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.