KEEP ON MOVING WHAT S NEW IN SMALL ANIMAL ARTHROLOGY?

Transcription

1 Vet Times The website for the veterinary profession KEEP ON MOVING WHAT S NEW IN SMALL ANIMAL ARTHROLOGY? Author : Heidi Radke Categories : Vets Date : June 14, 2010 Heidi Radke discusses how the latest research into joints is progressing, from salvage operations to replacement arthroplasty and physical therapy WITHOUT full joint function, a pain-free and full range of motion is not possible. Worldwide, millions of small animals are affected by joint disease, and the economic impact is enormous. Joint disease can occur for a variety of underlying reasons inflammatory, developmental, genetic, degenerative or traumatic. Many of the diseases have been known and treated for many years, but some areas have seen surprisingly few advances. Various canine hip improvement schemes and associated breeding programmes have failed to lead to a significant improvement in dogs hip statuses, despite many schemes operating for several years. With the most common orthopaedic disease in dogs rupture of the cranial cruciate ligament we are far away from finding the best treatment. Nonetheless, some exciting new insights are available regarding joint disease in dogs and cats. Generally, we tend to be more critical when assessing our patients, but also when judging the outcome of our cases a fact shown by a series of scientific reviews on the subject. 1 / 7

2 This article aims to provide an overview of some of the latest concepts and treatment options regarding joint disease. Developmental joint disease Developmental abnormalities occur during the growing stages of the animal s life, and often have a genetic basis. Osteochondrosis is a wellknown developmental orthopaedic disease in dogs and has also been described in cats, although rarely. The aetiopathogenesis is most likely multifactorial. The humeral head, medial humeral condyle, lateral femoral condyle and medial talar ridge are most commonly affected. Surgical treatment has typically involved removal of the cartilage flap and debridement of the underlying subchondral bone to stimulate fibrocartilaginous ingrowth. However, most dogs remain lame to some degree, despite clinical improvement. Osteochondral autograft transfer (OAT) is an emerging technique in canine orthopaedics. It offers the possibility of reconstructing the defect and resurfacing it with hyaline cartilage, with the aim of allowing an early return to function with minimal donorsite morbidity ( Figures 1a to 1c ). Early results from using this technique in the elbow joint are encouraging (Fitzpatrick, 2009), but more data is necessary to assess medium and longterm outcomes. End-result osteoarthritis? Every joint disease inevitably results in some degree of osteoarthritis (OA). However, the degree to which this will clinically affect the animal is not predictable. Clinical signs can vary from mild stiffness after rest to severe pain and debilitating lameness. Pathological changes include a partial or complete loss of articular cartilage. Multimodal management of the disease is recommended, which entails a combination of different medical and nonmedical therapies (such as NSAIDs and analgesics), nutraceuticals, functional foods, weight control and exercise management. Surgery may also be part of the treatment, such as replacement of the whole joint. A review of canine OA management strategies found strong evidence for the efficacy of carprofen, fibrocoxib and meloxicam, along with moderate evidence of the efficacy of etodolac, glycosaminoglycans, licofelone, elk velvet antler and green-lipped mussel (Sanderson, 2009). The risk of serious adverse effects from long-term NSAID use is low, according to the current literature (Innes, 2010). Several studies support weight loss as an effective treatment for OA in affected and overweight dogs. Bodyweight reduction will alleviate clinical signs of OA. Exercise that provides a good range 2 / 7

