Limb loss after lower extremity bypass

BACKGROUND: Infrainguinal bypass now has a limb salvage rate approaching 90% at 10 years. This study helps elucidate the causes of limb loss despite bypass surgery. METHODS: A retrospective chart review of all patients undergoing a major lower extremity amputation after attempted bypass surgery. RESULTS: Between July 1987 and January 1997, 87 major amputations (52 below knee, 15 above knee) followed infrainguinal bypass for limb salvage in 64 patients. Of these patients, 53 (83%) were diabetic and 10 (16%) were on dialysis. The etiology of limb loss included thrombosed bypass (n = 33, 49%), lack of limb salvage despite patent bypass (n = 23, 34%), intraoperative bypass failure (n = 6, 9%), and exposed/infected bypass (n = 5, 8%). The 23 patients with patent grafts required amputations because of hindfoot necrosis (n = 6), persistent forefoot necrosis (n = 6), acute diabetic foot infection (n = 6), and various other reasons (n = 5). Using life-table analysis, survival for the whole group was 56% at 12 months and 17% at 48 months. Patients with limb loss despite a patent bypass fared the worst with survival of 21% at 2 years. CONCLUSIONS: Bypass thrombosis caused half of the amputations after limb salvage surgery. A patent bypass was functioning at the time of amputation in another third. Survival after failure of limb salvage was abysmal, especially in patients with patent bypasses.