Lateral release associated with MPFL reconstruction in patients with acute patellar dislocation

Abstract

Objective Medial patellofemoral ligament (MPFL) injury occurs in the majority of the cases of acute patellar dislocation. The role of concomitant lateral retinaculum release with MPFL reconstruction is not clearly understood. Even though the lateral retinaculum plays a role in both medial and lateral patellofemoral joint stability in MPFL intact knees, studies have shown mixed clinical outcomes following its release during MPFL reconstruction surgery. Better understanding of the biomechanical effects of the release of the lateral retinaculum during MPFL reconstruction is warranted. We hypothesize that performing a lateral release concurrent with MPFL reconstruction will disrupt the patellofemoral joint biomechanics and result in lateral patellar instability. Methods A previously developed and validated finite element (FE) model of the patellofemoral joint was used to understand the effect of lateral retinaculum release following MPFL reconstruction. Contact pressure (CP), contact area (CA) and lateral patellar displacement were recorded. abstract. Results FE modeling and analysis demonstrated that lateral retinacular release following MPFL reconstruction with tibial tuberosity-tibial groove distance (TT-TG) of 12 mm resulted in a 39% decrease in CP, 44% decrease in CA and a 20% increase in lateral patellar displacement when compared to a knee with an intact MPFL. In addition, there was a 45% decrease in CP, 44% decrease in CA and a 21% increase in lateral displacement when compared to a knee that only had an MPFL reconstruction. Conclusion This FE-based analysis exhibits that concomitant lateral retinaculum release with MPFL reconstruction results in decreased PF CA, CP and increased lateral patellar displacement with increased knee flexion, which may increase the risk of patellar instability.

Adding Lateral Retinacular Release to Medial Patellofemoral Ligament Reconstruction Fails to Demonstrate Clinical Benefit Compared With Isolated Medial Patellofemoral Ligament Reconstruction

“…This was confirmed by the finite element model analysis performed by Kheir et al. 22 that demonstrated adding LRR to MPFL reconstruction results in decreased patellofemoral contact pressure, contact area, and increased lateral patellar displacement with increased knee flexion. Based on the growing evidence in the literature, LRR adjunct should be cautioned against in the patellar instability treatment algorithm unless clinical benefit is substantiated.…”

Combined MPFL reconstruction and tibial tuberosity transfer avoid focal patella overload in the setting of elevated TT–TG distances

“…Understanding the role of isolated MPFL reconstruction will further help to establish objective criteria to design the optimal surgery for each patient with patellar instability [22, 45].…”