Hypertrophic scar formation after wound healing remains a clinical challenge in plastic surgery. Ultra Tension-Reducing Suture Technique is currently the primary surgical option for preventing and reducing hypertrophic scarring.An ideal tension-relieving effect requires sustained support for 3 months postoperatively to align with the natural recovery cycle of skin tissue tensile strength. Studies both domestically and internationally have confirmed that slow-absorbing sutures yield better scar improvement outcomes than fast-absorbing sutures; non-absorbable sutures carry a relatively significant risk of scar hyperplasia due to Existing domestic and international evidence confirms superior scar outcomes with slow-absorbing sutures; non-absorbable sutures tend to aggravate scar hyperplasia due to obvious foreign-body responses. Other studies have shown that there are no statistically significant differences in infection rate, wound healing and scar formation between absorbable and non-absorbable sutures for cutaneous closure, Nevertheless, absorbable sutures eliminate suture removal, relieve patients' anxiety and discomfort, and lead to superior patient satisfaction. To date, no self-controlled studies have directly verified the specific effects of absorbable sutures with disparate absorption rates on postoperative scar formation during super-tension relieving suturing.

Accordingly, this study conducted a randomized, wound-self-controlled, evaluator-blinded comparative efficacy trial. Within the same surgical incision, supertension-relieving sutures were performed using both fast-absorbing and slow-absorbing sutures to compare postoperative scar morphology and outcomes. This study is the first to investigate the impact of sutures with different absorption rates on scar formation in super-tension-relieving suturing.

This single-center, evaluator-blinded, split-incision self-controlled investigator-initiated clinical trial is performed in the Department of Plastic Surgery, The Second Hospital of Lanzhou University, aiming to compare postoperative scar formation between fast-absorbable and slow-absorbable sutures under ultra tension-reducing cosmetic closure. Hypertrophic scar remains a common troublesome complication after wound repair; adequate long-term dermal support is essential to reduce scar hyperplasia. Current clinical evidence regarding scar performance of different-speed absorbable sutures under ultra tension-releasing suture technique is inconsistent, and relevant split-wound self-controlled clinical evidence is lacking.

All eligible subjects receive equal bisection of a single linear surgical incision. Segment A is repaired with 5-0 polydioxanone (PDS, slow-absorbable suture), and Segment B uses 5-0 polyglactin 910 (Vicryl Rapide, fast-absorbable suture). Subcutaneous tension fixation, dermal ultra tension-reducing backstitch and superficial 6-0 interrupted nylon skin closure are standardized identically across both wound segments; stitch spacing, cutting edge distance and surgical manipulation are unified to eliminate operative confounders. Postoperative wound dressing, dressing change timing and epidermal suture removal at 7-10 days follow uniform clinical routine.

Prespecified outpatient follow-up visits are scheduled at postoperative 1 week, 1 month and 3 months for scar measurement, standardized clinical photography and adverse event documentation. Two independent blinded assessors complete POSAS scoring for primary endpoint evaluation to avoid assessment bias. Collected adverse events include surgical site infection, wound dehiscence, hemorrhage, seroma, hematoma and suture foreign body reaction. Statistical analysis adopts intention-to-treat principle; paired t-test and McNemar's test are utilized for outcome comparison via SPSS 25.0 software.

No interim analysis or early stopping rules are set for this trial, and an independent Data Monitoring Committee is not established. All safety monitoring is undertaken by the study research team, with serious adverse events promptly reported to the institutional ethics committee. This research is supported by The Natural Science Foundation of Gansu Province (Grant No. 26JRRA839).

Inclusion Criteria:

1. Incision length ≥ 5 cm;
2. Clean, non-infected surgical wounds;
3. Ability to provide written informed consent voluntarily;
4. Scheduled for dermatologic surgery with intended linear wound closure;
5. Able to complete required postoperative follow-up;
6. No restriction on surgical site.

Exclusion Criteria:

1. Incision length ≤ 5 cm;
2. Infected or contaminated wounds;
3. Cognitive impairment precluding provision of independent informed consent;
4. Pregnant women;
5. Any other conditions judged inappropriate for enrollment by investigators.

The study will not share individual participant data (IPD) due to ethical considerations regarding patient privacy and the small sample size of this single-center study.