Degradation behavior of ZE21C magnesium alloy suture anchors and their effect on ligament-bone junction repair

Current materials comprising suture anchors used to reconstruct ligament-bone junctions still have limitation in biocompatibility, degradability or mechanical properties. Magnesium alloys are potential bone implant materials, and Mg2+ has been shown to promote ligament-bone healing. Here, we used Mg-2 wt.% Zn-0.5 wt.% Y-1 wt.% Nd-0.5 wt.% Zr (ZE21C) alloy and Ti6Al4V (TC4) alloy to prepare suture anchors to reconstruct the patellar ligament-tibia in SD rats. We studied the degradation behavior of the ZE21C suture anchor via in vitro and in vivo experiments and assessed its reparative effect on the ligament-bone junction. In vitro, the ZE21C suture anchor degraded gradually, and calcium and phosphorus products accumulated on its surface during degradation. In vivo, the ZE21C suture anchor could maintain its mechanical integrity within 12 weeks of implantation in rats. The tail of the ZE21C suture anchor in high stress concentration degraded rapidly during the early implantation stage (0-4weeks), while bone healing accelerated the degradation of the anchor head in the late implantation stage (4-12weeks). Radiological, histological, and biomechanical assays indicated that the ZE21C suture anchor promoted bone healing above the suture anchor and fibrocartilaginous interface regeneration in the ligament-bone junction, leading to better biomechanical strength than the TC4 group. Hence, this study provides a basis for further research on the clinical application of degradable magnesium alloy suture anchors.