Between 1988 and 2009, endoprosthetic replacement and alloplastic reconstruction of the extensor mechanism after resection of tibial bone tumors was performed in 17 consecutive patients (9 females and 8 males) with a mean age of 31.1 years (range 11-65 years). There were no local recurrences. Until now, 5 patients have died of tumor disease. One or more operative revisions were necessary in 53.9% of the patients. According to Kaplan-Meier survival analysis, the implant survival at 5 years was 53.6% and 35.7% at 10 years, respectively. In 2 cases, a distal transfemoral amputation had to be performed due to deep infection. There were 3 cases of tibial stem revision due to implant failure and aseptic loosening, respectively. In 3 patients, the hinge of the prosthesis had to be revised. Impaired wound healing occurred in 2 cases. Peroneal nerve palsy was observed in 3 patients with recovery in only one. The mean Oxford knee score for 9 of the 12 living patients was 30.7 ± 7.5 (24-36). No patient had a clinically relevant extension lag. The mean range of motion at the last follow-up was 90.2° ± 26.7 (range 35-130°). All patients were well satisfied with their postoperative outcomes.