Colour Doppler sonography in the preoperative assessment of the vascular pedicle from the anterolateral thigh flap: proposal for a mathematical formula to predict pedicle length

INTRODUCTION: The anterolateral thigh flap (ALT) is one of the most commonly used grafts in head and neck reconstructive surgery. In this type of surgery, it is essential that the vascular pedicle be long enough to ensure proper vascular anastomosis. However, it is difficult to accurately estimate the pedicle length preoperatively. In this context, the current study had two aims: (1) to assess the value of colour Doppler sonography (CDS) in the preoperative assessment of the vascular pedicle and (2) to develop a mathematical model to predict the length of the vascular pedicle based on the ultrasound findings. MATERIALS AND METHODS: Retrospective review of patients who underwent primary surgery for head and neck cancer followed by ALT flap reconstruction at our institution from 2014 to 2018. All patients underwent CDS prior to surgical excision of the flap. RESULTS: Preoperative CDS was useful to identify the location of the vascular perforators, to estimate the pedicle length, and to identify the vascularization variant. Using the proposed mathematical formula, the estimated minimum pedicle length and actual length agreed in 73.9% of cases, increasing to 84.1% when a 5 mm margin of error was allowed. Moreover, preoperative ultrasound accurately distinguished the two anatomical variants of the ALT vasculature in nearly all cases (97.1%). CONCLUSION: This study confirms the value of preoperative colour Doppler sonography for ALT flap reconstruction. The proposed mathematical model provides a highly accurate method of preoperatively assessing the length of the vascular pedicle, which may be of value in head and neck surgery.