Anatomical posterior cruciate ligament transplantation: a biomechanical analysis.

BACKGROUND Although current techniques of posterior cruciate ligament reconstruction may successfully stabilize the posterior cruciate ligament-deficient knee, no studies have demonstrated restoration of intact-knee kinematics. HYPOTHESIS Posterior cruciate ligament transplantation will successfully restore posterior stability and kinematics to the posterior cruciate ligament-deficient knee. STUDY DESIGN Controlled laboratory study. METHODS Seven pairs (donor/recipient) of size-matched cadaveric knees underwent a novel technique for posterior cruciate ligament transplantation. The grafts were fixed at the femoral origin and tibial insertion using an inlay technique with rigid fixation. The knees were tested in the intact (intact group), posterior cruciate ligament-deficient (deficient group), and posterior cruciate ligament-transplanted (transplant group) states. A 3-dimensional electromagnetic tracking system during an active knee extension and passive knee flexion maneuver was used to quantify kinematics, specifically looking at femoral rollback. KT ligament arthrometry was used to quantify posterior stability at the quadriceps neutral angle (70 degrees ). RESULTS For femoral rollback, the intact versus deficient groups was significantly different (P = .045) as was deficient versus transplant groups (P = .008) but not intact versus transplant groups. Similar differences were noted with the measurements of posterior stability (P < .001). Total posterior laxity between the intact versus deficient groups was significantly different (means, 1.32 mm vs 11.1 mm; P < .0001), as was deficient versus transplant groups (means, 11.1 mm vs 2.04 mm; P < .126) but not intact versus transplant groups. CONCLUSION In a posterior cruciate ligament-deficient cadaveric model, we demonstrated the technical feasibility and efficacy of posterior cruciate ligament transplantation for restoring femoral rollback and posterior stability at the quadriceps neutral angle. CLINICAL RELEVANCE Future studies in posterior cruciate ligament reconstruction should not only address stability but also restoration of normal knee kinematics in assessing the success of a given technique.