ELBOW LAMENESS: BASIC

Transcription

1 6/26/16 ELBOW LAMENESS: BASIC Ursula Krotscheck, DVM DACVS Cornell University Outline Main focus: Developmental elbow disease Signalment and History Diagnostics Surgical options and outcomes Elbow Dysplasia 1

2 Elbow Dysplasia Elbow Dysplasia! Definition:! Ununited Anconeal Process (UAP)! Medial Compartment Disease (MCD)! Fragmented Medial Coronoid Process (FMCP)! Osteochondritis Dissicans! Joint Incongruity?! Where does this belong? Elbow Dysplasia! Medial compartment disease! Fragmented medial coronoid process! OCD! Incongruity! Ununited anconeal process OCD FMCP Incong MCD #%

3 Elbow Dysplasia! Medial compartment disease! Fragmented medial coronoid process! OCD! Incongruity! Ununited anconeal process OCD FMCP Incong MCD FMCP! Pathophysiology:! Elbow incongruity (ulna too long/radius too short)! Causes the animal to bear more weight on it s medial coronoid process! Results in separate piece of cartilage and trabecular bone attached by fibrous tissues (chip fracture)! Histopathology: ineffective fracture repair! Will develop DJD! Cartilage of medial humeral condyle may be eroded Progress! &%

4 Progress! Are we making any? Progress! Are we making any? How can we talk about treatment if we don t even know what s going on? Clinical Scenario! Fragments:! Single or multiple! Small section of MCP or majority! Different locations may represent different underlying pathologies '%

5 So what does that mean?! We have no idea. Really.! But we do have LOTS of theories New Theories!Instability!Impingement!Bone/vascular abnormality Danielson 2006 What do we know?! Bone of the medial coronoid process is abnormal at time of diagnosis! Less dense, more compressive! Microfractures! Why?! When does this occur? (%

6 Normal MCP Development Wolschrijn, CF. The Anatomical Record, 2004 Wolschrijn, CF. The Anatomical Record, 2004 Normal MCP Development! Relatively fast development of a functional trabecular structure:! Initial high bone density, sharp drop at 8 10 weeks, gradual increase to high values at 24 weeks! Significant mechanical loading at early age! Primary axis of trabecular orientation:! Perpendicular to the humeroulnar surface during normal weight bearing 4w 10w 18w Lau SF, Vet J, Abnormal MCP Development! Micro-CT of Labradors with incipient FCPs! 14 purpose-bred Labradors! 6 bilateral disease, 1 unilateral disease! 7 normal! weeks! Subchondral bone density is NOT affected in the early stages of MCD! GAG content is affected, but can not determine if cause or effect!%

7 MCP Response! Increase in density 6 m after surgery 2,500 2,400 HU 2,300 2,200 2,100 Normal PreOp PostOp 2,000 1,900 MCP RadMed So!! Can we assume disease not originating in subchondral bone?! Cartilage matrix abnormalities! Genetics:! Some of the candidate genes have been known to cause cartilage abnormalities! Biomechanics:! Overload, instability, incongruity all may be able to affect cartilage Different Diseases or Spectrum? )%

8 Incisure Fragments! Radio-ulnar conflict? Michelsen J. Vet J, 2013 Incisure Fragments! Muscular imbalance/instability? Michelsen J. Vet J, 2013 Tip Fragments! Incongruity static or dynamic?! Radio-ulnar! Humero-ulnar *%

9 Combination! All of the above? Clinical Presentation! One of most frequent canine developmental orthopedic diseases! Can occur in conjunction with OCD! Often bilateral Clinical Presentation! Age (in retriever-type dogs)! Bimodal! 5.9 months and 4.5 years! Dogs with bilateral disease present later! Bilateral lameness harder to recognize! Sex! 65-75% males in some studies! Controlled breeding: M = F +%

10 Clinical Presentation!Stiff/stilted gait! 4-7 months of age!standing:! Inward rotation of elbow! Supination of paw!pain on hyper-extension/ flexion, palpation of medial compartment!joint effusion Typical Exam Findings! Cubital Test! Internal and external rotation while flexing limb! Direct palpation of medial compartment! Joint effusion! Balloon under anconeus muscle! Even when bilaterally affected, rarely perfectly symmetrical Diagnostics! Medial coronoid disease can be difficult to definitively diagnose! CT is recommended modality! Occasionally need invasive imaging (arthroscopy) for diagnosis! With more common use of MRI, this need will likely decrease $,%

