and 5 other(s)
Introduction Chondral and osteochondral defects are often associated with significant pain and disability. Osteochondral allograft (OCA) transplantation can functionally restore large articular defects in the knee. Studies have reported 10- to 15-year survivorship between 71% and 85%, and functional outcomes after OCA transplantation of the femoral condyle have been good to excellent, with 88% of patients returning to sport. While bipolar OCA transplantations for partial and whole joint resurfacing (“BioJoints”) have resulted in successful outcomes, these surgeries have traditionally had less favorable results than single-surface transplants. The factors reported to consistently influence success for BioJoints have been reported to relate to donor chondrocyte viability, donor allograft bone integration, implantation technique, patient co-morbidities, and patient demographics (e.g., BMI, tobacco use). With the advent of technologies and strategies to address these limiting factors, a comprehensive approach to optimizing outcomes for unicompartmental bipolar biologic joint resurfacing has been employed and assessed. To delineate the mechanistic components for success and complete a head-to-head comparison of BioJoint versus typical standard-of-care non-operative treatment, this study was designed to use a large animal model to test the hypothesis that unicompartmental bipolar osteochondral and meniscal allograft transplantation would be as or more effective for treatment of medial compartment gonarthrosis based on functional, diagnostic imaging, gross and histologic assessments. Methods With IACUC approval, medial compartment osteoarthritis (gonarthrosis) was induced in one knee of skeletally mature purpose-bred research hounds (n=8, weighing > 20 kg) using a validated arthroscopic meniscal release (MR) model. Three months after MR, the presence of OA in the operated knees was documented radiographically and arthroscopically, and pre-treatment assessments were performed. Three months after induction of OA, dogs were randomly assigned to one of two treatment groups: • NSAID Control group (n=4) dogs received no surgical intervention (arthroscopic assessment only) and were managed with daily NSAIDs (Carprofen 4.4 mg/kg po q24h) for the study duration. • BioJoint (n=4) received MOPSSM-preserved tissue allografts. Complete distal femur and proximal tibia allografts were obtained from canine cadavers euthanatized for reasons unrelated to this study. Allografts were preserved for 30 days using MOPSSM, and were then implanted into the medial femoral condyle and medial tibial plateau (unicompartmental BioJoint) of the MR knee in each dog using custom-cut techniques and instrumentation. The allografts effectively replaced the entire medial femorotibial joint of each dog in the BioJoint group. Dogs were maintained for 6 months after implantation with clinical assessments (lameness scoring, forcemat kinetics, range of motion, and VAS pain scores), radiographic assessment, and arthroscopic assessments at 1, 3 and 6 months after surgery. Dogs were humanely euthanatized 6 months after surgery and the knees evaluated by OARSI whole joint histologic assessments and cell viability, biochemical content and biomechanical properties of grafts. Treatments were compared for statistically significant (p<0.05) differences. Results All dogs survived for intended study duration without complications. At the 6-month study endpoint, functional measures, radiographic assessment of integration and joint health, and arthroscopic evaluation of graft appearance and joint health showed non-inferior or superior (p<0.05) outcomes (range of motion, pain, radiographic OA, arthroscopic OA) for BioJoints compared to NSAID Controls (Fig. 1). Based on mechanistic outcome measures (cell viability, biochemical and biomechanical assessments), osteochondral and meniscal transplants maintained donor cell viability, integrated into host tissues, and allowed for maintenance of joint function without progression of OA as noted in NSAID-treated controls (Fig. 2). Discussion The findings support the safety and efficacy of unicompartmental bipolar osteochondral and meniscal allograft transplantation in a rigorous preclinical large animal model. The improved results for extensive bipolar OCA transplantation noted in this study compared to historical controls are thought to be related to high chondrocyte viability in OCAs at time of transplantation, anatomically-shaped grafts, use of fresh meniscal allografts with intact meniscotibial ligaments, BMC to enhance allograft bone integration, and careful attention to postoperative management. Significance These pre-clinical animal model data suggest that unicompartmental bipolar osteochondral and meniscal allograft transplantation for treatment of medial compartment gonarthrosis can result in highly functional outcomes that prevent early progression of knee osteoarthritis.
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