Acetabular orientation is commonly described by parameters in both the frontal and axial planes. Frequently studied angles such as femoral and acetabular anteversion, neck shaft angle (NSA) and acetabular abduction have been shown to be highly variable, even among asymptomatic subjects. However, it is still not known how these parameters affect functional activities such as gait. The purpose of our study is to investigate the relationship between skeletal and kinematic parameters of the hip during walking.

One hundred and forty six asymptomatic adult subjects (age=29.3±11.1 years, 70F) with no prior orthopedic treatment underwent 3D gait analysis and the following kinematic parameters were generated: ROM, Mean, Minimum, Maximum. All subjects underwent full body biplanar X-rays with 3D reconstruction of the pelvis with the following skeletal parameters generated: acetabular abduction, acetabular anteversion (AAnt), NSA and femoral anteversion (FA). Agglomerative Hierarchical Clustering was used for the aforementioned skeletal parameters in order to delimitate 3 classes in each. Kinematics were compared between classes using ANCOVA while controlling for confounding demographic factors (sex, age, height, weight).

We found no significant differences in gait between the classes of acetabular abduction. As for the femoral anteversion (average FA: class 1: 4.7°, class 2: 16.1° and class 3: 26.9°), 7 kinematic parameters related to the hip in the frontal and axial planes and to the knee in the sagittal plane were found to be significantly different between classes. As for the acetabular anteversion (average AAnt: class 1: 14.1°, class 2: 20.3°, class 3: 25.6°), 7 kinematic parameters related to the hip in both frontal and axial planes and to the knee in the sagittal plane were significantly different. The NSA (average NSA: class 1: 122°, class 2: 129°, class 3: 136°) showed 2 significantly different parameters in sagittal knee kinematics and a significant difference in step length.

This is the first study to assess the role of the skeletal parameters of the hip in dictating gait in asymptomatic subjects. Among frontal parameters, only NSA was related to gait kinematics. As for axial parameters, both acetabular and femoral anteversion (FA). Agglomerative Hierarchical Clustering was used for the aforementioned skeletal parameters in order to delimitate 3 classes in each. Kinematics were compared between classes using ANCOVA while controlling for confounding demographic factors (sex, age, height, weight).