3 of motion and muscle building, and limits wear and tear on the joints, is the best option. Leash walking, swimming, walking on treadmills, slow jogging and going up and down stairs are excellent, low-impact exercises. An exercise programme should be individualised for each dog, based on the severity of the OA and the dog s weight and condition. Different components of the conservative treatment might need to be modified before the optimal combination for a particular patient is found. In many cases, lifestyle modification can help significantly. However, we should also be critical and admit that when conservative treatment fails to improve quality of life sufficiently, it will be necessary to reconsider surgical options for the patient. Degenerative joint disease in cats It has been found that a high percentage of cats have radiographic signs of OA ( Figures 2a and 2b ), but only small numbers show clinical signs. A contemporaneous review summarises what is known about feline degenerative joint disease (DJD) so far (Lascelles, 2010a). Most frequently, the elbow and hip are affected, followed by the stifle and tarsus often bilaterally. However, signs of DJD, enthesophytes and soft tissue mineralisation may not necessarily represent OA ( Figures 3a and 3b ). Meniscal mineralisation is a common condition in domestic cats and seems to indicate medial compartment DJD, but whether it is a cause, or a consequence, of joint degeneration is unknown (Freire, 2010). It has been suggested that a large proportion of DJD in cats is primary, which means it is most commonly related to ageing, without any other initiating factors. It is also possible that so-farunrecognised factors play a role in feline DJD. Hip dysplasia is a known cause of secondary DJD. Interestingly, hip DJD s radiographic appearance is different in cats compared to dogs, with overall less bone formation on the femoral head and neck, and more prominent new bone formation on the cranial acetabulum. Trauma and obesity have been suggested as other causes of secondary DJD. In cats with clinical signs of pain and impaired mobility, treatments combining NSAIDs, nutraceuticals, weight loss and environmental changes to stimulate activity are recommended (Montavon, 2009). Meloxicam is the only NSAID licensed in Europe for long-term use in cats. One commercially available chondroprotective for cats contains glucosamine hcl, chondroitin sulphate and manganese. Dietary modulation might be an additional method to improve mobility in cats with DJD-associated 3 / 7

4 pain, but this is not yet commercially available (Lascelles, 2010). Last resort joint salvage When an acceptable result using more conventional medical or surgical treatment options cannot be achieved, the patient may be a candidate for a joint salvage procedure. The aim is to allow painless limb function without preservation of the normal anatomy. Excision arthroplasty is the most traditional joint salvage procedure. It is considered effective for the coxofemoral, temporomandibular and phalangeal joints. The other two options for joint salvage are arthrodesis and joint prosthesis. The carpus and tarsus are most commonly fused either in a partial-arthrodesis or pan-arthrodesis. Typical indications include hyperextension injuries of the carpus in large-breed dogs, plantar tarsal instability in collies or Shetland sheepdogs, or fracture luxations of the tarsus in dogs and cats to name a few. With these surgeries, return to function is expected to be good to excellent, although the complexity of the procedures means the incidence of complications is relatively high. Newer implants are better adapted to the anatomic and biomechanical requirements, with the aim of minimising the complication rate. For the carpus, the castless PCA plate has been developed with the aim of abolishing the need for postoperative external coaptation (Clarke, 2009). The 2mm/2.7mm intertarsal arthrodesis plate for Shetland sheep-dog-sized dogs, and the laterally applied 1.5mm/2mm/2.7mm pantarsal arthrodesis plate for cats are other examples of newer, specifically developed implants. Both are hybrid plates, which allow differentsized screws to be applied proximally and distally to account for the special anatomic location ( Figure 4 ). Joint prosthesis Active research and development into replacement arthroplasty is ongoing. Total hip replacement in dogs is a well-established technique, and excellent outcomes have been reported. Cemented; uncemented and hybrid; and cemented and uncemented systems are available, and enable the surgeon to tailor the implants accurately to the patient s needs. With small and even microsized implants, small dogs and cats can also receive a total hip prosthesis (Liska, 2009). While hip dysplasia is still the most common indication for performing a total hip replacement, other situations, such as trauma (fractures or luxations) or neoplasia, are also increasingly seen as indications for performing the procedure. So far, little information is available on the relative merits of the different implant types used. To 4 / 7

5 improve the understanding of the long-term success rate of total hip replacement in dogs, the British Veterinary Orthopaedic Association (BVOA) and the University of Liverpool have launched the UK Canine Hip Registry. All surgeons performing total hip replacements are encouraged to sign up to the registry. The plan is to follow the cases anonymously over at least 10 years. Important information on long-term outcomes and differences with regard to breeds, bodyweight and age will be collected. Canine elbow and stifle replacements have only become commercially available relatively recently. Although indication for these surgeries is not as frequent as for total hip replacements, they will certainly benefit some patients. The main indication for canine total elbow replacement is severe osteoarthritis of the elbow, most commonly due to coronoid disease and elbow dysplasia. Other salvage procedures, such as elbow arthrodesis or excision arthroplasty of the humeroradial joint, can only lead to acceptable outcomes at best. Two different systems for elbow replacement are on the market. Canine total knee replacement s primary indication is degenerative joint disease, most commonly secondary to cranial cruciate ligament injury, as the majority of dogs present with a history of at least one surgical procedure. Since infection is an absolute contraindication for total joint replacement, synovial fluid analysis and tissue culture are recommended for the stifle joint of any possible candidate. Complication rates are still quite high therefore, patient selection must be strict and the benefits of surgery need to be weighed against the possible risks. If successful, both elbow and stifle replacement surgery can improve quality of life significantly. Postoperative management Recovery speed, overall prognosis and the time after surgery are as important as the surgery itself. Success or failure will depend strongly not only on the patient, but also on owner compliance. Therefore, thorough client information from the specialist surgeon, followed by an open discussion about the feasibility of the recommended treatment, are crucially important for the overall success of any joint surgery. Every client and every animal is different, and it is our responsibility to ensure our recommendations can be followed by this particular owneranimal team. Close cooperation between the referring vet and the specialist surgeon is also very important. If the owners are in doubt about something, the referral hospital should always be contacted and should be ready to see the animal for a recheck. Most patients need strict exercise restriction after the surgery in a kennel, crate or room for two to six weeks, followed by a gradual increase in exercise for another four to six weeks. Sufficient 5 / 7

