Biomechanical in vitro comparison of suture anchors for thumb UCL repair.

Different types of intraosseous suture anchors can be used for thumb ulnar collateral ligament (UCL) repair surgery. Some of them have already been tested biomechanically in intact bone; however, there exists little knowledge of their stability when implanted in avulsion fracture. In this biomechanical in vitro study, three anchor types (hard, soft and novel BoneWelding) were tested on 24 fresh frozen human thumbs from 12 body donors. After the repair of an iatrogenic ligamentous UCL rupture, the thumbs were cyclically loaded. A new set of anchors was implanted at the contralateral radial side of the same specimen into an iatrogenic avulsion fracture and pulled out of the bone. The most common mode of failure in ligamentous UCL repairs was the suture-ligament interface, especially when using soft anchors. In avulsion fractures, the novel anchor withstood significantly higher pullout forces than the hard or soft anchor (65 N vs. 42 N vs. 27 N; p = .006). The BW anchor provides sufficient anchorage in trabecular bone for UCL repair in case of avulsion fractures.