Casted Femur-Knee Endoprosthesis with Spongy Metal Surface and Length Adaption In Situ

Summary

Technical innovations in limb salvage surgery are based on four conditions: (a) Development of implant stems adapted to the cavities of the femur and tibia; (b) development of cancellous custom-made alloy based on cobalt-chromium. These implants are incorporated by bone ingrowth; (c) cementless implantation of all stems or acetabular cups. The implants are cast individually with a spongy metal surface for trabecular ingrowth; (d) Lengthening mechanism of the tumor endoprostheses, based on a worm-gearing construction, moved by an inbus screwdriver and controlled by a stop mechanism. The results of seven cases resected between May 1984 and April 1986 (five boys, two girls, aged 10–16 years) were: five osteosarcomas IIB—two excellent, two good, one fair; one osteosarcoma IB—excellent; one chondrosarcoma IIB—initially good, later vertebral metastases, died after 2 years.

The operational guidelines were: prepare the knee and proximal tibia, cut the knee ligaments; implant the tibial and patellar endoprostheses; prepare the femur with soft tissues as necessary in the distal-proximal direction; remove the femur after osteotomy or exarticulation; implant the endoprosthesis and adapt the lengths; examine knee movement and soft tissue tension before closing the fascia and skin.