Predictive Factors of Free Flap Volume Evolution in Head and Neck Reconstruction.

[OBJECTIVE] The aim of our study was to determine the factors influencing the evolution of the total volume and bone volume of free flaps commonly used in head and neck surgery, with a 30-month prospective study, to establish volume change predictions and thus propose a degree of overcorrection to be expected before reconstruction.

[STUDY DESIGN] We prospectively included all consecutive free flap.

[SETTING] Our maxillofacial surgery department between August 2021 and January 2024.

[METHODS] We collected information on preoperative, per-operative, and postoperative factors, on patients, surgical techniques, and adjuvant treatments. We measured on each postoperative imaging the overall flap volume and bone volume if applicable. Multivariate mixed models were then used to select clinical parameters associated with volume loss.

[RESULTS] We included 166 flaps, performed on 155 patients. The mean age was 60.1 ± 15.1 years. A total of 634 imagings were segmented (487 computed tomography [CT] scans, 77%; 147 magnetic resonance imagings [MRIs], 23%). The use of the superior thyroid or lingual veins for venous anastomosis, such as the use of small couplers, resulted in negative volume changes. Predicted bone volumes decreased by 23% at 30 months for deep circumflex iliac artery (DCIA) free flaps, 19% for fibula free flap (FFF), and 38% for scapular system free flap (SFF).

[CONCLUSION] These findings allow us to envisage a volume overcorrection of around 60% for fasciocutaneous or osteocutaneous flaps, and 75% for muscle or osteomuscular flaps. The choice of vein and microsurgical technique seems to have more impact on the evolution of free flap volume than patient characteristics or adjuvant treatments.