SLR - April 2021 - Kayla L. Wright

Amputation Versus Free Flap: Long-Term Outcomes of Microsurgical Limb Salvage and Risk Factors for Amputation in the Diabetic Population

Reference: Kotha VS, Fan KL, Schwitzer JA, Youn R, Black CK, Attinger CE, Evans KK. Amputation versus Free Flap: Long-Term Outcome
s of Microsurgical Limb Salvage and Risk Factors for Amputation in the Diabetic Population. Plast Reconstr Surg. 2021 Mar 1;147(3):742-750. doi: 10.1097/PRS.0000000000007644. PMID: 33587553.

Level of Evidence: Level III

Scientific Literature Review

Reviewed By: Kayla L. Wright, DPM
Residency Program: Carl T. Hayden VA Medical Center – Phoenix, AZ

Podiatric Relevance: Diabetic limb salvage is an important and relevant aspect of podiatric medicine. It has been shown that free tissue transfer (FTT) is an effective means for treatment of diabetic foot ulcers and prevention of amputations. Treatment with FTT and thus prevention of amputation can decrease mortality rate. However, failure rate of FTT remains high in this patient population. Therefore, it is imperative to identify risk factors for FTT failure and eventual amputation. This study seeks to identify those risk factors for amputation following FTT in diabetic lower extremity.

Methods: This was a retrospective review of patients who underwent FTT by the senior author from August 2011-January 2018, including only patients ≥ 18 years old with a diagnosis of DM. All patients underwent endovascular and biomechanical evaluation as recommended. Preoperative variables assessed included: demographics, comorbidities, wound condition, vascular condition. Operative variables included flap characteristics. Postoperative variables included: flap success, microanastomotic complication, complications including hematoma, infection, success of limb salvage, and ability to ambulate. Fisher’s Exact test, Pearson chi-square test, and Wilcoxon rank-sum were utilized to identify statistically significant risk factors. 

Results: Sixty-four patients with mean follow up of 20.7 months were included in the study. Overall, the limb salvage rate was 78 percent. For patients who were not successful in limb salvage, average time to amputation was 5.3 months. Baseline HbA1c and platelet levels were significantly higher in those who eventually underwent amputation. Regression analysis on patients in whom limb salvage was unsuccessful showed diagnosis of ESRD, location of wound at the hindfoot, and positive post-debridement cultures to be significant risk factors for failure of limb salvage. The authors also assessed age, gender, race, tobacco use, BMI, history of PVD, HTN, CAD, and/or HLD, Hemoglobin, Hematocrit, Creatinine, Angiography findings, presence of venous reflux, FTT donor site location, location of wound, and length of surgery, and all were found to be insignificant factors in determining limb salvage following FTT. Indications for those who underwent amputation following FTT included, most commonly, recurrent osteomyelitis, vascular insufficiency, and hematoma. 

Conclusions: Free tissue transfer is a viable means to limb salvage in the treatment of non-healing diabetic foot ulcerations. This study is an important step forward in identifying statistically significant risk factors to limb salvage failure. Patients with diagnosis of ESRD are shown to have a 30-fold risk of limb salvage failure and therefore are not likely to have success with FTT. Similarly, patients with high HbA1c (>7.0 percent), high platelets, hindfoot wounds, and recurrent infections, are not ideal candidates for limb salvage via FTT. Although vascular status was not shown to be a statistically significant risk factor, it is important to note that vascular/arterial insufficiency was a common indication for amputation following attempted limb salvage. Risk stratification including presence of ESRD, high HbA1c, high platelets, location of ulceration, and presence of infection, could be useful in the preoperative consideration of FTT for purposes of limb salvage and treatment of diabetic foot ulcerations.  

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