Biomechanical and topographic considerations for autologous osteochondral grafting in the knee

This study characterizes the donor and recipient sites involved in osteocho ndral autograft surgery of the knee with respect to articular cartilage con tact pressure, articular surface curvature, and cartilage thickness. Five c adaveric knees were tested in an open chain activity simulation and kinemat ic data were obtained at incremental knee flexion angles from 0 degrees to 110 degrees. Surface curvature, cartilage thickness, and contact pressure w ere determined using a stereophotogrammetry method. In all knees, the media l trochlea, intercondylar notch, and lateral trochlea demonstrated nonloadb earing regions. Donor sites from the distal-medial trochlea were totally no nloadbearing. For the intercondylar notch, lateral trochlea, and proximal-m edial trochlea, however, the nonloadbearing areas were small, and typical d onor sites in these areas partially encroached into adjacent loadbearing ar eas. The lateral trochlea (77.1 m(-1)) was more highly curved than the typi cal recipient sites of the central trochlea (23.3 m(-1)), medial femoral co ndyle (46.8 m(-1)), and lateral femoral condyles (42.9 m(-1)) (P < 0.05). O verall, the donor sites had similar cartilage thickness (average, 2.1 mm) w hen compared with the typical recipient sites (average, 2.5 mm). The latera l trochlea and medial trochlea curvatures were found to better match the re cipient sites on the femoral condyles, while the intercondylar notch better matched the recipient sites of the central trochlea. The distal-medial tro chlea was found to have the advantage of being nonloadbearing. Preoperative planning using the data presented will assist in more conforming, congruen t grafts, thereby maximizing biomechanical function.