Medial retinaculum plasty versus medial patellofemoral ligament reconstruction for recurrent patellar instability in adults: a randomized controlled trial.

PURPOSE: The purpose of this study was to evaluate the clinical results of medial retinaculum plasty (MRP) and medial patellofemoral ligament reconstruction (MPFLR) with concomitant lateral retinacular release with respect to imaging and functional results.

METHODS: Seventy patients with recurrent patellar instability were randomly divided into 2 groups based on their birth years (even/odd), receiving either MRP or MPFLR. Lateral retinacular release was also performed in all patients. Preoperatively, all patients received magnetic resonance imaging to evaluate the injury to the medial patellofemoral ligament. Computed tomography was performed before surgery and at follow-up. The subjective symptoms and functional outcome were evaluated preoperatively and postoperatively with the Kujala score, the Tegner activity score, and a subjective questionnaire. The physical apprehension test was examined, and redislocation was recorded.

RESULTS: Patients were followed up for a mean period of 40 months (range, 24 to 55 months). The measurement results for the congruence angle, patellar tilt angle, and patellar lateral shift decreased significantly from the pretreatment measurements to the normal range at the latest follow-up, without a statistically significant difference between the 2 groups (P > .05). The median Kujala score had significantly improved after surgery. However, no statistically significant difference was found between the 2 groups at the latest follow-up (P > .05). In 6 cases in the MRP group (19%) and 3 in the MPFLR group (9%), we found patellar lateral shift that exceeded 1.5 cm but was less than 2.0 cm with a firm endpoint for the apprehension test, without a significant difference between the 2 groups.

CONCLUSIONS: This prospective randomized study showed that MPFLR for recurrent patellar instability could achieve good clinical results, with a good congruous patellofemoral joint and good knee function. MRP could yield similar results to MPFLR for recurrent patellar instability in adults with medial patellofemoral ligament injuries from the patella or midsubstance portions.

LEVEL OF EVIDENCE: Level II, prospective comparative study.