Forty-six adult patients had a through-the-knee amputation (disarticulation of the knee) in a four-year period. Thirty-four of the patients had peripheral vascular insufficiency and were judged to lack the potential for using a prosthesis functionally, although the evaluation indicated that they had the potential for healing of the wound at the below-the-knee level of amputation. At a minimum follow-up of one year, the amputation wound had healed in thirty of these patients, and no joint contracture had developed. Two patients died in the first postoperative month, and two had failure to heal and needed revision to an above-the-knee amputation. The remaining twelve patients who had a through-the-knee amputation were judged to be potentially able to use a prosthesis functionally, but they did not have the capacity for wound-healing at the below-the-knee level. Therefore, in these patients, a through-the-knee amputation was performed as an alternative to an above-the-knee amputation. The amputation wound healed in eight of these patients, but four (33 per cent) had failure to heal and needed subsequent revision to an above-the-knee amputation. All twelve patients were able to use a prosthesis. The through-the-knee amputation provides good muscular balance and has a low risk for the late development of joint contracture. The residual limb (stump) provides an excellent surface area for sitting balance and a lever-arm for transfer. In a patient who has the potential to use a prosthesis functionally, the residual limb allows direct load-transfer (end weight-bearing).(ABSTRACT TRUNCATED AT 250 WORDS)