Open access data for 2-year percutaneous osseointegrated implants - A sheep model

Percutaneous osseointegrated (OI) devices for amputees are metallic endoprostheses, surgically implanted into the residual bone that protrude through the skin, allowing attachment of an exoprosthetic. In contrast to standard socket-type systems, these percutaneous OI devices can provide an improved prosthetics attachment platform. However, bone adaptations, which include atrophy and/or hypertrophy along the extent of the host bone-endoprosthetic interface, are known clinical outcomes and are dependent upon the load transfer region of the device to the host bone. The goal of this study was to determine if a percutaneous OI device, designed with a porous coated distal region and a collar, could promote and maintain stable bone attachment. A total of eight, 18 to 24-month old, mixed-breed sheep were surgically implanted with a percutaneous OI device. For 24-months, animals were allowed to bear weight as tolerated and monitored for signs of bone remodelling. At necropsy, the endoprosthesis and the surrounding tissues were harvested, radiographically imaged, and histomorphometrically analyzed to determine the periprosthetic bone adaptation in five animals. Bone growth into the porous coating was achieved in all five animals. Serial radiographic data showed stress-shielding related bone adaptation based on the placement of the endoprosthetic stem. When collar placement achieved end-bearing against the transected bone, distal bone conservation/hypertrophy was observed. The results supported the use of distally porous coated percutaneous OI devices for distal load-transfer and host bone maintenance.