Radiographic Evaluation of Bone Remodeling Around Osseointegration Implants Among Transfemoral Amputees

Objectives: To examine periprosthetic bone remodeling among the recipients of 2 types of lower-limb osseointegrated systems, the Integral Leg Prosthesis (ILP) and the Osseointegration Prosthetic Limb (OPL) type A, over a >24-month period. Design: Retrospective cohort study. Setting: Private hospital, with a specialized osseointegration unit. Patients: Twenty-eight patients with transfemoral lower-limb amputations were fitted with osseointegrated systems. Of these patients, 15 received the ILP and 13 the OPL osseointegrated implant. Intervention: Radiographic measurements were taken at baseline (0.4 +/- 0.5 years) and at follow-up (3.0 +/- 0.8 years) after the osseointegration procedure. Main Outcome Measurements: Radiographic bone density, longitudinal bone coverage, and bone width outcomes were measured in inverse "Gruen zones." Bone remodeling was evaluated by comparing changes between baseline and follow-up measurements. Results: Radiographic bone density decreased in all zones among both ILP and OPL groups. Cortical bone thickness increased among the OPL group in zones 3 (P < 0.05) and 5 (P < 0.05). Distal bone coverage of the ILP implant decreased by 2.3% (P < 0.01) and 4.1% (P < 0.05) of the total implant length on the medial and lateral sides, respectively. Conclusions: Decreased bone density with increased periprosthetic cortical thickness suggests a change in the bone architecture for the OPL group. The findings of this study raise concerns for the long-term success of the ILP implant. Radiographic analysis of x-rays seems to be a useful tool for clinicians to evaluate bone remodeling around osseointegrated prosthesis.