Finite element analysis of wedge and biconcave deformity in four different height restoration after augmentation of osteoporotic vertebral compression fractures

Xiao-Hua Zuo,Yan-Na Si,Xiang-Yun Xue,Qian-Xi Zhang,Ben Shan,Xiao-Bing Zhang,Hong-Guang Bao,Peng Xie,Yin-Bing Chen,Wen-Dong Zhang

doi:10.1186/s13018-021-02225-8

Abstract

PurposeBiomechanical comparison of wedge and biconcave deformity of different height restoration after augmentation of osteoporotic vertebral compression fractures was analyzed by three-dimensional finite element analysis (FEA).MethodsThree-dimensional finite element model (FEM) of T11-L2 segment was constructed from CT scan of elderly osteoporosis patient. The von Mises stresses of vertebrae, intervertebral disc, facet joints, displacement, and range of motion (ROM) of wedge and biconcave deformity were compared at four different heights (Genant 0–3 grade) after T12 vertebral augmentation.ResultsIn wedge deformity, the stress of T12 decreased as the vertebral height in neutral position, flexion, extension, and left axial rotation, whereas increased sharply in bending at Genant 0; L1 and L2 decreased in all positions excluding flexion of L2, and T11 increased in neutral position, flexion, extension, and right axial rotation at Genant 0. No significant changes in biconcave deformity. The stress of T11-T12, T12-L1, and L1-L2 intervertebral disc gradually increased or decreased under other positions in wedge fracture, whereas L1-L2 no significant change in biconcave fracture. The utmost overall facet joint stress is at Genant 3, whereas there is no significant change under the same position in biconcave fracture. The displacement and ROM of the wedge fracture had ups and downs, while a decline in all positions excluding extension in biconcave fracture.ConclusionsThe vertebral restoration height after augmentation to Genant 0 affects the von Mises stress, displacement, and ROM in wedge deformity, which may increase the risk of fracture, whereas restored or not in biconcave deformity.

Highlights

Osteoporotic vertebral compression fractures (OVCFs) are among the most common complications of osteoporosis, a systemic bone disorder with a decline in bone mineral density and degradation skeletal microarchitecture [1,2,3]
The vertebral restoration height after augmentation to Genant 0 affects the von Mises stress, displacement, and range of motion (ROM) in wedge deformity, which may increase the risk of fracture, whereas restored or not in biconcave deformity
We demonstrated whether different fracture type has a potentially effect on height restoration after augmentation of OVCFs

Summary

Introduction

Osteoporotic vertebral compression fractures (OVCFs) are among the most common complications of osteoporosis, a systemic bone disorder with a decline in bone mineral density and degradation skeletal microarchitecture [1,2,3]. Wedge fracture is the loss of the height of the anterior vertebral, which can lead to the change of kyphosis angle, forward center of gravity, and the sagittal imbalance [13, 14]. The biconcave fracture does not affect the kyphosis It can directly affect the upper and lower endplates and the intervertebral disc, affecting the stress distribution. The crush fracture does not affect the kyphosis, it affects the stress distribution and the collapse of the posterior vertebrae resulting in reduced intervertebral foramen. In patients with OVCFs, the fractured vertebral height can be completely, partially, or not restored after vertebral augmentation. The fractured vertebral collapses again after PVA in some patients, which may be related to the stress unevenness after vertebral augmentation

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Conclusion