Comparison of 2 different techniques for anatomic reconstruction of the medial patellofemoral ligament: a prospective randomized study

Abstract

Background: The comparative clinical outcome of anatomic reconstruction of the medial patellofemoral ligament (MPFL) between the Y-graft technique and C-graft technique for chronic patellar instability is unknown.

Hypothesis: Anatomic reconstruction of the MPFL with a Y-graft technique (a Y-shaped graft: femoral fixation first with separate tensioning of the 2 bundles) would yield better clinical results than a C-graft procedure (a C-shaped graft: patellar fixation first with simultaneous tensioning of both bundles) for chronic patellar instability.

Study design: Randomized controlled trial; Level of evidence, 2.

Methods: Ninety patients with symptomatic chronic patellar dislocations or instability were randomly divided into 2 groups to undergo double-bundle MPFL reconstruction either with the Y-graft technique or C-graft technique. Follow-ups were performed at 3, 6, 12, and 24 months postoperatively. The patellar stability was evaluated with the apprehension test at follow-up. The patellofemoral morphological characteristics were evaluated on axial computed tomography (CT) scans at 30° of knee flexion, and knee function was evaluated using the Lysholm and Kujala scores preoperatively and at 24 months postoperatively.

Results: Forty patients in the Y-graft group and 42 patients in the C-graft group were followed for 24 months. No recurrent dislocation or subluxation was reported in either group. On CT scans, congruence angle, patellar tilt angle, lateral patellar angle, and lateral displacement were restored to the normal range. The mean postoperative Lysholm scores for the Y-graft group and C-graft group were 92.3 ± 3.9 and 88.4 ± 6.8, respectively (P = .001). The mean postoperative Kujala scores were 95.9 ± 4.7 and 91.3 ± 9.7 for the Y-graft group and C-graft group, respectively (P = .001), with a good or excellent rate of 97.5% in the Y-graft group compared with 83.3% in the C-graft group (P = .031).

Conclusion: With no patellar redislocations reported, the Y-graft technique for the double-bundle anatomic MPFL reconstruction achieved statistically better knee function than the C-graft procedure at a minimum 2-year follow-up. However, the increase was less than the minimal clinically important difference, and further research is required to demonstrate its meaningful clinical improvement.

Keywords: anatomic reconstruction; medial patellofemoral ligament; patellar dislocation.