[Implantation of the endo-exo femur prosthesis to improve the mobility of amputees]

Abstract

Objective: Improvement of function following above-knee amputation with an osseointegrated, transcutaneous femoral implant as a hard point for the exo prosthesis, the so-called endo-exo femur prosthesis (EEFP).

Indications: Above knee amputation following trauma, tumor, or infection.

Contraindications: Diabetes, PAOD, psychiatric diseases, use of chemotherapeutic or corticosteroid medication, nonconcluded bone growth, lack of compliance, and florid infection at the time of implantation.

Surgical technique: Performed as a two-step procedure: Stage 1 (implantation): sharp dissection of the end of the residual bone, adequate access to the intramedullar canal, cortical reaming using curettes and a flexible drill followed by cement-free, press-fit implantation of the endoprosthesis itself, closing of the soft tissue coat of the femur stump to reduce the risk of infection, assurance of primary and secondary stability via the metal spongiosa-like surface of the implant (Spongiosa Metal 2®). Stage 2 (exteriorization): 6 weeks postoperatively, opening of the skin at the distal point of the femur stump, the soft tissue between the skin and endoprosthesis is then removed and the double conus and the connecting adapter for the exoprothesis is attached.

Postoperative management: Ascending weight bearing depending on bone quality. On average, full weight bearing can be achieved 8-10 weeks after stage 1 surgery.

Results: The first endo-exo femur prosthesis (EEFP) was implanted in 1999. Through December 2009, 39 cases were operated in Lübeck, early serosanguinous drainage, soft tissue problems at the stoma, and ascending infections after mobilization of the patients could be minimized by further development of the design of the EEFP. Intramedullary infections were the exception (1 of 39 patients). A total of 4 explantations had to be performed (3 due to infection and 1 due to prosthetic failure). Two of those patients were again provided with an EEFP. Overall, the EEFP improved the gait pattern because of the bone-guided transmission of muscle power, increased osseoperception, and improved economical energy balance. Of the 39 patients, 37 said that they would again undergo operation.