Morphological Criteria for Assessing Reparative Processes in Striated Skeletal Muscle Tissue Using Modified Suture Material

Background : The development of infectious postoperative complications remains a significant challenge in modern surgical practice. Such complications prolong patient hospitalization, worsen overall well-being, and cause cosmetic defects in the suture area. To prevent postoperative infectious complications, an innovative method of implanting a new surgical suture material in laboratory animals was developed and successfully tested. The material is unique due to its coating of calcium hydroxyapatite enriched with metal ions known for their antibacterial properties. The experimental results confirm the effectiveness of the proposed technology (Russian Patent No. RU 2819984 C1, dated May 28, 2024). Objective : To study the reparative processes in skeletal muscle tissue after implantation of surgical suture material modified with metal-substituted calcium hydroxyapatite in experiment. Materials and methods : An experimental study was conducted on 40 white male rats. To model a linear surgical wound, a sterile surgical scalpel was used. The wound was located over the trapezius muscle, 1 cm lateral to the posterior midline. The incision measured 2.5cm in length and was made from cranial to caudal along the spine. The penetration depth was approximately 4 mm, including subcutaneous fat and muscle tissue. The experimenter manually placed layered sutures using simple interrupted suture without tissue tension. Stitches were applied to ensure precise approximation of the wound edges. The surgeon was unaware of the group allocation of the suture material. Four experimental groups of 10 animals each were formed, according to the composition of the suture material (unmodified, modified with calcium hydroxyapatite, substituted with zinc, silver, copper). On day 10, muscle tissue samples were taken for histological preparations. Morphological analysis included assessment of cellular composition of granulation tissue, its area, the degree of perivascular edema, and the number of hemocapillaries. The research results are presented with qualitative and semi-quantitative data, such as transverse striation, perivascular edema. Qualitative data were statistically processed using the MatLab R2018b data analysis system of the Statistics Toolbox software package. Results : Morphometric analysis of histological preparations showed that the area of granulation tissue in the experimental groups was lower than in the comparison group, while the values in the group using filaments modified with zinc-substituted calcium hydroxyapatite were 49% lower compared to the control group. Also, a decrease in the number of granulocytes to 3.6 per high-power field was observed in the experimental group. Application of modified sutures resulted in tissue characterized by a high density of newly formed hemocapillaries. Conclusions : When implanting suture material modified with metal-substituted calcium hydroxyapatite into muscle tissue, a reduction in the severity of inflammation and the development of conditions favorable for muscle tissue regeneration are observed. The antibacterial properties and enhanced regenerative activity of the tested material may help address a key challenge in surgical practice – the prevention of postoperative complications at the surgical site.