Osteogenic surgical sutures for tendon traction and fixation: A model of achilles tendon sleeve avulsion

Currently, the repair of Achilles tendon sleeve avulsion is a challenge due to their limited research and particularly difficult treatment. In tendon repair surgery, the construction of bone tunnels is required for the suspensory fixation of ruptured tendon by sutures. However, due to the biologically inert of commonly used tendon sutures, postoperative fixation instability, bone tunnel enlargement, and even tendon reconstruction failure can easily occur under stressful conditions. In this study, core-spun nanoyarns containing β-tricalcium phosphate (β-TCP) were prepared by electrospinning to serve as surgical sutures for tendon traction and fixation. The suture of 6 core-spun nanoyarns spun again into one strand had stronger mechanical properties, which could effectively pull the tendon. The silk fibroin micron yarn of the suture core layer and the polycaprolactone/silk fibroin/β-TCP nanofibers of the shell layer demonstrated favorable biocompatibility, which facilitated cell adhesion and expression in the tendon and bone. In the repair surgery of the Achilles tendon sleeve avulsion in rabbits, compared with non-degradable and high mechanical properties commercial sutures, the β-TCP in the nanofibers of sutures could induce osteogenesis, thereby reducing the gap in the bone tunnel and preventing enlargement of the bone tunnel. In conclusion, the suture could weave the ruptured tendon, fix the tendon to the bone, promote the formation of new bone in the bone tunnel, avoid the instability of the existing commercial sutures to the bone tunnel, and ultimately improve the success rate of tendon repair surgery. STATEMENT OF SIGNIFICANCE: Nowadays, there is very limited research on the Achilles tendon sleeve avulsion model. This model presents challenges due to inadequate tendon tissue in the calcaneus for direct repair and insufficient bone tissue on the avulsed tendon for fixation. The incidence of this model is low, but treatment once it occurs is particularly difficult. In this study, we proposed to compound osteogenesis-promoting β-TCP materials onto nanoyarns to prepare surgical sutures that could weave the ruptured tendon, fix the tendon to the bone, induce osteogenesis, and reduce the gap in the bone tunnel, thus avoiding the instability of the existing commercial sutures in the bone tunnel, and ultimately improving the success rate of the surgery.