Correct Positioning of the Medial Patellofemoral Ligament: Troubleshooting in the Operating Room

Abstract

Medial patellofemoral ligament (MPFL) reconstruction is often required after failed nonoperative management of lateral patellar instability. It is important to properly re-create the native ligament to avoid altering patellofemoral biomechanics. Such alterations can cause knee stiffness, anterior knee pain, and patellofemoral chondrosis. Incorrect femoral location is the most common mistake that affects MPFL graft biomechanics. Authors have described multiple radiographic and anatomical landmarks that assist in determining the appropriate location, and time should be taken to accurately localize this position. Regardless of the reconstruction technique used, the knee should be taken through its full range of motion, before the MPFL graft is secured, to test the biomechanics and reduce the risk of postoperative complications. If the graft becomes too tight as the knee moves into flexion, the femoral location is too proximal and should be adjusted ("high and tight"). By contrast, if the graft becomes too loose in flexion, then the femoral location is too distal ("low and loose"). These simple rules can be used to intraoperatively troubleshoot the tunnel placement.