The case for advancement and repairof the medial patellofemoral ligament in patients with recurrent patellar instability

Abstract

In much of the literature about patellar instability, the role of the passive medial patellar stabilizers traditionally has been ignored or afforded only passing comment. But excessive passive lateral patellar mobility must be considered an essential element in the majority of patients with recurrent acute lateral patellar instability. In patients who have sustained patellar dislocation, numerous authors have shown excessive lateral or total mediolateral patellar mobility compared with normal controls. Clinical and laboratory magnetic resonance evidence suggests that the medial retinaculum shows typical patterns of injury in many cases of acute lateral patellar dislocation. Residual laxity of these soft tissue restraints can be sufficient to allow recurrent lateral instability of the patella after the initial dislocation event. Several studies suggest that the medial patellofemoral ligament (MPFL) is the primary passive soft tissue restraint to lateral patellar displacement. These studies have shown promising evidence that repair and/or advancement of the MPFL is capable of restoring normal lateral patellar mobility in cadaver specimens. If the MPFL is repaired effectively in patients who have sustained retinacular injury in the setting of patellar dislocation, then it should reduce the risk of recurrent patellar instability. In this article, the senior author's surgical technique for advancement and repair of the MPFL is presented. Postoperative rehabilitation is also discussed.