposed surgical treatments, the technique remains unproven. Proximal ulnar osteotomy is big surgery with a lengthy convalescence and a risk of significant complication. In conclusion, if the surgical management of elbow dysplasia can be justified at all then proximal ulnar osteotomy is worthy of consideration especially for young dogs with significant pain/lameness and whose owners aspire to having a very active or working animal. References Bardet (1995) Pratique medicin et chirugerie, 30 Bardet (1996) Pratique medicin et chirugerie chez le chien 31, Bennett and colleagues (1981) Vet Record, 109, Grondalen (1979) Arthrosis in the elbow joint of young rapidly growing dogs. I V; Nordisk, Veterinary Medicine, 31 and 33 Guthrie (1989) PhD Thesis, University of London Huibregtse and colleagues (1984) JAVMA Ness (1998) JSAP 39(1), 8-15 Preston CA, Schultz KS, Taylor KT, Kass PH, Hagan CE, Stover SM. (2001) Am J Vet Res; 62(10) p1548 Read and colleagues (1990) JSAP, 31, Snelling and Lavelle (2004) Aust Vet J 82:5, Thomson and Robbins (1995) Aust Vet J 72: BVOA: Proceedings Autumn Scientific Meeting November

22 ELBOW DYSPLASIA 2 CLINICAL ISSUES TREATMENT OPTIONS FOR FMCP Subtotal coronoid ostectomy (SCO) for the treatment of medial coronoid disease: a prospective study of 228 dogs (389 elbows) evaluating short and medium term outcome N. Fitzpatrick Fitzpatrick Orthopaedic/Neurology Referrals, Tilford, Surrey, GU10 2DZ, UK INTRODUCTION Disease of the medial coronoid process including fragmented medial coronoid process (FMCP) as a component of elbow dysplasia is a frequent cause of lameness in medium to large breed dogs and is the most common cause of elbow osteoarthritis in large breeds. Elbow incongruency is a primary contributor to pathogenesis of FMCP (Kirberger 1998; Ness 1998; Collins 2001; Puccio 2003). A number of surgical techniques have been reported for treatment, which broadly adopt two approaches focal treatment of the medial coronoid process and treatment of perceived incongruity by osteotomy. Conventional treatment of coronoid disease has included fragment removal and curettage (Grondalen 1979; Bennett 1981; Boudrieau 1983; Henry 1984; Read 1990; Tobias 1994; Huibregste 1994) and fragment removal plus abrasion arthroplasty or micro-fracture of the visible extent of cartilage disease (Schulz 2000; Bardet 2002). Osteotomies have also been proposed either with or without fragment removal. Proximal ulnar osteotomy (Thompson 1995; Ness 1998) has been shown to restore normal coronoid contact area in 60% of cases (Preston 2001). More recently, humeral wedge and sliding humeral osteotomies (Mason 2003; Schulz 2005) have been proposed to shift weight-bearing from the medial to the lateral aspect of the elbow joint. Though the long-term effects of osteotomies have yet to be clinically documented in statistically relevant numbers, they may have a role to play in the amelioration of joint pathology. However, it is well accepted that conventional fragment removal, abrasion arthroplasty or micro-picking of the diseased coronoid may provide short-term mitigation of clinical signs but progression of osteoarthritis (OA) invariably occurs and persistence of lameness is common. In spite of this, early surgical management of coronoid disease has become the standard of care and prolonged medical management has become less palatable to both owners and clinicians. Though early reports proposed little difference between surgical and medical management of coronoid disease, the conclusions are difficult to substantiate in a new era of evidence based medicine, refined patient selection criteria and objective measures of outcome. The free fragments associated with lesions of FMCP contribute to frictional abrasion of the opposing medial aspect of the humeral condyle but are probably less important in the progression of OA and joint morbidity than pathology of the subchondral bone and cartilage erosions of the coronoid process. A more aggressive arthroplasty has recently been advocated to lower the joint surface of the medial portion of the coronoid by motorised shaving during arthroscopic procedures in an effort to ameliorate the effects of medial compartment pain associated with friction of joint surfaces (Puccio 2003; Van Ryssen 2003). Conventional focal treatment of coronoid pathology depends on healing in the persistent friction environment of the medial compartment of the elbow. BVOA: Proceedings Autumn Scientific Meeting November

23 ELBOW DYSPLASIA 2 CLINICAL ISSUES The objectives of this study were to standardise the approach to focal treatment of the coronoid as an isolated pathology regardless of the degree of visible cartilage disease (provided that coronoid disease had been confirmed), to provide intact samples for further analysis and to adopt a standardised protocol of outcome assessment in an attempt to objectify measures of efficacy. The procedure was termed subtotal coronoid ostectomy (SCO). The rationale for treatment with SCO is the removal of a standardised portion of the medial aspect of the coronoid process to include all fragments, diseased cartilage and subchondral bone. The hypothesis was that this would ameliorate frictional abrasion of the opposing surface of the medial aspect of the humeral condyle, obviate the requirement for cartilage healing in a pressure contact environment and thereby minimize progressive joint pathology and optimise speed of lameness resolution. The objectives of histopathological analysis of the excised fragments were to validate the rationale for SCO and to help elucidate the aetiopathogeneis of the condition (i.e. whether FMCP was a primary manifestation of osteochondrosis or a secondary manifestation of aberrant pressure distribution in the elbow). The results of these analyses will be alluded to in this abstract and have recently been published (Danielson 2006). MATERIALS AND METHODS In this prospective study 228 dogs between January 2000 and July 2005 were treated with SCO by the author. Inclusion criteria for this study were dogs with thoracic limb lameness due to elbow pathology that could be exclusively attributed to medial coronoid disease with a minimum of one year follow-up after SCO was performed. Clinical, neurological and orthopaedic examination aided exclusion of concurrent conditions. Lameness evaluation was assessed at both walk and trot. Pain response to flexion, extension and simultaneous flexion and supination was noted. Radiographic assessment included medio-lateral projections of the shoulders and flexed and extended medio-lateral and cranio-caudal projections of both elbows. Cases were excluded from the study if another abnormality of the thoracic limbs was identified, if elbow disease attributable to any cause other than coronoid disease was identified or if there was a history of previous thoracic limb surgery. Elbow arthrosis was graded according to the International Elbow Working Group (IEWG) criteria, absolute anconeal new bone formation and an objective measure of extent of subtrochlear sclerosis. A small number of cases had CT examination of the elbows performed and spaniels were over-represented in this group due to routine assessment for incomplete ossification of the humeral condyle prevalent in this breed. Maximal flexion and extension angles were measured using a goniometer under sedation. Arthroscopic evaluation via a standard medial portal was performed in all cases and the joint surveyed for any abnormality including synovitis, osteochondrosis, ununited anconeal process, incomplete ossification of the humeral condyle, fragmentation or cartilage disease of the medial or lateral aspects of the coronoid process, abrasions of the humeral condyle ( kissing lesions ) and joint incongruency. The modified Outerbridge grading system was used to attribute a score to cartilage lesions of the coronoid or humeral condyle and the extent of cartilage pathology in terms of area affected was also noted. An arthroscopic probe was used to distinguish between cases of fissuring and undisplaced fragmentation. SCO was performed in patients with fragmentation or fissuring of the medial coronoid process evidenced by arthroscopy or CT scan and in dogs with thoracic limb lameness greater than 4 weeks duration exhibiting clinical signs of pain upon elbow manipulation which had radiographic evidence of arthrosis and/or subtrochlear sclerosis or arthroscopic evidence of edge margin fibrillation of the medial coronoid, or active synovitis for which all causes other than FMCP had reasonably been excluded. BVOA: Proceedings Autumn Scientific Meeting November

24 ELBOW DYSPLASIA 2 CLINICAL ISSUES SCO was performed via a 2-3 cm incision over the craniomedial aspect of the humeral condyle, separating between the flexor carpi radialis/pronator teres and the superficial/deep digital flexor muscles caudal to the medial collateral ligament. An osteotomy was created which traversed the medial portion of the coronoid process from its medial border to the most caudal extent of the radial incisure cranial to the sagittal ridge of the ulnar trochlear notch. The cut was angled disto-cranially, creating a triangular segment which was separated from annular ligament attachments and removed en bloc in addition to any loose fragments. An osteotome and mallet was used to create the cut for the first 38 cases and thereafter an air powered oscillating saw with a 5.8mm blade (2m141, MDM Medical UK) was used. Bilateral SCO s were performed concurrently if indicated. Joint lavage was performed and bupivicaine was instilled during routine closure. All patients received four sequential weekly injections of pentosan polysulphate 3mg/kg (Cartrophen Vet ) starting 2 weeks post-operatively. Cage confinement and lead exercise were employed for six and twelve weeks respectively and NSAID medication was provided in the immediate post-operative period. Clinical reexamination was performed at two and five weeks post-operatively for all cases and if lameness had failed to resolve by five weeks, further re-checks were scheduled as necessary and NSAID medication was appropriately prescribed. All owners were asked to report if lameness re-occurred at any time after resumption of normal activity at 12 weeks postoperatively. Telephonic interview and clinical re-assessment were scheduled accordingly. Variables which could not be strictly controlled during follow-up included whether owners adopted hydrotherapy as part of the recovery and whether the owners provided nutraceutical therapy on an ongoing basis. Hydrotherapy was prohibited for all cases within 8 weeks postoperatively and a nutraceutical containing pharmaceutical grade chondroitin sulphate and glucosamine was recommended on an on-going basis for all cases. All cases were invited back for follow-up clinical and radiographic examinations at 1, 3 and 5 years post-operatively. All owners were mailed questionnaires at appropriate time-points postoperatively involving visual analogue scale (VAS) assessments of commonly performed daily activities and these were analysed using a transparent template to attribute numerical scores to each observation as determined by the position of a mark placed by the owner along a calibrated 100mm line. A value of 0 was awarded for poor and 100 for excellent outcomes. At each follow-up clinical examination a standardised questionnaire was also completed by one of three clinicians. In addition to gradation of lameness and assessment of pain on elbow manipulation, goniometric measurement of maximal extension and flexion angles of the both elbows were measured following sedation and a standardised video-gait assessment was performed and evaluated by six experienced independent clinicians. Radiographic examination included mediolateral flexed and craniocaudal views of both elbows for all patients at follow-up time-points. Radiographic examinations were attributed a score according to IEWG criteria. Clinical, radiographic and arthroscopic parameters preoperatively were compared with clinical and radiographic parameters at various time-points after surgical intervention. RESULTS 389 dogs were investigated between January 2000 and July 2005 for thoracic limb lameness attributed to elbow dysplasia. Of these, 161 cases were excluded as they did not meet the study criteria due to concurrent conditions of the thoracic limb including osteochondrosis lesions of the humeral head and medial aspect of the humeral condyle, ununited anconeal process, ununited medial epicondyle, flexor enthesiopathy, incomplete ossification of the humeral condyle, panosteitis, sesamoid disease, previous fractures, bicipital tenosynovitis, mineralization of the supraspinatus tendon, periarticular ligamentous pathology of the BVOA: Proceedings Autumn Scientific Meeting November

25 ELBOW DYSPLASIA 2 CLINICAL ISSUES shoulder, carpal or digital problems. Of 228 cases assessed, 389 elbows were operated. Breeds represented included Labrador retriever (101), Rottweiler (31), Golden retriever (9), Border collie (8), German shepherd dog (6), Boxer (5), Staffordshire bull terrier (4), Spaniels (10) and 21 other breed groups. Male:female ratio was 7:4. Bilateral SCO was performed in 161 cases (71%) and unilateral in 67 cases (29%). Average age at time of surgery was 26 months (range months), 49% being less than 12months, and 31% between months. 65% of cases presented for investigation of unilateral thoracic limb lameness but clinical examination revealed bilateral lameness in 66% of cases. Duration of lameness before surgery was on average 20 weeks (range weeks) with 4 cases lame from 12 weeks of age. Lameness had been present in 24% cases for less than 4 weeks, 26% between 5 and 10 weeks, 25% between weeks, and 25% greater than 19 weeks. Resolution of lameness was documented for 73% of cases by 5 weeks postoperatively, 91% by 12 weeks and 97% by 24 weeks. Concurrent disease included 1 case bilateral hock osteochondrosis, 3 unilateral cranial cruciate ligament insufficiency, 1 case medial patellar luxation and 16 cases clinically affected by hip dysplasia. All cases had been treated with NSAID medication for variable periods prior to referral. Ancillary treatment before referral included exercise restriction, physical therapy, aquatic therapy, acupuncture, injections of pentosan polysulphate, and administration of nutraceuticals. Owner-assessed VAS score of function was found to have improved significantly from preoperatively to follow-up (paired t-test) for each question asked. 90% of dogs were less than 1/5 lame at follow-up to five years postoperatively as determined by six ACVS boarded surgeons from video gait analysis. Pain on manipulation, typically in flexion, pronation in flexion and supination in flexion, was elicited for some dogs but almost without exception was considered to be mild at follow-up examination (VAS score <30mm). Less than 20% of dogs received regular NSAIDs at the time of follow-up to five years. The time between occurrence of lameness and presentation for surgery was markedly variable in this study and likely reflected the insidious intermittent nature of the lameness, primary care treatment regimes, owner willingness for referral and variations in owner perception of the start of lameness. Many had been referred for investigation of putative shoulder lameness. There was no case in this series that had pathology confirmed arthroscopically that did not have pain evident by vocalisation or significant resentment when deep digital pressure was applied to the medial aspect of the affected elbow or when the elbow was manipulated in flexion-supination. 58% of elbows were found to have pre-operative IEWG scores of 0 or 1, while a small number of cases, with Border Collies and Boxers over-represented, had no discernable radiographic evidence of disease. Free fragments were rarely radiographically detectable when present, and cartilage erosion of the opposing humeral condyle was variably evident radiographically (as distortion of subchondral bone contour). Subtrochlear sclerosis was found to be a reliable predictor of coronoid disease and an objective measure and guidelines for interpretation have been proposed. Radiographic progression of OA was noted as 1 IEWG grade or more in 56% of cases to 3 years and 72% of cases to 5 years, but there was no correlation between radiographic progression of arthrosis and clinical signs. 28% of cases showed no radiographically discernable progression of periarticular osteophytosis to five years. There was a definitive trend for cases with low Outerbridge score at the time of surgery to have less progression of radiographic OA. Rather than comparing the IEWG scores at various time points, it may be BVOA: Proceedings Autumn Scientific Meeting November

26 ELBOW DYSPLASIA 2 CLINICAL ISSUES more meaningful to compare actual measurement of periarticular osteophytosis at various time points in a standard location. New bone formation over the cranio-proximal aspect of the anconeal process was employed in this regard. Data analysis revealed that IEWG score provided a less sensitive measure than absolute measurement of new bone over the cranioproximal aspect of the anconeal process. For most dogs this measure was found to be progressive, and was not predicted by age at surgical intervention, age at follow-up or by preoperative anconeal new bone formation. Crucially, the value of such data is questionable as periarticular osteophytosis was found to be poor indicator of clinical status in our study, supporting the contention of many authors that there is a poor correlation between radiographic and clinically relevant progression of disease. Arthroscopic findings at the time of SCO included synovitis, synovial proliferation, cartilage lesions of the medial coronoid and medial aspect of the humeral condyle, fissuring and fragmentation of the medial aspect of the coronoid process. The average Outerbridge score for medial coronoid lesions for all elbows assessed was % of elbows had no overt fragmentation. More than 50% of elbows with gross fragmentation of the medial aspect of the coronoid process had cartilage pathology of the medial aspect of the distal humerus ( kissing lesion ) as might be anticipated. However, 38% of elbows with no gross fragmentation also exhibited medial humeral cartilage damage of Outerbridge grade 1 or more, consistent with an aetiopathogenesis of incongruency rather than solely abrasion from a free fragment. Complications were noted in 36 elbows (10%) and included infection in 30 elbows, seroma in 3 elbows, swelling in 2 elbows and wound breakdown in 1 elbow. 9 elbows were judged refractory to treatment. The average age of cases with complications was 37 months (range 4-96 months) and average length of lameness 8 weeks (range 3-12 weeks). The average Outerbridge grade for cartilage lesions of the medial coronoid for cases with complications was 3.6 (range 1-5) and for the medial aspect of the humerus 3.3 (range 0-5). Two cases were revised with further intervention by ulnar osteotomy and two cases by sliding humeral osteotomy. Three non-responsive cases were euthanized at the owners request. The two further refractory cases had ongoing low-grade lameness and were medically managed. DISCUSSION There are four key differences between the patients operated in this study and those reported by previous authors. This study was prospective; a standardised portion of the medial coronoid process was removed regardless of the degree of pathology, all causes of lameness other than coronoid disease were excluded and the age of intervention was younger than in previous reports. This makes the findings of this study difficult to directly compare with previously published data, especially where studies failed to distinguish different forms of elbow dysplasia in the subject population. Many of the osteochondral samples excised in this study were the subject of additional analysis. Initially histology was performed which intimated that there was a chronological sequence of events, beginning with subchondral micro-fissure and progressing to cartilage disease and overt fragmentation (Fitzpatrick 2004). Fissuring occurs both within obviously diseased cartilage (eburnation/malacia) and also outside visibly diseased areas. Fissures were found to extend to a variable distance from the articular surface into the subchondral bone, some of which had attempted fibrocartilagenous repair, concomitant with non-ossified chondrocytes in bone spicules below the subchondral junction. The samples analyzed suggested that there may be an association between time of onset of lameness and recent BVOA: Proceedings Autumn Scientific Meeting November

