An investigation of 2 techniques for optimizing joint surface congruency using multiple cylindrical osteochondral autografts

Purpose: To compare 2 techniques for optimizing joint congruency for miniat ure osteochondral autografting in the knee: intrinsic postoperative forces acting on overdrilled autografts protruding from the femur versus alignment by a surgeon at the time of grafting. Type of Study: Controlled animal mod el experiment. Methods: A full-thickness cartilage defect was created on th e weight-bearing surface of the medial femoral condyle of 13 mature sheep. Three 4.5 x 10 mm cylindrical autografts were inserted into 14-mm deep reci pient holes such that the grafts were held in place by side-wall friction a lone. One treatment group received grafts that were delivered flush with th e surrounding cartilage and the second group received grafts that were left 2-mm proud of the joint surface. Results: Three months postoperatively, th e proud grafts had been repositioned by weight bearing but perigraft fissur ing and fibroplasia, and subchondral cavitations were serious complications . It is suspected that these complications were caused by excessive motion between the graft and recipient site in the proud grafts. Conclusions: Graf ts should be delivered flush with the joint surface when performing osteoch ondral transfers to avoid graft micromotion and the consequent interference with graft integration and function.