In vitro contact stress distributions in the natural human hip.

Time variant distributions of intra-articular contact stress were assembled from direct measurement in seventeen grossly normal fresh cadaveric hips. Local stresses were sensed by arrays of 24 compliant miniature transducers inset superficially in the femoral head cartilage. Local contact stress magnitude was usually found to rise nearly linearly with applied joint loads in excess of about 1000 N. The sites of maximum local stress were found to underlie the general region of the acetabular dome. For a resultant joint load of 2700 N, the spatial mean contact stress and peak local contact stress averaged 2.92 MN m-2 and 8.80 MN m-2, respectively, for the 68 loading cycles analyzed. The full contact stress patterns were irregular and complex, but most commonly the general feature was a central band or 'ridge' of pressure elevation, oriented in an approximately anterior-to-posterior direction.