The Synthesis And Characteristics Of New Composite Calcium Phosphate Bone Cement

objective: To study preparation method of calcium phosphate cement(CPC) combined with bone matrix gelatin(BMG) artificial composite bone cement and calcium phosphate cement(CPC) combined with bone matrix gelatin(BMG) mixed with Poly(lactic-co-glycolic acid) microspheres artificial composite bone cement. To study the physical-chemical characteristics of the new type composite bone cement samples of different proportions by evaluating the setting time, compressive strength of biomechanics, biological degradation performance, and so on. To lay the foundation for finding another new artificial composite bone cement that are more applicable than in the past, in order to treat elder patients with osteoporotic vertebral compression fractures(OVCF). Methods :1. The fresh long tubular bone of rabbit limbs, cleaned, crushed, decalcified, defatted, and by other procedures, was made into bone matrix gelatin particle, then be packaged and stored after ethylene oxide sterilization. 2. A certain amount of CPC and BMG powder, was evenly mixed in dry environment at room temperature according to the different ratio. Powder was mixed into a paste through different solid to liquid ratio, then injected into the prefabricated mold to be made into cylindrical composite artificial bone material samples. The sample was removed from the mold after solidification; 3. By scanning electron microscope observation, degradation test in vitro,X-ray diffraction phase analysis, biomechanical strength testing, and the porosity measuring, the physical and chemical properties of CPC combined with BMG composite artificial bone cement with different proportions were discussed. 4. PLGA-microspheres were prepared by W/O method and observed under scanning electron microscope. 5. CPC combined with BMG in accordance with the mass ratio of 5:1, and then be added 5% or 10% of the PLGA microspheres. 6. Artificial composite bone cement samples of CB(5:1) group, CB(5:1) +5%PLGA group, and CB(5:1)+10%PLGA group were observed by scanning electron microscopy, and the porosity was measured, the biomechanical strength was tested. Results: The composite bone cement of different weight ratio has different suitable ratio of solid-liquid, and has good syringeability and anticollapsibility. The best solid to liquid ratio of CPC to BMG(3:1),(5:1),(7:1) and(1:0)group was finally determined to be 1:0.6, 1: 0.55, 1:0.5 1:0.4(g / ml), respectively. In addition to the setting time is too long of CPC:BMG(3:1) group, the setting time of other groups is in less than 30 minutes, and meet the needs of clinical practice. Different bone cement groups have high porosity, but those with more BMG mass proportions have higher porosity, in which more than 100?m macropores increase significantly, degradation is faster, easier to induce new bone formation and revascularization. But with the weight proportion of the BMG increased, the biomechanical compressive strength of the material decrease. In the initial it has considerable compressive strength, it can satisfy the need of repair in patients with OVCF. But CPC to BMG(3:1) group samples after 4 weeks of degradation, the compressive strength decrease significantly, and easy to cause the failure of repair. 2. According to the W/O method of preparation,the microspheres have good spherical, appropriate size. PLGA-microspheres to be added further increase the porosity of the samples, but the ultimate compressive strength of the samples has a significant adverse effect. Conclusion:1. CPC have sufficient biomechanical strength, can be used to treat patients with OVCF as injectable bone cement. 2. Calcium phosphate / bone matrix gelatin artificial composite bone cement can be constructed under the control of a certain mass ratio. The addition of BMG can improve some physicochemical properties of CPC, which is beneficial to the formation of new bone. 3. After comprehensive evaluation of experimental results in vitro, CPC to BMG(5:1) can balance the contradiction between promoting the new bone regeneration and reducing the compressive strength. 4. On the base of CPC to BMG(5:1) combined, to be added PLGA-microspheres, can increase the porosity and pore size, but the compressive strength decrease significantly. This type of composite bone cement especially suitable for patients, need topical administration,but does not require early weight-bearing.