Combined medial patellofemoral ligament reconstruction and distal femoral derotation osteotomy in recurrent patellar dislocation with Jumping J sign

Abstract

Recurrent patellar dislocation (RPD) is commonly associated with patellar maltracking, and the Jumping J sign may indicate a severe instability phenotype. The optimal surgical strategy for patients with this sign remains unclear. The purpose of this study was to compare clinical outcomes, patellar tracking correction, and patellofemoral stability between patients with RPD and a Jumping J sign treated with medial patellofemoral ligament reconstruction (MPFL-R) alone versus MPFL-R combined with derotational distal femoral osteotomy (DDFO). It was hypothesized that adding DDFO would improve objective patellar tracking and stability. Cohort study; Level of evidence, 3. This retrospective matched cohort study included 48 knees from 43 patients with RPD and a documented Jumping J sign treated between 2018 and 2023. Patients underwent MPFL-R alone (control group, n = 24) or MPFL-R combined with DDFO (DDFO group, n = 24) after 1:1 matching by age, sex and femoral anteversion angle (FAA). The patellar medial laxity index, bisect offset index (BOI), patellar-trochlear groove distance (PTG), patellar lateral tilt angle (PLTA), residual Jumping J sign, and patient-reported outcomes were assessed at final follow-up. The DDFO group had a significantly lower patellar medial laxity index than the control group (18.0% vs. 24.3%; P = 0.016). Postoperative bisect offset index (BOI) (87% ± 14% vs. 103% ± 25%), PTG (− 5.3 ± 5.3 mm vs. 0.6 ± 7.5 mm), and patellar lateral tilt angle (PLTA) (13.3° ± 6.8° vs. 23.2° ± 10.5°) were also significantly lower in the DDFO group, indicating improved patellofemoral congruency. No significant between-group differences were found in postoperative patient-reported outcomes. Residual J sign remained common, with no significant difference between groups. However, residual Jumping J sign was significantly less frequent in the DDFO group than in the control group (4% vs. 25%; P = 0.048), suggesting improvement in the more severe dynamic maltracking pattern. In RPD patients with a Jumping J sign, MPFL-R combined with DDFO was associated with improved patellofemoral congruency, reduced medial patellar laxity, and a lower incidence of residual Jumping J sign compared with MPFL-R alone. However, residual J sign and patient-reported outcomes did not differ significantly between groups at final follow-up.