Background

Medial patellofemoral ligament (MPFL) reconstruction is the most currently performed procedure for recurrent patellar instability (RPI). However, most reports present only a short/mid-term follow-up. Also, the influence of predisposing factors and femoral tunnel positioning remains controversial.

Purpose

To evaluate medium and long-term results of isolated MPFL reconstruction and the correlation to main risk factors for RPI and femoral tunnel positioning.
STUDY DESIGN: case series.

Methods

A total of 69 patients (86 knees) underwent isolated MPFL reconstruction with a medial third of the patellar tendon between 2004 and 2016 were recorded at a mean follow-up of 72.2 ± 37.5 months (range, 24-163 months). Evaluated parameters: age, gender, follow-up period, recurrence, Kujala score, pre-existing chondral lesion, trochlear dysplasia (Dejour classification), patellar height (Caton-Deschamps index - CDI), femoral tunnel positioning (modified Schöttle method) and patellofemoral osteoarthritis (Iwano classification). Uni- and multivariate analysis correlated the variables to Kujala scores and patellofemoral osteoarthritis. Significance was set at P < .05.

Results

The mean age at surgery was 26.1 ± 8 years (range, 15-45 years) and females were 68.1%. Femoral tunnel positioning was excellent in 60.4% of knees, good in 23.3%, and poor in 16.3%. The mean CDI was 1.2 ± 0.2 (range, 0.9-1.8) and 22.1% of knees had patella alta. Pre-existing chondral lesions were found in 40.7% of knees and trochlear dysplasia in 79% (A, 51.2%; B, 24.4%; C, 3.4%). No recurrences occurred. The mean Kujala was 77.7 ± 18.2 (range, 25-100) and all patients improved after surgery. Patellofemoral osteoarthritis development was 16.3% (grade 1, 11.6%; 2, 3.5%; 3, 1.2%). Multivariate analysis showed that long-term had a positive correlation to Kujala (P = .043) and that high-grade types (B/C) of trochlear dysplasia correlated to lower Kujala scores (P = .022) and patellofemoral osteoarthritis (P = .004).

Conclusion

Isolated MPFL reconstruction with medial third of patellar tendon showed good functional results, no recurrences and a low rate of clinically significant patellofemoral osteoarthritis in the medium and long-term. However, the high-grade types of trochlear dysplasia did correlate to lower Kujala scores and patellofemoral osteoarthritis development.