Effect of an Intraoperative Polynucleotide Injection on Scar Quality After Thyroidectomy and Parathyroidectomy

This is a prospective, single-center, two-arm, parallel-group, randomized, placebo-controlled clinical trial designed to evaluate the effect of a single intraoperative polynucleotide injection on postoperative scar quality after open thyroidectomy, thyroid lobectomy, or parathyroidectomy.

A total of 80 participants will be randomly assigned in a 1:1 ratio to either the polynucleotide group or the placebo group using a computer-generated randomization list. Participants assigned to the intervention group will receive PLINEST One PN-HPT (Polynucleotides Highly Purified Technology). Participants assigned to the control group will receive sterile 0.9% sodium chloride solution.

The study solution will be administered immediately after completion of skin closure and before the final surgical dressing is applied. In both groups, the total injection volume will be calculated according to incision length at 0.5 mL per centimeter. The solution will be distributed evenly along the entire incision line using a 34-gauge needle and will be injected intradermally or into the superficial subdermal plane. The placebo will be administered using the same volume, anatomical plane, needle size, syringe type, and injection pattern as the active treatment.

Study solutions will be prepared in coded syringes by a member of the research team who is not involved in postoperative scar assessment. Participants, postoperative scar assessors, and the researcher performing the statistical analysis will be blinded to treatment allocation. If differences in injection characteristics make treatment allocation apparent to the person administering the injection, that individual will not participate in postoperative assessments or data analysis.

Surgical skin closure and postoperative wound care will be standardized between the two groups to reduce factors that could affect scar formation.

Participants will undergo preoperative assessment and postoperative evaluations on day 1, days 7 to 10, and at weeks 4, 12, and 24. An optional long-term assessment may also be performed at week 52. Standardized digital photographs will be obtained using consistent lighting, camera distance, participant position, and background whenever possible.

Scar quality will be evaluated over time using the Patient and Observer Scar Assessment Scale (POSAS), the Vancouver Scar Scale, clinical scar measurements, standardized photographs, scar-related symptoms, participant satisfaction, wound complications, and local or systemic reactions related to the injection. The primary assessment time point is postoperative week 24. Changes over time and differences between treatment groups will be evaluated using appropriate repeated-measures statistical methods.

Inclusion criteria

• Adults aged 40 to 60 years.
• Scheduled to undergo open thyroidectomy, thyroid lobectomy, or parathyroidectomy through a standard anterior cervical (Kocher) incision.
• Undergoing anterior neck surgery for the first time.
• Able to provide written informed consent.
• Willing to attend the planned postoperative follow-up visits.
• Able and willing to comply with the study procedures.

Exclusion criteria

• Younger than 40 years or older than 60 years.
• Previous anterior neck surgery.
• Pre-existing scar in the planned incision area.
• History of hypertrophic scar or keloid formation.
• Previous radiotherapy to the neck.
• Active dermatologic disease involving the anterior neck.
• Active local or systemic infection.
• Uncontrolled diabetes mellitus.
• Current use of systemic corticosteroids or immunosuppressive medications.
• Pregnancy or breastfeeding.
• Known hypersensitivity to fish, salmonid-derived products, polynucleotides, or any component of PLINEST One.
• Coagulation disorder or clinically significant bleeding tendency.
• Use of anticoagulant therapy that constitutes a contraindication to intradermal injection.
• Any contraindication to mesotherapy, intradermal injection, or injectable biostimulant procedures.
• Inability or unwillingness to comply with the planned follow-up assessments.