Biomechanical comparison of 3 medial patellofemoral complex reconstruction techniques shows medial over- constraint but no significant difference in lateralization and contact pressure.

Offizielle URL: https://www.sciencedirect.com/science/article/abs/...

PURPOSE The purpose of this study was to investigate biomechanical differences of medial patellofemoral ligament (MPFL) reconstruction, medial quadriceps tendon femoral ligament (MQTFL) reconstruction and a combination of these techniques to restore lateral patellar constraint and contact pressures. METHODS Eight fresh frozen cadaver knees were mounted to a custom jig with physiologic quadriceps tendon loading. Flexion angles and contact pressure (CP) were dynamically measured using Tekscan® pressure sensors and Polhemus® Liberty 6 degree of freedom (6DOF) positioning sensors in the following conditions: 1. Intact 2. MPFL and MQTFL deficient 3. MPFL reconstructed 4. Combined MPFL + MQTFL reconstructed 5. MQTFL reconstructed Lateral patellar translation was tested using horizontally directed 30N force applied at 30° of knee flexion. The knees were flexed in dynamic fashion and CP values were recorded for 10°, 20°, 30°, 50°, 70°, and 90° degrees of flexion. Group differences were assessed with ANOVA's followed by pairwise comparisons with Bonferroni correction. RESULTS MPFL (p=0.002) and combined MPFL/MQTFL (p=0.034) reconstruction significantly reduced patellar lateralization from +19.28% (9.78%, 28.78%) in the deficient condition to -17.57% (-27.84%, -7.29%) and -15.56% (-33.61%, 2.30%) respectively. MPFL reconstruction was most restrictive and MQTFL reconstruction the least -7.29% (-22.01%, 7.45%). No significant differences were found between the three reconstruction techniques. Differences in CP between the three reconstruction techniques were not significant (<0.02 MPa) at all flexion angles. CONCLUSION The present study found no significant difference for patellar lateralization and patellofemoral CP between MPFL, combined MPFL/MQTFL and MQTFL reconstruction. All 3 techniques resulted in stronger lateral patellar constraint compared to the native state while the MQTFL reconstruction emulated the intact state the closest. CLINICAL RELEVANCE Various surgical techniques for medial patellofemoral complex reconstruction can restore patellar stability with similar patellofemoral articular pressures.