Titanium and resorbable polymers are the materials of choice when reattaching the ACL with an interference screw. While titanium screws possess sufficient strength to withstand insertion and the holding power to retain the ACL in the bone, tearing of the ACL and difficulty in removing the screw during revision have motivated the development of resorbable polymer ACL screws. However, polymer screws often break during insertion or once implanted and result in intra-articular bodies in the knee joint and the potential for "locking knees." Metal and polymer materials result in the formation of fibrous scar tissue around the implantation and prevent tissue bonding. Metallic screws have been associated with chronic pain, tenderness and bone atrophy at the implantation site and polymeric implants and their degradation by- products have resulted in multiple complications. Consequently, there is a need for an ACL interference screw that bonds to bone without scar tissue formation and that resorbs without any associated morbidities. Tricalcium phosphate (TCP) has the ability to be resorbed in vivo and be replaced by the ingrowth of natural bone in vivo. However, conventionally processed TCP materials have poor mechanical properties. Using proprietary nanostructure processing of TCP, crystallinity and stoichiometry as well as particle size and morphology can be controlled to produce superior mechanical strengths and improved in vitro and in vivo bioactivity. In this application, the objectives are focused on producing dense nanocrystalline TCP (nTCP) and testing this material to confirm that nTCP confers both mechanical strength and biocompatibility advantages for its use in soft tissue and bone fixation applications. While many nanotechnology applications still remain several years away from commercialization, this project will demonstrate a successful translation of nanotechnology into a superior product for the marketplace and demonstrate that nanotechnology can be used to imbue common materials with exceptional properties
