Isolated medial patellofemoral ligament reconstruction provides similar outcomes in patients with increased versus normal tibial tubercle–trochlear groove distance

PURPOSE: The primary aim of this study was to compare clinical outcomes following isolated medial patellofemoral ligament (MPFL) reconstruction in patients with increased tibial tubercle-trochlear groove (TT-TG) distance and those with normal TT-TG distance. Secondary aims were to compare the complication and recurrence rates between groups. METHODS: This prospective single-centre study included 121 consecutive patients who underwent isolated MPFL reconstruction between 2011 and 2022 for recurrent patellar dislocation (RPD). Patients were divided into two groups according to preoperative TT-TG distance: <20 mm (n = 90) and ≥20 mm (n = 31). Functional outcomes were assessed using the International Knee Documentation Committee (IKDC) score preoperatively and at a minimum follow-up of 24 months. Functional improvement (ΔIKDC) was calculated, and complication and recurrence rates were also collected. Anatomical risk factors for patellar instability, including trochlear dysplasia and patellar height, were assessed and compared between groups. RESULTS: Patients in both groups were comparable with respect to age (28.3 ± 6.5 vs. 26.1 ± 6.7 years; p = 0.138), gender (54.8% vs. 64.4% female; p = 0.497) and follow-up duration (79.7 ± 31.0 vs. 84.2 ± 38.0 months; p = 0.509). Postoperative IKDC scores were comparable between groups (80.1 ± 15.4 for TT-TG ≥ 20 mm vs. 78.9 ± 15.3 for TT-TG < 20 mm; p = 0.614). Functional improvement did not differ significantly between groups (ΔIKDC: 19.0 ± 17.3 vs. 25.8 ± 18.9; p = 0.075). After adjustment for baseline IKDC score, no between-group difference was observed (adjusted mean difference -0.9 [-7.2;5.3], p = 0.769). There was no difference in complications between groups. No recurrence of instability was reported in either group. CONCLUSION: An increased TT-TG distance was not associated with inferior short- to mid-term outcomes following isolated MPFL reconstruction for RPD with low-grade trochlear dysplasia and no patella alta. These findings reinforce the importance of a comprehensive, individualized assessment of patellar instability risk factors and suggest that TT-TG distance should not be used in isolation to determine the need for bony realignment procedures. LEVEL OF EVIDENCE: Level II.