Biomechanical Differences in Young Patients With True Femoral Retrotorsion: Correlations Between Gait Deviations, Clinical Measurements, and Imaging Data

BACKGROUND: Torsional abnormalities of the femur, such as femoral retrotorsion, can significantly impact gait and joint biomechanics in children and adolescents. However, the resulting gait patterns as well as the relationship between static imaging measurements and dynamic gait deviations remain unclear. This study aimed to investigate biomechanical differences in gait between young individuals with true femoral retrotorsion and typically developing peers, examining correlations between gait deviations, clinical measurements, and imaging data. METHODS: A multicenter retrospective study was conducted, including 31 patients with unilateral or bilateral femoral retrotorsion and a control group of typically developing children. Femoral torsion was assessed using MRI or CT, while 3D motion capture was used for gait analysis. Clinical hip rotation was measured, and statistical analyses, including correlation assessments, were performed to evaluate relationships between imaging, clinical, and gait parameters. RESULTS: Patients exhibited significantly increased hip external rotation and out-toeing gait compared with controls. However, no correlation was found between femoral torsion measured by imaging and hip rotation during gait or foot progression angle. In contrast, the midpoint of clinical hip rotation correlated moderately with both hip rotation and foot progression angle during gait. In addition, patients had higher BMI and demonstrated compensatory knee valgus, despite no radiologic evidence of knee malalignment. CONCLUSION: Children and adolescents with femoral retrotorsion exhibit distinct gait deviations, but static imaging alone does not reliably predict dynamic gait patterns. This emphasizes the need for dynamic assessment in clinical decision-making.