Tensile strength testing in feline skin with different sizes of nylon suture material: a biomechanical in vitro study

ObjectivesThis in vitro study aimed to evaluate the failure loads and failure types of sutured feline skin samples using different sizes of nylon (polyamide 6/6.6) suture material.MethodsA total of 88 skin samples from the lateral thorax and abdomen of 11 cadaveric cats were harvested using an hourglass-shaped template. In total, 80 samples from 10 cats were bisected and sutured with three simple interrupted sutures using randomly assigned nylon suture sizes (2-0, 3-0, 4-0 and 5-0 USP). Control samples remained intact. Uniaxial tensile tests were performed using a universal testing machine. Failure load and failure type were recorded and analysed. Failure mechanisms were classified as either suture material failure or tissue failure, with tissue failure defined as linear tears perpendicular to the suture line at the penetration site.ResultsSuture size significantly influenced failure load. No significant reduction in force was observed between 2-0 and 3-0 (P = 0.089), but all other pairwise comparisons showed significant differences (P <0.05). Load to failure decreased by 25.7% between 3-0 and 4-0, and by 40.0% between 4-0 and 5-0. Suture failure rates increased as suture size decreased, with failure occurring in 4/20 samples for 3-0, 17/20 samples for 4-0 and all samples for 5-0. A strong correlation was found between suture failure and suture size (r = 1.000 and P <0.001, Spearman's rank correlation), indicating a higher risk of breakage with smaller suture diameters. All 2-0 sutures failed because of tissue rupture.Conclusions and relevanceNylon 2-0 and 3-0 provided sufficient mechanical stability. Nylon 4-0 exhibited a high risk of suture breakage but may be suitable for thin-skinned areas with tension-relieving measures. Nylon 5-0 showed an unacceptably high failure rate and is not recommended for feline skin closure. Evidence-based suture selection guidelines could improve feline surgical outcomes.