A finite element analysis of a self-designed eccentric balloon dilator for osteoporotic vertebral compression fractures

Abstract

Objectives To study the biomechanical performance of a self-designed eccentric balloon dilator used in percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fracture (OVCF) by finite element analysis.Methods We created a three-dimensional finite element model of OVCF (T12-L1-L2) in which bilateral PKP with a normal balloon dilator (M1),unilateral PKP with a normal balloon dilator (M2) and unilateral PKP with a self-designed eccentric balloon dilator (M3) were respectively simulated.The 8 N · m moment with a compressive preload of 260 N was respectively imposed on the superior surface of the T12 vertebral body when it was at flexion,extension,left rotation,right rotation,left lateral bending and right lateral bending.Then the changes in stresses at the operated vertebra,endplate and intervertebral disk of the adjacent segment,and posterior structure were analyzed and compared.Results Compared with M1,the peak stresses of the operated vertebra at compression,extension,left rotation and right rotation in M3 were decreased by respectively 20.1％,8.7％,47.1％ and 41.8％,but increased by15.6％,8.1％ and 4.4％ at flexion,left lateral bending and right lateral bending; compared with M2,the peak stresses of the operated vertebra at compression,extension,flexion,left lateral bending and right lateral bending in M3 were increased significantly,but decreased by 2.0％ and 6.8％ at flexion,left rotation and right rotation.All models increased the local stress at the endplate and intervertebral disk of the adjacent segment,and obviously enhanced the peak stresses at adjacent vertebrae.The effects of M3 on the endplate and intervertebral disk of the adjacent vertebrae were between those of M 1 and M2.Conclusions The self-designed eccentric balloon dilator may have better biomechanical performance than a conventional balloon dilator.It may be an option used in treatment of OVCF in that it can effectively restore partial biomechanical performance of the fractured vertebra and reduce the influence on adjacent segments. Key words: Spinal fractures; Osteoporosis; Vertebroplasty; Finite element analysis