Lower extremity minor amputations: The roles of diabetes mellitus and timing of revascularization

Introduction: Despite the frequent performance of minor foot amputations in patients with lower extremity vascular disease, little is known regarding the rate of conversion to major amputations and the role of bypass graft timing in relation to amputation. Methods: Between January 1990 and December 2001, 670 patients underwent 920 minor amputations (interphalangeal, ray, or transmetatarsal) on 747 limbs. Results: Of 670 patients, 468 were men (69.9%), 616 had diabetes mellitus (91.9%), and 137 (19.7%) had a serum creatinine level >2.0 mg/dL, of whom 92 were on dialysis (end-stage renal disease) (11.5%). Ipsilateral revascularization was performed ≤30 days before the initial amputation in 64.9% (485 of 747), whereas 9.8% (73 of 747) had a bypass ≤30 days postamputation. The initial amputation levels were 466 interphalangeal (62.4%), 159 transmetatarsal (21.3%), and 122 ray (16.3%). Operative 30-day mortality was 0.7% (6 of 920). Limb salvage was 89.8% at 1 year and 82.3% at 5 years. Diabetes mellitus had no impact on limb salvage (P = .61). Limb loss predictors included end-stage renal disease (odds ratio [OR], 1.72, 95% confidence interval [CI], 1.12 to 2.83, P < .01) and the need for transmetatarsal amputation as the initial procedure (OR, 1.62; 95% CI, 1.15 to 1.93; P < .01). Patients with revascularizations subsequent to an initial amputation had a significant increase in limb loss (OR, 2.11; 95% CI, 1.39 to 4.21, P < .005). Patient survival was 83.9% at 1 year and 43.5% at 5 years. Neither gender nor diabetes mellitus impacted survival; however, serum creatinine levels >2.0 mg/dL (5 years, 48.8% ± 2.3% vs 23.9% ± 4.2%, P < .0001) and the need for a major amputation ≤30 days (3 years, 60.8% ± 2.1% vs 40.1% ± 7.8%, P < .01) adversely affected survival. Conclusions: Although minor amputations can lead to limb preservation in most patients, the performance of a revascularization subsequent to amputation, transmetatarsal as the initial amputation, and end-stage renal disease are poor prognostic indicators. Inferior long-term patient survival is most closely associated with renal insufficiency and conversion to major amputation early after the initial procedure.