27 ELBOW DYSPLASIA 2 CLINICAL ISSUES necrosis or fissuring of subchondral bone; too rapidly for increased osteoblastic activity or fibrocartilagenous replacement A subsequent study employed epifluoroscent microscopy to assess and quantify the nature and degree of subchondral pathology of excised segments (Danielson 2006). This study illustrated that samples of the medial coronoid process in clinically lame dogs with pain associated with the medial compartment of the elbow may not be affected by overt fragmentation or fissuring and still be affected by significant subchondral pathology typified by micro-cracks in the trabecular bone. Furthermore, there was no sample submitted from the cases in this study that was not affected by subchondral pathology, even where there were only subtle radiographic or arthroscopic findings. This may lend valid rationale for performing SCO in cases where radiographic progression of OA is evident in the absence of arthroscopically detectable fissures or significant cartilage pathology or where synovitis is arthroscopically evident and lameness attributable to medial elbow pain is refractory to medical management. The micro-crack study also revealed that SCO does not completely excise the region of cartilage and subchondral bone pathology for all cases, as pathology was found to extend to the osteotomy line in severely affected patients. The author recommends the use of an oscillating saw for SCO rather than an osteotome and mallet as an accurate cut can be reproducibly created in all cases and iatrogenic trauma can be avoided. SCO reduces frictional abrasion in the medial compartment of the diseased elbow and removes diseased cartilage and bone which is irreversibly damaged. Pathology extends beyond the area of visible fragmentation and non-displaced fissures can be missed even on arthroscopic and standard CT evaluations. Subchondral fissuring and micro-fractures may give rise to pain associated with mechanical weakness or access for synovial fluid, which combined with friction on exposed subchondral bone, may result in persistent lameness in spite of attempts at cartilage regeneration following conventional debridement. There was some concern that excision of the major portion of the medial coronoid process may result in collapse of the medial compartment over time, but this has not been observed in any case assessed to 5 years at the time of writing. This will be the subject of further study, but at this time it seems reasonable to postulate that weight re-distribution across the radial head is sufficient to attain clinical improvement. It has not yet been established what degree of cartilage pathology of the medial compartment is likely to respond poorly to SCO and may require a more radical procedure such as sliding humeral osteotomy. This is the subject of another abstract at this meeting. Owner compliance was important for the avoidance of post-operative complications with particular attention to prevention of self-mutilation and exercise restriction in the immediate post-operative period. Self-mutilation was involved with the majority of cases where infection or wound breakdown were noted and delayed resolution of lameness was common in patients where exercise restriction was not adhered to. Since all cases were lead-exercised until 12 weeks post-operatively, it could be argued that functional assessment is not complete until free-range exercise is re-introduced and all medication is withdrawn. Since all owners were asked to re-present if lameness had not resolved by 12 weeks post-operatively and since there is a close association between referring clinicians and the centre where surgeries were performed (both geographically and in terms of communication), it was felt that the margin for misinterpretation was minimised. For the majority of cases, both short and medium term data was further verified by telephonic communication or subsequent questionnaire. Clinical assessments pre-operatively and at the time of follow-up examinations by three individuals reduced variability of interpretation of clinical signs and application of the visual analogue BVOA: Proceedings Autumn Scientific Meeting November

28 ELBOW DYSPLASIA 2 CLINICAL ISSUES scale optimised validity of functional assessment by owners. The post-operative variables of whether owners employed hydrotherapy after eight weeks or persisted in provision of a standardised nutraceutical are potential weaknesses in this study. However, owner questionnaires to date would suggest that less than 10% of cases adopted hydrotherapy as part of the rehabilitation regime on a sustained basis and that more than 80% of patients received ongoing supplementation with pharmaceutical grade chondroitin sulphate and glucosamine. It is therefore unlikely that these variables will have a major impact on long-term clinical or radiographic assessments of disease progression. CONCLUSIONS The study to date suggests that SCO is effective for the treatment of medial coronoid disease. Longitudinal clinical examination suggests that redistribution of load-bearing across the radial head does not induce clinically relevant collapse of the medial compartment or abnormal ulnar notch loading by five years postoperatively. SCO may have advantages over conventional procedures both in terms of amelioration of lameness and progression of clinically relevant arthrosis in the short and medium term, albeit that periarticular osteophytosis progresses. Second-look arthroscopic assessment and longer term outcome measures are lacking to definitively validate these observations. The results of this study compare favourably with other published data for the treatment of disease of the medial coronoid process, albeit other studies were less selective regarding inclusion criteria. The author feels that the clinical, arthroscopic, radiographic and histologic parameters measured in this study justify widespread application of the technique and intends that statistical analysis should provide prognostically relevant factors which can help guide decision-making by the owner and surgeon regarding this challenging condition. Selected References: Boulay JP (1998) Fragmentation of the medial coronoid process of the ulna in the dog. Vet Clin North Amer 28:51 Berzon JL, Quick CB (1980): Fragmented coronoid process: anatomical, clinical and radiographic considerations with case analyses. J Am Anim Hosp assoc16: Danielson KC et al (2006) Histomorphometry of fragmented medial coronoid process in the dog: A comparison of affected and normal coronoids. Vet Surg 35: Eckstein F, et al (1993) Physiological incongruity of the humeroulnar joint: A functional principle of optimized stress distribution acting upon the articulating surface? Anat Embryol 188:449 Fitzpatrick N (2004) Clinical and radiographic assessment of 83 cases of subtotal coronoid ostectomy (SCO) for treatment of fragmented medial coronoid process (FMCP). VOS Spring meeting, Big Sky, Montana 2004 and BSAVA Annual Conference, Birmingham, UK Hornoff WJ, et al (2000): Canine elbow dysplasia: The early radiographic detection of fragmentation of the coronoid process. Vet Clin North Am 30:257 Maierl J, et al (2000): New aspects of the functional anatomy of the canine elbow joint. Proceedings, 10 th Annual European Society of Veterinary Orthopaedics and Traumatology, Munich, Germany, p90. Mason D, Schulz KS, Samii VF, et al (2002). Sensitivity of radiographic evaluation of radio-ulnar incongruence in the dog in vitro. Vet Surg 31: Meyer-Lindenberg A, et al (2002): Prevalence of fragmented medial coronoid process of the ulna in lame adult dogs. Vet Rec 151(8):230 Nap RC (1996) Pathophysiology and clinical aspects of canine elbow dysplasia. Vet Comp Orthop Traumatol 9:58 Preston C, et al (2000) In vitro determination of contact areas in the normal elbow joint of dogs. Am J Vet Res 61:1315 Preston C, et al (2001) In vitro experimental study of the effect of radial shortening and ulnar ostectomy on contact patterns in the elbow joint of dogs. Am J Vet Res 62:1548 BVOA: Proceedings Autumn Scientific Meeting November

29 ELBOW DYSPLASIA 2 CLINICAL ISSUES Puccio M, et al (2003) Clinical evaluation and long term follow up of dogs with coronoidectomy for elbow incongruity. J Am Anim Hosp Assoc 39:473 Read RA, et al (1990) Fragmentation of the medial coronoid process of the ulna in dogs: A Study of 109 cases. JSAP 31:330 Samii VF, et al (2002) Computed tomographic osteoabsorptiometry of the elbow joint in clinically normal dogs. Am J Vet Res 63:1159 Schulz KS, et al (2002) Current research in the pathophysiology of elbow dysplasia. Proceedings, 1 st World Orthopaedic Vet Congress, Munich, p179. Suess RP, et al (1994) Exposure and post operative stability of three medial surgical approaches to the canine elbow. Veterinary Surgery 23:87-93 Tobias TA, et al (1994) Surgical removal of fragmented medial coronoid process in the dog: comparative effects of surgical approach and age at time of surgery. J Am Anim Hosp Assoc 30:360 Van Ryssen B, Van Bree H (1997) Arthroscopic findings in 100 dogs with elbow lameness. Vet Rec 140:360 Wind AP, Packard ME (1986) Elbow incongruity and developmental elbow diseases in the dog. Part II. J Am Anim Hosp Assoc 22:725 Wosar MA, et al (1999) Radiographic evaluation of elbow joints before and after surgery in dogs with possible fragmented medial coronoid process. J Am Vet Med Assoc 214:52 BVOA: Proceedings Autumn Scientific Meeting November

30 ELBOW DYSPLASIA 2 CLINICAL ISSUES TREATMENT OPTIONS FOR FMCP The role of sub-total arthroscopic partial coronoidectomy and concurrent distal ulnar osteotomy Ian Holsworth BVSc MACVSc (Surgery) Diplomate American College of veterinary Surgeons Surgical treatment of dysplastic patients has two potential components. Firstly the removal of a portion of the medial coronoid process including identifiable fragments. Results with this procedure alone have been variable with many dogs having an apparent improvement in their gait and degree of joint pain. There is no evidence that supports that this procedure slows or stops the ongoing development of elbow osteoarthritis. The second surgical manipulation is an osteotomy or ostectomy of the ulna, radius or humerus to attempt an improvement in the elbow congruity and decrease the biomechanical loading of the medial joint compartment. Increasing in popularity recently has been the performance of sub-total coronoidectomy with concurrent fragment removal. The procedure has been proposed both as an open miniarthrotomy and arthroscopically. The increased visualization of the medial joint compartment, the decrease in iatrogenic trauma to the peri-articular tissues and potential decrease in postsurgical morbidity all are factors that have increased interest in the arthroscopic technique. Several studies measuring the change in elbow contact patterns and medial joint load have been performed over the past five years with different osteotomy types in the ulna and humerus. There has been no prospective, standardized study with control groups and force plate data that has looked at the effect of any of these procedures in clinically affected elbow dysplasia dogs. The decision to perform an osteotomy following arthroscopic debridement of the coronoid must therefore be made with little scientific data as support and with the knowledge that some procedures have an inherently high morbidity. Potential complications are serious and if they develop may lead to the decreased functional use of the thoracic limb. These risks are balanced against the subjective opinion of some experienced surgeons. Their belief is that without an attempt to improve joint congruity and biomechanical loading of the medial compartment the surgical results with coronoid debridement or partial coronoid resection alone are sub-optimal. When attempting a procedure with potentially serious complications the individual surgeon must fully inform the client of the potential benefits and possible complications with the proposed procedure. The surgeon must continue to honestly assess the individual results that they achieve to justify the semi-experimental nature of the treatment. References Preston CA, Schulz KS, Taylor KT, Kass PH, Hagan CE, Stover SM (2001). In vitro experimental study of the effect of radial shortening and ulnar ostectomy on contact patterns in the elbow joint of dogs. Am J Vet Res 62(10): Fujita Y, Schulz KS, Mason DR, et al (2003) Effect of humeral osteotomy on joint surface contact in canine elbow joints. Am J Vet Res 64(4): Snelling SR, Lavelle RB (2004). Radiographic changes in elbow dysplasia following ulnar osteotomy case report and literature review. Aust Vet J 82(5): Puccio M, Marino DJ, et al (2003) Clinical evaluation and long-term follow-up of dogs having coronoidectomy for elbow incongruity. J Am Anim Hosp Assoc 39: BVOA: Proceedings Autumn Scientific Meeting November

31 ELBOW DYSPLASIA 2 CLINICAL ISSUES DOES THE PRIMARY TREATMENT METHOD CHANGE THE LONG TERM OUTCOME IN FMCP? Angus Anderson BVetMed PhD DSAS (Orth) MRCVS Anderson & Abercromby Veterinary Referrals, Ockley, Surrey There are a number of options available to us in the management of FMCP but the long term outcome in terms of clinical function for each management option is still unclear. Our management options include: ÿ Conservative management that usually involves a combination of exercise restriction, drug treatment (NSAIDs or pentosan polysulphate), nutraceuticals and physical therapies such as hydrotherapy. ÿ Removal of the FMCP either by arthrotomy or arthroscopy ÿ Removal of the FMCP together with a part of the MCP (subtotal coronoidectomy) that is performed by arthrotomy or arthroscopically. ÿ Ulnar osteotomy (proximal or distal), that is normally combined with removal of the FMCP The outcomes of most of these procedures have been described in peer-reviewed literature but there are a number of problems that are encountered when comparison of results is attempted. Some of the literature involves very small numbers of animals and drawing conclusions from these studies must be done with great caution. Insufficient standardisation between studies precludes meta-analysis. The major areas where there is variation between studies include: ÿ The clinical evaluation of cases (how lameness is graded). This is made harder by the frequent presence of bilateral disease and bilateral lameness. The majority of reports describe subjective measures of lameness evaluation but Bouck (1995) and Huibregtse (1994) performed kinetic gait analysis in small numbers of dogs. The follow-up of cases is either by clinical examination or client questionnaire or by a combination of the two and the period of follow-up varies significantly between reports. ÿ Long term radiographic evaluation. There is significant variation in how radiographs are evaluated with subjective and objective measures of osteoarthritis described. The literature available on treatment of FMCP can be divided into a number of categories; 1. Comparison of conservative and surgical treatment (removal of the FMCP) 2. Descriptions of surgical treatment (FMCP removal) with results 3. Results of proximal ulnar osteotomy 4. Comparisons of surgical treatment (eg different techniques of medial arthrotomy or comparing arthrotomy with arthroscopy) Non peer-reviewed information is available on other techniques such as distal ulnar ostectomy and subtotal coronoidectomy (achieved through an arthrotomy or arthroscopically) 1. Comparison of conservative and surgical treatment One of the most critical aspects of comparing these management options in published reports is whether treatment has been randomised and in the majority of studies this is not stated or dogs that have been managed conservatively have been less severely affected either clinically, radiographically or both. In the majority of reports dogs have shown an improvement with conservative and surgical management over follow up times of months to years (some authors state mean follow up times of 9-16months whereas others will give ranges of anything from 3 BVOA: Proceedings Autumn Scientific Meeting November

32 ELBOW DYSPLASIA 2 CLINICAL ISSUES months to 8 years). Some authors have failed to find any significant improvement with surgery (FMCP removal) compared to conservative treatment (Grondalen 1979 and Houlton 1984) in clinical outcome. From owner questionnaires Read (1990) stated that there was no significant difference in outcome between groups in terms of the presence of lameness but operated dogs did appear to be more active according to their owners. There are 2 reports of objective evaluation of lameness by gait analysis and in both cases differences could not be detected in peak vertical ground reaction forces and mean vertical forces at follow up (up to 9 months following treatment in the study by Bouck [1995] but follow-up time not stated by Huibregtse [1994]). All authors are in agreement that regardless of treatment the radiographic signs of osteoarthritis progress but there is no correlation between the severity of the clinical signs and the severity of osteoarthritis evaluated from radiographs. 2. Descriptions of surgical treatment (FMCP removal) with results The results shown in these papers mirror those found in the previous section. 3. Results of proximal ulnar osteotomy There are only 2 published reports (Bardet 1996, Ness 1998) showing the results of this procedure. Both have follow-up times of about 18 months and show that the clinical outcome is good or excellent (these terms are not defined by Bardet) in about 90% of cases. In both reports radiographic evidence of progression of osteoarthritis was present in the majority of dogs. 4. Comparisons of surgical treatment Some authors have compared different surgical approaches to the elbow to determine whether this affects outcome. Several authors have compared the results of a standard medial arthrotomy with osteotomy of the medial epicondyle. There appears to be no obvious difference in outcome when these surgical approaches are compared but there may be a higher incidence of complications that require further surgery in the latter group Arthroscopy has been used to diagnose and treat FMCP for over 10 years. However there is only 1 report that has attempted to compare the results of arthroscopic treatment of FMCP with arthrotomy (Meyer-Lindenberg 2003). These authors showed that a significantly larger number of dogs went sound following arthroscopic treatment of FMCP compared to those treated by arthrotomy. However in the majority of cases the radiographic signs of osteoarthritis progressed and no difference was noted between the two groups. Results of other procedures (non peer-reviewed) Some authors have advocated the use of a distal ulna ostectomy in very young dogs (Vezzoni 2000) but the results of this procedure have not been clearly defined. Recently there have been reports on subtotal coronoidectomy (by arthrotomy or arthroscopy with the use of a shaver)(fitzpatrick 2004, Van Ryssen 2004). Significant improvements in lameness have been reported by both authors but the long-term effects of these procedures are unclear.. SUMMARY From the literature some conclusions can be drawn on the long term outcome of FMCP treatment. In the majority of cases there will be radiographic progression of osteoarthritis but BVOA: Proceedings Autumn Scientific Meeting November

