Osseointegrated thumb prostheses: a concept for fixation of digit prosthetic devices

Three patients with traumatic amputation of the thumb at the metacarpophalangeal joint level underwent a two-stage reconstruction aimed at fixation of a thumb prosthesis to the first metacarpal bone via an osseointegrated titanium fixture. The first stage included insertion of the fixture into the medullary cavity of the first metacarpal bone in combination with transplantation of cancellous bone from the iliac crest. After 3 months, when the fixture was firmly osseointegrated into the bone, a skin-penetrating abutment was placed on top of the fixture, the surrounding skin being thinned to the thickness of a split-skin graft to minimize relative mobility. A thumb prosthesis could then be firmly attached to this fixture. At follow-up examinations between 18 months and 3 years; postoperatively perfect osseointegration of the implant persisted. There were no skin problems. Some extent of tactile discrimination was achieved in the prosthesis hypothetically based on transfer of tactile stimuli to endosteal nerves in the bone via the titanium fixture.