2 The procedure
2.1.1 In the UK, lower limb amputation is the most common indication for a prosthesis. Amputation is most frequently a consequence of peripheral arterial disease; other causes include trauma or tumour. Upper limb or digit amputations are less common and usually result from trauma. A small proportion of patients require a prosthesis for a congenital deficiency.
2.1.2 Conventionally, the prosthesis is attached to the residual stump by belts and cuffs or by suction. The prosthesis usually has a socket, which is custom made from a plaster cast of the stump. However, friction between the stump and socket can cause pain and ulceration. Stump problems may significantly limit users of conventional prosthetic limbs.
2.2.1 The procedure aims to establish an osseointegrated implant, produce a secure junction between the soft tissues and the implant to prevent infection, and provide an abutment for prosthetic attachment. The implant may be in one piece or modular (with a separate abutment) and its surface may be modified (for example, using a screw thread, a porous or roughened surface or adding a special coating) to enhance bone and soft tissue integration. During the procedure, the implant is introduced into the medullary cavity of the residual bone. The procedure may be done during a single operation (in which the wound is closed with the abutment protruding through the skin) or in two stages (first stage: insertion of the implant and second stage: attachment of the abutment). A period of rehabilitation is usually required.
Sections 2.3 and 2.4 describe efficacy and safety outcomes which were available in the published literature and which the Committee considered as part of the evidence about this procedure. For more details, refer to the Sources of evidence.
2.3.1 A non-randomised comparative study of patients with transfemoral amputations reported restriction of hip flexion in 37% (16/43) of patients treated with a socket prosthesis compared with 0% (0/20) of patients treated with direct skeletal fixation of a limb prosthesis using an intraosseus transcutaneous implant (osseointegrated prosthesis) (p value not stated). 'Moderate trouble' to 'a great deal of trouble' when sitting was reported by 44% (19/43) and 5% (1/20), respectively. In a second non-randomised comparative study of 32 patients with upper or lower limb amputations, patients treated with bone-anchored prostheses demonstrated significantly lower thresholds for vibratory stimulation of the prosthetic limb than patients treated with socket prostheses (73.1–84.7 Hz and 84.9–95.4 Hz, respectively; p < 0.05).
2.3.2 In a case series of 11 patients with transfemoral amputations, 9 patients (82%) used their osseointegrated prosthesis all day, every day (mean follow-up period not stated). This study reported that 45% (5/11) of patients had implant abutments replaced because of damage caused by falls. A case series of 3 patients with finger amputations reported that all patients were able to perform normal daily activities using the prosthesis at follow-up periods of 16, 19 and 24 months.
2.3.3 One Specialist Adviser considered a key efficacy outcome to be improved function for patients with high amputations compared with conventional prostheses.
2.4.1 In the case series of 11 patients, infection requiring removal of the abutment and implant was reported in 18% (2/11) of patients with transfemoral amputations (both after 1 year).
2.4.2 The Specialist Advisers listed anecdotal adverse events including infection and failure at the interface between the skin and the implant, peri-implant bone infections, loosening of the implant fixture, abutment deformity after falls and abutment fracture.