33 ELBOW DYSPLASIA 2 CLINICAL ISSUES its severity does not correlate with clinical function. A majority of dogs will improve with conservative management or surgery for FMCP but many reports have failed to show a significant long term benefit from the latter. It is unclear whether dogs benefit long term from any form of ulna osteotomy and there are insufficient reports on the long term outcome of subtotal coronoidectomy to know whether this treatment is more efficacious than the alternatives. It is clear from reviewing the literature that more studies are required that investigate the long term function following treatment for FMCP. References Bardet J-F, Bureau S La fragmentation du processus coronoide chez le chien (1996) Prat Med Chir Anim Comp 31, Bennett D, Duff SRI (1981) Osteochondritis dissecans and fragmentation of the coronoid process in the elbow joint of the dog. Vet Rec 109, Berzon JL, Quick CB (1980) Fragmented coronoid process: Anatomical, clinical and radiographic considerations with case analyses. JAAHA 16, Bouck GR, Miller CW, Taves CL (1995) A comparison of surgical and medical treatment of fragmented coronoid process and osteochondritis dissecans of the canine elbow. VCOT 8, Denny HR, Gibbs C (1980) The surgical treatment of osteochondritis dissecans and ununited coronoid process in the canine elbow joint. JSAP 21, Fitzpatrick MN, O Riordan J (2004) Clinical and radiographic assessment of 83 cases of subtotal coronoid ostectomy for treatment of fragmented medial coronoid process (FMCP). BSAVA Congress Proceedings p584 Grondalen J (1979) Arthrosis in the elbow joint of young rapidly growing dogs III. Nord Vet-Med 31, Guthrie S (1989) Use of a radiographic scoring technique for assessment of dogs with elbow osteochondrosis. JSAP 30, Henry WB (1984) Radiographic diagnosis and surgical management of fragmented medial coronoid process in dogs. JAVMA 184, Houlton JEF (1984) Osteochondrosis of the shoulder and elbow joints in dogs. JSAP 25, Huibregste BA, Johnson AL, Muhlbauer MC, Pijanowski GJ (1994) The effect of treatment of fragmented coronoid process on the development of osteoarthritis of the elbow JAAHA 30, Mason TA, Lavelle RB, Skipper SC, Wrigley WR (1980) Osteochondrosis of the elbow joint in young dogs JSAP 21, Meyer-Lindenberg A, Langhann A, Fehr M, Nolte I (2003) Arthrotomy versus arthroscopy in the treatment of fragmented medial coronoid process of the ulna in 421 dogs. VCOT 16, Ness MG (1998) Treatment of fragmented coronoid process in young dogs by proximal ulnar osteotomy. JSAP 39, Olsson S-E (1983) The early diagnosis of fragmented coronoid process and osteochondritis dissecans of the canine elbow joint. JAAHA 19, Read RA, Armstrong SJ, O Keefe JD, Eger CE (1990) Fragmentation of the medial coronoid process of the ulna in dogs: A study of 109 dogs. JSAP 31, Tobias TA, Miyabayashi T, Olmstead ML, Hedrick LA (1994) Surgical removal of fragmented medial coronoid process in the dog: Comparative effects of surgical approach and age at the time of surgery. JAAHA 30, Van Bree HJJ, Van Ryssen B (1998) Diagnostic and surgical arthroscopy in osteochondrosis lesions. Vet Clin N America: Small Animal Practice 28, Van Ryssen B, Van Vynckt D, Samoy Y, Van Bree H (2004) FCP in old dogs. Advanced canine arthroscopy course. Liverpool University Vezzoni A (2000) Dynamic Ulna osteotomy in elbow dysplasia. WSAVA Proceedings Amsterdam BVOA: Proceedings Autumn Scientific Meeting November

34 ELBOW DYSPLASIA 2 CLINICAL ISSUES SALVAGING THE CANINE ELBOW Arthroscopy, ulnar and humeral osteotomy, arthrodesis and replacement arthroplasty. Ian Holsworth BVSc MACVSc (Surgery) Diplomate American College of Veterinary Surgeons The veterinary orthopedist's goals in treatment of joint disease are to alleviate pain, maintain function, and prevent or remove the potential for further degeneration of the joint. In the dysplastic or severely traumatized canine elbow where degeneration of the articular surfaces is well advanced and severe osteoarthrosis is present the primary goal of salvage treatment is pain control. The secondary goal of elbow salvage is maintenance of acceptable clinical function. The three options available are; intra-articular debridement of articular surface pathology with concurrent alteration of joint load via osteotomy above or below the joint, elbow arthrodesis or total elbow replacement. Elbow exploration, cartilage disease grading and articular debridement have been regarded as unrewarding in the past in older elbow patients. WithW the advent of arthroscopy and its minimally invasive nature, end-stage joint arthroscopy is becoming more widespread. Combining this approach with either ulna osteotomy or humeral osteotomy has shown promise in some early clinical trials. Elbow arthrodesis is an invasive surgical salvage that has been associated with a high rate of complications and poor clinical function. Infection, implant failure, delayed or non-union of the arthrodesis site are all complications that have discouraged surgeons from adopting this procedure. The recent improvements in implant systems and increased surgeon experience with osteotomies has allowed surgeons to revisit elbow arthrodesis. Results have surprised some individuals with pain-free function being present in patients with moderate gait abnormalities. Complications are still a major concern with this procedure. Total elbow replacement for dogs has evolved over the past fifteen years through experimental prototypes in normal dogs in several US centers to a commercially available implant for use in clinical cases. The implant is a cemented polyethylene radial-ulnar component with a cemented non-constrained cobalt chrome humeral component. Approximately eighty clinical cases were implanted in the US last year with a major complication rate of 15%. Several other groups have recently investigated other TER designs, however complication rates remain unacceptably high at this time in these new prototypes. References Flo GL (1998). Surgical removal of fragmented coronoid processes and fractured anconeal process in an older dog with evidence of severe degenerative joint disease. J Am Vet Med Assoc 213(12):1780-2, 175 Mason DR, Schulz KS, Fujita Y, et al (2005). In vitro force mapping of normal canine humeroradial and humeroulnar joints. Am J Vet Res 66(1): Fujita Y, Schulz KS, Mason DR, et al (2003) Effect of humeral osteotomy on joint surface contact in canine elbow joints. Am J Vet Res 64(4): Conzemius MG, Aper RL, Corti LB (2003). Short-term outcome after total elbow arthroplasty in dogs with severe, naturally occurring osteoarthritis. Vet Surg 32(6): BVOA: Proceedings Autumn Scientific Meeting November

35 ELBOW DYSPLASIA 2 CLINICAL ISSUES SALVAGING THE CANINE ELBOW Technique of application and initial clinical experience with sliding humeral osteotomy (SHO) for treatment of medial compartment disease (MCD) of the canine elbow Noel Fitzpatrick Fitzpatrick Orthopaedic/Neurology Referrals, Tilford, Surrey, GU10 2DZ. UK INTRODUCTION Elbow dysplasia is the most commonly reported thoracic limb disorder recognised in large and giant breed dogs. Most frequently pathological changes within the elbow joint are associated with the medial aspect of the coronoid process and medial aspect of the humeral condyle. Commonly recognised lesions associated with medial coronoid disease are typified by cartilage malacia, fibrillation, fissuring and erosion in addition to subchondral bone microcracks and fragmentation. Frictional erosion of the medial humeral condyle ( kissing lesion ) is frequently associated with coronoid disease whilst osteochondrosis of the medial aspect of the humeral condyle may give rise to lesions of osteochondritis dissecans. This plethora of pathology and ensuing full thickness cartilage erosion with subchondral bone exposure in the region defined by the medial coronoid process and medial aspect of the humeral condyle has been referred to as medial compartment disease (MCD). Elbow incongruity such as radioulnar step defects, humero-ulnar incongruence/conflict, varus deformity of the humerus or imbalance between skeletal and muscular mechanics may contribute to medial compartment syndrome of the elbow joint in dogs. Pathology of the lateral aspect of the elbow joint is far less commonly observed. Surgical treatments may include radial or ulnar osteotomies to address perceived incongruity, removal of free fragments and cartilage debris, debridement of lesions and subchondral micro-picking. Osteochondral Autograft Transfer System (OATS, Arthrex, Naples FL) allows resurfacing of lesions associated with OCD. Osteotomy of the ulna may lead to varus deformity of the limb and subsequent increased load on the medial compartment (Mason, 2003). Radial osteotomy protocol is yet to be well defined and thus-far has produced variable results. None of these techniques are applicable in cases of advanced elbow arthrosis and regardless of the technique employed, arthrosis is progressive. In cases where even these newer techniques are unlikely to result in a favourable clinical outcome because of chronicity of the lesions or because of severity of cartilage disease of the medial compartment at the time of presentation, there is a rationale and a clinical need for alleviation of pain and, if possible, amelioration of disease progression. Many of these patients are young and total elbow arthroplasty or elbow arthrodesis represent suboptimal therapeutic choices either because of potential complications or potentially poor functional outcome. Unicompartmental osteoarthritis of the human knee (medial compartmental goniarthritis) has been treated using wedge osteotomies for over 40 years. The efficacy of this treatment is well accepted but there is still significant debate regarding case selection criteria and outcome measures. The concept of force redistribution within a joint, from an area of profound cartilage and subchondral pathology to a more normal area has been embraced and pursued for the benefit of canine elbow dysplasia patients. The ability to redistribute the major joint forces from the medial compartment in favour of the lateral one has potential merit in light of the unicompartmental nature of elbow dysplasia. BVOA: Proceedings Autumn Scientific Meeting November

36 ELBOW DYSPLASIA 2 CLINICAL ISSUES In vitro studies of normal canine elbows have mapped force distribution across the humeroradial and humero-ulnar joints and found approximately 50:50 distribution (Mason, 2005) with three distinct contact areas in the elbow joints of normal dogs (Preston, 2000). There is a radial contact area located on the caudo-medial aspect of the proximal radial articular surface with its longest dimension orientated medio-laterally; a second located on the medial aspect of the distal articular surface of the trochlear notch and extending to the lateral edge of the medial coronoid and a third contact area is located on the cranio-lateral surface of the proximal trochlear notch (Mason, 2005). Initial studies looked at the merits of both a wedge osteotomy and a sliding humeral osteotomy for force redistribution using a mid-diaphyseal humeral osteotomy. The primary goal of osteotomies for the management of osteoarthritis is the redistribution of force through the lateralisation of contact areas and pressure. Load distribution across an articular surface is a result of force and contact area. Medial opening wedge osteotomy or lateral sliding osteotomy (lateral translocation of the proximal humeral diaphysis with respect to the elbow) had been proposed to elicit lateral shifting of the load axis (Fujita, 2003). Increased lateralisation of the proximal humeral segment was achieved by shimming placing spacers either beneath the proximal end of a medially applied bone plate to force the segment laterally, or placing a wedge between the ends of a mid humeral osteotomy, widest medially. In vitro, this resulted in reduction of force on the cranio-medial edge of the radial head and an increase in contact on the lateral edge. Lateral sliding osteotomy of 4 and 8 mm was compared to wedge osteotomy of 10 and 20 degrees (Mason, 2003). Force at the proximal articular surface of the ulna decreased after lateral sliding humeral osteotomy of 8 mm by 28%. It was proposed that a similar osteotomy performed clinically may be useful in the management of coronoid disease and medial compartmental osteoarthritis by decreasing pain and increasing protential for fibrocartilage healing of the articular surfaces. It was noted that the technique would increase loading of periarticular tissues and that the results of such alteration were uncertain such that iatrogenic injury to the soft tissues surrounding the joint should be avoided. Concern has been expressed that induced joint incongruency resulting in decreased overall contact area and increase in transarticular pressure distribution over a smaller area might lead to detrimental effects on the in-contact cartilage areas if forces become supra-physiological. Long-term clinical data is not yet available. In the clinical setting, application of a 10 degrees lateral closing wedge technique in 9 cases subjectively gave 4 excellent and 4 good results (Schulz, 2006). One case had pre- and post-operative force plate analysis and achieved >90% normal ground reaction force. One case had a poor result associated with septic arthritis. Major complications were experienced in 3 cases resulting in implant pull-out thought to be due to high moment arch that was generated by the angulation. It was proposed that humeral sliding osteotomy may address these complications and two clinical cases were performed. The first case (translocation of 5mm) showed no clinical improvement but the second case (10mm translocation) yielded promising results (Schulz, 2006). There are significant outstanding concerns with regard to clinical application of humeral osteotomy. In vitro studies looked at normal rather than pathologic elbows and the effect of removing a pathologic area of the medial coronoid process (fragmentation) in addition to redistribution of force with sliding osteotomy has not yet been established. Additionally, validation of magnitude of translation of the humeral segments has not been established relative to cross-sectional area of the bone and body mass for individual patients. The most recent development for application of sliding humeral osteotomy has been the partnership of New Generation Devices (NGD, Glen Rock, NJ) and UC Davis to produce a SHO plate with NGD patented locking plate technology. The plate is manufactured in two BVOA: Proceedings Autumn Scientific Meeting November

37 ELBOW DYSPLASIA 2 CLINICAL ISSUES sizes to accept eight 3.5mm or 2.7mm self-tapping locking screws or standard AO screws. The step is positioned at the mid-point of the eight holes, a 10mm step in the 3.5mm plate and a 7mm step in the 2.7mm plate. Studies are ongoing comparing the stiffness of the SHO locking plate to standard SHO plates and comparing the stiffness of medial versus lateral locking plate application. Locking plate technology provides a greater level of security against screw loosening and failure of implants. The plate provides ovoid holes applicable to either locking or standard screw application. When using standard screws.75 mm of compression per screw insertion may be achieved. Top-side detents allow for uniform bending stiffness and a locking drill guide which is screwed into the hole at either end of the ovoid hole facilitates accurate screw placement relative to the thread of the screw hole. MATERIALS AND METHODS The purpose of this study was to establish criteria for successful clinical application of SHO and to evolve reproducibly successful application technique with 3.5mm and 2.7mm NGD SHO locking plates. The short term clinical results with 25 elbows in 20 dogs are reported. Dogs presented for the investigation of thoracic limb lameness at our clinic between December 2005 and October 2006 diagnosed with MCD and treated surgically with SHO were included in this study. Each dog was clinically examined and the gait assessed and documented using video recordings. Owner and vet questionnaires using visual analogue scale were completed for all cases and functional assessment was performed at walk, trot and athletic trot. Elbow examination included response to extension and flexion plus supination and pronation with simultaneous elbow flexion. The presence of elbow effusion was noted. Maximal extension and flexion angles were measured both before and after sedation of the patient. All joints were inspected arthroscopically and subtotal coronoid ostectomy (SCO) was performed at the time of surgery (9 elbows) if overt fragmentation was visible and it was perceived that this could contribute to persistent discomfort with the fragments rising proximal to the normal ulnar joint surface, even after translational humeral osteotomy. 14 elbows had previously been operated with SCO or fragment removal between 2 weeks and 7 years earlier. Two cases was operated due to progressive cartilage erosion 12 and 16 weeks after osteochondral transplant for OCD of the medial aspect of the humeral condyle concurrent with SCO for medial coronoid disease. Only dogs with full-thickness cartilage erosion of the medial compartment (modified Outerbridge grade 4-5) were selected for the study. Post operative radiographic assessment for this case series included cranio-caudal and mediolateral views of the humerus including the shoulder and elbow joints. Radiographic assessment included screw length, screw position with particular reference to the supratrochear foramen, plate alignment, extent of bone contact of the distal surface of the plate step and the cut end of the distal segment and the amount of cortical overlap at the osteotomy site. Carprofen (Rimadyl, Pfizer) 4mg/kg daily for 1 week and 2mg/kg daily for 2 further weeks was provided for all cases. Post operative management included cage confinement for 6 weeks and lead exercise only for 12 weeks, increasing periods of exercise by 5 minutes weekly, 4-6 times daily starting with 10 minutes. Follow up examinations were undertaken at two, four, six, twelve and twenty four weeks post-operatively. Follow-up radiographic examination was performed for all cases at six, twelve and twenty four weeks post-operatively. At three and six months postoperatively client and vet functional assessment questionnaires were completed, video gait recording was BVOA: Proceedings Autumn Scientific Meeting November

