Degradation Behavior of Biodegradable Ze21c Magnesium Alloy Suture Anchors and Their Effect on Ligament-Bone Junction Repair

Abstract

Current materials comprising suture anchors used to reconstruct ligament-bone junctions still have limited mechanical properties, degradability, and biocompatibility. Magnesium alloys are potential bone implant materials, and Mg2+ has been shown to promote ligament-bone healing. Here, we used an Mg-2wt% Zn-0.5wt% Y-0.5wt% Nd-0.4wt% Zr (ZE21C) and a Ti6AL4V (TC4) alloy to prepare suture anchors to reconstruct the patellar ligament and proximal 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 suture anchor in high stress degraded the fastest during the early healing stage, while the healing of the bone tissue above the anchor in the late stage accelerated the degradation of the anchor head. Radiological, histological, and mechanical assays indicated that the ZE21C suture anchor promoted bone formation above the suture anchor and healing 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.

Keywords: ZE21C, suture anchor, degradation behavior, reparative effect, ligament-bone junction