Animation of latissimus dorsi flap in breast reconstruction: a retrospective analysis based on 203 cases

Background: Breast animation is a common postoperative complication of breast reconstruction surgery. This study investigates the factors affecting the onset and degree of animation to suggest an ideal treatment strategy for this complication. Methods: This study included patients who underwent latissimus dorsi reconstruction at Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, between 2009 and 2020 and had an outpatient visit after July 2020. Statistical analysis was performed and the patients' background and surgical factors were examined to determine whether they affected the animation incidence rate. Results: The animation incidence rate was 69.6%. There was no significant relationship between animation incidence and any patient background or surgical factors, except for the complete dissection of insertion into the humerus of the latissimus dorsi muscle (p = 0.0039). The rate of uncomfortable animation was 4% and recurrence of animation was observed in one of the two patients who underwent denervation. Conclusion: Prophylactic denervation is not considered necessary and should be offered only for persistent discomfort with animation. Instead, the muscle insertion must be dissected during flap elevation to prevent animation, and the thoracodorsal nerve must be preserved to avoid muscle atrophy.