Botulinum toxin type A iontophoresis for post-burn hypertrophic scars: a randomised controlled trial

Introduction Hypertrophic scars (HSs) are caused by excessive collagen synthesis due to fibroblast proliferation. Botulinum toxin type A (BoNT-A) slows fibroblast proliferation and collagen deposition, thereby improving HSs. Methods The study enrolled 76 male and female patients aged 20 to 40 years with post-burn HSs (PBHSs) who were randomly allocated into experimental and control groups and followed a three-month program. The experimental group received BoNT-A iontophoresis and traditional physical therapy (TPT), while the control group only received the TPT program. High-resolution ultrasonography assessed scar thickness, while the Patient Scar Assessment Scale (PSAS) and Observer Scar Assessment Scale (OSAS) evaluated scar characteristics at the end of the three-month treatment (post I) and at the six-month follow-up (post II). A mixed-model multivariate analysis of variance (MANOVA) examined the impact of therapy on scar thickness and the Patient and Observer Scar Assessment Scale (POSAS). Results Scar thickness decreased in the experimental group compared to the control group at post-I and post-II, with effect sizes 0.77 and 1.45, respectively. Furthermore, there was a significant decrease in OSAS total score and general opinion for the experimental group compared to the control group at post-I and post-II, with effect sizes of 0.95 and 2.02, and 0.53 and 1.30, respectively. PSAS total score and general opinion decreased for the experimental group compared to the control group at post-I and post-II, with effect sizes of 0.89 and 1.95, and 0.81 and 1.39, respectively. Conclusions BoNT-A iontophoresis had a long-lasting effect on reducing HS thickness and improving its characteristics. The process has several advantages, such as being noninvasive, painless, and externally controlled.