Autologous platelet-rich fibrin matrix (Obsidian RFT) as a sphincter-preserving treatment for anal fistula: a retrospective cohort study and subgroup analysis.

introductionThe treatment of anal fistula remains a delicate balance between achieving healing and preserving anal continence. Sphincter-preserving strategies, such as autologous platelet-rich plasma/fibrin (PRP/PRF) matrices, offer a regenerative approach with minimal morbidity. This study aims to evaluate the efficacy and safety of a specific autologous fibrin matrix system (Obsidian RFT) in the management of anal fistula and to identify predictors of treatment success.

methodsWe conducted a retrospective analysis of patients treated with the Obsidian RFT system for anal fistula at a single institution between January 2020 and September 2025. The primary endpoint was fistula healing, defined as the complete cessation of drainage and closure of the external opening. Secondary endpoints included secondary healing (after a simple adjunctive procedure), overall final healing (after any reintervention), and postoperative fecal incontinence (Wexner score). A subgroup analysis was performed to evaluate outcomes in "ideal candidates" (single-tract, non-supralevator fistulas, no associated abscess).

resultsA total of 86 patients were included (mean age 52.4 ± 14.4 years; 64% male). The majority of fistulas were transsphincteric (96.5%). The median follow-up was 8.7 months. Primary healing was achieved in 45.3% of patients (39/86) after the first application. With the addition of a simple secondary procedure (repeat matrix application or limited fistulotomy), the secondary healing rate increased to 58.1% (50/86). Overall final healing, including patients requiring complex reinterventions, reached 64.0% (55/86). Persistence accounted for most failures, while true late recurrence was uncommon. Postoperative fecal incontinence was rare, occurring in only 2.3% of patients. In the "ideal patient" subgroup, primary healing was significantly higher (51.4%) compared to non-ideal candidates (18.8%; p = 0.018), rising to 65.7% with reintervention (p = 0.003).

conclusionThe Obsidian RFT system is a safe, sphincter-preserving option associated with minimal morbidity and negligible impact on continence. While primary healing rates are modest, the cumulative success rate significantly increases with a sequential approach, validating its use as a "staged" strategy. This modality serves as a valuable first-line treatment in a stepped-care algorithm to minimize incontinence risk before escalating to more invasive procedures.