38 ELBOW DYSPLASIA 2 CLINICAL ISSUES performed and measurement of flexion and extension angles determined for comparison with preoperative assessments. 12 dogs (14 elbows) have been followed to 12 weeks, and 5 dogs (5 elbows) to 24 weeks at the time of writing The function assessment questionnaires using a visual analogue scale were analysed by using a transparent calibrated template allowing a numerical score to be awarded to each assessment as determined by the position of a mark placed by the owner along a 100mm line. A value of 0 was awarded for poor and 100 for excellent outcomes. SURGICAL TECHNIQUE The patients were placed in lateral or dorsal recumbency for lateral or medial plate application respectively via a standard surgical approach to the humeral shaft. The plate was applied laterally for only one case in this series and the technique will be described for medial plate application of the 3.5mm plate only. Application of the 2.7mm plate uses the same technical principles but is yet to be definitively refined pending further development of instrumentation. A customised cutting jig which had been designed for the osteotomy was employed for two cases. The jig was aligned on the humeral diaphysis with particular attention to preventing the proximal or distal ends migrating off the shaft toward the metaphyses and anchored using a screw proximal and distal to the proposed osteotomy site such that the osteotomy would be perpendicular to the long axis of the bone. The osteotomy was created using a microsagittal saw (Stryker, UK) and a 5.8 mm saw blade (MDM Medical, UK) mounted at 35 degrees to the saw shaft. Lavage was provided throughout osteotomy. Following the osteotomy the jig was replaced with the plate. Plate holes were filled with self-tapping locking screws of appropriate length using the locking drill guide for accurate hole placement and a standard depth gauge. For subsequent elbows, a technique was developed using the step on the plate as the guide for the saw cut to circumvent difficulties encountered with unwanted migration of the bone segments after the jig was removed. The methodology has been termed drill-guide-slide (DGS) technique. This method allows the distal humeral segment to be translated medially with respect to the proximal segment in a controlled manner, minimising the possibility of malalignment. With the patient in dorsal recumbency the operated leg was held with the humerus parallel to the table-top on an appropriately sized sandbag allowing a standard medial approach. Proximal and distal pairs of custom drill guides were locked on the plate. The plate-guide assembly was positioned on the medial cortex of the humerus with the proximal plate segment in contact with the proximal humeral diaphysis and the distal plate segment stepped away from the humerus. The plate was orientated longitudinally such that the most distal plate hole was proximal to the supracondylar fossa and the proximal aspect of the plate was not impinging the distal extent of the bicepital groove. Particular attention was paid to central placement of the most proximal and distal screws to prevent plate drift off the cranial cortex proximally and the caudal cortex distally. This was achieved by drilling hole #1 first and leaving the drill bit in situ whilst the plate was moved in a pendulum-like manner such that hole #8 could also be centralised. The drill bit in hole #8 was also then left in situ in the sleeve of the drill guide. Two locking screws were used to apply the plate to the proximal segment, and two over-long standard screws were applied through the plate to the distal segment. A transverse osteotomy of the humerus was created using the step of the plate as a cutting guide. Saline lavage was employed during cutting and drilling. Alternate tightening of the two standard screws in the distal segment resulted in controlled medial translocation of the distal segment relative to the BVOA: Proceedings Autumn Scientific Meeting November

39 ELBOW DYSPLASIA 2 CLINICAL ISSUES proximal segment. The plate was locked down by application of locking screws in the remaining screw holes. The standard over-long screws were finally replaced with standard screws of appropriate length. RESULTS Breeds represented were Labrador retriever (10), Labrador-cross (2), Springer spaniel (2) and six other breeds. The male to female ratio was 13:7. 17 dogs were household pets, two dogs had been active gundogs until 12 and 18 months earlier, and one dog had been involved in competitive agility until 2 years earlier. Reasons for presentation were varied including overt lameness, exercise intolerance, refusal to perform functional tasks such as climbing down steps or an owner s perception of pain. Owner functional assessment scores were consistently low indicating poor ability to perform functions including descending stairs, jumping and running. Preoperative veterinary assessment documented varied level of lameness and gait abnormality. Pain upon manipulation, particularly during maximal flexion and pronation in 90 of flexion, was consistently noted. Age at time of SHO fell into two main groups, with 9 dogs under 2 years old, 7 dogs aged years and only 4 dogs between 2 and 7 years. 13 right and 12 left humeri were operated. Two dogs received single-session bilateral procedures and three dogs received staged bilateral procedures (staged by 4, 4 and 6 weeks). By two weeks all cases were weight bearing with good ambulatory function. Lameness scores had improved by 12 weeks for 7/14 elbows, remained the same for 6/14 elbows and was worse for 1/14 elbows. At 24 weeks, lameness had resolved in 3/5 elbows and had improved from 3/5 to 1/5 lame for the other 2/5 elbows. Several dogs experienced change in gait characterised by circumduction of the limb in the early pre-operative period, although this has resolved in all affected cases at the time of writing. Pain on manipulation gradually decreased throughout the follow-up period. Owner-assessed VAS scores for ability to perform certain tasks revealed that 10/12 dogs had substantially improved at 12 week follow-up assessment while 2 dogs were assessed to have shown mild deterioration. All 5 dogs assessed to 6 months were deemed to have markedly improved by owner-assessed function VAS scores. Veterinary assessment scores have improved with a notable decrease in pain upon elbow manipulation, but numbers are not yet sufficient for statistical analysis. Major complications to date include humeral fracture through proximal screw holes 9 days post-operatively requiring revision (1 case), multiple screw breakage at the head-shaft interface 11 days post-operatively requiring revision (1 case) and delayed union of the osteotomy observed at 8 weeks which healed following autogenous cancellous bone grafting (1 case). Minor complications included single screw failure not requiring revision (3 cases) and soft tissue infection which resolved following antibacterial therapy (1 case). Radiographic evidence of union and bone remodelling between proximal and distal segments was documented by 12 weeks for the other 13/14 humeri. DISCUSSION Short-term outcome intimates that patients may recover levels of quality of life experienced before clinical symptoms became apparent. There is a need for more objective assessment of improved gait and this will be possible for future cases with force-plate analysis. The technique uses the custom locking drill guide to drill all holes such that locking screws can be placed in optimal alignment. Single screw breakage noted in 2/3 cases were BVOA: Proceedings Autumn Scientific Meeting November

40 ELBOW DYSPLASIA 2 CLINICAL ISSUES attributable to technical error before DGS technique had evolved. The author recommends medial application of the plate since the medial cortex of the humerus is more uniform than the lateral aspect and the locking plate is designed to be applied without contouring. Technique of application is easier on the medial than on the lateral aspect of the humerus. Application by DGS technique is technically easier than use of the jig in our experience and when the jig was used, it was difficult to avoid unwanted migration of the segments when the plate was applied and difficult to accurately achieve the intended cut-end/plate step compression. Cutting of the osteotomy using a thin saw blade immediately distal to the step minimises loss of bone stock and the blade thickness alone provides enough clearance for segmental translation perpendicular to the plate without impingement. A thin blade allows tactile sensation as the trans-cortex is breached and minimises iatrogenic trauma to soft tissues. Application of the DGS technique avoids unwanted cranio-caudal translation, rotation or malalignment of the bone segments. We recommend that the tolerance between the hole in the drill guide and the drill be minimised to avoid wobble when the drill bit is used as a jig pin. An extended-length locking drill guide is currently being trialled to this aim. Compression between the cut end of the distal segment and the step, or the proximal and distal segment cortices is not achieved with DGS technique. This would lessen the stress placed upon the screw-plate construct, but this limited case series suggests that compression may not be important since cortical overlap is minimal when the NGD 3.5mm stepped plate was applied to this canine population. The stepped bone plate therefore acts in buttress mode with no force shared by the cut ends but locking screws maximise construct stiffness with the plate/screw construct performing as an internal fixator. In this case series the plate has shown no radiographic evidence of bending or fracture. There is structural disadvantage associated with the use of two non-locking screws in the distal segment, but to date this has not resulted in observable clinical ramifications. Placing locking screws in holes threaded for standard screw placement is a technical error as the thread pitches differ for the two screw types. Owner compliance is critical and all 3 major complications experienced could be attributed to poor owner or patient compliance with post-operative exercise restriction. Increased focal stresses on peri-articular soft tissue structures may be responsible for acute deterioration in lameness during the short-term pre-operative period if close confinement and a controlled limited exercise routine are not strictly adhered to. Physical and aquatic therapies may assist recovery, but the effects have not been objectively evaluated to date. The precedent for application of osteotomies to alter forces acting across joints is well established in veterinary surgery as typified by tibial plateau levelling and ulnar osteotomies. Controversy still surrounds long established osteotomy techniques and research continues to elucidate their efficacy. SHO has been proven in vitro to unload the medial compartment of the elbow, but more objective data is required to assess efficacy in clinical cases, as is the long-term effect on the lateral compartment of the elbow. Osteotomy of a major long bone may be associated with significant morbidity, but the author considers that current improvements in technical application and careful case selection should not dissuade from widespread clinical application. Further work is required to elucidate specific selection criteria for case-suitability in terms of both clinical and arthroscopic findings. The size of plate and plate step for various degrees of pathology and sizes of patients also requires refinement and will be the subject of further investigation since it seems unlikely that a single plate size is appropriate for all patients affected by medial compartment disease of the elbow. BVOA: Proceedings Autumn Scientific Meeting November

41 ELBOW DYSPLASIA 2 CLINICAL ISSUES CONCLUSIONS Early experience with the SHO technique suggests that it may be applied both therapeutically and prophylactically. SHO is more obviously indicated where cartilage cover of the medial compartment is significantly compromised and where impairment of quality of life is associated with pain emanating from the medial aspect of the elbow, but more controversially, may be considered in immature dogs where primary anomalies such as FCP, OCD and erosive condylar lesions causing significant embarrassment of the articular surfaces of the medial compartment. At this time there is no perceived upper age limit but data to support early intervention is lacking as is data indicating the long-term effects of altering the biomechanics of the thoracic limb with SHO for patients of any age. The author proposes that SHO is likely to become a widely adopted procedure for the alleviation of discomfort associated with elbow disease in the dog, though it is too early to judge what the long-term effects may be in terms of disease progression and maintenance of desirable quality of life. Selected References: Preston CA, Schulz KS, Kass PH (2000) In vitro determination of contact areas in the normal elbow joint of dogs. AJVR, 61 (10) Fujita Y, Schulz KS, Mason DR, Kass PH, Stover SM (2003) Effect of humeral osteotomy on joint surface contact in canine joints. AJVR, 64 (4) Mason DR, Schulz KS, Fujita Y, Kass PH, Stover SM (2003) Measurement of the humero-radial and humero-ulnar transarticular joint forces in the canine elbow joint following humeral wedge and humeral slide osteotomies. Presented 30 th Annual conference of the Veterinary Orthopedic Society, Steamboat Springs, CO Mason DR, Schulz KS, Fujita Y, Kass PH, Stover SM (2005) In vitro force mapping of the normal canine humeroradial and humeroulnar joints. AJVR, 66 (1) Ackroyd CE (2003) Medial compartment arthroplasty of the knee. J Bone Joint Surgery 85(7): Koshino T, Yoshida T, Ara Y, Saito I, Saito T (2004). Fifteen to twenty-eight years follow-up results of high tibial valgus osteotomy for osteoarthritic knee. Knee 11(6): Schulz, KS (2005) Private communication, Notes: Locking Sliding Humeral Osteotomy Clinical evaluation BVOA: Proceedings Autumn Scientific Meeting November

42 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE THE PATHOGENESIS OF INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Mark Glyde BVSc MACVSc MVSDipECVS HDipUTL MRCVS RCVS Recognised Specialist in Small Animal Surgery School of Veterinary and Biomedical Sciences Murdoch University Humeral condylar fractures (HCFs) are common and account for 17% 54% of all humeral fractures. They may occur traumatically or atraumatically during normal activity. Animals with atraumatic HCF may have incomplete ossification of the humeral condyle (IOHC). Spaniel breeds appear to be over-represented for IOHC however other breeds are also affected. Bilateral disease in IOHC is common and evaluation of the contralateral condyle is advised. Some controversy exists in the literature over whether most HCFs occur consequent to major trauma or during normal activity such as running, jumping or climbing stairs. Marcellin-Little et al (1994) reviewed 157 humeral fractures in which 54% (85/157) were HCFs. Of the 54% of HCFs, 65% (55/85) occurred in skeletally mature dogs and were examined more closely. Of these 55 skeletally mature dogs with HCF, 78% (41/55) occurred with no history of trauma [64% (33/55) occurred during normal activity and a further 14% (8/55) occurred with no4 known history of trauma]. Vannini et al (1987b) looked at 139 distal humeral fractures in dogs of which 63% (88/139) were HCFs. Of these 88 HCFs, 69% (61/88) were due to minor trauma (defined as normal activity of running, jumping from heights under 1m and climbing stairs). When unicondylar fractures were considered separately, 90% (46/51) occurred due to minor trauma. In addition to HCF dogs with IOHC may present with occult IOHC, unilateral or bilateral lameness referable to IOHC +/- associated degenerative joint disease +/- disease of the medial part of the coronoid process (FCP) (Brunnberg et al 2001, Butterworth and Innes 2001, Robin and Marcellin-Little 2001, Meyer-Lindenberg 2002). Lateral condylar fractures are the most common form of HCF in dogs with IOHC followed by dicondylar fractures. Medial condylar fractures are least common: ÿ lateral part of the condyle 51% ÿ intercondylar or dicondylar T or Y fracture 36% ÿ medial part of the condyle 13% Why is the lateral part of the condyle most commonly fractured? The lateral part of the condyle (capitulum) is: ÿ the major load-bearing part of the humeral condyle ÿ eccentric to the humeral shaft causing load -bearing forces to be directed through the lateral epicondylar ridge rather than through the humeral shaft ÿ weaker than the medial part of the condyle (the lateral epicondylar ridge is considerably smaller than the medial epicondylar ridge) BVOA: Proceedings Autumn Scientific Meeting November

43 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE The greater load and the relative biomechanical weakness predispose the lateral part of the condyle to fracture. HISTOPATHOLOGY AND IOHC When considering the pathogenesis of HCFs it is important to distinguish between skeletally immature and mature dogs. The high incidence of condylar fractures in immature dogs as a result of minor trauma is due to the normal relative weakness of the developing humeral condyle. The humeral condyle develops as two separate centres of ossification that appear approximately 14 days (+/- 8 days) after birth. The lateral and medial centres of ossification are separated by a thin cartilaginous plate and normally unite at 70 days (+/- 14 days). HCFs consistently occur along this fusion line in both immature and mature animals. In skeletally mature animals the condyle should be fused and the cartilaginous plate completely ossified. In normal animals condylar fracture should only occur as a result of major trauma directed through the humeroradial joint. Atraumatic fracture in mature dogs during normal activity suggests underlying abnormality through the condylar fusion zone. Marcellin-Little et al (1994) proposed a condition of incomplete ossification of the humeral condyle (IOHC) exists in dogs with atraumatic HCF and that this may be inherited as a recessive gene in Spaniel breeds. Further supportive histopathological evidence has been subsequently published however the genetic basis has yet to be further defined. BVOA: Proceedings Autumn Scientific Meeting November

44 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Both elbows should be investigated in occult IOHC or atraumatic HCF as IOHC is commonly bilateral and higher failure rates after surgical repair of atraumatic condylar fracture are reported. Neoplasia has also been reported as a cause of HCF (Burger et al 2003). Histopathological examination of bone from HCF sites in mature dogs with atraumatic fracture reveals dense cancellous bone with non-specific evidence of chronic inflammatory change and previous remodeling. Fibrous tissue, increased osteoclastic activity and increased numbers of plasma cells are typically seen. Chondrocytes and cartilage matrix were not identified (Marcellin-Little et al 1994). A microangiographic study of the blood supply to the humeral condyle in Cocker Spaniel and non-cocker Spaniel dogs found that Cocker Spaniels had a decreased vascular density in the humeral condyle (Larsen et al 1999). Atraumatic HCF consequent to IOHC has also been reported in Vietnamese pot-bellied pigs in association with unilateral or bilateral forelimb lameness and elbow degenerative joint disease (Samii 2000). Medial condylar fracture is the most common presentation of HCF in these pigs, presumably as a result of articulation of the radial head in pigs with both the medial and lateral parts of the condyle. While this condition shares some similarities with IOHC in dogs, some significant differences exist. Pigs have a single centre of ossification of the humeral condyle. Skeletally immature pigs appear to be more commonly affected than mature pigs although IOHC is also seen in mature pigs. Histopathological examination revealed the condylar cleft in these pigs was lined with articular cartilage containing some degenerate foci. These changes were typical of incomplete endochondral ossification and may be more characteristic of a form of osteochondrosis. Robin and Marcellin-Little (2001) have suggested that the pathogenesis of IOHC may be related to impaired antebrachial bone growth, similar to the pathogeneses of elbow dysplasia and radius curvus. They suggest the occurrence of fragmentation of the medial part of the coronoid process (FMCP) and IOHC may support a related pathogenic mechanism between these two conditions. Meyer-Lindenberg (2002) reported IOHC in 13 dogs. Of these, two had concurrent FMCP and two had humeral condylar OCD. FMCP has also been observed in association with IOHC in Cocker Spaniels and Springer Spaniels (Marcellin-Little et al 1994, Glyde et al 2003). The significance of this association is not clear though may support Robin and Marcellin-Little s theory of asynchronous antebrachial growth in the pathogenesis of IOHC. Gnudi et al (2003) have compared IOHC with atraumatic fracture of the radial carpal bone in dogs, which is also commonly bilateral. The radial carpal bone has three separate centres of ossification (the primitive radial carpal bone, the central and intermediate carpal bone) that fuse at 3-4 months of age. Histopathological findings in these cases revealed fibrous connective tissue on the fracture surfaces suggestive of incomplete ossification rather than a true fracture of the radial carpal bone. The pathogenesis of this condition is not unknown. SIGNALMENT AND IOHC HCFs have been reported in many breeds and crossbreeds however Spaniel breeds appear to be predisposed to HCF. Spaniel breeds also have a significantly higher incidence of bilateral HCF. BVOA: Proceedings Autumn Scientific Meeting November

