Adaptive changes in the femur after implantation of an Austin Moore prosthesis.

We studied the bone adaptation in a retrieved femur six years after implantation of an Austin Moore prosthesis. Strains caused by loading of the femoral head and greater trochanter were measured in this femur as well as in the contralateral, normal femur before and immediately after postmortem implantation of a prosthesis. Immediately after implantation the strains were abnormally high, particularly in the calcar region. However, six years after implantation all strains were close to normal. This was found to be due to an increase in both the bone density and the bone area. Changes were also noted in the structure of the osteons, particularly adjacent to areas of endosteal compressive stress-transfer.