POSTERIOR CRUCIATE LIGAMENT RECONSTRUCTION - AN IN-VITRO STUDY OF FEMORAL AND TIBIAL GRAFT PLACEMENT

We studied posterior cruciate ligament reconstruction in a cadaveric m odel using two substitutes: a 1-mm diameter flexible cable and an 11-m m diameter Achilles tendon autograft. The thin cable allowed us to stu dy five femoral and five tibial attachments in each knee. A nearly iso metric attachment was located after cutting the posterior cruciate lig ament while the tibia was reduced with a 100 N anterior force. The fiv e femoral locations studied were the isometric location and four locat ions centered around this isometric point. The Achilles tendon reconst ruction was used with both an isometric and a nonisometric femoral sit e, allowing us to confirm the results with the wire cable. Posterior m otion limits were measured under a 100 N posterior force in the intact , posterior cruciate ligament-deficient, and posterior cruciate ligame nt-reconstructed knees. We found that the restoration of knee stabilit y in flexion depended strongly on the femoral attachment location. A f emoral attachment that was nonisometric by intraoperative measurement, but within the posterior cruciate ligament anatomic footprint, most c losely reproduced the intact knee's posterior motion limits. Variation s in the tibial attachment site produced only minor changes in the pos terior motion limits. We concluded that the proximal-distal location s elected for the femoral attachment of a posterior cruciate ligament su bstitute was particularly important in the restoration of normal poste rior motion limits.