Revision Medial Patellofemoral Ligament Reconstruction: Prevalence of Anatomic Risk Factors and Early Outcomes

The rate of recurrent instability following primary medial patellofemoral ligament (MPFL) reconstruction has been reported to be as high as 6.7%. However, limited studies have reported on clinical outcomes and complications following revision MPFL reconstruction. Furthermore, the role of previously identified risk factors for primary failure (e.g., patella alta and trochlear dysplasia) warrants further study in this patient population. Therefore, the goal of this study was 2-fold. First, to evaluate the prevalence of anatomic risk factors and technical errors among patients presenting for revision patellofemoral surgery. Second, to report early clinical outcomes following revision MPFL reconstruction. A single-surgeon registry was queried for patients who underwent revision MPFL reconstruction (including prior MPFL imbrication, MPFL reconstruction, tibial tubercle osteotomy [TTO]) from November 2015 to June 2022. Preoperative imaging was evaluated for risk factors including (1) misplacement of the femoral tunnel, (2) Caton-Deschamps index, (3) tibial tubercle-trochlear groove distance (TT-TG), (4) patellar tilt, and (5) trochlear dysplasia. Patient-reported outcomes and complications were obtained at final follow-up (minimum 1 year). The study included 32 patients (72% female, age: 23.9 ± 6.6 years). Mean time from index surgery to revision MPFL reconstruction was 4.8 ± 4.7 years (range 0.6 to 17.9 years). The most prevalent anatomic risk factors were patella alta (72%), TT-TG >15 mm (53%), trochlear dysplasia (Dejour type B, C, or D) (50%), and excessive patellar tilt (41%). The median number of risk factors was 3 (range 0-6), and 17 patients (53%) had three or more risk factors. At final follow-up (24.1 ± 14.5 months), no patients experienced recurrent patellofemoral instability or graft failure. Postoperative IKDC (p < 0.001) and SF-12 PCS (p < 0.001) scores improved significantly compared with preoperatively. In conclusion, the majority of patients presenting for revision MPFL reconstruction had three or more risk factors for recurrent dislocation.IV, Case Series.