| Purpose:Vertebral augmentation is widely applied in treating osteoporotic vertebral compressive fracture,which is able to stabilize fractured vertebra,relieve back pain and correct kyphosis by expanding fractured vertebra and filling bone cement.As the major filling material used in vertebral augmentation,Polymethylmethacrylate(PMMA)has advantages like high compressive strength and valid fixation,but it also has many disadvantages which may do harm to the safety and efficacy of the procedure.So this study is aimed to explore the fabrication of a degenerative starch modified calcium phosphate cement available for vertebral augmentation and study its material and mechanical properties.Methods:The traditional CPC powder,corn starch and iohexol were mixed in the given ratio to produce CPI cement.Properties such as injectability,setting time,compressive strength were tested by immersion test,Gilmore needles and mechanical testing machine.The samples of CPI were soaked in the stimulated body fluid and then scanned by scanning electron microscope and X-ray diffraction.Cytotoxicity of CPI leachate was measured by CCK-8 and live/dead dyeing.Finally,developing ability,biocompatibility and biomechanical property of CPI were examined in animal models as subcutaneous implant and femur deficit models.Results:CPI cement showed greater injectability and anti-washout ability over traditional CPC;the initial and final setting time of CPI were 15.1±3.9 min and 21.5±5.9 min respectively.The compressive strength of CPI reached 44.92±3.66 MPa,while that of CPC was only 13.21±2.45 MPa.The degeneration rate of CPI in vitro was 19.32±1.02%,which was significantly higher than CPC(2.92±2.64%),and the compressive strength after soaking still reached 26.28 MPa after 8 weeks.CCK-8 and live/dead dyeing tests of leaching liquid of CPI implied no cytotoxicity to MC3T3.Animal test revealed that CPI had great developing ability in vivo after 8 weeks;HE staining of harvested samples showed CPI was surrounded by connective tissue,and no obvious inflammatory cell was observed.Three-point bending test of harvested femurs showed the maximum loading of CPI group was significantly higher than that of CPC(130.53 N and 92.67 N,respectively),suggesting that CPI had great ability of promoting osteogenesis and femurs repaired by CPI had better biomechanical properties.Conclusion:CPI cement effectively improves the shortcomings of traditional CPC,and is expected to be a new alternative for bone filling material. |
