The goal of this clinical trial study: is to determine the effect Botulinum toxin type A iontophoresis in hypertrophic scars for post burned patients. The main question is it aims to answer is:

• Does Botulinum toxin type A iontophoresis may help in minimizing postburn hypertrophic scars?
• Participants will receive the treatment for 3 months.
• Assessment will be done before and after treatment.

1. Subjects:

   Seventy-six Patients from both genders who have post burn hypertrophic scar will participate in this study. Their ages will be ranged 20 to 40 years.

2. Design of the study:

In this study the patients will be randomly assigned into two equal groups (38 patients for each group):

1. Group A (Study group):

   This group includes 38 patients who will receive botulinum toxin type A iontophoresis once monthly for 3 months, in additional to traditional physical therapy (Positioning, Stretching exercises, Pressure Therapy and Massage) 2 sessions per week for 3 months.

2. Group B (Control group):

   This group includes 38 patients who will receive traditional physical therapy (Positioning, Stretching exercises, Pressure Therapy and Massage) 2 sessions per week for 3 months.

   - Equipments:

   Measurement equipments:

   1. Sonography:

      It is high-resolution B-image sonogram which allows a good penetration depth of up to 40 mm into the skin and a resolution of around 158 micro m. It has been successfully utilized for objectively measuring pathological scars.

   2. Patient and Observer Scar Assessment Scale (POSAS):

      It consists of two parts; one for the patient (Patient scale; POSAS Patient) and one for the physician (Observer scale; POSAS Observer). Both contain six items on a 10-point rating scale and an extra category "Overall Opinion". All characteristic features of the pathological scars are covered by the questionnaire: vascularity, pigmentation disorders, relief/texture, thickness, pliability, surface area, pain, and itching/pruritus. The latter items, in particular, concern the well-being of the patients.

      • Sonography:

        • High frequency ultrasound is the most common used technique for scar assessment.

        • The working mechanism is based on refection of sound waves of structures with different acoustic impedances and the analysis of the refection time to determine the depth of the structure.

        • The penetration depth ranges from the upper dermal layers to full-thickness skin and subcutaneous structures, depending on the employed frequency b. Patient and Observer scar Assessment Scale (POSAS):

        • The scar will be rated numerically on a ten-step scale by both the patient and doctor.

        • Six items on the Observer Scale: vascularity, pigmentation, thickness, relief, pliability, and surface area.

        • The Patient Scale consists of pain, itchiness, color, stiffness, thickness, and irregularity of the scar.

        • One of the reasons POSAS was chosen for scar evaluation is because it is the only scar assessment tool to include a component for patients to fill in.
        • Furthermore, its distinctive feature of reflecting subjective symptoms like pain and pruritus and because of its appropriateness for everyday practice.
        • Both sonography and POSAS will be used for assessment of hypertrophic scar pre-treatment and post treatment (after 3 months then after 6 months as follow up).

      • Procedures of iontophoresis drug delivery device:

      the iontophoresis group will receive botulinum toxin type A iontophoresis using an iontophoretic drug delivery system (Phoresor IIAuto,Model PM850, IOMED.) - Procedures of botulinum toxin type A iontophoresis:

      • Botulinum toxin type A (Botox Allergan ®, Irvine, CA, USA) will be used.

      • 100 U vacuum-dried powder in a single-use vial for reconstitution diluted in 2 mL of sterile, preservative-free 0.9% saline to constitute a solution at a concentration of 4 U/0.1 mL) will be administered once a month for a total period of three months.

      • The dose will be adjusted to 2.5 U/cm2 of the lesion.

      • The dose shouldn't exceed 100 units per session.

        • Physical therapy program for both groups:

      traditional physical therapy (Positioning, Stretching exercises, Pressure Therapy and Massage) 2 sessions per week for 3 months

Inclusion Criteria:

• Patient with hypertrophic scar (3-6) months after burn healing.
• Age range between 20-40 years.
• Male and female patients will participate in the study.
• All patients have a postburn hypertrophic scar at different body sites.
• All patients enrolled on the study will have their informed consent.

Exclusion Criteria:

• Patients with prior medical histories of cardiac arrhythmias.
• Patients with cardiac pacemakers.
• Patients with orthopedic implants.
• Areas of skin with lesions and impaired sensation.
• During pregnancy and breastfeeding.
• Patient with diabetes mellitus.
• Patients with a history of hypersensitivity or adverse reactions associated with (BTX_A).
• Recent BTA administration 6 months before the study.
• Any subject complaining of psychiatric disorders or neurological disorders such as myasthenia gravis.