Ten patients aged 55-85 years with a tibial head fracture AO B3 or C3 were treated primarily by implantation of an endoprosthesis. There were one unilateral, three superficial, and six revision-type prostheses. Follow-up was 6 months to 3 years; two patients were lost to follow-up. There were no intra- or postoperative complications except one deep infection which could be cured by repeated arthroscopic lavage. At last follow-up all eight patients were completely or almost pain free; the extension deficit was less than 10 degrees , and flexion was 100 degrees or more. Primary endoprosthetic replacement of the knee joint is a valuable procedure for the treatment of complex tibial head fractures in elderly patients.