Bipedalism results in strong constraints on the human hip joint. This joint ensures transmission of the forces between trunk and lower limbs. This PhD work addresses questions in physical anthropology, evolutionary biology and clinical orthopaedics.
An important methodological study was conducted in order to propose accurate methods to determine the three-dimensional axes of the two neighbouring components of the human hip joint, i.e. the acetabular region and the proximal femur. Next, variations in the three-dimensional orientations of the acetabulum and the femoral neck were quantified on a sample of modern humans. To better understand the nature of these variations, a review of the biomechanical literature was performed, and ontogenetic analyses were conducted.
An integrative analysis revealed complex relationships between the biomechanical systems governing the three-dimensional orientations of the acetabulum and the femoral neck. Some forces are shared by the two systems, making coherent the covariations quantified between the axes of the acetabulum and the femoral neck. However, each system is also governed by independent forces resulting in a low concordance of these same axes in a bipedal posture. We suggest that this poor concordance in a bipedal posture may partly be due to the phylogenetic history of the human hip joint. To test this hypothesis, comparative analyses were pursued and showed that maximal concordance was obtained for the genera Homo, Pan, Gorilla and Pongo in a quadrupedal posture.