Objective: The purpose of this study was to clarify sequential volumetric changes of anterolateral thigh (ALT) flaps transferred to head and neck lesions. Patients and methods: We retrospectively analyzed volumetric changes in fat and muscle of 22 ALT flaps. We assessed “true” flap volume using the water-displacement method intraoperatively. Postoperative flap volume was assessed using three-dimensional volume-calculating software. Results: The average duration until the entire flap volume decreased to its minimal size was 8.7 months. After 8.7 months, entire flap volume decreased to 47.4% of its initial intraoperative volume. The fat volume decreased to 62.5%, and the muscle volume decreased to 30.2%. The rate of muscle volume decrease was significantly larger than that of fat volume decrease (p<0.005). The only significant factor which affected entire flap volume decrease was the recipient site where the ALT flap was transferred (oral and pharyngeal lesions) (p=0.001), and the factor that affected fat volume decrease was postoperative body-weight loss (p=0.046). Conclusion: To minimize the influence of postoperative ALT flap volume decrease, an ALT flap should mainly comprise fatty tissue, and its size should be 1.6-times larger (100/62.5) than the ideal volume intraoperatively. Maintaining the body weight is crucial to avoid ALT flap volume decrease.
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