45 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Marcellin-Little et al (1994) investigated 43 atraumatic HCFs in 36 dogs and found that 28/36 were Spaniel-type dogs (24 Cocker Spaniels, 3 Brittany Spaniels and 1 spaniel cross). Further investigation of eight of these Cocker Spaniels with available pedigree information found a significantly higher coefficient of inbreeding than in 100 unaffected Cocker Spaniels suggestive of a recessive mode of inheritance. (Anecdotal evidence would suggest that American Cocker Spaniels are prone to HCF while English Cocker Spaniels may not be. Further work is needed in this area.) Vannini et al (1987a) reported that of 20 adult dogs with atraumatic HCFs 11 were Cocker Spaniels. Vannini et al (1987b) found that Cocker Spaniels were over represented in HCFs from minor trauma when compared to the overall clinic population. Occult IOHC and atraumatic fracture has now been reported in a number of breeds and cross breeds including Springer Spaniels, Cocker Spaniels, Brittany Spaniels, Labrador Retrievers, Rhodesian Ridgebacks, Boxer dogs, Rottweiler, German Wachtel, Bernese Mountain Dogs and cross breed dogs. The average age of skeletally mature dogs with atraumatic HCF was six years (range 2 13 years) (Marcellin-Little et al 1994, Vannini et al 1987a). Male dogs appear to be more prone to atraumatic HCF than female dogs comprising 83%, 75% and 69% of cases in three studies that considered gender. The reason for this is not known. RADIOGRAPHY AND IOHC IOHC cases have a moderate incidence of bilateral fracture and a high incidence of bilateral disease. Marcellin-Little et al (1994) in their study of 36 dogs with HCF suffered during normal activity found 20% suffered bilateral fractures. Of those with unilateral fractures, 86% had a vertical radiolucent condylar line apparent on a craniocaudal radiograph of the contralateral elbow. Vannini et al (1987a) reported 25% of dogs that had an HCF during normal activity suffered a subsequent contralateral HCF at an average of 8.3 months (range 5 days to 14 months) after the initial fracture. Common radiographic findings in the contralateral elbow joint of dogs with atraumatic HCF include (Marcellin-Little et al 1994): ÿ a vertical radiolucent line (0.5mm 1.0mm wide) between the lateral and medial parts of the condyle in the same location as the cartilaginous line separating the separate centres of ossification in immature dogs. Sclerosis is typically apparent adjacent to this line which may extend partially or completely from the articular surface to the supracondylar foramen (86%) ÿ degenerative joint disease (92%) ÿ periosteal proliferation on the lateral epicondylar ridge presumably due to increased stress on the epicondylar ridge due to incomplete ossification / weakness of the humeral condyle (50%). The specificity of this radiographic change for incomplete ossification of the humeral condyle has not been investigated. It is an unusual radiographic finding however and should certainly provide a high index of suspicion BVOA: Proceedings Autumn Scientific Meeting November

46 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE for incomplete ossification and justify further craniocaudal radiographs if a radiolucent line is not readily apparent. ÿ fragmented medial coronoid process (25%). This is presumed to be due to micro motion between the lateral and medial parts of the condyle placing abnormal stress on the medial coronoid process as FCP is uncommon in spaniels. Bibliography Anderson, T.J., Carmichael, S., Miller, A. (1990)Intercondylar humeral fracture in the dog: A review of 20 cases. Journal of Small Animal Practice, 31, Bardet, J.F. et al. (1983) Fractures of the humerus in dogs and cats. Veterinary Surgery, 12, Brown, D.C., Conzemius, M.G., Shofer, F.S. (1996) Body weight as a predisposing factor for humeral condylar fracture, cranial cruciate rupture and intervertebral disc disease in Cocker Spaniels. VCOT, 9, Burger, M. et al. (2003) An incomplete intracondylar fracture of the humerus caused by an osteosarcoma. Kleintierpraxis 48 (9): Butterworth, S.J. and Innes, J.F. (2001). Incomplete humeral condylar fractures in the dog. Journal of Small Animal Practice 42: Cockett,P.A., Clayton Jones, D.G. (1985) The incidence of humeral condylar fractures in the dog: a survey of seventy-nine cases. Journal of Small Animal Practice, 26, Denny, H.R. (1983) Condylar fractures of the humerus in the dog; a review of 133 cases. Journal of Small Animal Practice, 24, Gnudi, G. et al. (1983) Radial carpal bone fracture in 13 dogs. VCOT 16 (3): Larsen, L.J. et al.( 1999) Microangiography of the humeral condyle in Cocker Spaniel and non-cocker Spaniel dogs. VCOT, 12, Glyde, M, Doyle, R, and Connery, N. (2003) Humeral condylar fracture in dogs. Irish Veterinary Journal. 56(3): Marcellin-Little, D.J. et al. (1994) Incomplete ossification of the humeral condyle in spaniels. Veterinary Surgery, 23, Meyer-Lindenberg, A. et al. (2002) Incomplete Ossification of the Humeral Condyle as the cause of lameness in dogs. VCOT 15(3), Piermattei, D.L. (1993) An Atlas of Surgical Approaches to the Bones and Joints of the Dog and Cat, 3 rd edn. W.B. Saunders, Philadelphia Robin, D. and Marcellin-Little, D.J. (2001). Incomplete ossification of the humeral condyle in two Labrador Retrievers. Journal of Small Animal Practice 42: Samii, V.F. (2000) Incomplete ossfication of the humeral condyle in Vietnamese pot-bellied pigs. Vet Radiol Ultrasound 41, Slatter, D. (1993) Textbook of Small Animal Surgery, 2 nd edn. W.B. Saunders, Philadelphia Vannini, R., Olmstead, M.L., Smeak, D.D. (1987a) Humeral condylar fracture caused by minor trauma in 20 adult dogs. JAAHA, 24, Vannini, R., Olmstead, M.L., Smeak, D.D. (1987b) An epidemiological study of 151 distal humeral fractures in dogs and cats. JAAHA, 24, Volta, A., et al. (2005) Incomplete humeral condylar fracture in two English Pointer Dogs. Vet Comp Orthop Traumatol 18, BVOA: Proceedings Autumn Scientific Meeting November

47 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE THE DIAGNOSIS AND CURRENT TREATMENT OF INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Imaging, arthroscopy and basic fixation. Ian Holsworth BVSc MACVSc (Surgery) Diplomate of the American College of Veterinary Surgeons Incomplete ossification of the humeral condyle (IOHC) is reported in middle-aged, mediumsized dogs. The cartilaginous plate in this location is normally replaced by bone at about 70 days of age (+/-14 days) as the two ossification centers of the humeral condyle fuse. Male cocker spaniels are identified as being at higher risk for this condition. Springer spaniels, Brittany spaniels, and Cavalier King Charles spaniels are reportedly also affected. Labrador In affected animals a radiographically visible may be visible in the humeral condyle. Radiographically the pathognomonic radiographic feature is a radiolucent line, in the sagittal plane, through the condyle. The partial or complete cleft contains dense cancellous bone and fibrous tissue with no cartilaginous tissue able to be identified histologically. Radiographic confirmation of IOHC may be somewhat frustrating and computer tomographic imaging of the elbow joint increases diagnostic accuracy. On arthroscopic examination there may be little disturbance to the articular cartilage of the condyle. Once fractured arthroscopic-assisted reduction of the displaced fracture segments may improve fracture reduction and joint congruity. The classical surgical treatment of IOHC involves placement of a transcondylar bone screw across the condylar cleft in lag or neutral fashion. This technique is relatively straightforward but osseous obliteration of the cleft may not occur and condylar fracture with implant failure may still result in those cases. References Marcellin-Little DJ, DeYoung DJ, Ferris KK, et al. (1994) Incomplete ossification of the humeral condyle in spaniels. Vet Surg 23: Rovesti GL, Fluckiger M, Margini A, Marcellin-Little DJ (1998) Fragmented coronoid process and incomplete ossification of the humeral condyle in a rottweiler. Vet Surg 27(4): Butterworth SJ, Innes JF (2001) Incomplete humeral condylar fractures in the dog. J Small Anim Pract 42(8):394-8 Gnudi G, Martini FM, Zanichelli S, et al. (2005) Incomplete humeral condylar fracture in two English Pointer dogs. Vet Comp Orthop Traumatol 18(4):243-5 Robin D, Marcellin-Little DJ (2001). Incomplete ossification of the humeral condyle in two Labrador retrievers. J Small Anim Pract 42(5):231-4 Samii VF, Hornof WJ (2000) Incomplete ossification of the humeral condyle in Vietnamese potbellied pigs. Vet Radiol Ultrasound 41(2): BVOA: Proceedings Autumn Scientific Meeting November

48 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE THE DIAGNOSIS AND CURRENT TREATMENT OF INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Autogenous bone core dowel graft and variably pitched self-compressing canulated screw fixation N. Fitzpatrick Fitzpatrick Referrals, Greenhills Rural Enterprise Centre, Tilford, Surrey GU10 2DZ UK INTRODUCTION The humeral condyle in the developing dog has two (medial and lateral) centres of ossification separated by a cartilaginous intermediate zone. These are reported to unite in the normal dog by 70+/-14 days of age (Hare 1966) with completion of ossification by 32 weeks of age (Valerie 2000). A rare condition affecting the integrity of the humeral condyle in spaniels was first reported by Meutstege (1989) and subsequently in medium and large breed dogs. The condition is now widely referred to as incomplete ossification of the humeral condyle (IOHC) and is overrepresented in the spaniel (Marcellin-Little et al 1994) and hunting dogs (Piccionello 2006). Dogs with IOHC may present with mild intermittent to acute non weight bearing lameness. It is proposed that IOHC decreases the stability of the condyle predisposing it to complete condylar fracture, often following a minimally traumatic event. IOHC was first diagnosed radiographically as linear sagittal radiolucency in the humeral condyle in the region of the developmental cartilage zone separating the two condylar centres of ossification. Magnetic resonance imaging, scintigraphy and arthroscopy have been reported helpful in establishing a diagnosis. It is now appreciated that diagnosis may prove elusive using these modalities but Computed Tomography (CT) is definitive. Conservative treatment of IOHC is generally discouraged as it is associated with high rates of condylar fractures. Marcellin-Little (1996) noted that 43% of dogs with IOHC fractured their humeral condyle between 11 days and 18 months after diagnosis. Traditional surgical treatment uses a transcondylar screw, either fully or partially threaded, applied in either a neutral or lag position (Kaderley 1992, Marcellin-Little et al 1996, Butterworth et al 2001, Robin 2001). The use of anti-rotational support has been judged unnecessary providing the epicondyles are intact. Other reports include the concurrent use of a screw and transcondylar bone tunnels to allow vascular in-growth and subsequent osseous unification (Butterworth et al 2001, Marcellin-Little et al 1994), the proposed solitary use of a transcondylar cancellous bone graft (Rovesti 1998), and arthroscopic debridement of the articular cartilage (Van Ryssen 2005). Complications following surgical treatment includes recurrence of lameness (Butterworth and Innes 2001, Rovesti et al 1998), condylar fracture (Butterworth and Innes 2001, Marcellinlittle et al 1996), widening of fissure (Butterworth and Innes 2001), failure to document osseous unification either radiographically (Butterworth and Innes 2001, Rovesti et al 1998, Meyer-Lindenberg et al 2002), or using CT examination (Robin and Marcellin-Little 2001, Rovesti et al 1998). Surgical failure is usually a result of cyclic stress fatigue of the screw (Meyer-Lindenberg et al 2002) or screw bending (Marcellin-Little et al 1996). BVOA: Proceedings Autumn Scientific Meeting November

49 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE To the best of the author s knowledge a case series detailing the successful treatment of lameness attributed to IOHC using autogenous cortico-cancellous bone grafts to promote osseous unification of the condyle has not been previously reported. This technique has been used by the author as the sole treatment of lameness attributed to IOHC between January 2004 and September The objective of this retrospective clinical study is to describe evolution and application of technique and outcome following use of combined autogenous bone core dowel (ABCD) graft and a variably pitched self-compressing screw (Acutrak, Acumed, USA) for treatment of IOHC. MATERIALS AND METHODS Medical records of dogs that had undergone surgical treatment of IOHC using bone grafting procedures between January 2004 and September 2006 were identified. Results of clinical, radiographic, arthroscopic and CT examinations, surgical technique, post operative complications, resolution of lameness and follow up examinations were used. Clinical Examination In all cases owner interview regarding clinical history elucidated the type and intensity of lameness and any noted traumatic events. A full clinical, orthopaedic and neurological examination was performed. Gait was assessed at walk and lameness attributed a score between 0 and 5 (0=sound, 5=non-weight-bearing). Elbow examination included assessment of the response to elbow flexion, extension, and flexion with simultaneous pronation or supination. The response to deep palpation of the lateral epicondylar ridge was noted. Diagnostic Imaging Radiographic examination under sedation of both elbows included craniocaudal, mediolateral flexed and extended views. If no sagittal radiolucent line was evident on the routine craniocaudal view these were repeated with the elbow positioned in varying degrees of obliquity in an attempt to direct the radiographic beam through the suspected fissure. CT examination of both elbows was performed under general anaesthesia. Arthroscopic examination was performed in dorsal recumbency evaluating the medial compartment, intercondylar area, anconeal process and as much of the lateral compartment as could be assessed through a standard medial portal (Beale 2003). A 2.4 mm 30 angled arthroscope (Hopkins, Karl Storz) was connected to a video camera and image recording device. The intercondylar cartilage was surveyed for evidence of cartilage fracture, fissuring or lucency diagnostic of incomplete ossification of the humeral condyle. The presence of synovitis, medial coronoid disease and osteochondrosis/kissing lesions of the medial aspect of the humeral condyle were noted and modified Outerbridge scores attributed to the degree of cartilage erosion. The presence of intercondylar instability was tested using an arthroscopic probe and by joint manipulation. Surgical technique Patients were placed in dorsal recumbency and elbows with fragmentation of the medial aspect of the coronoid process underwent subtotal coronoid ostectomy via a mini-medial arthrotomy. A medial approach to the humeral condyle was made (Piermattei and Johnston 2004) with extension of the incision to expose both the caudal and cranial aspects of the articular surface of the humeral condyle. Preparation of the recipient site for transcondylar corticocancellous bone dowel placement included initial placement of a titanium, headless, tapered, variably pitched, cannulated, self tapping, self compressing screw (Acutrak TM, Acumed, USA) before creation of a transcondylar recipient socket. BVOA: Proceedings Autumn Scientific Meeting November

