Femorotibial rotation does not affect clinical outcomes after patellofemoral stabilizing surgery

TL;DR

This study finds that increased femorotibial rotation does not worsen outcomes after patellar stabilization surgery, though it may be linked to slightly less improvement.

Contribution

The study provides new clinical evidence that femorotibial rotation does not significantly impact post-surgery outcomes in patellar instability cases.

Findings

Functional outcomes after surgery were similar regardless of femorotibial rotation.

Patients with increased femorotibial rotation showed a tendency for less functional improvement.

There was no increased risk of complications or recurrent instability in patients with higher femorotibial rotation.

Abstract

The role of femorotibial rotation in patellar instability treatment and prognosis remains unclear. This study examines whether increased femorotibial rotation, indicated by a positive winking sign, affects functional outcomes and recurrent instability after patellofemoral stabilizing surgery.

All patients undergoing patellofemoral instability surgery at our institution (2014–2022) with complete rotational imaging (magnetic resonance imaging/computed tomography [MRI/CT]) and functional assessments (Kujala, Tegner) and at least 1‐year follow‐up were included. Patients were grouped based on the presence of a radiological winking sign. Surgical treatment was tailored to individual deformities, including medial patellofemoral ligament reconstruction, trochleoplasty, derotational osteotomy and tibial tuberosity osteotomy.

A total of 121 knees (114 patients, mean age 23.5 years) with a mean follow‐up of 2 years were analyzed. Preoperatively, the winking sign was present in 19.8% (n = 24) and absent in 80.2% (n = 97). Demographics and preoperative deformity analysis were similar between groups (n.s.) except for increased femorotibial rotation (11.8° ± 7° vs. 8.5° ± 5°; p = 0.031) and patellar tilt (p = 0.006) in patients with a positive winking sign. Functional outcome scores either improved (Kujala: 68.9 ± 16 to 80.8 ± 19; p < 0.001) or remained unchanged (Tegner: 3.6 ± 1.4 to 3.4 ± 1.6; p = 0.347) from pre‐ to postoperative. Patients with a positive winking sign tended to show less improvement (Δ Kujala: 7.6 ± 18 vs. 13.0 ± 20; p = 0.170; Δ Tegner: 0.0 ± 1.7 vs. −0.1 ± 2.0; p = 0.373). Surgical procedures were evenly distributed between groups (n.s.). One patient (0.8%) with a negative winking sign had a recurrent instability. Complications did not differ between groups (n.s.).

Patients with increased femorotibial rotation achieve similar functional outcome following patellofemoral stabilizing surgery without increased complications or persistent instability. A tendency for less functional improvement in these patients raises questions about the need to assess femorotibial rotation as an independent deformity. Further research is needed to investigate this topic more deeply.

Level III.

Figures