Influencing factors on mechanical properties of tendon-suture system during graft preparation: a multiple linear...

Guiding the graft through the bone tunnel is a crucial step during arthroscopic ligament reconstruction, which is the preferred surgical treatment for anterior cruciate ligament tearing. Comparative studies on suture selection and fixation methods during graft preparation existed, while longitudinal and linear research was lacking to elucidate the effects of tendon cross-sectional area, knot number, and knot interval on the mechanical properties of the tendon-suture system.

The flexor tendons from the hind paws of fresh domestic swine were used to simulate graft preparation in vitro. After recording the cross-sectional area, the knot number ranged from 1 to 4, and the knot interval was set to 5-10 mm. The SpeedTrap™ technique was employed to construct the tendon-suture system. Subsequently, the grafts were stretched on a biomechanical instrument, and the peak force before the interfacial sliding between the tendon and suture occurred was recorded. After determining the correlations and significances of each variable, univariate and multivariate statistical analyses were performed with the peak force as the dependent variable.

90 valid data points were collected. Univariate analysis indicated that the peak force was associated with the cross-sectional area of the tendon and the knot number (P = 0.004). Multiple linear regression analysis of the full-scale data also showed that the cross-sectional area had a significant effect on the peak force (β = 0.19, P = 0.017). The multiple linear regression model optimized by stratifying the knot number revealed that in the group with the knot number ≥ 2, the peak force was significantly correlated with both the cross-sectional area and the knot interval (β = 0.48, P = 0.002; β = 0.37, P = 0.009), and their independent effects were significant, with variance inflation factors of 1.1 and 1.05 respectively.

The cross-sectional area significantly impacts the mechanical properties of the tendon-suture system and positively contributes to the peak force before sliding. Increasing the knot interval within 10 mm can enhance the mechanical stability of the tendon-suture system during graft preparation.