Effect of Medial Patellofemoral Complex Reconstruction Technique on Patellofemoral Contact Pressure and Kinematics

Objectives: Medial patellofemoral ligament reconstruction (MPFL-R) is the gold standard treatment for lateral patellar instability, however, isolated medial quadriceps tendon-femoral ligament reconstruction (MQTFL-R) or a combination MPFL/MQTFL reconstruction (MPFL/MQTFL-R) have been reported with good clinical results. While a handful of studies have preliminarily investigated the biomechanical consequences of these various stabilizing procedures, no existing study has included multiple medial patellofemoral complex (MPFC) reconstructions and assessed kinematics and contact mechanics at distinct flexion angles. The purpose of this study was to evaluate patellofemoral contact areas, forces, and kinematics in five distinct states: (1) intact knee, (2) transected MPFC, (3) isolated MPFL-R, (4) isolated MQTFL-R, and (5) combined MPFL/MQTFL-R. Methods: Ten adult cadaveric knee specimens were prepared and analyzed under five different conditions: (1) intact state, (2) transected MPFC, (3) isolated MPFL-R, (4) isolated MQTFL-R, and (5) combined MPFL/MQTFL-R. Patellar tilt, lateral patellar translation, patellofemoral contact forces, and patellofemoral contact areas were measured in each condition from 0° to 80° through simulated knee flexion utilizing a custom servo-hydraulic load frame with pressure sensor technology and a motion capture system for kinematic data acquisition. Results: The isolated MPFL, isolated MQTFL, and combined MPFL/MQTFL reconstruction conditions produced significantly less lateral patellar tilt compared to the transected MPFC state (P<0.05). In deep knee flexion (70° and 80°), all three reconstructed states had significantly less lateral patellar contact forces compared to the sectioned state. There were no statistically significant differences comparing each reconstruction technique to the intact state in patellar tilt, lateral patellar translation, contact forces, and contact areas. Conclusions: Isolated MPFL-R, isolated MQTFL-R, and combined MPFL/MQTFL-R all restore patellofemoral stability comparable to the intact MPFC state without overconstraint that could be concerning for increasing risk of patellofemoral arthritis. For all measured variables at all flexion angles, all three reconstructed states were statistically indistinguishable from the native state.