Orthopedic suture, as an implantable surgical device for skeletal and soft tissue connection, is vital in tendon or ligament injury repair. Resorbable therapy approaches exhibit excellent biocompatibility in the field of suture materials but lack a long-term fixation effect in orthopedic treatment. Herein, this study focused on a series of partially absorbable orthopedic sutures, which were composed of absorbable polycaprolactone (PCL) multifilament and non-absorbable ultra-high molecular weight polyethylene (UHMWPE) multifilament. Comprehensive in vitro mechanical evaluations were conducted to probe the relationship between material composition and mechanical properties of the sutures. The results showed that the partially absorbable sutures, especially P/U = 50/50 and P/U = 25/75, exhibited significant improvements in mechanical properties compared to single-material sutures. The tensile strength of P/U = 50/50 and P/U = 25/75 was 180.99 and 210.91 N, respectively, which was about two times higher than that of absorbable PCL suture P/U = 100/0 (62.42 N). Furthermore, their suture-to-suture friction force was 1.89 times and 2.51 times that of non-absorbable UHMWPE suture P/U = 0/100, respectively, which guaranteed good knot security. Compared with the clinically used orthopedic suture Ethibond (110 N), P/U = 50/50 and P/U = 25/75 also presented superior tensile properties. Notably, P/U = 50/50 and P/U = 25/75 had similar tensile curves to that of the native tendon/ligament, which might be beneficial to tissue healing. Moreover, the R2 of Eyring's model to simulate the creep curves of each suture was higher than 0.99, which indicated that Eyring's model could be used in predicting the long-term creep behavior of the sutures.
