Osseointegrated Transcutaneous Device for Amputees:A Pilot Large Animal Model

Traditional above-the-knee amputation prosthetics utilize a stump-socket interface that is well-known for skin/socket problems,sitting difficulty, disuse osteopenia, and increased work of ambulation. As a result, we evaluated a novel osseointegratedtranscutaneous implant in a large animal. The implant was designed to promote osseointegration at the bone-implant interfaceand minimize complications. As proof of concept, four Dorset sheep underwent a two-stage surgery for forelimb placement of anosseointegrated transcutaneous implant utilizing Compresstechnology (Biomet, Inc., Warsaw, IN). Two sheep received a longanchor plug (90 mm long x 9 mm in diameter) and two received a short anchor plug (46 mm long x 9 mm in diameter). Sixteenweeks after the initial surgery, the operative limbs, along with the attached implant, underwent radiographic and histologicalanalysis for osseointegration. Periprosthetic fractures occurred in the two animals that received the longer internal prosthesis; onehealed with splinting and the other animal underwent a second surgical procedure to advance the amputation site more proximal.No fractures occurred in the shorter internal prosthesis group. There was no histological evidence of infection and none of thetranscutaneous adapters failed. Bone-implant osseointegration was demonstrated in two of three limbs that underwent histologicalanalysis. This unique implant demonstrated osseointegration without transcutaneous adapter failure, all while displaying minimalinfection risk from the outside environment. Although it involved short-term follow-up in a limited number of animals, this pilotstudy provides a platform for further investigation into the valid concept of using Compresstechnology as an endo-exo device