SLR - May 2020 - Stephanie A. Oexeman

Smartphone Thermography for Lower Extremity Local Flap Perforator Mapping

Reference: Pereira N, Hallock GG Smartphone Thermography for Lower Extremity Local Flap Perforator Mapping. J Reconstr Microsurg. 2020 Feb 23. doi: 10.1055/s-0039-3402032

Scientific Literature Review

Reviewed By: Stephanie A. Oexeman, DPM 
Residency Program: Franciscan Health System-St. Francis Hospital – Federal Way, WA

Podiatric Relevance: When performing perforator flaps within the lower extremity the use of smartphone thermography gives the surgeon the ability to rapidly assess perforators in real time and overall help local flap survivability. A prospective study was performed to assess accuracy of local flap viability when analyzing perforators with use of smartphone thermography. 

Methods: This is a prospective study of twenty eight perforator local flaps performed within the lower extremity which were assessed using smartphone thermography pre, intra and postoperatively. Flaps were grouped into peninsular, advancement, island or propeller perforator flap. Preoperatively, the use of thermography helped identify preferable perforators, or vascular “hot spots”, for proper and optimal flap design. Intraoperatively, the device was able to confirm immediate flap vascularity and  flap insetting. Postoperatively this method was used to further evaluate flap viability. Flaps were followed until healed. 

Results: A smartphone thermography device was used to identify perforators used in all local perforator flaps. Prediction of flap viability was made after use of thermography based on selected perforators or hot spot zones. Twenty-three out of the 28 flaps were predicted to have a 100 percent success rate determined with thermography. All twenty-three flaps indeed had 100 percent success rate. Five out of 28 flaps were predicted to have  marginal viability. In reality, two of these grafts survived completely while the other three required only minor readjustments. There was no predicted total graft loss and none occurred. Authors also reported thermography was accurate in deciding whether a proximal, or distal, peninsular flap would be more advantageous. 

Conclusions: Thermography not only helps identify preferable perforators, but also allows intraoperative evaluation of  whether a clockwise or counterclockwise rotation will least interfere with perfusion. There are several different methods used to image and identify perforators, such as: CT angiography, magnetic resonance angiography, or color Duplex ultrasound. While these modalities are reliable, they tend to be expensive, require contrast, time consuming, and not always readily available. Smartphone thermography is a reliable, affordable, and readily available modality that is able to be used pre-,  intra- and postoperatively to assess perforators and flap viability. Some limitations of smartphone thermography include lack of exact perforator morphology and possible interference from surrounding vascular structures. Any reconstructive foot and ankle surgeon is able to use smartphone thermography as the learning curve is short. Overall, the use of thermography is able to help safely design of local perforator flaps preoperatively, give intraoperative management insight, and a helpful method for postoperative flap monitoring. 

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