OSSEOINTEGRATED THUMB PROSTHESES - A CONCEPT FOR FIXATION OF DIGIT PROSTHETIC DEVICES

Three patients with traumatic amputation of the thumb al the metacarpo phalangeal joint level underwent a two-stage reconstruction aimed at f ixation of a thumb prosthesis to the first metacarpal bone via an osse ointegrated titanium fixture. The first stage included insertion of th e fixture into the medullary cavity of the first metacarpal bone in co mbination 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, t he surrounding skin being thinned to the thickness of a split-skin gra ft to minimize relative mobility. A thumb prosthesis could then be fir mly attached to this fixture. At follow-up examinations between 18 mon ths and 3 years; postoperatively perfect osseointegration of the impla nt persisted. There were no skin problems. Some extent of tactile disc rimination was achieved in the prosthesis hypothetically based on tran sfer of tactile stimuli to endosteal nerves in the bone via the titani um fixture.