Dose-Dependent Effects of Botulinum Toxin Type A on Prevention of Postoperative Scars in Various Regions in the Body: A Prospective, Double-Blind Randomized Controlled Trial.

[BACKGROUND] Botulinum toxin type A (BTXA) can improve wound healing and reduce scar formation; however, the exact dose required to prevent postoperative scarring across various anatomical sites remains unclear. This study aimed to investigate the effectiveness and optimal concentrations of BTXA for preventing postoperative scarring across various common surgical sites throughout the body.

[METHODS] In this prospective randomized controlled trial, 46 patients with benign skin tumors received injections of 1, 2.5, or 5 U/0.1 mL of BTXA or 0.9% saline immediately following surgical tumor excision on both sides of the incisions. Follow-ups were conducted at 7 days, 15 days, and 1, 3, and 6 months postoperatively. Patient-reported adverse events and standardized digital photographs were collected. Scar formation was assessed using the modified Stony Brook Scar Evaluation Scale (mSBSES).

[RESULTS] All 46 patients completed the trial without severe complications. The mSBSES scores were higher in the experimental groups at all follow-ups. The 5 U/0.1 mL BTXA dose group demonstrated optimal scar prevention at all high-risk sites for scar hyperplasia. No significant difference was observed between the 2.5 U/0.1 mL and 5 U/0.1 mL doses for intermediate-risk sites, while 1 U/0.1 mL dose was sufficient for low-risk sites. Overall, 86.5% of patients were satisfied with their treatments, with 16.3% being very satisfied.

[CONCLUSIONS] Early postoperative BTXA injection can reduce or prevent hypertrophic scarring, with optimal doses ranging from 1 to 5 U/0.1 mL depending on the surgical site, supporting broader clinical application of BTXA. The effectiveness of different concentrations of botulinum toxin type A (BTXA) in preventing postoperative scarring was compared, expanding the scope of previous research, which focused only on the head, face, and neck regions, to include the trunk and extremity areas. Different optimal injection strategies were determined based on different surgical sites and their risks of developing hypertrophic scars. The study demonstrates that BTXA not only reduces scar formation but also enhances patient satisfaction and reduces postoperative itching and pain, contributing to overall better postoperative outcomes. By establishing the efficacy and optimal dosing of BTXA for various surgical sites, this research supports the potential for broader clinical application of BTXA in aesthetic and reconstructive surgeries.

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