[Experimental study of the deformations of the acetabulum in unipodal stance]

This work is based on an experimental simulation of unipodal stance using skeletons obtained from fresh nonembalmed cadavers, including pelvis, the two last lumbar vertebrae, and both femurs. Periacetabular deformations in unipodal stance were recorded in 10 pelves, which were bilaterally tested (20 acetabuli). Measurements concerned circumferential deformations (tangential to the periphery of the acetabulum), and normal deformations (perpendicular to the periphery of the acetabulum). Deformations of the medial wall and relative displacements between both acetabular walls were simultaneously recorded. A tridimensional interpretation of acetabular deformations is proposed based on the following classification: acetabuli in which the acetabular notch widens and acetabuli in which the acetabular notch closes itself with lateral displacement of the acetabular walls on the circumference of the femoral head. Acetabular deformations appeared dependent on the shape of the femoral head, but were not influenced by the action of the muscular model.