Biomechanical Effects of Cement Distribution in the Fractured Area on Symptomatic Osteoporotic Vertebral Compression Fractures: A Three-Dimensional Finite Element Analysis

Abstract

Introduction According to some clinical studies, insufficient cement distribution in fractured area and asymmetrical cement distribution around fractured area were thought to be the reasons for unrelieved pain and recollapse after percutaneous vertebral augmentation (PVA) in the treatment of symptomatic osteoporotic vertebral compression fractures (OVCFs). Materials and Methods Finite element methods were utilized to investigate the biomechanical variance among three patterns of cement distributions (insufficient [ID] and sufficient [SD] cement distribution in the fractured area, asymmetrical cement distribution around the fractured area including upward [BU] and downward [BD] cement distribution). Results Compared with fractured vertebrae before PVA, distribution of von Mises stress in cancellous bone was transferred to be concentrated at cancellous bone surrounding cement after PVA, while it was not changed in cortical bone. Compared with SD group, maximum von Mises stress in cancellous bone and cortical bone and maximum displacement of augmented vertebrae increased significantly in ID group, while asymmetrical cement distribution around the fractured area in BU and BD groups mainly increased maximum von Mises stress in cancellous bone significantly. Similar results could be seen in all loading conditions. Conclusion Insufficient cement distribution in the fractured area may lead to unrelieved pain after PVA in the treatment of symptomatic OVCFs as maximum displacement of augmented vertebral body increased significantly. Both insufficient cement distribution in the fractured area and asymmetrical cement distribution around the fractured area are more likely to induce recollapse of augmented vertebrae because they increased maximum von Mises stress in cancellous bone and cortical bone of augmented vertebrae significantly.