Safety of osseointegrated implants for transfemoral amputees: A two-center prospective cohort study

Background: Osseointegrated implants are an alternative for prosthetic attachment for individuals unable to wear a socket following an amputation. The concept of an integrated metal implant communicating with the external environment raises substantial concern about the risk of ascending infection. We report on the safety of press-fit osseointegrated implants currently used in Australia and the Netherlands. Methods: We prospectively recorded all adverse events in all patients with transfemoral amputation who were managed with an osseointegration implant system between 2009 and 2013 at two centers. The procedure was performed in two stages. A customized porous-coated implant was placed in the first stage, and a stoma was created in the second. Adverse events were categorized according to type (infection or "other") and severity. Infections were classified according to four grades of severity based on clinical and radiographic findings: (1) low-grade soft-tissue infection, (2) high-grade softtissue infection, (3) bone infection, and (4) septic implant failure. Results: Eighty-six patients (ninety-one implants), twenty-five to eighty-one years of age, were included in the study and followed for a median of thirty-four months (range, twenty-four to seventy-one months). Thirty-one patients had an uneventful course with no complications; twenty-nine developed infection (all grade 1 or 2); and twenty-six did not develop infection but had one or more other complications requiring intervention, including stoma hypergranulation (seventeen patients), soft-tissue redundancy (fourteen), proximal femoral fracture (three), inadequate osseointegration leading to implant replacement (one), implant breakage (two), and breakage of the pin used as a fail-safe mechanism (twenty-five). Conclusions: Mild infection and irritation of the soft tissue in the skin-penetration area are common in transfemoral amputees who have an osseointegrated implant. These complications were successfully managed with simple measures. Severe infections resulting in septic implant loosening are rare.