# Favourable mid‐ to long‐term clinical and functional outcomes and low redislocation rates following derotational distal femoral osteotomy for the treatment of recurrent patellofemoral instability

## TL;DR

Surgery to correct femoral antetorsion improves long-term knee function and reduces instability in patients with recurring patellar issues.

## Contribution

Demonstrates favorable mid- to long-term outcomes of derotational distal femoral osteotomy for recurrent patellofemoral instability.

## Key findings

- 87% survival probability free of instability and revision surgery at 5 years.
- 84% of patients returned to sports after a mean follow-up of 8.7 years.
- Good knee function and quality of life reported via multiple patient-reported outcome measures.

## Abstract

To assess the mid‐ to long‐term clinical and functional outcomes and return to sports following derotational distal femoral osteotomy (DDFO) for the treatment of recurrent patellofemoral instability and associated increased femoral antetorsion.

Patients who underwent DDFO as well as concomitant procedures between 2007 and 2016 were eligible for inclusion. Recurrent instability, complications, revision surgery and return to sports rates were evaluated after a minimum follow‐up of 5 years. Kaplan–Meier survival analysis was performed for the risk of recurrent instability or undergoing further surgery other than hardware removal. Patient‐reported outcome measures (PROMs; Visual Analog Scale [VAS] for pain, Tegner Activity Scale [TAS], Kujala score, Banff Patellofemoral Instability Instrument [BPII] 2.0 and Patellofemoral Instability‐Return to Sport after Injury [PFI‐RSI] scale) were recorded.

Of 44 knees in 42 patients eligible for inclusion, 25 knees in 24 patients (64% female) with a mean age of 27.3 ± 9.0 years at the time of surgery were available for follow‐up at a mean of 8.7 ± 2.7 years (follow‐up: 57%). Two patients (5%) underwent early revision surgery due to loss of osteosynthesis at the distal femur. Three patients (12%) reported subjective recurrent instability at a median of 3.9 (3.5–7.0) years post‐operatively. The Kaplan–Meier estimator showed a survival probability free of recurrent instability and revision (except hardware removal) of 87% (95%‐confidence interval 76%–100%) at 5 years. At final follow‐up, patients reported good knee function (Kujala score: 78.5 ± 16.6), knee‐related quality of life (BPII: 68.3 ± 22.3), psychological readiness to return to sport (PFI‐RSI: 73.3 [43.8–90.0]), and moderate activity levels (TAS: 4.0 [3.0–4.0]). The majority of patients returned to sports (84%).

DDFO provided effective treatment for recurrent patellofemoral instability associated with increased femoral antetorsion. Favourable clinical and functional outcomes as well as high return to sport rates were observed at a mid‐ to long‐term follow‐up.

Level IV, retrospective case series.