The rotational profile: A study of lower limb axial torsion, hip rotation, and the foot progression angle in healthy adults.

The purpose of this study was to compare the rotational profile of adults with higher versus lower foot progression angles (FPA). Tibial torsion, femoral torsion, hip internal and external rotation and FPA data were collected on one hundred two healthy volunteers. Data were stratified into Low, Mid, and High FPA groups to study relationships among the components of the rotational profile and if there were group differences in the magnitude of torsion angles. Direction of torsion was also studied as an attempt to look at the incidence of offsetting between the tibia and femur. Tibial torsion was significantly higher in the High FPA group (p<0.001) and was significantly related to the FPA (p≤0.01). Femoral torsion was related to hip internal rotation (p<0.05). Offsetting tibial and femoral torsions occurred in 59% of subjects with low FPA and 56% of subjects with high FPA. All subjects in the low FPA group with offsetting had tibial torsion that followed the FPA and the femurs that were directed opposite. In the High FPA group, 68% of subjects with offsetting had tibias that followed the FPA. Stratifying the data by FPA revealed there were significant differences in tibial torsion among the groups and provided evidence that tibial torsion influences the direction and magnitude of the FPA. Offsetting torsions between the tibia and femur were more common in people with higher and lower FPA and had clearer patterns where the tibia tended to follow the direction of the FPA.