Distal femoral osteotomy for the treatment of chronic patellofemoral instability improves gait patterns

Abstract

Purpose: The purpose of this study was to evaluate pre- to postoperative changes in clinical and functional outcomes as well as gait patterns in patients who underwent surgery for chronic patellofemoral instability (PFI). Methods: Patients who underwent surgery for the treatment of recurrent PFI according to an individual risk factor analysis were included. Pre- and minimum 12 months postoperatively, patient-reported outcome measures (PROM; Kujala score, Lysholm score, Tegner Activity Scale [TAS] and Visual Analog Scale for pain) as well as gait (dynamic Q-angle) and function (dynamic valgus and dynamic Trendelenburg during single-leg squat) via videography were evaluated. Subgroup analysis was performed based on whether or not patients underwent concomitant distal femoral osteotomy (DFO) due to coronal and/or torsional malalignment. Results: Twenty-three patients were included (follow-up: 12.5 [12.1–13.0] months), of which 60.9% patients underwent a concomitant DFO. All PROM improved significantly (p < 0.05). Overall, dynamic Q-angle (p = 0.016) and dynamic valgus (p = 0.041) were observed significantly less frequently postoperatively when to compared to preoperatively. Subgroup analysis showed that only the group that underwent DFO had a significant improvement of dynamic Q-angle (p = 0.041). Dynamic Trendelenburg did not improve (p > 0.05). Regression analysis showed that the presence of a postoperative dynamic Q-angle was associated with a worse postoperative Kujala score (p = 0.042) and TAS (p = 0.049). Conclusion: Patient-individualized surgery for PFI improved gait patterns and functional testing, especially in patients who also underwent DFO. The presence of dynamic Q-angle postoperatively was associated with significantly worse functional outcome and sporting ability. Level of evidence: Level III.