Risk Factors for Amputation Following Lower Extremity Free Tissue Transfer

Purpose: There is a paucity of outcome-data regarding lower extremity limb salvage among diabetic patients undergoing free tissue transfer, specifically post-operative amputation. The purpose of this study was to evaluate potential risk factors for lower extremity amputation following lower extremity free tissue transfer for limb salvage among a diabetic patient population.

Methods: A retrospective review of all diabetic patients who underwent lower extremity free tissue transfer for the purpose of limb salvage was conducted at a single center.

Results: 61 lower extremity free flaps were performed among diabetic patients from a single institution from 04/2011-08/2017. The overall microsurgical success rate in this patient population was 93.4% (57/61). Most commonly performed free flaps were Anterolateral thigh (27/61), Vastus Lateralis (17/61), and Gracilis (6/61). 45 patients were male (77%), mean A1C was 7.37 (SD 0.41), and mean BMI was 29.86 (SD 5.52). 16 (26.2%) patients eventually underwent lower extremity amputation. Mean time to amputation was 180 days (SD 154. 41). When studying potential risk factors for amputation between the amputation vs non-amputation cohorts, none  of the following, relevant, variables were found to be statistically significant: Presence of peripheral vascular disease (PVD)  (50.0% in the amputation cohort  vs  35.6% in the non-amputation cohort, p=0.31),  tobacco use (56.3% vs 48.9%, p= 0.61), mean Hemoglobin A1C (7.6+/- 2.4 vs  7.3 +/- 2, p=0.74), presence of osteomyelitis/chronic infection (93.8% vs 80.0%, p=0.20), preoperative hemoglobin (9.9 +/- 0.9 vs  10.2 +/- 1.1, p=0.41), and pre-operative creatinine (0.9 +/- 0.3 vs  1 +/- 0.5, p=0.38).

Conclusions:

Interestingly enough, potential risk factors for amputation including PVD, tobacco use, renal disease and HgbA1 were not found to be statistically significant when comparing diabetic patients who underwent lower extremity amputation following lower extremity free tissue transfer compared to those who did not undergo amputation. Given the variable outcomes among patients undergoing free tissue transfer for lower extremity limb salvage, the decision to perform these procedures needs to be evidence-based. Patient selection is crucial in the initial decision for limb salvage, and based on the above data, more studies should be performed to help determine who are appropriate candidates for salvage with free tissue transfer.