Clinically Relevant Biological Strategies for Cartilage Resurfacing in Dogs
James L. Cook, DVM, PhD, DACVS, DACVSMR
Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO, USA
Biological resurfacing of articular cartilage is the 'Holy Grail' of joint surgery. While no current resurfacing treatment option consistently results in recreation of fully integrated and functional hyaline cartilage and subchondral bone long term and the available options are more limited in veterinary medicine compared to human medicine, there are still some viable biological treatment options that can result in very good outcomes in our patients. We will discuss osteochondral autografts, osteochondral allografts and synthetic resurfacing as realistic clinical options, and cell-based and tissue engineering strategies as potential future modalities.
Osteochondral autograft treatment system (OATS) has been reported to improve outcomes in human patients when compared to other treatment modalities. Based on the human success, we adapted the concept and the OATS (Arthrex) technique to veterinary surgery for use in dogs and horses. We performed a body of research using cadavers, research dogs and, finally, clinical cases. We have reported the results of that work in the peer-reviewed literature. We have found the OATS procedure can be successfully performed in the stifle of dogs for treatment of osteochondrosis dissecans (OCD). Clinical results have been excellent with respect to graft viability and integration and improved clinical function. Others have reported their work on the technical aspects of this technique in dogs and use of OATS in other joints including the elbow and shoulder. Further work is needed to determine appropriate indications and long-term results.
Again, based on the research and clinical use in people, we implemented osteochondral allografts (OCA) for treatment of severe articular defects in canine patients. Dogs presenting for lameness associated with major articular defects of the elbow, stifle or hock were included when owners consented to OCA and allowing data to be collected, analysed and reported. After full diagnostic work-up, discussion of treatment options, costs and prognosis, and consent to treatment, the affected joint was treated with OCA via open arthrotomy. OCA grafts were harvested aseptically in an operating room from dogs euthanased for unrelated reasons and immediately cultured in sterile chondrogenic media using a protocol developed in our laboratory.
Preoperative, intraoperative and postoperative treatments varied among patients. Outcome measures included complications, radiographic assessment and clinical function. Six patients were included: 10-month-old Husky with humeral condyle dysgenesis of the humeral condyle; 4-year-old Labrador Retriever with a patellar malunion; 20-month-old Mastiff with stifle OCD; 3-year-old mixed-breed dog with stifle OCD; 14-month-old St. Bernard with hock OCD; 7-year-old Pointer with severe stifle osteoarthritis (OA). Appropriately sized OCA grafts were cultured with no evidence of contamination or infection and successfully implanted in all six patients using various methods of fixation. No evidence of frank rejection, infection, or fixation failure was noted. Clinical follow-up was performed 8–10 weeks after surgery and at variable time points (range 8 weeks–29 months). Radiographic assessments indicated graft incorporation in all cases; however, OA progressed for all patients and implant migration requiring K-wire removal occurred in two cases. Four of six cases returned to full athletic function. The hock OCA was improved, but did not achieve intended athletic function by 14 months. The Pointer with femoral condylar and tibial plateau OCAs returned to work and competition. These data suggest that OCA can be successfully performed in selected dogs with major articular defects in the elbow, stifle or hock and result in acceptable functional outcomes.
Synthetic grafts for treatment of focal cartilage defects are available from Arthrex and have been successfully used in the elbow, shoulder and stifle of clinical canine patients. This technique is in its infancy of clinical use and further work is needed before we can make definitive recommendations regarding indications and efficacy. To date, the technique has proven to be safe.
We have also developed a system for synthetic resurfacing of the medial compartment of the canine elbow for treatment of medial compartment disease. Medial compartment disease (MCD) refers to pathology of the medial aspect of the humeral condyle and medial coronoid process. The surgical treatment we have developed for MCD is the canine unicompartmental elbow (CUE) arthroplasty. To date, we have performed all of the preclinical testing and have treated 26 clinical cases for which we have at least 6-month follow-up. Examinations at 6–8 weeks and ~6 months postoperatively were performed and included assessment of lameness, pain, range of motion and radiographs. At the time of writing, the overall success rate for return to intended function is 80% with a 24% major / catastrophic complication rate. These data provide initial evidence for safety and efficacy of the Arthrex CUE arthroplasty system and justify further clinical study, which is ongoing.
Cell-based and tissue engineering strategies for articular cartilage regeneration are being researched intensively all over the world. Some of these strategies, including autologous chondrocyte implantation (ACI), MACI, CAIS, DeNOVO, and others, have made it to clinical use. None of these current techniques has reached the 'Holy Grail' of complete regeneration of large articular cartilage surfaces such that full function is consistently seen long term, but these and others do have promise for providing biological solutions for articular cartilage problems in dogs, horses and humans.