Absorbable versus Non-Absorbable Sutures in Achilles Tendon Rupture Repair: A Retrospective Cohort Study Evaluating Medium- to Long-Term Outcomes via Musculoskeletal Ultrasound and Functional Metrics

Objective Suture material selection probably impacts outcomes after surgical repair of acute Achilles tendon rupture. Absorbable and non-absorbable sutures possess distinct mechanical and biocompatibility properties. This study compared medium-to-long-term functional recovery and ultrasonographic healing characteristics between patients receiving absorbable versus non-absorbable sutures. Methods This retrospective cohort study screened 210 patients undergoing primary acute Achilles tendon repair (2013–2024). Propensity score matching generated comparable cohorts of 50 patients each: the absorbable group received Interfascicular Repair, and the non-absorbable group received modified Kessler Repair. Identical postoperative rehabilitation protocols were followed. Primary outcomes assessed at 6 and 12 months included: ultrasonographic parameters (Achilles tendon thickness ATT, mm), margin echotexture (ME) at the repair site, blood flow signals (BFS) at the repair site, active gliding function (AGF), passive gliding function (PGF) and functional assessment (VISA-A score). Results At 6 months, statistically significant differences were observed between the absorbable and non-absorbable suture groups across ATT; AGF; BFS. The absorbable suture group exhibited significantly lower ATT compared to the non-absorbable group (7.07 ± 0.41 mm vs. 7.81 ± 0.52 mm; p < 0.001). The absorbable suture group demonstrated greater AGF (1.86 ± 0.35 vs. 1.06 ± 0.31; p < 0.001). VISA-A score were also significantly higher in the absorbable suture group (81.82 ± 7.48 vs. 74.44 ± 6.71; p < 0.001). The BFS was significantly reduced in the non-absorbable suture group (1.28 ± 0.88 vs. 2.32 ± 0.82; p < 0.001). At the twelve-month follow-up, no significant intergroup differences were detected in ATT (p = 0.126), AGF (p = 0.650), VISA-A score (p = 0.063), and BFS (p = 0.569). At 6 months, ATT correlated inversely with AGF (r = -0.487, p < 0.001) and VISA-A score (r = -0.311, p = 0.002). Complication (absorbable: 1 re-rupture; non-absorbable:2 inflammatory reactions). Conclusion Although functional and structural outcomes converge by 12 months, absorbable sutures confer early advantages in tendon morphology and gliding function during the initial healing phase. Suture material selection should be individualized, considering patient-specific factors such as anticipated rehabilitation adherence and activity demands.