Bioabsorbable Screws for Anterior Cruciate Ligament Reconstruction Surgery: A Review

One of the popular orthopedic implants is utilizing fixation screws to fix Anterior Cruciate Ligament (ACL) grafts and secure the graft into femur and tibia. Currently, these screws are made of titanium or bioabsorbable materials. In this respect, bioabsorbable screws were generated in order to overcome some of the potential problems caused by metallic screws. Although the bioabsorbable screws are susceptible to some drawbacks includingbone ingrowth features as well as good in vitro and in vivo mechanical properties. The biomechanical results of ACL screws showed that the ultimate failure loads and yield point loads varied from 800-1500 N and 600-1000 N, respectively. Moreover, the evaluations of in vivo degradation behaviorshowed the almost complete or fully complete resorption of ACL screws from 6 month to 2 years. However, it was proved that the addition of bone mineral phases such as Hydroxyapatite (HA), β-Tricalcium Phosphate (β-TCP), and Calcium Carbonate (CC) could enhance this degradation rate. Incorporation of biceramics into pure polymeric ACL screws may contribute to enhancing the osteogenesity of bone after full resoprption of screws,function as buffering agents that decrease the acidity of screw adjacents resulting from degradation of products, andimprovee the mechanical properties of ACL screws. In this paper, the latest bioabsorbable ACL screws which are currently available for graft fixation in orthopedic markets are discussed. A brief review of the literature regarding the physical, biological, and mechanical properties of bioabsorbable ACL screws was made. Besides,the insertion technique, various manufactured sizes, and in vitro and in vivo mechanical properties for each screw were addressed.