[Transcutaneous osseointegration for amputees: foundational principles and current concepts]

Transcutaneous osseointegrated prostheses, which anchor titanium alloy implants into the residual limb bone, offer an alternative for amputees suffering from socket-related complications (occurring in up to 75% of cases). The principle is based on the direct titanium-bone interface, which forms a microscopic gap of approximately 20-50 nm that physically blocks bacteria (typically about 500 nm in diameter); combined with the use of high-purity titanium, this makes percutaneous infection risk much lower than that of traditional implants. Mainstream systems include the hollow-screw design (OPRA), the retrograde-nail design (TiTON), and the compression design (Compress), among which TiTON has wide applicability and is mostly implantable in a single-stage surgery. Clinical studies confirm that the technique significantly improves walking efficiency (by about 20%), wearing time, and quality of life, while osseoperception enhances balance and prosthesis embodiment; combined with nerve reconstruction, it can alleviate neuropathic pain. Major complications such as infection (mostly mechanical skin irritation), periprosthetic fractures (mostly traumatic), and implant fracture are rare, and the risk of severe disability or death is only 0.4%, far lower than infection-related risks in joint replacement. Future research should focus on stabilizing the skin penetration site and further exploring the anti-infective mechanisms of the titanium-bone interface to broaden its application.