Major lower extremity amputations – risk of re-amputation, time to re-amputation, and risk factors: a nationwide cohort study from Denmark

Background and purpose — Re-amputation after lower extremity amputation is frequent. The primary aim of our study was to investigate cumulative re-amputation risk after transtibial amputation (TTA), knee disarticulation (KD), and transfemoral amputation (TFA) and secondarily to investigate time to re-amputation, and risk factors. Methods — This observational cohort study was based on data from the Danish Nationwide Health registers. The population included first-time major lower extremity amputations (MLEA) performed in patients ≥ 50 years between 2010 and 2021. Both left and right sided MLEA from the same patient were included as index procedures. Results — 11,743 index MLEAs on 10,052 patients were included. The overall cumulative risks for re-amputation were 29% (95% confidence interval [CI] 27–30), 30% (CI 26–35), and 11% (CI 10–12) for TTA, KD, and TFA, respectively. 58% of re-amputations were performed within 30 days after index MLEA. Risk factors for re-amputation within 30 days were dyslipidemia (hazard ratio [HR] 1.2, CI 1.0–1.3), renal insufficiency (HR 1.2, CI 1.1–1.4), and prior vascular surgery (HR 1.3, CI 1.2–1.5). Conclusion — The risk of re-amputation was more than twice as high after TTA (29%) and KD (30%) compared with TFA (11%). Most re-amputations were conducted within 30 days of the index MLEA. Dyslipidemia, renal insufficiency, and prior vascular surgery were associated with higher risk of re-amputation.