Digital evaluation of finite element model for percutaneous kyphoplasty with bone cement injection / 中国组织工程研究

ABSTRACT

BACKGROUND: The treatment principle, long-term therapeutic effects, and complications of percutaneous kyphoplasty are closely related to blomechanlcs. Its blomechanlcs have attracted wide attention. OBJECTIVE: To establish a virtual digital evaluation system for biomechanical changes and bone cement leakage after percutaneous kyphoplasty and bone cement injection. METHODS: Percutaneous kyphoplasty with bone cement injection was performed based on previously established three-dimensional model of L3-L5. The model was processed using the software Abaqus2016 for finite element analysis. The effects of bone cement injection model, injection pressure, and injection volume on the stress of fractured L4 vertebral endplate were analyzed. RESULTS AND CONCLUSION: (1) After simulated percutaneous kyphoplasty with bone cement injection, the stress of L4 fractured vertebral endplate decreased significantly under the partial pressure of cement. Different injection methods had no significant effect on the stress of fractured L4 vertebral endplate (P > 0.05), but bilateral injection made the distribution of bone cement more uniform and produced the best effect. (2) Different injection pressures had no significant effect on the stress of fractured L4 vertebral endplate (P > 0.05), but with the increase of injection pressure, the distribution of bone cement was more dispersed and leakage was more likely to occur. (3) With increase in bone cement injection dose, the stress of fractured L4 vertebral endplate gradually decreased (P < 0.05). The physiological stiffness of the vertebral body could not be restored when 2 mL of bone cement was injected. The distribution of bone cement was more concentrated when 4 mL of bone cement was injected. The breakdown point was reached when 8 mL of bone cement was injected. (4) After injection of bone cement, the upper endplate of the lower vertebral body was more prone to suffer from fracture than the lower endplate of the upper vertebral body. (5) These results suggest that the stress of L4 vertebral endplate shifted obviously after simulated surgery compared with before surgery, that is, the stress of L4 upper endplate increased and that of L4 lower endplate decreased. Different injection methods had little effect on the surgical results, but the distribution of bone cement injected bilaterally was more uniform, which reduced the incidences of re-fracture and collapse. Lower injection pressure could reduce the risk of cement leakage after surgery. Injection of 4 mL bone cement can restore good stiffness and physiological curvature of the diseased vertebra, without reaching the yield point or causing refracture.