6 analgesia is mandatory. Physical therapy is an important adjunct to every postoperative plan. One of the easiest and most effective therapies is simply slow and controlled walking of the animal. Depending on the procedure, the animal may need to be supported by a harness or sling to prevent slipping. After joint surgery, the majority of patients will be able to walk; therefore, this solution can be applied for most of them. If the animal is cautious about using the affected leg, then proprioceptive and weightshifting exercises in combination with gently massaging and extending the limb are easy to perform and very effective. Cool packing the surgical site for 10 minutes every two to four hours in the postoperative period is another powerful and uncomplicated, but well-tolerated, measure. Some patients will also profit from cool packing after that period when applied after every exercise. For dogs, hydrotherapy is often a very useful addition to postoperative rehabilitation ( Figure 5 ). Usually, this can be started two to four weeks after the surgery, with two sessions per week. In more complex cases, physiotherapists may be consulted to apply more specific exercises tailored to the patient s needs. The future Advances in molecular genetics and technology will hopefully enable the identification of susceptible genes for OA and other joint problems and, therefore, open new routes to better and more fundamental treatment. With more sophisticated surgical techniques, we can strive for better outcomes and less complications. Preventing joint disease in the first place would be the optimal outcome in many aspects, and is an area of intensive research. Sometimes the results are surprisingly simple. In humans, obesity has consistently been identified as a risk factor for OA development. In dogs, it has also been shown that preventing the development of obesity reduces the prevalence of hip dysplasia and OA of the hip and other joints (Marshall et al, 2010). The reason is unknown, and it may not be the result of decreased bodyweight alone. Understanding the complex relationship between obesity and OA might help to develop novel therapies that will actually modify the disease process. To prevent and treat joint problems in future, we will need it all top research, high-end surgical techniques and implants, sophisticated drugs and very basic, but essential measures, such as weight management and adequate exercise. To download published Veterinary Times articles, or to discuss this subject with fellow veterinary professionals, log on to 6 / 7

7 Powered by TCPDF ( References and further reading Clarke S P et al (2009). Clinical evaluation of pancarpal arthrodesis using a CastLess plate in 11 dogs, Vet Surg 38: Fitzpatrick N et al (2009). Early clinical experience with osteochondral autograft transfer for treatment of osteochondritis dissecans of the medial humeral condyle in dogs, Vet Surg 38: Freire M et al (2010). Meniscal mineralization in domestic cats ( Innes J F et al (2010). Review of the safety and efficacy of longterm NSAID use in the treatment of canine osteoarthritis, Vet Rec 166: Lascelles B D X (2010). Feline generative joint disease, Vet Surg 39: Lascelles B D X et al (2010). Evaluation of a therapeutic diet for feline degenerative joint disease, J Vet Intern Med 24: Liska W D et al (2009). Total hip replacement in three cats: surgical technique, short-term outcome and comparison to femoral head ostectomy, Vet Comp Orthop Traumatol 22: Marshall W et al (2009). A review of osteoarthritis and obesity: current understanding of the relationship and benefit of obesity treatment and prevention in the dog, Vet Comp Orthop Traumatol 22: Montavon P M et al (2009). Feline Orthopedic Surgery And Muscoloskeletal Disease (1st edn), Elsevier. Sanderson et al (2009). Systematic review of the management of canine osteoarthritis, Vet Rec 164: / 7