50 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Humeral coring and screw placement A calibrated guide wire was driven parallel to the transverse axis of the humeral condyle in the most distal position possible. This was facilitated by placing a standard or mini size Acutrak screw (depending on patient size) over the wire such that the tread of the screw at its maximal dimension would be positioned subchondrally, even at the narrowest isthmus of the condyle and would not cause structural embarrassment or encroachment of the articular surface. The guide wire was driven until the trans cortex was engaged whereupon depth was measured using a mark etched on the wire held against a customised cannulated depth gauge. The Acutrak screw was then inverted and threaded over the guide wire with the base of the screw contacting the cis cortex to act as a spacer such that a reamer (OATS ; Arthrex, Naples, FL) of maximal diameter could be centralised over the dorsal portion of the humeral condyle. The central position of the reamer was ensured by advancing a central guide drill through the trans cortex before reaming began. The reamer was then removed. The screw guide wire was advanced through the trans cortex and secured using a wire graspers to minimise wire movement. A customised cannulated calibrated conical shaped drill bit was advanced over the guide wire 3-4 mm increments at a time with concurrent saline lavage. Intermittent removal of the drill allowed removal of bone swarf. The drill tip depth was estimated using the external calibrations and driven within 2-4 mm of the transcondylar depth previously measured. An Acutrak screw of length at least 2 mm less than drill hole depth was selected and a customised cannulated screw driver engaged to thread the screw over the guide wire. The self tapping screw was driven to finger tightness. The reamer was repositioned on the central guide drill and aligned parallel to the axis of the condyle using the guide wire to aid socket-screw parallelism. The required socket depth was measured preoperatively from either the radiographs or CT images. The reamer was advanced to a depth approximately 75% the width of the condyle. The definitive depth of the autogenous bone core dowel (ABCD) required was measured using a calibrated alignment rod placed in the recipient socket, which simultaneously confirmed that the graft would traverse the fissure line. Dowel Harvesting A trabecular corticocancellous bone dowel was extirpated from the proximal tibia or distal femur using a core harvesting chisel (OATS ; Arthrex, Naples, FL) 1mm wider than the required transcondylar core. The core harvester constitutes a calibrated, cylindrical cutting chisel with louvered grooves at 4 equidistant points on the circumference. The louvers engage the bone core when hammer-tapped into the donor site and the bone dowel is extirpated by twisting motion in the line of the harvester or slight rocking ( toggling ) whereupon the louvers engage the cancellous bone and break the dowel off at its base. The core harvester is inserted an adequate depth to provide a bone dowel long enough to fill the recipient site previously measured. Dowel Placement Dowel placement was achieved using the OATS system, placing the core as a press fit. Fine-adjustment of dowel position was by gentle percussion using the OATS tamping rods and monitoring of the associated auditory signal. Wound closure was routine. Variations from this method were associated with: Case 1 ABCD was used without any implant augmentation BVOA: Proceedings Autumn Scientific Meeting November

51 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Case 2 ABCD was augmented with cancellous bone graft harvested with a curette from the dowel donor site and the dowel repair was supported with two 3 mm Ellis pins placed in a cross pattern Case 4 The recipient socked was filled with cancellous bone graft harvested from both proximal humeri in a routine manner using curettes and ABCD was not employed Immediate postoperative radiographs were taken of the treated elbow and donor site. Postoperative medication included carprofen 2 mg/kg (Rimadyl, Pfizer) orally twice daily for 1 week, then as necessary according to current licensing guidelines. Strict cage confinement with leash exercise only was enforced for 6 weeks, followed by increasing levels of lead exercise for six further weeks and then off lead exercise was resumed. Biopsy and Histopathology: Biopsy samples of the intercondylar fissure were obtained at the time of humeral coring in two cases by use of a recipient core harvester through the central portion of the condylar isthmus in place of the reamer. These were fixed in 10% formalin solution and transported to a commercial laboratory for decalcification and histopathological examination. Follow-up Post-operative clinical assessments were performed at 2, 4 and 8 weeks. Radiographic and CT examinations were performed at 12 weeks. Visual Analogue Scale questionnaires documenting function was completed by all owners approximately 1 year post-operatively. This involved assessments of commonly performed daily activities which were analysed using a transparent template to attribute numerical scores to each observation as determined by the position of a mark placed by the owner along a calibrated 100 mm line. A value of 0 was awarded for poor and 100 for excellent outcomes. RESULTS Seven dogs were included in the study with an average age at the time of surgery of 3y8m (range 1y9m-7y1m). Breeds included three cocker spaniels, two English Springer spaniels and two Cavalier King Charles spaniels. Male to female ratio was 5:2. Mean weight was 15.1kg (range 7.7kg-21.0kg). The mean duration of lameness prior to examination was 161 days (range days). Pain was consistently observed upon elbow extension, flexion and palpation of the lateral epicondyle. IOHC was diagnosed in two, five and seven elbows using arthroscopic, radiographic and CT examination respectively. IOHC was diagnosed in the right, left and bilaterally in one, four and two cases respectively. Cases 1 and 4 had bilateral fragmentation of the medial coronoid process and were treated with subtotal coronoid ostectomy. Case 2 had radiographic evidence of IOHC bilaterally diagnosed radiographically by the referring veterinary surgeon but the right condyle fractured in the days preceding referral. This elbow was repaired using a conventional lag screw technique combined with a transcondylar ABCD but this elbow is not included in this study. Case 7 had an incomplete lateral epicondylar fissure evident on radiography. The average ABCD diameter was 4.6 mm (range 4-7mm). Histopathology of the intercondylar fissure showed a haphazard distribution of variably sized chondrocytes with little evidence of osteoid deposition, vascular invasion of these areas was not evident. BVOA: Proceedings Autumn Scientific Meeting November

52 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Resolution of lameness was noted at an average of 5.7 weeks (range 1-12 weeks). Radiographic assessment at weeks demonstrated bridging of the intercondylar fissure for all elbows transplanted with ABCD but not for two elbows where autogenous cancellous graft had been employed. CT follow-up in five cases, six elbows at an average time postoperatively of 3.5 months (range 3-5months) documented osseous unification in five elbows. The elbow that did not demonstrate osseous unification used an Acutrak screw placed distally to a core filled with free cancellous bone graft. VAS functional questionnaires for 5/7 dogs returned between 10 and 25 months post-operatively showed an improvement in all functional parameters for all cases. Lameness was not a feature in any of the elbows and all owners indicated they would have the procedure performed again. Complications included soft tissue infection at the donor site in case 1 and seroma at the recipient site in case 2 both of which responded to symptomatic medical treatment. DISCUSSION Marcellin-Little et al (1994) report that the aetiopathogenesis of IOHC could be a failure of complete ossification of the humeral condyle or a form of stress fracture in which the condylar fissure develops after ossification of the condyle is complete. Butterworth et al (2001) suggested that whichever of these two possible aetiologies is correct the underlying primary cause may be that of elbow incongruency creating abnormal forces leading to these sequelae drawing parallelism to the possible separate aetiology of ununited anconeal process and fragmentation of the medial aspect of the coronoid process (Sjostrom et al 1995, Wind 1986, Wind and Packard 1986). Regardless of aetiology, the objective of surgical intervention is resolution of lameness and achievement of durable osseous unification of the humeral condyle. Reported treatment modalities attempt to promote osseous unification by intercondylar compression, stabilisation or vascular growth across the fibrous tissue separating the medial and lateral aspects of the humeral condyle. Failure to achieve durable functional osseous unification can explain the complications seen with failure of lameness resolution, implant fatigue and in rare cases condylar fracture. The authors postulate that IOHC is optimally managed as an atrophic nonunion and AO techniques sanction the use of cancellous bone graft to promote osseous unification. The use of a cortico-cancellous dowel as a biological implant to promote osseous unification would function as a self-perpetuating, biologically responsive implant capable of responding to mild chronic stresses. A single case report discussed this concept of promotion of osseous unification with an autogenous bone graft but was not performed due to concerns of communication of the fissure and the joint (Rovesti et al 1998). The use of a bone dowel should provide biological fusion capable of responding to ongoing cyclic stresses across the fissure line in contrast to an inert metallic implant. ABCD was used alone for Case 1 with a good clinical response and documented unification but the authors considered the trabecular cancellous bone harvested would yield poor mechanical strength in the immediate postoperative period. Case 2 fractured the right condyle prior to referral and following this repair an ABCD was used to treat the lameness on the left condyle attributed to IOHC. Initial mechanical stability of the condyle in the immediate post operative period was considered paramount due to suboptimal weight bearing on the right elbow. The structural ability of the core came under scrutiny and the consideration of augmentation of the dowel iteratively evolved to employ a cross pin configuration for case 2 and subsequently an Acutrak screw for remaining cases. BVOA: Proceedings Autumn Scientific Meeting November

53 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE The concurrent use of a screw and dowel in parallel presented technical challenges to afford largest possible dowel diameter for maximal cross sectional osseous unification plus maximization of screw diameter providing an increased area moment of inertia to resist fracture. The Acutrak screw provides reproducibly accurate placement via guide wire and superior mechanical characteristics by comparison with a comparably sized AO screw (Wheeler and McLoughlin 1998, Eddy et al 2004, Galuppo et al 2002). We propose that positioning the screw distal to the graft optimizes resistance of distractive forces at the intercondylar interface immediately subjacent to the articular surface which intuitively would constitute the focus of maximal load. We felt it important that the technique could be evolved for application without fluoroscopy, to facilitate widespread use in clinical practice. In this series we have considered a return to soundness as a successful outcome in the short term and CT evidence of osseous unification as a positive treatment outcome (as defined by an area of continuous trabecular bone uniting the medial and lateral components of the humeral condyle and spanning the previous area of incomplete ossification). The mechanical properties and minimal effective diameter of the transcondylar bridge, in addition to long term efficacy of this technique has yet to be elucidated. The failure of osseous unification in Case 4 was associated with use of free packed cancellous bone graft and an Acutrak screw. Causes of failure of unification could include bacterial infection, poor vascularity, lack of intact continuous trabecular structure and overzealous tamping of the graft resulting in concretion crushing of fragmented trabecular bone pattern. Clinical, radiographic or CT evidence of bacterial infection was absent. Poor vascularity in the area of fissures may be a concern. Histopathology in one case demonstrated an absence of vascularity and Larsen et al (1999) documented poor blood supply in cocker spaniels that may predispose to fracture or incomplete ossification. Subjectively there is less haemorrhage from the intercondylar bone noted during core removal than is seen during similar coring procedures in the application of OATS grafting for OCD lesions of the medial humeral condyle. Positive angiography during CT scanning could elucidate the vascularity of cases with IOHC. The effects of loss of intact trabecular structure in the transplanted bone remain a significant concern and the author has abandoned use of free cancellous autograft for treatment of IOHC in favor of the biologically undisturbed structure of an ABCD. Osteochondral plugs in rabbits have been noted to have united into the subchondral bed at between 2 and 4 weeks. (Makino et al 2001, 2004) The optimal donor site should maximize trabecular, cellular and structural properties of the ABCD and yield a dowel of suitable length. Proximal tibia and distal femur are currently preferred sites. Morbidity at the donor site was low with no major complications noted in the short to medium term. CONCLUSIONS The use of transcondylar ABCD can achieve osseous unification of the humeral condyle and resolution of associated lameness in cases of IOHC. CT was useful to establish the efficacy of this technique. The Acutrak TM system allows reproducibly accurate screw placement affording maximal ABCD diameter and a postulated increase in mechanical stiffness of the condyle-graft construct. The authors propose that the combination of a transcondylar ABCD and Acutrak screw placed distal to the graft affords short-term stability and long-term condylar fusion, with resolution of lameness in the short and medium term at least. This technique is deemed worthy of consideration for treatment of IOHC in medium to large breed dogs. BVOA: Proceedings Autumn Scientific Meeting November

54 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE References Anderson TJ Carmichael S, Miller A (1990) Intercondylar humeral fracture in the dog: A review of 20 cases. Journal of Small Animal Practice 31: Beale BS, Hulse DA, Sculz KS, Whitney WO (2003) Small Animal Arthroscopy. Saunders, Philadelphia, Pennsylvania Butterworth SJ, Innes JF (2001) Incomplete humeral condylar fractures in the dog. Journal of Small Animal Practice 42(8): Carrera IC, Hammond GH, Sullivan M. (2006) Computerised tomographical features of the incomplete ossification of the humeral condyles. Clinical Abstract, BSAVA Congress Cook JL, Jordan RC (1997) What is your diagnosis? Journal of American Veterinary Medical Association 310(3) Eddy AL, Galuppo LD, Stover SM, Taylor KT, Jensen DG (2004) A biomechanical comparison of headless tapered variable pitch compression and AO cortical bone screws for fixation of a simulated midbody transverse fracture of the proximal sesamoid bone in horses. Veterinary Surgery 33: Galuppo LD, Stover SM, Jensen DG (2002) A biomechanical comparison of equine third metacarpal condylar bone fragment compression and screw pushout strength between headless tapered variable pitch and AO cortical bone screws. Veterinary Surgery 31: Hare WC (1961) The ages at which the centres of ossification appear roentgenographically in the limb bones of the dog. American Journal of Veterinary Research 90: Kaderly RE, Lamothe M (1992) Incomplete humeral condylar fracture due to minor trauma in a mature cocker spaniel. Journal of the American Animal Hospital Association 28: Larsen LJ, Roush JK, McLaughlin RM, Cash WC (1999) Microangiography of the humeral condyle in cocker spaniel and non-cocker spaniel dogs. Veterinary Comparitive Orthopaedics and Traumatology 12: Makino T, Fujioka H, Kurosaka M, Matsui N., Yoshihara H, Tsunoda M, Mizuno K (2001) Histological analysis of the implanted cartilage in an exact-fit osteochondral transplantation model. Arthroscopy 17(7): Makino T, Fujioka H, Terukina M, Yoshiya S, Matsui N, Kurosaka M (2004) The effect of graft sizing on osteochondral transplantation. Journal of Arthroscopic and Related Surgery 20(8): Marcellin-Little DJ, DeYoung DJ, Ferris KK, Clifford MB (1994) Incomplete ossification of the humeral condyle in spaniels. Veterinary Surgery 23: Marcellin-Little DJ, Roe SC, DeYoung DJ (1996) What Is Your diagnosis? Journal of American Veterinary Medical Association 209(4) Miller A (1995) Letter to the editor. Veterinary Surgery 24:176 Piccionello AP, Martini FM, Bottarelli E (2003) Risk factor analysis in humeral condyle fractures in the dog: retrospective study. Free Communication 13 th ESVOT Congress, Munich 2003 Robin D, Marcellin-Little DJ (2001) Incomplete ossification of the humeral condyle in two labrador retrievers. Journal of Small Animal Practice 42: Rorvik AM (1993) Risk factors for humeral condylar fractures in the dog: A retrospective study. Journal of Small Animal Practice 34: Rovesti GL, Fluckiger M, Margini A, Marcellin-Little DJ (1998) Fragmented coronoid process and incomplete ossification of the humeral condyle in the rottweiler. Veterinary Surgery 27:354-7 Samii VF, Hornof WJ (2001) Incomplete ossification of the humeral condyle in the vietamese potbellied pigs. Veterinary Radiology and Ultrasound 41(2) Smith,TJ, Fitzpatrick N, O Riordan J (2006) Treatment of incomplete ossification of the humeral condyle (IOHC) using autogenous cancellous bone graft and a self-compressing variably pitched screw. Abstract, Scientific Programme, BSAVA congress, Birmingham. April Vahey JW, Lewis JL, Vanderby R Jr. (1987) Elastic moduli, yield stress and ultimate stress of cancellous bone in the canine proximal femur. Journal of Biomechanics 20(1):29-33 Van Ryssen B (2005) Advanced Arthroscopy Course, BSAVA Spring Scientific Meeting, 6 th April 2005, Birmingham, UK Vannini R, Olmstead ML, Smeak DD (1988) Humeral condylar fractures caused by minor trauma in 20 adult dogs. Journal of the American Animal Hospital Association 24: BVOA: Proceedings Autumn Scientific Meeting November

55 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Vannini R, Smeak DD, Marvin L (1988) Evaluation of surgical repair of distal humeral fractures in dogs and cats. Journal of the American Animal Hospital Association 24: Voorhout G, Nap RC, Hazewinkel HAW (1987) A radiographic study on the development of the antebrachium in Great Dane pups on different calcium diets. Veterinary Radiology 28(4): Wheeler DL, McLoughlin SW (1998) Biomechanical assessment of compression screws. Clinical Orthopaedics and Related Research 350: Wind AP, Packard ME (1986) Elbow incongruity and developmental elbow diseases in the dog Parts 1 and 2: Journal of the American Animal Hospital Association 22: BVOA: Proceedings Autumn Scientific Meeting November

