Evaluation of Botulinum Toxin Type A Injections for Dystrophic Scar Prevention Post-Sternotomy: A Placebo-Controlled Randomized Clinical Trial

The primary objective of this clinical trial is to evaluate the improvement of **scar appearance** following sternotomy surgery through the immediate post-operative injection of **botulinum toxin**. This assessment is conducted using the Stony Brook Scar Evaluation Scale, which is a clinically relevant tool for measuring scar quality and appearance. The significance of this objective lies in its potential to enhance post-surgical outcomes by reducing the incidence of dystrophic scars, thereby improving patient satisfaction and quality of life.

Secondary objectives include:

• Comparing the two scar halves (botulinum toxin vs. placebo) in terms of scar appearance at 3, 6, 12, and 18 months post-surgery.
• Evaluating the scarring experience in patients receiving botulinum toxin versus placebo.
• Assessing local tolerance to the botulinum toxin injection compared to placebo.
• Analyzing scar outcomes in subgroups defined by dystrophic scar risk factors, focusing on the Stony Brook Scar Evaluation Scale at 6 and 18 months, and patient satisfaction at 18 months.

The clinical trial focused on evaluating the improvement of scar appearance following **surgery with sternotomy** through botulinum toxin injection. The study population included both male and female participants aged 18 years and older. Participants were required to have undergone surgery involving sternotomy and be covered by medical insurance. They also needed to be capable of attending follow-up visits and providing informed consent. The trial did not involve a vulnerable population. Unfortunately, the sponsor did not provide information regarding the total number of participants. Lifestyle considerations such as diet, physical activity, or habits were not specified in the available data.

The clinical trial is designed to evaluate the efficacy of **botulinum toxin type A** injections in improving scar appearance following sternotomy surgery. This study is a **randomized**, **double-blind**, placebo-controlled trial, ensuring that neither the participants nor the assessors are aware of the treatment allocation, thereby minimizing bias. The trial is expected to commence recruitment on May 5, 2025, and conclude by September 6, 2027. Participants will be involved in the study for a maximum treatment period of one day, with follow-up assessments extending up to 18 months post-treatment.

Participants will undergo an initial **screening visit** to confirm eligibility, which includes criteria such as being 18 years or older, having undergone surgery with sternotomy, and the ability to attend follow-up visits. Following successful screening, participants will be randomized to receive either the active treatment, **botulinum toxin type A**, or a placebo, **sodium chloride solution 0.9%**, both administered via intradermal injection. The primary endpoint is the comparison of scar appearance using the Stony Brook Scar Evaluation Scale at six months, assessed by a dermatology team blinded to the treatment allocation.

Subsequent **follow-up visits** are scheduled at three, six, twelve, and eighteen months post-treatment to evaluate secondary endpoints, including scar width and assessments using the Patient and Observer Scar Assessment Scale and the Physician's Global Assessment. These visits are crucial for monitoring the long-term effects of the treatment and ensuring participant safety. The **end-of-study visit** will occur at the 18-month mark, concluding the participant's involvement in the trial.

Participants may be withdrawn from the study if they experience adverse reactions, are unable to comply with the study protocol, or choose to withdraw consent. The trial's rigorous design and comprehensive follow-up schedule aim to provide robust data on the potential benefits of botulinum toxin type A in improving post-surgical scar outcomes.

The clinical trial involves the administration of **BOTOX 50 UNITÉS ALLERGAN**, a **botulinum toxin type A** preparation, which is provided in the form of a powder for solution for injection. This experimental medication is administered via **intradermal injection**. The dosage is set at a maximum of 50 international units (IU) per day, with a total maximum dose of 50 IU. The treatment period is limited to one day. The product is manufactured by ABBVIE and is identified by the European medicinal product number PRD10119123. The administration of this medication is conducted under blinded conditions, with the syringe masked to prevent knowledge of the treatment by the administering personnel.

The comparator treatment in this study is **SODIUM CHLORIDE SOLUTION 0.9%**, which serves as a placebo. This solution is also administered via **intradermal injection**. The pharmaceutical form is an injection, with a maximum daily and total dose of 1 milliliter. The treatment period for the placebo is similarly restricted to one day. The sodium chloride solution is utilized to maintain the blinding of the study, ensuring that neither the participants nor the investigators are aware of the treatment allocation.

Efficacy in this clinical trial will be assessed by evaluating the improvement of scar appearance following sternotomy, with the primary endpoint being the comparison of means of the Stony Brook Scar Evaluation Scale (SBSES) at 6 months (M6). This assessment will be conducted by a dermatology team assessor who is blinded to the randomization of the treatment. The trial will involve the administration of **botulinum toxin type A** injections in the immediate postoperative period, with a placebo-controlled design.

Secondary endpoints include the comparison of mean scores for each scar half (toxin-treated vs. placebo) at multiple timepoints: M3, M6, M12, and M18. These assessments will cover scar width (mm), the Patient and Observer Scar Assessment Scale (POSAS) observer scale, and the Physician's Global Assessment. The Stony Brook Scar Evaluation Scale will also be used at M3, M12, and M18. All evaluations will be performed by a dermatology team observer blinded to the treatment allocation.