A study published August 6 in Prosthetics and Orthotics International evaluated changes in bone mineral density and bone turnover markers in people with transfemoral amputations who were treated with osseointegrated (OI) implants. The research concluded that implant removal was associated with loss of periprosthetic bone mineral density.
The research team followed up with 19 patients who had an OI transfemoral transplant for 30 months or until the implant was removed. Bone mineral density was measured in the lumbar spine, proximal femur, and seven periprosthetic regions. 25-hydroxyvitamin (D2 + D3), parathyroid hormone, N-terminal propeptide of type-I procollagen, C-telopeptide of type-I collagen, bone-specific alkaline phosphatase, and osteocalcin were measured in blood samples.
Among the participants, four fixtures and three abutments were removed. Patients with removed implants had a decreased bone mineral density in the seven periprosthetic regions between 27 percent and 38 percent at the 30-month follow-up compared to the baseline, whereas bone mineral density around non-removed implants normalized to baseline values. C-telopeptide of type-I collagen was significantly different between the groups at 18- and 24-month follow-up. None of the measured variables were significant predictors of implant removal.
The study authors concluded that implant removal was associated with loss of periprosthetic bone mineral density and an increase in C-telopeptide of type-I collagen in the years following OI surgery. They wrote that the results could contribute to clinical guidelines for monitoring rehabilitation progress and implant removal through dual-energy X-ray absorptiometry or surrogate markers like C-telopeptide of type-I collagen.
