Finite element analysis of cement volume affecting adjacent vertebral endplate in percutaneous kyphoplasty

Abstract

Objective To analyze the stress contribution of different cement volume to the adjacent vertebral endplates in percutaneous kyphoplasty (PKP) so as to explore the possible mechanism of adjacent vertebral fractures after PKP. Methods The three-dimensional finite element model of osteoporotic thoracolumbar vertebral compression fractures was established to simulate vertebral body partial restoration (80％) with PKP.During the process,two doses of bone cement ( polymethylmethacrylate,PMMA) were filled in the vertebral body (4.0 ml bone cement filling 15％ of the vertebral body volume and 8.0 ml bone cement filling 30％ of the vertebral body volume).Endplate stress under conditions of axial compression,flexion and extension was analyzed. Results Regarding the two filling doses in PKP,the adjacent vertebral endplate stress under the above-mentioned conditions was all increased at T11 and L1 vertebral body compared with that before operation.Meanwhile,endplate stress had positive correlation with the cement volume and the stress concentrated largely in the anterior and middle parts of endplate. Conclusions The stress of adjacent vertebral endplate is positively correlated with cement volume,with anterior and middle parts of endplate as the stress concentration.The probability of adjacent vertebral fractures shows a rising trend with the increase of cement volume in PKP. Key words: Kyphosis; Arthroplasty; Finite element analysis