Improving the Mechanical Function of a Nucleus Pulposus Implant for Intervertebral Disc Repair

Low-back pain is one of the chief complaints of patients to their primary physicians, and its main cause is degeneration in the intervertebral disc (IVD). Direct and indirect costs of disc degeneration total more than 100 billion dollars a year in the United States alone. Frequently, this degeneration starts in the nucleus pulposus (NP), the main load-bearing section of the IVD. Previous work has been done to create an implant to replace degenerate NP from acellular bovine NP (ABNP), but the mechanical function must be improved. To optimize the implant, ABNP was tested with different levels of osmotic compression and different concentrations of a crosslinking solution. Dynamic mechanical analysis (DMA) was performed to test the mechanical capabilities of the ABNP, differential scanning calorimetry (DSC) was attempted to confirm crosslinking, and a water content analysis was taken. The results of the DMA showed that the ABNP with higher levels of crosslinking had greater stiffness under mechanical stress than those without. DSC data was obscured due to water artifacts, and it could not be concluded if crosslinking had occurred. Water content of the NP tissues stayed consistent between variables. Overall in this study, it was shown that crosslinking impacts mechanical capabilities but osmotic pressures did not