Objectives: To compare the outcomes of AKA and BKA and to identify risk factors for poor outcome following leg amputation.

Methods: This retrospective cohort study comprised 188 consecutive patients (mean age 72 years, range 25–103, 71% males) who underwent 198 amputations (91 AKA, 107 BKA, 10 bilateral procedures) between February 2007 and May 2010. Included were male and female adults who underwent amputations for ischemic, infected or gangrenotic foot. Excluded were patients whose surgery was performed for other indications (trauma, tumors). Mortality and reoperations (wound debridement or need for conversion to a higher level of amputation) were evaluated as outcomes. Patient- and surgery-related risk factors were studied in relation to these primary outcomes.

Results: The risk factors for mortality were dementia [hazard ratio (HR) 2.769], non-ambulatory status preoperatively (HR 2.281), heart failure (HR 2.013) and renal failure (HR 1.87). Resistant bacterial infection (HR 3.083) emerged as a risk factor for reoperation. Neither AKA nor BKA was found to be an independent predictor of mortality or reoperation.

Conclusions: Both AKA and BKA are associated with very high mortality rates. Mortality is most probably related to serious comorbidities (renal and heart disease) and to reduced functional status and dementia. Resistant bacterial infections are associated with high rates of reoperation. The risk factors identified can aid surgeons and patients to better anticipate and possibly prevent severe complications.