SLR - March 2020 - Gavin C. Lee

Healing and Mortality Rates Following Toe Amputation in Type 2 Diabetes Mellitus

Reference: Vassallo IM, Gatta A, Cassar K, Papanas N, Formosa C. Healing and Mortality Rates Following Toe Amputation in Type 2 Diabetes Mellitus. Exp Clin Endocrinol Diabetes. 2019 Jun 17. Doi: 10.1055/a-0942-1789.

Scientific Literature Review

Reviewed By: Gavin C. Lee, DPM
Residency Program: Kaiser Permanente North Bay Consortium – Vallejo, CA

Podiatric Relevance: Limb salvage in the presence of uncontrolled Diabetes and its associated complications pose a notable challenge to the podiatric surgeon in that a patient’s first toe amputation may not be the last. Surgeons and patients work together with the goal of limb salvage in mind, however, the need for repeated intervention can stem from various etiologies including poor surgical planning, patient noncompliance, and poor systemic health, among others. This study set out to determine the rates of healing, re-ulceration, re-amputation, and mortality at one year after toe amputations in patients with Diabetes type 2.

Methods: This single-center, prospective non-experimental research time-series study included patients with Diabetes type 2 without prior foot amputation who were admitted for toe amputation of at least one digit for gangrene or ulceration with exposed bone and joint. Exclusion criteria included need for emergent amputation, previous amputation, and cognitive impairment. All patients were evaluated for distal sensory polyneuropathy via the fivepoint Semmes-Weinstein 10g monofilament test and peripheral arterial disease via palpation, clinical presentation, spectral doppler waveform analysis, and ankle brachial index. All wounds were ultimately classified within the PEDIS (perfusion, extent/size, depth/tissue loss, infection, sensation) classification. Patients were evaluated every three months after amputation for one year to assess for infection, the need for further intervention, the presence of new ulceration, and mortality.

Results: A total of 81 of 100 patients met all inclusion/exclusion criteria with a male majority, average age of 70 years old, average HbA1c of 8.46 percent, and overall smoking rate of 77.8 percent. Wound etiology was broken down as 53 percent neuroischemic, 32 percent neuropathic, and 15 percent ischemic. 81.5 percent of patients underwent an isolated digital amputation comprising of 29.6 percent hallux amputations and 51.8 percent lesser digit amputations (second digit 14.8 percent, third digit 13.6 percent, forth digit 11.1 percent, fifth digit 12.3 percent) versus 18.5 percent patients had multiple digital amputations. Thirty-seven percent of amputations were performed for gangrene and 63 percent for chronic ulcerations with exposed bone or joint. The vascular surgeon determined the necessary number of digits and level of amputation as well as the need for revascularization, which occurred in nearly 50 percent of patients (primarily those with monophasic pulses). Participants were followed every three months for one year. Within one year, 60 percent of participants required further surgery with 31 revision amputations and 17 new amputations. Forty-five percent developed a new ulcer at a different location. There was an overall 7.4 percent mortality rate during the study period.

Conclusions: The results of this study highlights a concerning high rate of failure in primary digital amputation in patients without previous amputation despite the exclusion criteria of emergent amputation. The high rate of revisions, further amputation, and new ulcerations also raises concerns for questionable longevity. However, other factors that were not considered in this study were biomechanical in nature – i.e. the need to address equinus, digital deformity, locations of peak pressure, and post-operative protocol, for example, and this potentially could have resulted in different outcomes

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