11 Radiographs! Things that can be definitively diagnosed on radiographs:! UAP! Arthritis! Incongruities >2mm! Things that if you find them, it s there, if you don t it means NOTHING (best with CT)! OCD! FCP Radiographs! Anatomic location of the medial coronoid process, superimposition on the ulna with a lateral projection and the radius with a craniocaudal projection limits detection of FCP! Disto-medial proximolateral oblique:! 90% sensitivity, 80% specificity! 3 more traditional views at 90% specificity have:! craniocaudal (35%), mediolateral (43%), and flexed mediolateral (54%) sensitivity Radiographs!Sclerosis at base of trochlear notch can be early indicator?! (I have a hard time with this) $$%

12 Diagnosis! Using Arthroscopy as gold-standard:! Comparing CT, standard radiographs, linear tomography, xeroradiography! Definitive diagnosis! CT:! Highest accuracy (86.7%)! Highest sensitivity (88.2%)! Highest negative predictive value (85%) CT OA at Diagnosis! Influenced by:! Size of fragment! Mobility! Amount of time present $#%

13 6/26/16 Treatment Options OA is expected to progress All dogs should be started on conservative management regardless of surgical intervention Dietary control of growth Weight management Exercise moderation NSAIDs Chondroprotective agents Surgical Intervention Earlier = better? Better outcome than conservative management alone Especially so if companion animal Surgery before 2 years of age 78% returned to apparent soundness as per owner questionnaire Surgery Arthrotomy Muscle separation Arthroscopy 13

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15 Response to Arthroscopy! Use of CT to measure subchondral bone density! Pre-op:! Lower bone density at base of MCP! 6m Post-op:! Bone density at base on MCP normalizes! Bone can respond normally! But!what about the incongruity?! Procedures developed in order to unload medial compartment/alleviate incongruity 1.! Ulnar ostectomy with IM pin 2.! Dynamic (oblique) proximal ulnar osteotomy (DPUO) 3.! Bi-Oblique Proximal ulnar osteotomy (BOPUO) 4.! PAUL 5.! SHO 6.! CUE But!what about the incongruity?! Procedures developed in order to unload medial compartment/alleviate incongruity 1.! Ulnar ostectomy with IM pin 2.! Dynamic (oblique) proximal ulnar osteotomy (DPUO) 3.! Bi-Oblique Proximal ulnar osteotomy (BOPUO) 4.! PAUL 5.! SHO 6.! CUE $(%

16 Dynamic Ulnar Cuts! Osteotomy! Dynamic oblique proximal ulnar osteotomy (DPUO)! Bi-oblique Dynamic Proximal Ulnar Osteotomy (BODPUO)! Complications:! Bleeding! Radial invasion! Synostosis! Delayed/non-union! Excessive tipping Dynamic Ulnar Cuts! Osteotomy! Dynamic oblique proximal ulnar osteotomy (DPUO)! Bi-oblique Dynamic Proximal Ulnar Osteotomy (BODPUO)! Anyone with a sag saw can do! Complications:! Bleeding! Radial invasion! Synostosis! Delayed/non-union! Excessive tipping Ulnar Ostectomy! Ostectomy! Removal of segment of bone! Proximal! Adults! Large incongruity! Distal! Young! Premature closure of a physis PO 1m 6m $!%

17 Prognosis! Worsens with:! Age! Longer pre-op duration of lameness! Increase in elbow incongruence! Increase in OA grade! Presence of UAP or OCD Prognosis! OA is EXPECTED to progress in all dogs! Regardless of surgical intervention or not! Severity seems less in operated patients! Some studies show no difference, but most do Prognosis! Surgical intervention! Favorable result at 6 weeks and 6 months post-operatively, despite progression of OA! 75% of dogs operated at 4-6 months of age have a good outcome! 42% of dogs operated at an older age have a good outcome! This may be higher? 5 Trot IPSI Total Normal Scope ScPUO >300 Days $)%

18 Literature Conclusion (n=1350)! Regardless of surgical procedure:! OA progresses! Function improves! DPUO/BODPUO:! Alters anatomy of proximal ulna! Functional effects of this are unknown! Incongruity results in worse OA Recap! CT scan > radiographs for diagnosis! Labradors, etc! Due to??! Treatment is to remove fragment with or without other procedures! (we will touch on some of the fancy new procedures in the next lecture)! Prognosis is variable! We now have more options for significant OA! (see next lecture) Developmental Orthopedic Disease! Medial compartment disease! Fragmented medial coronoid process! OCD! Incongruity! Ununited anconeal process OCD FMCP Incong MCD $*%

