This study aims to evaluate the effectiveness of nano-fat grafting in treating hypertrophic scars caused by burns on the chest, shoulders, and back.

Burn scars in these specific areas are often difficult to treat because the skin is under constant tension and motion, which can prolong inflammation and worsen the scar. While conventional scar treatments like silicone patches, pressure garments, and steroid injections are widely used, they do not always completely restore normal tissue. Nano-fat grafting is emerging as a promising regenerative option. This procedure involves taking a small amount of the patient's own fat and processing it into a liquid that is rich in healing cells. This liquid is then injected directly into the scar to potentially improve skin texture, color, and flexibility.

The study will enroll 55 participants between the ages of 18 and 50. To be eligible, patients must have a post-burn hypertrophic scar on their chest, shoulder, or back that is less than 6 months old.

During the study, doctors will harvest a small amount of fat from the patient's abdomen or thighs using a small tube. This fat will be carefully washed, processed, and passed through a special filter to create liquid nano-fat. The liquid is then gently injected into the scar tissue.

Researchers will monitor the patients and evaluate the scars at 1, 3, and 6 months after the injection. They will use standard clinical scar assessments (the Vancouver Scar Scale and the Patient and Observer Scar Assessment Scale) alongside photographs to measure improvements in scar color, thickness, pliability, and overall appearance, as well as patient-reported symptoms like pain and itching.

Hypertrophic scar formation following burn injuries is a complex process driven by excessive collagen deposition, prolonged wound healing, and altered tissue remodeling. Post-burn hypertrophic scars located on the chest, shoulders, and back present a particularly significant clinical challenge. Because these anatomical regions are subjected to constant tension, stretching, and motion, the healing scar is repeatedly stressed, which can prolong inflammation and exacerbate scar thickness and stiffness. This persistent hypertrophy often leads to functional limitations, cosmetic disfigurement, severe discomfort, and psychological distress. While conventional scar therapies, such as silicone applications, pressure garments, corticosteroid injections, and laser treatments, are widely utilized, they do not reliably restore normal tissue architecture for all patients, particularly in these high-tension areas.

To address these limitations, autologous nanofat grafting has emerged as a promising regenerative biologic therapy. Unlike traditional structural fat grafting used primarily to fill tissue voids, mechanically processed nanofat is rich in stromal and cellular components that act to modulate local inflammation, support angiogenesis, and improve extracellular matrix remodeling. Recent histological, imaging, and clinical studies indicate that nanofat treatment can yield statistically significant improvements in scar pigmentation, pliability, vascularity, and height, while also reducing patient-reported symptoms like pain and itching.

The primary aim of this prospective study is to evaluate the safety and efficacy of intradermal nanofat injections for the management of post-burn hypertrophic scars specifically on the chest, shoulders, and back. By targeting these difficult and highly mobile anatomical regions, this research seeks to add focused clinical evidence to the existing literature using standardized scar assessment outcomes.

The study will be conducted at the Plastic Surgery Departments of Assiut University Hospital and Elmabarra Health Insurance Hospital. Enrolled participants will undergo a minimally invasive procedure where adipose tissue is harvested from the abdomen or thighs using low-pressure liposuction or a manual vacuum syringe. The harvested fat is washed with saline and mechanically emulsified by passing it between two 10cc syringes for 30 passes. It is then pushed through a nano-filter to isolate the liquid nanofat. This regenerative product is subsequently injected intradermally directly into the hypertrophic scar using a fine needle (27G or 30G) until slight blanching of the tissue is observed.

To evaluate the intervention, patients will undergo clinical assessments at baseline and during postoperative follow-up visits at 1, 3, and 6 months. The primary clinical evaluation tool will be the Vancouver Scar Scale (VSS), which quantifies changes in scar color, pigmentation, pliability, and height. Additionally, the Patient and Observer Scar Assessment Scale (POSAS) will be utilized to capture both the surgeon's objective evaluation (including vascularity, thickness, and surface area) and the patient's subjective experience (including pain, itching, and stiffness). Aesthetic outcomes and skin texture changes will be further analyzed using standardized photographic documentation, maintaining fixed lighting, backgrounds, and camera angles for all pre- and post-operative images. Participants will be continuously monitored for any potential complications associated with fat grafting, such as persistent erythema, hematoma, or infection.

Inclusion Criteria:

• Age 18 to 50 years.
• Presence of post-burn hypertrophic scars located on the chest, shoulders, or back.
• Age of the scar is less than 6 months.

Exclusion Criteria:

• Active infection or ulceration at the site of the scar.
• Patients with systemic connective tissue diseases or bleeding disorders.
• Hypertrophic scars older than 6 months.
• History of keloids or previous surgical excision of the same scar.
• Previous corticosteroid injections into the scar.
• Pregnancy and lactation.
• Refusal to undergo surgery.