Effects of small incongruities in a sheep model of osteochondral autografting

BackgroundExact reconstruction of an osteochondral defect by autogenous transplantation (mosaicplasty) is difficult given the variation in joint surface contour. Clinical and experimental studies do not show the extent to which incongruity can be tolerated in autografting.HypothesisGrafted articular cartilage will hypertrophy to correct the incongruity created by recession of the transplanted surface.Study DesignControlled laboratory study.MethodsTo test the response of grafts to incongruities, osteochondral autografts were transplanted from the trochlea to the femoral condyle in adult male sheep stifle joints. In groups of 6 animals, graft surfaces were placed flush, countersunk 1 mm or countersunk 2 mm, then histologically analyzed 6 weeks after surgery. Cartilage thickness, condition of the articular surfaces, and preservation of hyaline characteristics were the primary features compared.ResultsBony union, vascularization, and new bone formation were present in all grafts. Cartilage-to-cartilage healin...