# Increased tibiofemoral rotation is associated with anatomical risk factors for lateral patella instability

## TL;DR

Increased tibiofemoral rotation is linked to anatomical risk factors for lateral patella instability in patients with patellofemoral instability.

## Contribution

This study identifies tibiofemoral rotation as a novel anatomical correlate of patellofemoral maltracking risk factors.

## Key findings

- Tibiofemoral rotation correlated with TT–TG, TT–PCL, femoral torsion, and lateral trochlea inclination.
- Patients with patellofemoral instability showed significant variability in tibiofemoral rotation.
- Tibiofemoral rotation may improve anatomical assessment and clinical decision-making in PFI patients.

## Abstract

Chronic patellofemoral instability (PFI) and pain are influenced by axial malalignment of the patellofemoral joint. Tibiofemoral rotation, defined as the rotation between femur and tibia knee, has shown to be correlated to PFI. This study aimed to determine whether tibiofemoral rotation is associated with anatomical risk factors for patellofemoral maltracking in patients with PFI. It was hypothesised that greater tibiofemoral rotation correlates with other predisposing factors for PFI.

Eighty‐five consecutive patients (mean age 22.6 ± 8.9 years; 58 female) with PFI underwent standardised bilateral knee MRI in 0° extension for rotational analysis. Tibiofemoral rotation was measured as the angle between the posterior femoral condylar tangent and posterior tibial plateau tangent on axial images. Ipsilateral and contralateral values along other anatomical patellofemoral risk factors were recorded. One‐sample t‐tests compared to the healthy contralateral side. Pearson correlations assessed associations between tibiofemoral rotation and anatomic risk factors for patellofemoral maltracking.

Mean ipsilateral tibiofemoral rotation was 6.9° ± 6.0° (range: −6.5° to 21.6°). Contralateral version averaged 6.4° ± 6.2° with no significant side difference. Absolute side‐to‐side difference was 3.7° ± 2.7°. Ipsilateral tibiofemoral rotation correlated with the tuberositas tibiae–trochlea groove (TT–TG) and medial posterior cruciate ligament distance (TT–PCL) (r = 0.37, p < 0.001, r = 0.43, p < 0.001), femoral torsion (r = −0.32, p = 0.003) and lateral trochlea inclination (r = −0.344, p = 0.001) whereas other patellofemoral risk factors showed no correlation.

Tibiofemoral rotation showed a significant correlation with anatomical risk factors associated with lateral patellar maltracking in patients with PFI. Moreover, patients with PFI demonstrated a wide variability in tibiofemoral rotation. Consideration of tibiofemoral rotation may enhance anatomical assessment and aid clinical decision‐making in patients with PFI.

Level III.