Study And Design Of Anterior Cervical Bioabsorbable Fixation System

Objective With the increasing use of bioabsorbable implants in a variety of clinical conditions, potential advantages in select spinal applications are now being realized. Newer polymers with biomechanical properties relevant to the requirements of specific spinal implants and resorption rates appropriate for specific spinal applications are being developed. These new materials offer the necessary biomechanical stability of conventional spinal implants without the sequelae associated with metallic implants such as long-term loosening, implant migration, and imaging interference. At this time, the majority of clinical applications for these new polymers have involved tension band plating in the lumbar and anterior cervical spine, anterior spinal interbody reconstruction, posterior bone graft containment, and bone graft harvest site reconstruction. The main point of this study was to select a suitable material for the application of cervical spine, and set up a animal model to make sure whether the bioabsorbable anterior cervical internal fixation system are good at the fusion of cervical spine.Methods A biomechanical study and an in vivo monosegmental spinal fusion study were performed to evaluate a novel bioresorbable poly-L-lactic acid (PLLA) plate , screw and cage. The yield strength of a spinal segment was chosen as the main design parameter for the resorbable plate, screw and cages to be used in a rabbit model. A half-year in vivo study revealed a significantly faster and more complete fusion using PLLA plate , screw and cages as compared to titanium plate, screw and PLLA cages with the same dimensions.Results In the PLLA group, the intervertebral grafting height did not change and bone remodeling within the cage was found after implantation. In terms of degradation of the PLLA, similar features were observed in vivo and in vitro. Degradation was not completed half years after implantation. Tissue reaction wasmild during the observation period.Conclusion A trend of increased fusion stiffness, radiographic fusion, and histologic fusion was demonstrated from 3 weeks to 20 weeks. Device degradation was associated with a mild to moderate chronic inflammatory response at all postoperative sacrifice times.