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Objectives:
Infections occur frequently after major lower extremity amputations (LEA) performed in patients with the diagnosis of peripheral arterial disease. We sought to determine whether history of a prior infrainguinal bypass in the amputated extremity is associated with increased incidence of postoperative wound infection following major LEA.
Methods:
This was a retrospective cohort analysis on consecutive patients who underwent major LEA either below or above the knee. Indications for LEA included severe rest pain or tissue loss. For each patient included in the analysis a propensity score was calculated as the probability of having a prior infrainguinal bypass operation in the amputated extremity. Input variables for this calculation included demographics, comorbid conditions, and urgency and symptomatology of the initial presentation. The final risk adjustment was performed using the inverse propensity score weighting methodology.
Results:
We analyzed 294 major LEA that occurred over a 5 year period and led to 36 (12%) infections. Propensity score weighting resulting in excellent balance for all the variables that were included in the propensity score calculation. In the final multivariable model there was no association between native (OR: 1.19, p=0.88) or prosthetic (OR: 0.63, p=0.65) bypass and the occurrence of postoperative wound infection. However, the presence of an occluded bypass regardless of type of conduit was associated with infection (OR: 4.7, p=0.03). There was also a trend for increased incidence of wound infection in patients with lower extremity infection as indication for the amputation (OR: 3.1, p=0.06).
Conclusions:
The presence of an occluded bypass graft regardless of conduit increases the risk of wound infection after major lower extremity amputation.