56 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE SHOULD WE BE TREATING INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE MORE AGGRESSIVELY? John F Ferguson BVM&S CertSAO MRCVS East Neuk Veterinary Clinic Station Road, Netherton Estate, St Monans, Fife INTRODUCTION Incomplete ossification of the humeral condyle (IOHC) is an uncommon cause of forelimb lameness in dogs 1, 2, 3. IOHC may be a genetic disease with a recessive mode of inheritance in some Spaniel breeds predisposing them to humeral condylar fracture (HCF) 1. Once diagnosed, treatment of IOHC is usually recommended to resolve forelimb lameness and to prevent the occurrence of HCF 1, 2, 3, 4, 5, 6. One study showed that 43% of dogs with IOHC fracture their humeral condyle between 11 days and 18 months after diagnosis 1. Management of the condition is still controversial, however treatment of IOHC by placement of a transcondylar screw in either a positional 5 or lagged fashion is currently the treatment of choice 2, 3, 4, 5. In addition to screw placement, drill holes can be created across the intercondylar region adjacent to the screw in an attempt to achieve bony union 1, 2, 5, 6 although sometimes with limited success. One report describes the use of bone tunnels without screw placement to try and promote ossification but with a poor outcome 4. Despite good to excellent clinical results, in most cases treated with single transcondylar screw placement, post-operative radiography often reveals persistence of the fissure or only partial obliteration 2, 3. Furthermore, if the condyle does not unite, cyclical loading of the implant will occur potentially leading to implant failure 2, 7,10,11. Gnudi analysed bone biopsies histologically, removed at the time of fracture repair, in an English Pointer and reported the results to be consistent with an atrophic non-union fracture 5. Similar results were found in Marchellin-Little s study where biopsy samples were taken from the intercondylar fracture site in two Cocker Spaniels revealed fibrous tissue to be present. However, no evidence of chondrocytes or cartilage matrix was found 1. To the author s knowledge, there are no reports documented in the veterinary literature of the treatment of IOHC by osteotomy of the lateral epicondylar ridge creating a lateral humeral condyle fracture which allows exposure of the intercondylar area and insertion of autogenous cancellous bone graft into drill holes created in both the lateral and medial portions of the humeral condyle. Subsequently, this surgically created lateral humeral condyle fracture is repaired using a transcondylar lag screw and an anti-rotational lag screw placed across the lateral epicondylar ridge. BACKGROUND The creation of maximum stability and the encouragement of osteogenesis are of paramount importance in the treatment of non-union fractures 8, 9. This generally involves removal of fibrous tissue in combination with curettage (or even ostectomy of the fracture ends) of the fracture site and the use of bone grafts. The fracture then requires to be rigidly stabilised, generally with some form of internal fixation 8, 9. If one were to consider that if, as suggested, BVOA: Proceedings Autumn Scientific Meeting November

57 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE the pathology in dogs with IOHC was comparable to atrophic non-union, the recognised treatment would be that described above, namely: ÿ Open the fracture site ÿ Curette the fracture surfaces ÿ Create drill holes into bone to open vascular channels and increase the surface area of the fracture site ÿ Placement of autogenous cancellous bone graft ÿ Achieve rigid interfragmentary stability The question arises: Is the prognosis for dogs that lhave had IOHC and subsequently suffer a HCF more favourable than treatment of IOHC before fracture? Certainly, during the treatment for intercondylar fractures all the criteria listed above can be met 10. Therefore, how could these criteria for treating non-unions be instituted in the IOHC case? The author hypothesised that by creating an osteotomy through the lateral epicondylar ridge into the supracondylar foramen it would be possible to open the fracture at the IOHC site, allow curettage of the area, remove fibrous tissue present, create satellite drill holes, place cancellous bone graft and then achieve rigid interfragmentary stability by using a transcondylar lag screw and a second lag screw to repair the osteotomy. This should, in theory, result in an increased incidence of ossification in the intercondylar area. Only mature dogs with radiographic evidence of a discrete, narrow radiolucent line were chosen for this treatment. Immature dogs with IOHC land a wide radiolucent region in the intercondylar area were excluded due to the probable need to remove a large portion of nonossified material before healthy bone could be exposed. This would change the architecture of the intercondylar area significantly making reduction of the condyle difficult. SURGICAL TECHNIQUE The affected limb is prepared aseptically for surgery and the patient is positioned in laterall recumbency with the affected limb up. A craniolateral approach to the distal humerus and elbow is performed by elevation and reflection of the origin of the external carpi radialis muscle and the tissues of the joint capsule taking care to identify and protect the radial nerve 12. The cranial compartment of the elbow is exposed and usually the intercondylar fissure can be visualised confirming the presence of the IOHC. The supracondylar foramen is then located and a reciprocating saw is used to create a linear osteotomy through the proximal aspect of the foramen at around to the long axis of the humerus. Figure 1 illustrates the direction and position of the osteotomy. While the osteotomy is being created the saw blade is copious lavaged with saline to limit thermal necrosis. An elevator is then used to prize open the osteotomy site. The intercondylar area splits apart ldue to the presence of the IOHC and outward rotation of the lateral condyle of the humerus it therefore possible. Usually, fibrous tissue is present at the IOHC sitel and this is gently removed by curettage. A pilot hole is drilled in the lateral condyle and multiple small holes (usually 1.5mm diameter) are drilled around the pilot hole and on the medial surface of the intercondylar fracture in an attempt to stimulate osteogenesis and bony healing 1, 2, 6. The pilot hole BVOA: Proceedings Autumn Scientific Meeting November

58 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE is then enlarged to create a gliding hole to accept the transcondylar screw. Cancellous bone graft harvested from the drill flutes is packed into the drill holes and thel fracture is then reduced and a hole is then drilled into the medial condyle using a drill guide as described by Denny 13. The intercondylar fracture is then reduced, aligning the osteotomy of the lateral epicondylar ridge and ensuring the articular surface on the cranial aspect of the joint is also reduced accurately and held in position by large polinted reduction fragment forceps. A lag screw, slightly longer than the transcondylar distance, to aid removal if failure occurs, is placed and tightened and the osteotomy repaired by la second lag screw. Range of elbow flexion and extension is repeatedly assessed during surgery and the wound thoroughly lavaged. Cancellous bone graft is placed around the osteotomy site before routine wound closure. POST-OPERATIVE CARE AND FOLLOW-UP Post-operative radiographs are obtained to assess screw placement, position and length in addition to fracture alignment. A modified Robert-Jones bandage is placed on the limb for 3 days and the owners instructed that their animals should be confined to a kennel for 3 weeks then lead exercised only until follow-up radiography is performed at around between 9-12 weeks post-operatively. The dog is then permitted to return to full activity if satisfactory progress has been made. RESULTS Previously unpublished data from a retrospective study of 10 dogs (12 elbows) with IOHC treated at the East Neuk Veterinary Clinic between September 2000 and April 2006, including the results of CT scans performed on two of the treated elbows, will be presented. CONCLUSIONS A craniomedial approach to the elbow with osteotomyl of the lateral epicondylar ridge, creating a lateral humeral condyle fracture allows lcurettage of the incomplete ossification site, drilling of satellite holes and placement of autogenous cancellous bone graft. This method gave good to excellent clinical results in all treated cases of IOHC comparable to other published techniques 2, 3. In many dogs, post-operative radiographs showed evidence of increased ossification in the intercondylar region with no radiolucent line visible in 33% of cases. However, it was difficult to assess if this was due to complete bony union or to other factors such as variations in radiographic exposure and positioning. CT scans performed postoperatively on two elbows showed artefacts created by the transcondylar screw and were unhelpful in imaging the intercondylar area. It would appear that the described technique offers little advantage over the placement of a single transcondylar lag screw in the treatment of IOHC. Furthermore, the more involved surgery incrleases the risk of complications making the technique difficult to recommend. ACKNOWLEDGEMENTS The author wishes to thank Stephen Clarke for contributing a case to this series, for reviewing the radiographs and for his constructive comments during preparation of this presentation. References 1. Marcellin-Little, D.J., DeYoung, D.J., Ferris, K.K. & Berry, C.M. (1994) Incomplete ossification of the humeral condyle in Spaniels. Veterinary Surgery 23, Butterworth, S.J. & Innes, J.F. (2001) Incomplete humeral condylar fractures in the dogs. Journal of Small Animal Practice 42, BVOA: Proceedings Autumn Scientific Meeting November

59 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE 3. Meyer-Lindenberg, A., Heinen, V., Fehr, M. & Nolte, I. (2002) Incomplete ossification of the humeral condyle as the cause of lameness in dogs. Veterinary and Comparative Orthopaedics and Traumatology 15, Rovesti, G. L. Fluckiger, M., Margini, A. Marcellin-Little, D. J. (1998) Fragmented coronoid process and incomplete ossification of the humeral condyle in a Rottweiler. Veterinary Surgery 27, Gundi, G., Martini, F.M., Zannichelli, S., Volta, A., Bertoni, G., Del Bue, M. & Borghetti (2005) Incomplete humeral condylar fracture in two English Pointer dogs. Veterinary and Comparative Orthopaedics and Traumatology 18, Robin, D & Marcellin-Little, D.J. Incomplete ossification of the humeral condyle in two Labrador rerievers. Journal of Small Animal Practice 42, Carmichael, S. Incomplete humeral condylar ossification (2004). Proceedings of the 23 rd Veterinary Symposium of American College Veterinary Surgeons, Denver, Colorado, 6-9 October 2004, pp Bennet, D. (2006) Complications of fracture healing. In: Small Animal of Fracture Repair and Management 2 nd edn. Eds A.R. Coughlan and A.M. Miller. BSAVA, Gloucester. pp Sumner-Smith G (1991) Delayed unions and non-unions. Veterinary Clinics of North America. Small Animal Practice 21, Cook, L.J. Tomlinson, J.L. & Reed, A.L. (1999) Flouroscopically guided closed reduction and internal fixation of the lateral portion of the humeral condyle: Prospective clinical study of the technique and results in ten dogs. Veterinary Surgery 28, Larsen, L.J., Roush, J.K., McLaughlin, R.M. & Cash, W.C. (1999) Microangiography of the medial humeral condyle in Cocker Spaniel and non-cocker Spaniel dogs. Veterinary and Comparative Orthopaedics and Traumatology 12, Piermattei, D.L. (1993) The Thoracic limb. In: An Atlas of Surgical Approaches to the Bones and Joints of the Dog and Cat. 3 rd edn. Eds D.L. Piermattei and K. A. Johnson. W. B. Saunders, Philadelphia. pp Denny H. R. (2006) The humerus. In: Small Animal of Fracture Repair and Management 2 nd edn. Eds A.R. Coughlan and A.M. Miller. BSAVA, Gloucester. pp BVOA: Proceedings Autumn Scientific Meeting November

60 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE FRACTURES ASSOCIATED WITH IOHC: CURRENT CONCEPTS IN THE MANAGEMENT OF CONDYLAR FRACTURES OF THE HUMERUS Malcolm McKee BVMS MVS DSAO MACVSc MRCVS RCVS recognised specialist in small animal surgery (orthopaedics) Willows Referral Service, Solihull Why are condylar fractures of the humerus challenging? Condylar fractures of the humerus are articular fractures with relatively small distal fragments. The anatomy of the condyle, especially laterally, is complex. Exposure and reduction of Y-T fractures is difficult. Furthermore these fractures may have supracondylar comminution. Many fractures, especially lateral condylar fractures, are in immature dogs less than six months of age where bone stock is limited and quality of bone is poor. Incomplete ossification of the humeral condyle may predispose to condylar fracture and this has a number of important implications. As with all articular fractures the aims of management should include precise reconstruction of the articular surface and rigid fracture fragment fixation. These are necessary to enable early postoperative weight bearing and physiotherapy, and to limit the development of osteoarthritis. Controlled, early active motion of the affected joint and limb is important to minimise periarticular soft tissue contracture, restricted range of joint motion, muscle atrophy and osteoporosis ( fracture disease ). Concomitant incomplete ossification of the humeral condyle The width of the fissure in the condyle prior to fracture is quite variable. Transcondylar lag screw compression in dogs with a wide fissure may deform the condyle and result in poor joint congruency. This may contribute to pain and osteoarthritis. Failure of the intracondylar portion of the fracture to heal is not uncommon and this may predispose to re-fracture of the condyle in the long-term. The signalment and history may be suggestive of underlying IOHC, for example, a lateral condylar fracture developing with normal activity in a 3-year-old springer spaniel. Careful radiographic examination of the intracondylar fracture may reveal sclerosis. There may be evidence of remodelling on one or both of the epicolndylar crests. The contralateral elbow should be radiographed and examined for evidence of IOHC. CT is more sensitive compared to radiography at detecting IOHC (Rovesti and others 2002). The surface of the intracondylar fracture may be examined intraoperatively. IOHC is associated with hard sclerotic bone rather than soft cancellous bone. When underlying IOHC is suspected it should be considered that the intracondylar portion of the condyle may never heal. Furthermore radiography is insensitive for monitoring healing. CT is preferable. As large a transcondylar screw as possible should be used to reduce the risk of fatigue failure (Muir and others 1995). Screw stiffness is dependent on the area moment of inertia which is dependent on the radius of the core of the screw to the fourth par. Epicondylar crest repair should also be as strong as possible. Bone plates are generally preferable to pins, BVOA: Proceedings Autumn Scientific Meeting November

61 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE however, their use can be dictated by the available bone stock and quality of bone for screw purchase. Combined bone plate and pin (plate-rod) fixation should be considered. LATERAL CONDYLAR FRACTURES These are the most common type of condylar fracture. Dogs tend to be either less than six months of age or greater than two years of age (Denny 1983, Vannini and others 1998, Tonzing and others 2004). The management and prognosis vary between the two groups. IOHC may be more common in the older age group. Lateral condylar fractures are often missed on mediolateral radiographs and as a result are often referred many days later when they are more difficult to reduce and stabilise. The orthogonal craniocaudal view should be routinely obtained. Fixation in the immature dog A transcondylar lag screw should be placed distal to the physis if possible. A washer may be employed. If the screw strips the thread in the medial fragment a nylon nut may be attached to the end of a longer screw. It is important that fixation is applied to the latleral epicondylar crest fracture to counteract rotational instability. One or two pins are often sufficient provided this region is not comminuted. A lag screw would be preferable if the fracture orientation enabled placement. Bone plate +/- pin fixation should be considered in dogs with multiple limb injuries, e.g. bilateral condylar fractures. Fixation in the mature dog As large a transcondylar lag screw as possible should be placed generally 4.5 mm in an average springer spaniel. A bone plate +/- pin should be applied to the lateral epicondylar crest fracture. The pros and cons of applying the plate in compression, neutralisation or buttress mode should be considered. The author favours the use of a cuttable plate. Reconstruction plates are easier to contour, however, are likely to be more prone to failure. Use of a locking plate would avoid the necessity for accurate contouring. The plate should be placed on the caudolateral surface of the bone. Care should be taken to ensure screws do not penetrate the articular surface or olecranon fossa. Postoperative care A modified Robert Jones dressing may be applied for three to five days. Passive range-ofmotion exercise may be started following removal and hydrotherapy after one to two weeks. Exercise should otherwise be restricted to that on a lead (short walks frequently), for six to 12 weeks. At other times strict confinement should be enforced with avoidance of jumping and climbing. Prognosis The prognosis in immature dogs is generally good provided fractulre reduction is accurate, fixation is appropriate and postoperative care instructions are adhered to. Similar results may be obtained in adult dogs provided a large transcondylar screw is employed and a bone plate +/- pin is applied to the lateral epicondylar crest (Tonzing and others 2004). The use of pins alone to repair the latter is more likely to result in a catastrophic complication, especially when there is concomitant IOHC. The incidence of long-term re-fracture due to failure of the intracondylar fracture to heal is unknown. In the author s experience it is uncommon. BVOA: Proceedings Autumn Scientific Meeting November

62 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE MEDIAL CONDYLAR FRACTURES These are relatively uncommon compared to lateral condylar fractures. The medial epicondylar crest fracture is often oblique and may be repaired with a lag screw in combination with a transcondylar lag screw. A bone pllate in buttress mode may be readily applied to the relatively flat medial humerus to augment the fixation. The prognosis is generally good despite the inevitable development of osteoarthritis. Y-T CONDYLAR FRACTURES These fractures require careful pre-operative assessment. Consider (1) immature vs. mature dog, (2) Y vs. T fracture configuration, (3) 3-fragmnent fracture vs. supracondylar comminution, (4) unilateral vs. bilateral condylar fractures. Well positioned orthogonal view radiographs are essential. A craniocaudal view with the patient in dorsal recumbency and the limb directed caudally (abducted slightly from the chest), enables the humerus to be positioned perpendicular to the x-ray beam and parallel to the cassette. Anatomic reduction has been purported to be the primary component necessary for satisfactory long-term outcome with all articular fractures. However, in a study of 15 humeral condylar fractures accuracy of articular fracture rleduction did not correlate with follow-up osteoarthritis score, peak vertical force, vertical impulse, range of elbow joint flexion or extension. Osteoarthritis developed or progressed in all elbows (Gordon and others 2003). Furthermore, Cook and others (1999) reported that there was no significant difference between anatomically reduced fractures of the lateral portion of the humeral condyle when compared to poorly reduced fractures with regards to osteoarthritis score or range of joint motion. Despite these findings it is important the alrticular component of Y-T condylar fractures is reduced as accurately as possible. Surgical exposure Accurate articular fracture reduction requires good surgical exposure of the fragments. Approaching the distal humerus caudally by olecranon osteotomy or triceps tenotomy has been the tradition (Dueland 1974, Bardet and others 1983, Denny 1983, Vannini and others 1988, Anderson and others 1990, Sturgeon and others 2000). The caudal approach enables accurate anatomic reduction of the intracondylar fracture, however, it involves significant dissection of the joint capsule and other regional soft tissues, and complication rates with osteotomy of the olecranon have been reported to be as high as 37 % (Bardet 1983, Palmer and others 1988, Anderson and others 1990, Halling and others 2002). Furthermore, caudal retraction of the triceps muscle mass is restricted and thus access to the mid and proximal humeral diaphysis is limited. Exposure of the latter is often necessary when managing fractures with supracondylar comminution. Combined medial and lateral approaches provides excellent exposure of the entire medial and lateral humerus and avoids osteotomy complications. A disadvantage is inability to assess accuracy of intracondylar fracture reduction. In selected cases olecranon osteotomy may be combined with medial and lateral approaches. Methods of fixation A transcondylar lag screw is the preferred method of stabilising the intracondylar component of "Y-T" fractures. The repaired condyle may be attached to the humeral shaft using bone plates, lag screws, Steinmann pins or Kirschner wires. Unilateral fixation of the medial epicondylar ridge has been described more commonly than bilateral fixation of the medial and BVOA: Proceedings Autumn Scientific Meeting November

