MODEL-BASED JUSTIFICATION OF GEOMETRICPARAMETERS FOR SURGICAL ACCESS IN CUTANEOUS-SUBCUTANEOUS-FASCIAL PLASTY FOR PILONIDAL SINUS TREATMENT IN CHILDREN

Pilonidal sinus (PS) remains a relevant surgical problem due to its high recurrence rate (13.3-95.2%), postoperative complications (4.2-25.0%), and prolonged treatment period (30-70 days). The lack of a universally accepted treatment strategy necessitates the search for optimal surgical techniques. A promising approach is the cutaneous-subcutaneous-fascial plasty with a rotational flap, which helps to reduce tissue tension and redistribute soft tissues in the sacrococcygeal region. Objective. To develop a mathematical model to justify the shape and parameters of the surgical access for pilonidal disease treatment using the cutaneous-subcutaneous-fascial plasty method with a computational solution. Materials and Methods. We analyzed 50 pediatric cases of PS in patients aged 15-18 years who underwent inpatient treatment at the Municipal Children's City Clinical Hospital in Chernivtsi between 2020 and 2023. The patients were divided into two groups: Group I (n=35): Underwent classical technique (excision of PS with suturing of wound edges to the sacrococcygeal fascia). Group II (n=15): Underwent subcutaneous fascial flap plastic surgery using a customized mathematical model. The following parameters were analyzed: healing time, pain intensity (assessed by visual analog scale), duration of surgery, length of hospital stay, postoperative complications. Results. The mathematical model is based on geometric analysis and optimization of the incision shape to minimize the excision area while ensuring adequate coverage of pathological fistulous openings. An optimal quadrilateral shape was used instead of the traditional rhomboid shape. Spatial relationships of pathological tracts and rotational flap closure were considered. The primary incision was optimized to reduce tissue tension and decrease the risk of postoperative complications. On day 1, pain intensity in group II was more than twice as low as in the classic surgery group. On the second and third days, pain intensity was nearly 70% lower in the SFFP group compared to the classic closure group. Hospital stay was 17% shorter in the SFFP group and pain duration was 40% less than in the classic group. Wound healing time was almost 70% shorter in group II compared to group I. Conclusions. 1. The developed model for spatial justification of surgical access in pilonidal sinus treatment demonstrated the effectiveness of delta-shaped incisions, whose parameters are determined by the location of the external fistulous openings relative to the intergluteal fold. A precisely calculated incision contour allows for optimized plastic surgery procedures, reducing postoperative complications by 3.75 times and improving overall treatment outcomes. 2. The proposed method reduces postoperative pain intensity by 70% and pain duration by 40% in pediatric patients. In addition, it reduces wound healing time by a factor of 3, making subcutaneous fascial flap plastic surgery with mathematical model-based calculations a recommended technique of choice for pilonidal sinus treatment.