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2022, Vol. 26 ›› Issue (16): 2461-2466Comparison of biomechanical properties of calcium phosphate/polymethyl methacrylate composite bone cement and polymethyl methacrylate bone cementLi Shengkai1, 2, Li Tao2, Wei Chao2, Shi Ming2
Abstract: BACKGROUND: Polymethyl methacrylate (PMMA) is the most widely used bone cement in vertebral body reinforcement, but it still has some defects such as excessive elastic modulus. The in vitro mechanical test of bone cement for how to reduce its elastic modulus has a certain significance for guiding clinical practice. OBJECTIVE: To measure compressive strength of PMMA bone cement and its composite bone cement after adding self-solidifying calcium phosphate artificial bone, and evaluate the effect of adding calcium phosphate artificial bone on the elastic modulus of PMMA bone cement. METHODS: PMMA (100%), calcium phosphate/PMMA (87%) and calcium phosphate/PMMA (76%) bone cement were prepared by adding calcium phosphate artificial bone (0, 4, 8 g) and PMMA (26 g) to liquid phase monomer, respectively, and injected into the standard experimental module of human cancellous bone to prepare human osteoporosis model. The ultimate compressive strength and elastic modulus of each model were measured by standard compression test. PMMA (100%), calcium phosphate/PMMA (87%) and calcium phosphate/PMMA (76%) bone cement were prepared into cylindrical standard bone cement specimens; the highest curing temperature and the time required for each sample to reach the highest curing temperature were determined; and the ultimate compressive strength and elastic modulus of each model were measured by standard compression test. RESULTS AND CONCLUSION: (1) In the bone cement standard specimen model, the maximum compressive strength and elastic modulus of calcium phosphate/PMMA (87%) group and calcium phosphate/PMMA (76%) group were lower than those of PMMA (100%) group (P < 0.05), and the compressive strength of calcium phosphate/PMMA (76%) group was lower than that of calcium phosphate/PMMA (87%) (P < 0.05). The maximum curing temperature of calcium phosphate/PMMA composite bone cement was lower than that of PMMA bone cement, and there was no significant change in solidification time. (2) In the osteoporosis model, the maximum compressive strength of calcium phosphate/PMMA (87%) group and calcium phosphate/PMMA (76%) group was lower than that of PMMA (100%) group (P < 0.05); and the elastic modulus of calcium phosphate/PMMA (76%) group was lower than that of calcium phosphate/PMMA (87%) group (P < 0.05). (3) The results show that adding calcium phosphate to PMMA bone cement can reduce the elastic modulus. In a certain range, calcium phosphate/PMMA composite bone cement has better mechanical and structural properties than PMMA bone cement, and there is no obvious change in controllability, so it can be used for vertebral body reinforcement. Key words:bone cement, biomechanics, vertebroplasty, polymethyl methacrylate, self-curing calcium phosphate artificial bone, polyurethane rigid foam |