The effect of intertrabecular fluid on femoral head mechanics.

The effect of intraosseous fluid on the mechanical characteristics of bone is unclear. To determine the potential effects of alteration in the fluid boundary conditions of the femoral head, a decompression procedure was performed. The stiffness of femoral heads from normal adult mongrel dogs was measured after the heads were subjected to a physiologic mechanical load. When the fluid boundary conditions were altered by drilling the femoral neck, femoral head stiffness was reduced by more than 30% (p = 0.045). Refilling of the femoral specimen with saline restored the stiffness to the baseline value. These observations demonstrate that in vitro changes of fluid boundary conditions can alter the mechanical integrity of the femoral head. Alteration in osseous fluid boundary conditions in vivo could affect joint integrity and be of pathogenetic significance in joint disease.