Influence of failed vascular bypass procedures on conversion of below-knee to above-knee amputation levels.

From 1975 to 1980, 79 major limb amputations were performed from a group of 552 lower extremity vascular reconstructions with glutaraldehyde-stabilized umbilical vein grafts. All amputations were performed in instances in which limb salvage had been the indication for the attempted bypass (n = 520)--an incidence of 15.2%. Twelve of 51 below-knee (BK) amputations were converted to above-knee (AK) levels (crude failure rate, 23.5%). The highest crude failure rate occurred after failed bypass to the popliteal artery (33.3%); the lowest occurred after failed tibial bypass (16.7%), and the peroneal arteries were intermediate (22.2%). In addition to these 12, 28 primary AK amputations were performed. Excluding nine cases judged to require AK amputations before the attempted vascular reconstruction, success/failure rates for the entire series and each of the reconstruction types were calculated. Success, defined as a healed BK stump, occurred least after failed popliteal bypass, 44.5%, compared to 71.4% and 53.8% for the tibial and peroneal groups, respectively. Thus, failure of a popliteal bypass was more apt to lead to an AK amputation (56.5%) than failure of a distal bypass. In fact, tibial bypass failure leading to an AK stump occurred at a frequency (28.6%) almost similar to that obtained by other investigators when no previous bypass had been performed. Comparative cumulative graft patency and limb salvage rate data confirm the value of reconstructive vascular surgery, particularly in the peroneal group where negativism with regard to its clinical usefulness persists. With improved case selectivity and surgical expertise, increasing limb salvage rates can be secured while minimizing the definite morbidity of conversion of BK to AK amputation with failed vascular bypass.