OUTCOMES OF MEDIAL PATELLO-FEMORAL LIGAMENT RECONSTRUCTION FOR PATELLAR INSTABILITY IN CHILDREN AND ADOLESCENT. OBJECTIVE ASSESSMENT WITH CT SCANS AND PRELIMINARY RESULTS

Abstract

Background: The medial patellofemoral ligament (MPFL) is the primary stabilizer of the patellofemoral joint. Its reconstruction has been recommended in adults over the past decade after recurrent patellar instability. The purpose of this study was to assess outcomes after MPFL reconstruction in children and adolescent and to prospectively evaluate reconstruction by computed tomography (CT scans) before and after surgery.

Materials and Methods: Thirteen consecutive patients (5 boys and 8 girls)(13 knees) underwent a double bundle MPFL reconstruction with hamstring tendon autograft (gracilis:6, semitendinosus: 7) for patellar instability. A bone femoral fixation with interference screw in a tunnel was associated with patellar fixation according to Fithian in mature knees, and a soft tissue procedure was performed in skeletally immature knees. In 5 knees the MPFL reconstruction was isolated while it was associated with medialization and distalization of the tibial tubercle in 8 knees. The mean age at time of surgery was 14.4 years (range, 9.6– 16.5). Patients were evaluated preoperatively and postoperatively by physical, radiological and CT Scans examination and subjectively with the IKDC and Kujala questionnaires. During CT scans with knee fully extended and the quadriceps contracted or relaxed, the patellar tilt angle was assessed. In cases where tibial tubercle was mobilized, the tibial tubercle-trochlear groove (TT-TG) distance was measured pre and postoperatively.

Results: No recurrent episodes of dislocation or sub-luxation were reported after 10.5 months (range, 3–23) follow-up after surgery. Mean Kujala score was of 90.2 (range, 84–99) at latest follow-up. For all patients the moving patellar apprehension test was positive before and negative after surgery. A firm end point to lateral patellar translation was noticed in all patients at latest follow-up. Objective assessment with CT noted that the patellar tilt on relaxed quadriceps was significantly improved from 28° preoperatively (range, 16–41) to 16° at follow-up (range, 7–32). The patellar tilt on contracted quadriceps was significantly improved from 35° preoperatively (range, 21–52) to 24.6° at follow-up (range, 11–48). In the specific subgroup, the TT-TG distance decreased preoperatively from 15.4 mm (range, 12–19) to 9 mm postoperatively (range, 2.9–14.8).

Conclusion: MPFL reconstruction in children and adolescent is an effective procedure. The patellar tilt was efficiently improved by MPFL reconstruction and these results were correlated with Kujala score. Mid and long term results are still to be evaluated.