THE EFFECT OF COMPRESSIVE LOADING ON INTRAOSSEOUS PRESSURE IN THE FEMORAL-HEAD INVITRO

We measured intraosseous pressures in twenty human hips from cadavera during progressive serial applications of load using a materials-testing machine. Pressure rose in strict proportion to load at each of four different testing sites. In the femoral head, the mean response to loads applied over 0.1 second was 55 .+-. 66 millimeters of mercury per 980 newtons. This value was 3.6 times higher than the mean response in a region cephalad to the acetabulum and 2.6 and 2.8 times higher than the mean response in the femoral neck and intertrochanteric regions. In further studies within the femoral head, pressures were accentuated and reduced by factors of 1.7 and 0.4, respectively, at faster (0.03 second) and slower (1.0 second) loading times. Clinical Relevance: The juxta-articular cancellous bone of the femoral head becomes pressurized with compressive loading in vitro. In vivo, cyclic changes in intraosseous pressure may play a major role in the remodeling, perfusion, and load transmission of bone. In addition, load-induced pressure pulses may have a role in the etiology of atraumatic osteonecrosis.