Comparable clinical outcomes and redislocation rates after isolated medial patellofemoral ligament reconstruction in patients with and without borderline anatomical risk factors for patellar instability

Abstract Purpose The purpose of this study was to compare mid‐ to long‐term clinical outcomes and redislocation rates after isolated medial patellofemoral ligament (MPFL) reconstruction in patients with and without borderline anatomical risk factors. It was hypothesized that isolated MPFL reconstruction would provide comparable outcomes regardless of borderline anatomical abnormalities. Methods A retrospective comparative study was performed on 51 patients (55 knees) treated with isolated MPFL reconstruction for recurrent patellar instability between 2013 and 2023. Patients were divided into a standard group (Caton–Deschamps Index [CDI] < 1.2, tibial tubercle–trochlear groove [TT–TG] < 20 mm, absent or Type A trochlear dysplasia) and a borderline group (CDI 1.2–1.4, TT–TG 20–24 mm and/or Dejour Type B–D trochlear dysplasia without explosive J‐sign or large trochlear spur). Clinical outcomes were assessed using Knee injury and Osteoarthritis Outcome Score (KOOS), Kujala, Tegner and Visual Analogue Scale (VAS) scores at a mean follow‐up of 7.9 ± 3.9 years. Redislocations and complications were recorded. Results Twenty‐five knees were included in the standard group and 30 in the borderline group. Both groups showed significant improvement in all clinical scores from baseline to final follow‐up ( p < 0.001 for all). No significant differences were observed between groups at final follow‐up in KOOS (88.9 ± 10.3 vs. 86.1 ± 9.5; p = 0.159), Kujala (85.3 ± 18.8 vs. 86.9 ± 10.3; p = 0.713), Tegner (4.0 ± 1.1 vs. 3.9 ± 1.3; p = 0.765) or VAS scores (1.6 ± 1.1 vs. 2.1 ± 1.8; p = 0.260). Redislocation rates were comparable between groups (4.0% vs. 6.7%; p = 1.0). Within the borderline group, the cumulative burden of anatomical risk factors did not negatively affect outcomes. Conclusions Isolated MPFL reconstruction provides reliable and durable mid‐ to long‐term outcomes in carefully selected patients with borderline anatomical risk factors, with clinical results and redislocation rates comparable to those observed in standard patients. These findings support a patient‐specific surgical approach, suggesting that additional bony procedures should be reserved for clearly pathological anatomical abnormalities rather than routinely performed in borderline cases. Level of Evidence Level III.