Examination of a biodegradable magnesium screw for the reconstruction of the anterior cruciate ligament: A pilot in vivo study in rabbits.

The reconstruction of the anterior cruciate ligament is, for the most part, currently performed with interference screws made of titanium or degradable polymers. The aim of this study was to investigate the use of biodegradable magnesium interference screws for such a procedure because of their known biocompatibility and reported osteoconductive effects. The left tibiae of each of 18 rabbits were implanted with a magnesium-based (MgYREZr-alloy) screw, and another 18 with a titanium-based control. Each group was divided into observation periods of 4, 12 and 24weeks. After sacrifice, μCT scans were acquired to assess the amount of the gas liberated and the degradation rate of the implant. Histological evaluations were performed to investigate the local tissue response adjacent to the implant and to assess the status of the attachment between the tendon and the bone tissue. The μCT scans showed that liberation of gas was most prominent 4weeks after implantation and was significantly decreased by 24weeks. All screws remained in situ and formed a sufficient connection with the tendon and sufficient osseous integration at 24weeks. Histological evaluations showed neither inflammatory reactions nor necrosis of the tendon. The results of this pilot study in rabbits indicate that this magnesium-based interference screw should be considered as an alternative to conventional implant materials.