Data were collected retrospectively on thirty-five patients who had a failed osteotomy of the proximal part of the tibia for unicompartmental osteoarthrosis of the knee that was treated with a cruciate condylar, total condylar, kinematic condylar, or cemented porous-coated anatomical total knee prosthesis. The patients were evaluated clinically and roentgenographically before and after the arthroplasty. The minimum period of follow-up was twenty-nine months (mean, forty-four months). On the basis of the knee-rating scale of The Hospital for Special Surgery, 89 per cent of the patients had either an excellent or a good result after the arthroplasty. No result was a failure. One patient had loosening of the patellar component, but no other loosening was identified. The results of total knee arthroplasty after osteotomy of the proximal part of the tibia were found to be comparable with the results after arthroplasty in knees that had not had a prior osteotomy. The intraoperative and postoperative rates of complications were not higher, and no untoward technical difficulties were encountered at surgery. These data support the clinical impression that an osteotomy of the proximal part of the tibia does not "burn any bridges" insofar as a future successful arthroplasty is concerned.