Summary

Attention to the rotational profile of the knee is recommended during surgical planning in management of KOA due to high incidence of torsional deformities.

Abstract

Purpose

This study aims to investigate the incidence of lower limb rotational deformities in an Asian population with knee osteoarthritis (KOA), as well as analyze if these have any relationship with hip-knee-ankle angle (HKA), lateral distal femoral angle (LDFA) or medial proximal tibial angle (MPTA).

Methods

A total of 344 patients planned for operation from September 2018 to April 2024 were retrospectively analysed. Only 238 patients with 264 knees were included after exclusion of patients with previous lower limb procedures or underlying morphology. Femoral anteversion and tibial torsions were measured on Computed Tomography (CT) images, while HKA, LDFA and MPTA were measured on long limb X-Ray films. The relationships between femoral anteversion and tibial torsion with HKA, mLDFA, and mMPTA were determined with the Pearson correlation coefficient.

Results

The incidence of excessive femoral anteversion (>20° femoral anteversion) and tibial torsion (>30° external rotation) was 56.1% and 18.6% respectively. The mean femoral anteversion was 21.7° and external tibial torsion was 22.6°. Overall, femoral anteversion and tibial torsions were not significantly related to HKA, mLDFA, or mMPTA in accordance with the Pearson correlation (r<0.4). The intra- and inter-observer reliability was 0.85 and 0.82 for femoral anteversion, 0.83 and 0.78 for tibial torsion, 0.91 and 0.89 for HKA, 0.98 and 0.95 for LDFA and 0.95 and 0.91 for MPTA, respectively.

Conclusions

This study reports a high incidence of torsional deformities with no significant correlation between femoral or tibial torsion and HKA, LDFA or MTPA in the study population. Attention to the rotational profile of the knee is recommended during surgical planning in management of KOA.

Keywords: Knee Osteoarthritis, Femoral Torsion, Tibial Torsion, Knee Alignment