Sectioning the medial patellofemoral ligament alters patellofemoral joint kinematics and contact mechanics

Medial patellofemoral ligament (MPFL) disruption may alter patellofemoral joint (PFJ) kinematics and contact mechanics, potentially causing pain and joint degeneration. In this controlled laboratory study, we investigated the hypothesis that MPFL transection would change patellar tracking and PFJ contact pressures and increase the distance between the attachment points of the MPFL. Eight fresh frozen dissected cadaveric knees were mounted in a rig with the quadriceps and ITB loaded to 205 N. An optical tracking system measured joint kinematics, and pressure sensitive film between the patella and trochlea measured PFJ contact pressures. Length patterns of the distance between the femoral and patellar attachments of the MPFL were measured using a suture led to a linear displacement transducer. Measurements were repeated with the MPFL intact and following MPFL transection. A significant increase in the distance between the patellar and femoral MPFL attachment points was noted following transection (p < 0.05). MPFL transection resulted in significantly increased lateral translation and lateral tilt of the patella in early flexion (p < 0.05). Peak and mean medial PFJ contact pressures were significantly reduced and peak lateral contact pressures significantly elevated in early knee flexion following MPFL transection (p < 0.05). MPFL transection resulted in significant alterations to PFJ tracking and contact pressures, which may affect articular cartilage health. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1423–1429, 2013