Risk factors for failure of transmetatarsal amputation in diabetic patients: a cohort study

Abstract

Introduction and Aims: The cost-effective management of diabetic foot infections is a challenge to the Canadian health system. The objective of this study was to predict pre-operatively diabetic foot patients who will fail a transmetatarsal amputation (TMA) and end in a costly and disabling below knee amputation (BKA) and hence perform a primary BKA in select patients? Method: Twenty-one patients failing TMA and revised to BKA within the first year were compared with a matched cohort of 21 successful TMAs. The factors that were selected for comparison were: age at amputation, sex, smoking, type of DM, use of osetoset, presence of charcot fractures, previous contralateral surgery, previous debridement before TMA, debridement after TMA, dialysis, duration of ulcer prior to TMA, hemoglobin level at time of TMA, HbA1C, presence of heel ulcer, prior ipsilateral toe amputation, pulse status prior to TMA, vascular reconstruction and presence of unreconstructable vascular problem. Chi-square was done for group data, and ANOVA for numeric data. Results: Long-term control of blood glucose level (HbA1C) was found to be significant in predicting the success of TMA. Need of debridement after TMA was found to be a significant predictor of failure of TMA. There was a trend towards duration of ulcer prior to TMA and smoking being significant. All other variables, including vascular status or renal failure were not significantly different between the two groups. Conclusion: As we have previously achieved a 75% success rate with TMAs in diabetics, we recommend a TMA as the first procedure in all diabetics with major forefoot infection or ulceration instead of a BKA. Obtaining good diabetic control in patients at risk for or requiring amputation for foot infection may prevent the TMA from failing and the subsequent need for BKA.