Osseointegrated Implants for Trans-Femoral Amputees: Evaluation of Bone Mineral Density

Amputee patients are known to have decreased bone mineral density (BMD) and an increased risk of osteoporosis in the affected proximal femur and hip region. The major cause of these issues in Trans-femoral amputee (TFA) patients is the absence of an adequate loading environment that can encourage bone growth in accordance with Wolff`s law. As a solution to the stress distribution issues associated with socket prostheses in the treatment of TFA patients, osseointegrated implants have been used which are anchored directly to the bone and designed to favor the natural loading regime of bone. In this paper, we present a prospective study that investigates changes in BMD for TFA and TTA patients who have received osseointegrated implants.

This is a prospective study of 61 patients, consisting of 44 males and 17 females, aged 22-77 (mean 50.39) years at surgery, with minimum two-year follow-up. Selection criteria included age over 18 years, unilateral TFA patients who had socket-related problems, as well as wheelchair bound patients with short stumps and non-reconstructable limb pathology. All patients received osseointegrated implants which were press-fit into the amputated limb. BMD was assessed using DXA in the femoral neck and femoral head regions of each patient in both the operated and contralateral femurs. DXA scans were taken pre-operatively and annually following osseointegration surgery.

From preliminary observations, the post-operative BMD of the femoral neck showed significant improvement in mean Z-scores in TFA patients at one-year follow-up. These results suggest that osseointegrated implants are effective at encouraging bone growth and restoring the BMD in the operated limb for TFA patients, within a relatively short period of time following surgery. Osseointegrated implants therefore have the potential to address the stress distribution issues associated with socket prostheses and restore the normal bone loading regime in TFA patients.