Classification of Hypertrophic Gastrocnemius Muscle and Its Treatment with Botulinum Toxin A.

[BACKGROUND] Treatments including selective neurectomy, muscle resections and botulinum toxin A (BTX) injections have been used to improve the stocky appearance of calves. BTX injection has the advantages of high efficiency and is almost noninvasive. However, criterion standards of injection are still missing.

[OBJECTIVE] We aimed to establish a method to classify the hypertrophic calf for a personalized treatment and set up an injection protocol based on the findings.

[METHODS] Three-dimensional CT reconstruction was used to measure the thickness and cross-sectional area of the triceps surae. B-mode ultrasound and palpation were used to evaluate the muscle thickness and determine the dosage. Patients were followed 3 and 6 months after the treatment.

[RESULTS] A total of 112 legs were classified into three degrees of thickness (< 15 mm, 15-25 mm and > 25 mm). Twenty-seven subjects were treated with an individualized BTX (100-300 U). Maximal circumference decreased 0.33 ± 0.00 cm after 3 month (p < 0.05) and 0.67 ± 0.11 cm after 6 months (p < 0.01). The angulated calf contour was improved. No severe side effects were reported.

[CONCLUSIONS] Localizing and dosage are the key points when applying BTX. Dosage should be decided by muscle thickness instead of circumference. BTX treatment improves the prominent contour of the calf rather than reducing the volume.

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