Natural History After Below-knee Amputation: Analysis of Survival and Prosthetic Fitting Over 2 Decades

Introduction: This study sought to evaluate the natural history of patients undergoing below-knee amputation (BKA) and compare their evolution over 2 decades, as well as survival predictors, prosthetic fitting, and contralateral amputation.

Methods: Retrospective study of 209 consecutive patients (mean age 72.9 years; 68% males) who underwent BKA in 2 periods: 1996-2005 and 2006-2015. The fitting of prostheses, risk of contralateral amputation and survival, as well as their predictive factors, were assessed by survival analysis.

Results: 133 BKA were performed from 1996-2005 and 106 from 2006-2015. The etiology that motivated the BKA was acute ischemia (4.3%), chronic ischemia (34.0%), infection (9.1%) or mixed (chronic+infection, 52.6%), with no differences found between periods. Survival: mortality within one month=9.2%, one year=31.9%, 2 years=43.8% and 5 years=63.9%, with no significant differences between the 2 periods. Prosthetic: the fitting rate was 44.5% throughout the follow-up, with no significant differences between the two periods. 41.1% patients managed to walk. Contralateral amputation: 20.1% of the patients later required a major contralateral amputation, with no significant differences between the two periods.

Conclusions: In the last decade, fewer BKA have been performed probably, due to higher previous interventional revascularization. Despite this, the results of fitting, contralateral amputation or survival were not modified. In any case, the number of patients who are able to achieve ambulation is modest, so it emphasizes the need for an optimal selection of patients with BKA with the goal of prosthetic fitting.