SLR - June 2015 - Jason Mendivil

The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System:  Risk Stratification Based on Wound, Ischemia, and Foot Infection (WIfI)

Reference: Mills JL Sr, Conte MS, Armstrong DG, Pomposelli FB, Schanzer A, Sidawy AN, Andros G. The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System:  risk stratification based on wound, ischemia, and foot infection (WIfI); Society for Vascular Surgery Lower Extremity Guidelines Committee. J Vasc Surg. 2014 Jan;59(1):220-34

Scientific Literature Review

Reviewed By: Jason Mendivil, DPM
Residency Program: Southern Arizona VA Health Care System

Podiatric Relevance: When faced with the challenges of a salvaging a limb and preventing tissue loss, the wound environment, level of ischemia and infection are a few criteria to consider. In terms of podiatric treatment, a clinician must account for these factors and base a treatment protocol on these variables. The authors in this investigation provide a classification system that implements risk stratification to determine amputation risk and further clinical management.

Methods: The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System implements classifying wounds based on disease burden and degree of ischemia. The classification system discussed in this study grades on three major factors: Wound, ischemia and wound infection (WIfI). It has a numerical classification system, 0 to 3, where 0 represents no risk, 1 mild, 2 moderate and 3 severe.

Results: The WIfI classification system provides wound grades from grade 0 to grade 3. The grades were based on wound size, depth, severity and the challenges it may impose for healing. Grade 0 is classified as having no wound present. Grade 1 wound is classified as minor tissue loss with a salvageable limb with small digital amputation or tissue coverage. A grade 2 wound is classified as a more advanced wound, a limb salvageable with multiple digital amputations, with the possibility of a transmetatarsal amputation. A grade 3 wound requires a more proximal procedure, such as a LisFranc or Chopart amputation, involving more tissue loss. The classification system classified ischemia based on ABI values.  Patients with an ABI >0.8 are classified as having a grade 0. Patients with a wound and an ABI <0.4 are more likely to require a revascularization procedure in order to achieve wound closure. These patients are classified as a grade 3. Grades 1 and 2 lie within the intermediate range of an ABI between 0.4-0.8, correction of perfusion deficits may be of benefit. Further tests may also be used to quantify perfusion in this patient demographic, such as TP or TcPO2 measurements or pulse volume recordings. Infection grading was also provided by the classification scheme, taking into consideration both infected and degree of peripheral arterial disease. Group a patients are patients with no infection within 30 days, or a simple infection controlled by antibiotic use. Group b patients require incision and drainage, with debridement and/or partial amputation to sustain control.

Conclusions: The risk of amputation increases as the grade of WIfI classification increases. The risk of amputation increases as the wound sizes increases, with special attention paid to the depth of the wound. An infected wound, along with peripheral arterial disease, increases the likelihood that a revascularization procedure will be needed to achieve wound closure.

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