The Efficacy of Botulinum Toxin A Injection for Gastrocnemius Hypertrophy: A Prospective, Randomized, Double-blinded Controlled Trial.

[BACKGROUND] Many individuals hold an interest in aesthetic appeal, with one aspect of physical attractiveness being the alluring contour of the lower leg. Utilizing botulinum toxin A (BTX-A) injections offers several advantages, including a short procedure time, low pain, and a speedy recovery. With a demand for high-level evidence regarding the effectiveness of BTX-A injections for correction of lower leg contour, we evaluated the safety and efficacy of BTX-A injection for improvement of gastrocnemius muscle hypertrophy.

[METHODS] We conducted a prospective, randomized, and controlled clinical trial to evaluate whether the injection of BTX-A into the gastrocnemius muscle could decrease muscular hypertrophy. The patients were randomized into a low-dose injection (60 units) group and a high-dose injection group (100 units) for each leg. Demographics, clinical outcome, and satisfaction score were compared between the two groups.

[RESULTS] A total of 20 patients and 40 legs were enrolled in this study. Clinical and surgical demographics were similar between the two groups. BTX-A injection showed a significant decrease in the circumference of the calf after 8 weeks (preinjection: 36.35 ± 0.63 cm versus postinjection: 35.87 ± 0.61 cm; = 0.03). However, no significant difference was observed between the low- and the high-dose group (-0.52 ± 0.74 cm versus -0.44 ± 1.04 cm, = 0.78).

[CONCLUSIONS] BTX-A injection can be a good noninvasive method for the correction of hypertrophic gastrocnemius muscles. This study supports the use of BTX-A injections in patients unsatisfied with lower leg hypertrophy.