Estimation Of Profunda Artery Perforator Flap Weight Using Preoperative Computed Tomography Angiography
Nicolas Greige, BS, David Nash, MD, Katie E. Weichman, MD.
Albert Einstein College of Medicine, Montefiore Medical Center, Division of Plastic Surgery, Bronx, NY, USA.
Preoperative flap weight estimation is an indispensable tool in autologous breast reconstruction. Several techniques have been described for weight estimation of abdominal-based free flaps, however no study has developed a preoperative weight estimation technique in thigh-based autologous breast reconstruction. Given the relatively small size of thigh-based flaps and the possible necessity for a multi-flap reconstruction, it is imperative to arrive at an accurate estimation of flap weight during preoperative planning. It was our objective, therefore, to develop a novel technique for the preoperative estimation of profunda artery perforator (PAP) flap weight.
A retrospective review of all patients that underwent transverse PAP flap breast reconstruction at a single institution from March 2015 to April 2019 was conducted. Patient demographics and intra-operative pre-trimmed flap weights were recorded. Subcutaneous tissue thicknesses were measured on each computed tomography angiography (CTA) scan at the following predetermined points: at the lateral border of the long head of the biceps femoris, the junction of the adductor magnus and gracilis, and the posterior border of the sartorius. These point thicknesses were measured at both the plane where the dominant profunda artery perforator pierced the deep fascia and 4.5 cm caudal to the gluteal fold. The distance from the inferior gluteal crease to the dominant profunda artery perforator was also recorded. A forward stepping multiple linear regression analysis was performed to determine the parsimonious prediction formula.
A total of 17 flaps (9 patients) were analyzed. The mean intraoperative flap weight was 297±66 g. The parsimonious model yielded the following 2-variable formula: estimated flap weight = 52.5x + 18.3y –54.3, where x denotes thickness (in mm) at the lateral border of the long head of the biceps femoris 4.5 cm caudal to the inferior gluteal crease and y denotes distance (in mm) from the inferior gluteal crease to the PAP. The aforementioned formula yielded a mean estimated flap weight of 297±52 g and a median percent difference of 6.6% (IQR: 2.2–16.4%). The model was statistically significant (p<0.001) and explained 74% of the variability in flap weight. An additional single variable formula was also created, estimated flap weight = 36.1x + 125.1. The single variable formula yielded a mean estimated flap weight of 297±47 g and a median percent difference of 7.6% (IQR: 5.0–15.8%). The single variable model was also statistically significant (p<0.001) and explained 60% of the variability in flap weight.
The authors demonstrate two simple and accurate formulas for the preoperative estimation of transverse PAP flap weight for breast reconstruction.
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