Medial Patellofemoral Ligament Reconstruction for Adolescents With Acute First-Time Patellar Dislocation With an Associated Loose Body

Abstract

Background: The management of adolescents with acute first-time patellar dislocation with an associated loose body remains a debated topic. The rate of recurrent dislocation in these patients may be up to 61% if the medial patellofemoral ligament (MPFL) is repaired or not addressed surgically. To our knowledge, a prospective evaluation of MPFL reconstruction for adolescents with acute first-time patellar dislocation with an associated chondral or osteochondral loose body has not been previously performed.

Purpose/hypothesis: The purpose of this study was to analyze patients with a first-time patellar dislocation who required surgery for a loose body, comparing those who underwent MPFL repair or no treatment with those who underwent MPFL reconstruction during the index procedure. The hypothesis was that performing MPFL reconstruction would reduce the rate of recurrent instability and improve patient-reported outcomes compared with MPFL repair or no treatment. A secondary objective was to report outcomes of those patients who underwent reconstruction versus those who did not.

Study design: Case series; Level of evidence, 4.

Methods: This was a prospective analysis of adolescents treated with MPFL reconstruction for acute first-time patellar dislocation with associated loose bodies between 2015 and 2017 at a single pediatric level 1 trauma center with minimum 2-year follow-up. Retrospective analysis was previously performed for a similar cohort of adolescents treated with MPFL repair or no treatment. Patient characteristic data, radiographic measurements, and surgical variables were compared. Primary outcome measures included recurrent subluxation or dislocation and the need for further stabilization procedures. Secondary outcomes included Kujala score, Single Assessment Numeric Evaluation score, patient satisfaction, and ability to return to sport.

Results: A total of 76 patients were included, 30 in the MPFL reconstruction cohort and 46 in the MPFL repair or no-treatment cohort. The only difference noted in patient characteristic, radiographic, or surgical variables was a smaller Insall-Salvati ratio in the reconstruction group (1.29 vs 1.42; P = .011). Compared with MPFL repair or no treatment, MPFL reconstruction was associated with less recurrent instability (10.0% vs 58.7%; P < .001), fewer secondary procedures (6.7% vs 47.8%; P < .001), and more frequent return to sports (66.7% vs 39.1%; P = .003). No differences in patient-reported outcomes were noted.

Conclusion: Performing concomitant MPFL reconstruction in adolescents with first-time patellar dislocation and an intra-articular loose body results in a 5-fold reduction in recurrent instability, reduces the need for subsequent surgery, and improves patients' ability to return to sports compared with repairing or not treating the MPFL.

Keywords: loose body; medial patellofemoral ligament (MPFL) reconstruction; osteochondral defect; patellar dislocation; patellofemoral instability.