Additional Medial Patellotibial Ligament Reconstruction Reduced Lateral Patellar Translation Compared With Isolated Medial Patellofemoral Ligament Reconstruction Without Increasing Patellofemoral Contact Pressure: A Cadaveric Study.

Abstract

The medial patellotibial ligament (MPTL) is a secondary patellar stabilizer whose contribution increases with progressive knee flexion. Combined medial patellofemoral ligament (MPFL) and MPTL reconstruction is increasingly used clinically, but biomechanical data comparing it with isolated MPFL reconstruction for patellar translation and contact pressure are lacking. This cadaveric study compared with these 2 techniques and simulated patellar instability, evaluating patellar translation and mean/peak patellofemoral contact pressure at 0°, 30°, 45°, 60°, and 90° of knee flexion. We hypothesized that combined reconstruction would reduce lateral patellar translation to a greater degree than isolated reconstruction without increasing patellofemoral contact pressure. Eighteen fresh-frozen cadaveric knees underwent transection of the medial stabilizers to simulate patellar instability, then were randomized to isolated MPFL reconstruction or combined MPFL-MPTL reconstruction using peroneus longus tendon grafts. Three-dimensional patellar kinematics were captured with a six-camera motion capture system, and patellofemoral contact pressures were recorded using Tekscan sensors with the knee held statically at each angle. Patellar translation and contact pressure were compared between techniques. All specimens showed successful instability induction after medial stabilizer transection. Compared with the injured state, isolated reconstruction reduced lateral translation by 0.03 mm and combined reconstruction by 0.08-0.09 mm at all angles (each P-value < 0.05). The combined group showed 0.08-0.09 mm greater medial translation than isolated reconstruction at all angles (P-value ≤ 0.017), with the largest difference at 60° and 90°. No significant between-group difference was seen in proximal-distal translation. Both techniques restored a physiologic pattern of mean and peak contact pressure with no significant between-group difference in mean pressure at any angle. Peak pressure increased from baseline at 90° for isolated reconstruction (P-value = 0.05) and at 0°, 60° and 90° for combined reconstruction (P-value≤ 0.032). Peak pressure was significantly higher after combined than isolated reconstruction at full extension (P-value = 0.021) with no other between-technique differences. Combined MPFL-MPTL reconstruction reduces lateral patellar translation more than isolated MPFL reconstruction, particularly in deeper knee flexion, without increasing patellofemoral contact pressure. These findings support MPTL reconstruction as a biomechanically beneficial adjunct for managing patellar instability. Level V, descriptive laboratory study. Controlled Laboratory Study.