63 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE lateral epicondylar ridges. Complications and persistent lameness are not uncommon following unilateral fixation (Denny 1983, Vannini and others 1988, Anderson and others 1990). Anderson and others (1990) and Vannini and others (1988) reported limb function to be poor or fair in 36% (5/14) and 48% (11/23) of fractures respectively. Inadequate construct stability is considered to be a key problem and some authors have recommended cage rest or external support with a body cast for the first few weeks following surgery (Denny 1983, Anderson and others 1990). A reduced range of joint motion, especially flexion, is a common feature of humeral condylar fracture surgery (Sturgeon and others 2000, Gordon and others 2003). Bilateral fixation via bilateral approaches (McKee and others 2005) The sequence of fracture fixation and thus the order of the surgical approaches is dictated by the configuration of the fracture fragments. It is often preferable to reduce and stabilise the major fragments, with the exception of the lateral aspect of the humeral condyle, via a medial approach prior to reducing and stabilising the latelral aspect of the humeral condyle via a lateral approach. In this scenario the patient is positioned in dorsolateral recumbency with the affected limb down and the contralateral limb secured caudally. To assist repositioning the dog intraoperatively the affected limb is freely draped and the pelvis is supported in dorsal recumbency in a trough. A skin incision is made over the medial aspect of the distal humerus. The brachial artery and vein and the median nerve are carefully dissected and protected with a Penrose drain, and the biceps brachii muscle and the ulnar nerve are retracted cranially and caudally respectively. The medial aspect of the humeral condyle, any supracondylar fragments and the proximal humerus are reduced and stabilised with a bone plate or Kirschner wires. Where possible, lag screws or cerclage wires are also employed. When a blone plate is used it is positioned on the caudal aspect of the medial humerus and the screws are directed craniolaterally. Care is necessary to avoid the most distal screws penetrating the articular surface and the olecranon fossa. The wound is packed with saline soaked swabs and the patient repositioned in contralateral recumbency. The distal aspect of the lateral humerus is exposed taking care to protect the radial nerve. Outward rotation of the lateral aspect of the condyle enables removal of haematoma from the intracondylar fracture site. The fracture is reduced and a transcondylar lag screw placed via the "inside-out" technique. A washer is used in immature dogs. Alignment of the lateral epicondylar ridge fracture and, or, the articular surface (examined via a cranial arthrotomy), is used to assess reduction of the intracondylar fracture. Bone plate or Kirschner wire fixation is used to stabilise the lateral epiclondylar ridge fracture. Bone plates are positioned on the caudal aspect of the lateral humerus and the screws directed craniomedially. Care is taken to avoid the screws penetrating the articular surface and the olecranon fossa. Range of elbow flexion and extension are repeatedly assessed during surgery. The medial and lateral wounds are thoroughly lavaged prior to closure. An alternative to repairing the supracondylar fracture prior to reducing the intracondylar fracture is to repair the humeral condyle with a transcondylar lag screw via a lateral approach prior to reducing the supracondylar fracture(s). With this technique articular alignment may be assessed through an incision of the joint capsule on the cranial aspect of the capitulum. Although technically more difficult there is the advantage of being able to more accurately reduce the intracondylar fracture and thus avoid articular step and gap defects. The clinical and radiographic short-term outcome of bilateral fixation of 30 Y-T fractures via combined medial and lateral approaches in 29 dogs has recently been reported (McKee BVOA: Proceedings Autumn Scientific Meeting November

64 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE and others 2005). Age ranged from three months to nine years and body weight from 1.9 to 48 kg. The humeral condyle was reattached to the shaft using medial and lateral bone plates in 18 fractures, a medial plate and lateral Kirschner wire(s) in six fractures, and medial and lateral Kirschner wires in six fractures. Major complications were recorded in four fractures and minor complications in two fractures. Limb function at follow-up was graded as excellent in 12, good in 15 and fair in three. The range of elbow flexion was normal in seven, mildly reduced in 18, moderately reduced in four and severely reduced in one. Although in this series combined medial and lateral approaches enabled fracture reconstruction and load sharing in all cases, some highly comminuted humeral condylar Y-T fractures are not reconstructable. Bilateral buttress plate fixation may be appropriate in these non-load sharing fractures. References and further reading Anderson, T. J., Carmichael, S. & Miller, A. (1990) Intercondylar humeral fracture in the dog: A review of 20 cases. Journal of Small Animal Practice 31, Bardet, J. F, Hohn, R. B., & Rudy, R. L. (1983) Fractures of the humerus in dogs and cats. A retrospective study of 130 cases. Veterinary Surgery 12, Butterworth, S. J. & Innes, J. F. (2001) Incomplete humeral condylar fractures in the dog. Journal of Small Animal Practice 42, Cook, J. L., Tomlinson, J. L. & Read, A. L. (1999) Fluoroscopic guided closed reduction and internal fixation of fractures of the lateral portion of the humeral condyle: Prospective clinical study of the technique and results in ten dogs. Veterinary Surgery 28, Denny, H. R. (1983) Condylar fractures of the humerus in the dog: A review of 133 cases. Journal of Small Animal Practice 24, Dueland, R. T. (1974) Triceps tenotomy approach for distal fractures of the canine humerus. Journal of the American Veterinary Medical Association 165, Gordon, W. J., Besancon, M. F., Conzemius, M. G., Miles, K. G., Kapatkin, A. S. & Culp, W. T. N. (2003) Frequency of post-traumatic osteoarthritis in dogs after repair of a humeral condylar fracture. Veterinary and Comparative Orthopaedics and Traumatology 16, 1-5 Halling, K. B., Lewis, D. D., Cross, A. R., Kerwin, S. C., Smith, B. A. & Kubilis, P. S. (2002) Complication rate and factors affecting outcome of olecranon osteotomies repaired with pin and tension-band fixation in dogs. Canadian Veterinary Journal 43, Marcellin-Little, D. J., Deyoung, D. J., Ferris, K. K. & Berry, C. M. (1994) Incomplete ossification of the humeral condyle in spaniels. Veterinary Surgery 23, McKee W. M., Macias C. & Innes J. F. (2005) Bilateral fixation of Y-T humeral condyle fractures via medial and lateral approaches in 29 dogs. Journal of Small Animal Practice 46, Muir, P., Johnson, K. A. & Markel, M. D. (1995). Area moment of inertia for comparison of implant cross-sectional geometry and bending stiffness. Veterinary and Comparative Orthopaedics and Traumatology 8, Palmer, R. H., Aron, D. N. & Chambers, J. N. (1988) A combined tension band and lag screw technique for fixation of olecranon osteotomies. Veterinary Surgery 17, Rovesti, G. L., Biasibetti, M., Schumacher, A. & Fabiani, M. (2002) The use of computed tomography in the diagnostic protocol of the elbow in the dog: 24 joints. Veterinary and Comparative Orthopaedics and Traumatology 15, Sturgeon, C., Wilson, A. M., Mcguigan, P., Lawes, T. J. & Muir, P. (2000) Triceps tenotomy and double plate stabilization of Y-T fracture of the humeral condyle in three dogs. Veterinary and Comparative Orthopaedics and Traumatology 13, Tonzing, M. A., Mckee, W. M. & Macias, C. (2004) Management of fractures of the lateral aspect of the humeral condyle in 34 dogs. BSAVA Clinical Research Abstract, 573 Vannini, R., Smeak, D. D. & Olmstead, M. L. (1988) Evaluation of surgical repair of 135 distal humeral fractures in dogs and cats Journal of the American Animal Hospital Association 24, BVOA: Proceedings Autumn Scientific Meeting November

65 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE REPAIR OF Y-T HUMERAL CONDYLAR FRACTURES: A NOVEL TECHNIQUE USING EXTERNAL SKELETAL FIXATION AND A TRANSCONDYLAR LAG PIN WITH OLIVE John F Ferguson BVM&S CertSAO MRCVS East Neuk Veterinary Clinic Station Road, Netherton Estate, St Monans, Fife INTRODUCTION Fractures involving the medial and lateral condyles of the humerus are termed Y or T fractures because of the configuration of the fracture lines and can account for approximately 38% of all humeral fractures 1. They can be one of the most challenging type of fractures to repair in small animal orthopaedics and studies have shown that the prognosis for a Y-T fracture is less favourable than that for a unicondlylar fracture 2, 3, 4 with one study suggesting satisfactory results in only 52% of cases 2. The post-operative complication rate can be high using a transolecrannon approach to the elbow with a 37-56% complication rate related to the ulna osteotomy alone 5, 6. Combined medial and lateral approaches to the fracture site have been advocated 4, 7, 8 with a recent report showing good to excellent results in 90% of cases using this approach 9. Repair of supracondylar fractures of the humerus using external skeletal fixation with distal pins placed transcondylarly with the fixation augmented with or without the use of intramedullary pins has been described with good results 10, 11, 12, 24. Radasch reported a technique of repairing Y-T fractures using a single transcondylar lag screw and a transcondylar external fixator pin attached to a type I external fixator tied in to the proximal end of an intramedullary pin placed into the medial condyle of the humerus 8. Techniques for repairing unicondylar humeral fractures have been described using self-compressing Orthofix pins with good long term clinical and radiographic outcomes 13 14,. To the author s knowledge, there are no reports documented in the veterinary literature of repair of Y-T humeral fractures via a unilateral approach usingl a transcondylar external fixation lag pin to give compression across the intercondylar fracture site with external skeletal fixation as the main method of stabilising the fracture. BACKGROUND Numerous factors other than anatomical reduction and rigid fixation influence the overall outcome in the treatment of a Y or T fracture of the humerus. These factors may include the approach used for reduction and fixation and the degree of trauma to the regional soft tissues created by the surgical approach 4, 8, 9, 10. The degree of direct cartilage and soft tissue injury resulting from the forces that have caused the fracture and the surgeon s experience and technique are also important 4, 8, 9, 13, 16. The time taken for repair and the patients age and condition need also to be considered 8, 9, 14, 16. An early return of limb function will minimise the potential development of fracture disease 17. The surgeon can influence some of these factors and others they cannot. In an effort to reduce the degree of morbidity that can occur commonly after Y-T humeral fracture repair, a technique was devised to address some of the problems normally associated with this type of surgery: ÿ Avoid performing an olecranon osteotomy BVOA: Proceedings Autumn Scientific Meeting November

66 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE ÿ ÿ ÿ ÿ ÿ Perform only a unilateral approach to the fracture site Emphasise a more biologic strategy with regards to fracture repair/healing Reduce surgical time Create a relatively simple, repeatable and reliable method when treating Y-T humeral condylar fractures Develop an external fixation pin that would create interfragmentary compression across the intercondylar fracture site when inserted in a lag fashion After a number of home-made prototypes, a positive profile, end threaded extlernal fixation pin was designed and manufactured with an olive bonded to the pin approximately 30mm from its point (ESF lag pin with oliveÿ, Veterinary Instrumentation, Sheffield). This was placed across the intercondylar fracture site to achieve a lag effect using the protruding shaft as a handle to attach to the chuck so the pin could be suitably tightened. The protruding shaft could then be used to attach the connecting bar of the fixator system (Figures 1a and 1 b). SURGICAL TECHNIQUE The affected limb is prepared aseptically for surgery and the patient is positioned in lateral recumbency with the affected limb up. A craniolateral approach to the distal humerus and elbow is performed by elevation and reflection of the origin of the external carpi radialis muscle and the tissues of the joint capsule taking care to identify and protect the radial nerve 15. The fracture site and cranial compartment of the elbow is exposed and the fracture site cleared of haematoma. Outward rotation of the lateral condyle of the humerus allows inspection for any signs of fibrous tissue covering the fracture surfaces that could suggest preexisting incomplete ossification 18, 19, 20. Any fibrous tissue is gently removed by curettage. A pilot hole is drilled in the lateral condyle with a diameter corresponding to the size of the pin shaft using an inside-out technique as described by Denny 20. Multiple small holes (usually 1.5mm diameter) are drilled around the pilot hole and on the medial surface of the intercondylar fracture in an attempt to stimulate osteogenesis and bony healing 21, 22. The intercondylar fracture is then reduced, aligning the fractures of the lateral epicondylar ridge and ensuring the articular surface on the cranial aspect of the joint is also reduced accurately and held in position by large pointed reduction fragment forceps. The drill that was used to make the hole in the lateral condyle is replaced into the condyle and a hole is drilled in a normograde fashion through the medial condyle. The forceps are removed, the lateral condyle is outwardly rotated again and a drill equal to the external diameter of the threads on the olive pin is used to create a gliding hole in the lateral condyle. The fracture is reduced again and the olive external fixator pin is driven through the holes in the humeral condyles tapping its own threads in the medial condyle. Care is taken not to over-tighten the pin and therefore strip the threads in the medial condyle. lthe intercondylar fracture has been stabilised thus converting the Y or T fracture a supracondylar fracture. The distal end of the humeral diaphyseal fracture is now reduced completing reduction of the fracture. Usually the fracture ends will interdigitate with the arms of the ridges of the humeral condyles allowing accurate reduction. Point reduction forceps are used to stabilise the fracture segments and allow the placement of lag screws or cerclage wire (or a combination of both) to further stabilise the reconstructed fracture. Subsequently, an external fixator pin is placed into the proximal aspect of thle humerus just below the shoulder BVOA: Proceedings Autumn Scientific Meeting November

67 INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE Figure 1a. Figure 1b. following the safe corridors that have been previously described 23, 24, 25. The author uses a KE system because the clamps of the Imex system do not give the correct angulation for insertion of the second transcondylar pin. A connecting bar is now placed into clamps on the proximal and distal pins after first sliding two clamps onto the middle of the connecting bar. A second transcondylar end threaded external fixator pin of a much smaller diameter than the olive pin is placed taking case not to violate the articular surface of the humeral condyles. It is usually necessary to have the fixator clamp connecting this pin turned 180ÿ relative to the clamp of the olive pin to allow placement of the pin starting in the lateral condylar ridge. A third pin is then placed in the distal humerus justl proximal or distal to the radial nerve. This pin will often be placed through the surgical wound. A double connecting bar is placed on the most distal and proximal pins to increase the resistance of the apparatus to shear and axial compressive forces 26. Range of elbow flexion and extension is repeatedly assessed dulring surgery and the wound thoroughly lavaged. Corticocancellous bone graft harvested from the drill flutes is packed in and around the fracture site before routine wound closure. POST-OPERATIVE CARE AND FOLLOW-UP Post-operative radiographs are obtained to assess pin placement, position, length and fracture alignment. A bandage is placed around the fixator, packing the space under the bar with sponges over non-adhesive dressings. The whole limb is covered with a dressing for 3-7 days and the bandages changed every two days in the first week post-operatively. Owners are instructed on the care of the pin-skin interfaces 11 and advised their animals should be confined to a kennel and exercised on a leash until the fixator is removed. Follow-up radiography is performed at around 5 weeks and then usually 8-10 weeks post-operatively. If satisfactory radiographic evidence of bone healing is present and the fracture is stable on manipulation after removal of the connecting bars the external fixation pins are removed. In some cases there will be no radiographic evidence of healing of the intercondylar fracture around 5-9 weeks post-operatively, despite good radiographic signs of healing of the supracondylar fractures. This has previously been reported 9. A positional transcondylar screw is therefore usually placed through the hole where the transcondylar lag pin had been located to prevent possible re-fracture of the humeral condyles and radiographs shlould be obtained post-operatively to ensure correct screw placement. The dog is then allowed a graduated increased exercise regime over the month following fixator removal. BVOA: Proceedings Autumn Scientific Meeting November