19 Osteochondritis Dissecans! OCD, (dissecans or dessicans)! Definition:! Disturbance in endochondral ossification which leads to retention of cartilage! Occurs in either the physis or the articular epiphyseal complex! Leads to cartilage thickening Quick review! 2 types of bone formation! Intramembranous ossification! No cartilage model! Endochondral ossification! Cartilage model Pathophysiology of OCD! Developing cartilage is nourished initially by synovial fluid and later by vascularization through subchondral bone! Increase in cartilage thickness leads to malnourished and necrotic chondrocytes! Leads to formation of a cleft at junction of calcified and non-calcified tissues $+%

20 Normal OCD Pathophysiology of OCD! Degrees of Disease:! Clinically insignificant! Sufficiently severe to result in mild lameness but heal spontaneously! May manifest itself as OCD OCD! History:! Intermittent lameness! May be shifting leg lameness! Signalment:! Young (6-10 months)! Large breed dogs #,%

21 OCD! PE:! Pain on joint extension or flexion (depends on which joint it is)! Muscle atrophy (disuse)! Decreased range of motion! Secondary osteoarthritis (OA) in adult animals! Crepitus, joint effusion, periarticular swelling OCD!Diagnosis!Shoulder most commonly affected, also seen in distal humerus, stifle, and hocks! CONVEX surfaces!radiographs:! BOTH joints the disease tends to be bilateral! Even if only lame in one leg Medial humeral condyle #$%

22 OCD! Treatment:! Surgical premise:! Remove the flap, curette down to cancellous bone! Causes fibrocartilage formation in the defect! Can be done with arthrotomy or arthroscopy OCD! Treatment:! Surgical premise:! Remove the flap, curette down to cancellous bone! Causes fibrocartilage formation in the defect! Can be done with arthrotomy or arthroscopy! Newer treatment options! Unicompartmental elbow replacement! SynaCart OATS! Transfer of healthy articular cartilage to OCD lesion! Usually done in stifle, shoulder, can be done in elbow! Use articular cartilage lateral to trochlear ridges in stifle! Remove OCD lesion with large punch! Harvest donor site! Implant donor tissue ##%

23 OATS OCD! Outcome:! Not as good in the elbow as in the shoulder! OA progresses Developmental Orthopedic Disease! Medial compartment disease! Fragmented medial coronoid process! OCD! Incongruity! Ununited anconeal process OCD FMCP Incong MCD #&%

24 Joint Incongruity! There are probably two severities of this:! Obvious and severe! Often result of growth deformities! Subtle! Difficult to prove! Theory is that subtle incongruity is responsible for FCP and UAP Joint Incongruity! Pathophysiology:! Occurs when the radius and ulna are not aligned causing a step in the weight-bearing surface of the joint! 3 scenarios:! Short radius! Short ulna! Humero-ulnar incongruity Short Radius! Can be associated with medial compartment disease! Medial coronoid area has higher loads with short radius! Treatment! Evaluate medial compartment! Oblique ulnar ostectomy with or without IM pin! Care with bilateral procedures #'%

25 Extreme Example Short Radius! Can be associated with medial compartment disease! Medial coronoid area has higher loads with short radius! Treatment! Evaluate medial compartment! Oblique ulnar ostectomy with or without IM pin! Care with bilateral procedures Short Ulna! Associated with UAP?! Lesions on anconeal process! Limited extension on exam! Treatment:! Oblique ulnar osteotomy! Consider fat graft and ostectomy in young dog that might heal too quickly #(%

26 Short Ulna! Associated with UAP?! Lesions on anconeal process! Limited extension on exam! Treatment:! Oblique ulnar osteotomy! Consider fat graft and ostectomy in young dog that might heal too quickly Extreme example! Humero-Ulnar #!%

27 Humero-Ulnar Incongruity Incongruity: Prognosis! Because generally associated with other issues within the elbow, prognosis is dependent on amount of incongruity and underlying developmental orthopedic disease(s) Elbow Dysplasia! Medial compartment disease! Fragmented medial coronoid process! OCD! Incongruity! Ununited anconeal process OCD FMCP Incong MCD #)%

