Reconstruction of the extensor mechanism after proximal tibia endoprosthetic replacement

The proximal tibia is a difficult area in which to perform a wide resection of a bone tumor. This difficulty is due to the intimate relationship of tu mor in this location to the nerves, and blood vessels of the leg, inadequat e soft tissue coverage after endoprosthetic reconstruction, and the need to reconstruct the extensor mechanism. Competence of the extensor mechanism i s the major determinant of functional outcome of these patients. Between 19 80 and 1997, 55 patients under-went proximal tibia, resection with endopros thetic reconstruction for a variety of malignant and benign-aggressive tumo rs. Reconstruction of the extensor mechanism included reattachment of the p atellar tendon to the prosthesis with a Dacron tape, reinforcement with aut ologous bone-graft, and attachment of an overlying gastrocnemius flap. All patients were followed for a minimum of 2 years; 6 patients (11%) had a tra nsient peroneal nerve palsy, 4 patients (7.2%) had a fasciocutaneous flap n ecrosis, and 2 patients (3.6%) had a deep wound infection. Full extension t o extension lag of 20 degrees was achieved in 44 patients, and 8 patients r equired secondary reinforcement of the patellar tendon. Function was estima ted to be good to excellent in 48 patients, (87%). Reattachment of the pate llar tendon to the prosthesis and reinforcement with an autologous bone-gra ft and a gastrocnemius flap are reliable means, to restore extension after proximal tibia endoprosthetic reconstruction.