Level selection in leg amputation for arterial occlusive disease: a comparison of clinical evaluation and skin perfusion pressure

Abstract

In 102 leg amputations for arterial occlusion including 84 below-knee (BK), 16 above-knee (AD) and 2 through-knee (TK) amputations, the amputation level was determined by means of clinical criteria. The healing results and the selection of levels were then compared with sealed preoperative measurements of the skin perfusion pressure (SPP). Out of 62 BK amputations with an SPP above 30 mmHg wound healing failed in only 2 cases (3 per cent). Out of 13 BK amputations with an SPP between 20 and 30 mmHg 7 cases (54 per cent) failed and out of 9 BK amputations with an SPP below 20 mmHg no less than 8 cases (89 per cent) failed to heal. The difference in failure rate is significant (P less than 0.0001). Out of the 15 failed BK amputations at low pressures (below 30 mmHg) only one case had local signs of ischaemia, which might have warned the surgeons. On the other hand, in 13 out of the 18 cases of primary AK (or TK) amputations there were clinical signs of ischaemia of the calf, comprising temperature demarcation, cyanosis and/or necrotic skin lesion. The SPP below the knee appeared in all these cases to lie below 30 mmHg. In the 5 other cases of primary AK (or TK) amputation the knee was sacrificed for reasons other than signs of local ischaemia, e.g. poor physical or mental condition. It was moreover found that the presence of pulsations in the popliteal artery indicated an 89 per cent chance of healing of BK amputations. Infection was present in 24 BK amputations (28 per cent) and equally frequent among diabetic and non-diabetic cases. The postoperative SPP measured on the stumps averaged only 5 mmHg (P less than 0.05) higher than the preoperative SPP explaining why the preoperative SPP related closely to the postoperative course. It is concluded that ischaemia at the BK election site cannot be ruled out by clinical assessment alone and that preoperative determination of the SPP can be used in determining the chance of healing in BK amputations.