28 Ununited Anconeal Process! Definition:! Failure of anconeal process (AP) to undergo normal bony fusion with the ulnar metaphysis by 20 weeks of age! May exhibit partial or complete separation, may be fused in abnormal location! One new paper suggests that there is a difference between UAP and the secondary center of ossification! Food for thought Clinical Presentation! Occurs less frequently than FCP or OCD! Can occur in conjunction with these! 2 Populations! Large to giant breed dogs! German shepherd over-represented! Chondrodystrophic breeds! Trauma? Pathophysiology!Theories:! German shepherds, large breed dogs:! Secondary center of ossification! Asynchronous growth! Abnormal formation of ulnar trochlear notch! Osteochondrosis! Chondrodystrophic breeds:! Articular incongruity secondary to asynchronous growth of radius/ulna!spontaneous fusion is rare!if left in situ OA will progress #*%

29 Clinical Presentation! Males affected twice as commonly as females! Breeding not recommended Diagnosis! Radiographs! Maximally flexed lateral for diagnosis! Cranio-caudal view to document OA! Always radiograph both elbows (DOD)! Line of cleavage separating AP from ulnar metaphysis! Age at diagnosis:! Must be at least 5 months of age! PRIOR to this a cleavage line is normal in breeds with a secondary center of ossification of the AP #+%

30 Treatment options! Surgical disease! Medical therapy:! Weight management, controlled exercise, medications! Less successful than surgery and results in rapid OA progression Surgical Options! AP removal! AP reattachment to ulna! Ulnar osteotomy/ostectomy ± reattachment of AP to ulna UAP Shape Normal Abnormal >7m old <7m old Remove Lag screw and PUO Firmly attached PUO only Loose Lag screw and PUO &,%

31 6/26/16 Anconeal Process Removal Initial recommendation Due to inherent instability, prognosis is variable Leads to decreased ROM, increased OA, high incidence of post-operative dysfunction Generally considered less than ideal Animals remain/return to lameness OA progresses Indicated if: AP is very misshapen and its preservation would not restore joint congruity Advanced OA Anconeal Process Removal Guthrie % improved clinically 50% free of lameness Roy 1994 Good to excellent long-term function Increase in OA in 93% of animals reported in literature Some lameness may temporarily improve due to fragment removal Indicated in adults with severe OA Anconeal Process Reattachment Lag screw (compression screw) Stabilizes AP in normal anatomic position Encourages bony fusion Maintains joins stability and congruity Decreases OA formation Problems: Screw breakage due to continued shear forces across cleavage plane if underlying elbow incongruity not corrected Stabilizing the AP in an incongruent joint may increase forces acting on articular cartilage of AP and humeral trochlea Increased cartilage wear and potential screw failure, OA progression 31

32 Prognosis! Lag-screw only:! 38% cases will fuse! In one study those that did not fuse had implant failure! In other words: don t bother Ulnar Osteotomy/Ostectomy! Re-establishment of joint congruity! Advocated to allow dynamic repositioning of ulna relative to radius! Lessens pressure directed against AP! Encourages ossification of cleavage plane Ulnar Osteotomy/Ostectomy!Indicated when:! Dog is < 6-7 months of age! Firmly attached AP &#%

33 Ulnar Osteotomy/Ostectomy! Outcome:! Variable with this technique alone! Dependent on:! Dog age less likely to observe fusion if dog is > 6-7 months of age at time of surgery! Degree of AP fixation to ulna better if firmly fixed! If note incongruity at time of surgery this procedure is indicated Prognosis! Ulnar osteotomy/ostectomy only! 51% progress to bony union! If <7 months of age and AP firmly attached:! Good to excellent outcome! Worth a try (with the right case) Ulnar Ostectomy: Pre-Op &&%

34 Ulnar Ostectomy: Post-Op Ulnar Ostectomy: Week 6 &'%

35 Combination Approach! Lag screw & ulnar osteotomy/ ostectomy! Addresses underlying cause (incongruity) and resultant pathology (UAP) Combination Approach! Literature suggests excellent long-term outcome with minimal to no OA progression! 39 joints reported in the literature! >97% achieved radiographic fusion Combination Approach &(%

36 Combination Approach Combination Approach Combination Approach &!%

37 Prognosis! Combo approach:! If animal >7 months of age or fragment is loose! 97% progress to bony union! Difference in how fusion is defined! 82% are clinically normal even after strenuous exercise Recap! UAP:! Lateral radiograph for diagnosis! German Shepherds! Multiple surgical options! Good to excellent outcome >7m old Normal Shape Abnormal <7m old Remove Lag screw and PUO Firmly attached PUO only Loose Lag screw and PUO Recap of Elbow Dysplasia! CT best for medial compartment disease (FCP, OCD, Incongruity)! Rads best for UAP! All (probably) require surgical intervention! Prognosis fair to good &)%

38 Any Questions? &*%