Author(s)

Hiromitsu Takano¹, Ikuho Yonezawa¹, Mitsugu Todo², Muhammad Hazli Mazlan^3,4, Tatsuya Sato¹, Kazuo Kaneko¹

¹Division of Spine Surgery, Department of Orthopedic Surgery, School of Medicine, Juntendo University, Tokyo, Japan.
²Research Institute for Applied Mechanics, Kyushu University, Kasuga-City, Japan.
³Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga-City, Japan.
⁴Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, Parit Raja, Malaysia.

We used the finite element method (FEM) to investigate the stress profiles of vertebrae in patients who underwent balloon kyphoplasty (BKP) for vertebral fracture. BKP is often performed for persistent pain after vertebral fractures. However, fractures are frequently reported in the adjacent vertebrae after BKP. The purpose was to clarify the mechanism of fractures that occur in the adjacent vertebrae after BKP. The subjects were two patients (first case: 74-year-old woman; second case: 88-year-old woman) who had BKP for osteoporotic vertebral fractures (L1). A bone analysis software program, Mechanical Finder, was used to construct three-dimensional finite element models (T11-L3) from computed tomographic (CT) digital imaging and communications in medicine (DICOM) data. Moment loadings were examined to evaluate stress concentrations on the vertebrae. Young’s moduli were lower in the second case than in the first case at all vertebral levels. Maximum Drucker-Prager stresses after BKP were larger in the second case than in the first case for compression, flexion, extension, and axial rotation. Strain energy density decreased in L1 and increased in the adjacent ver-tebrae. Our results suggest that post-BKP fractures of the adjacent vertebrae not only are due to bone fragility, but also can be caused by increased rigidity in the vertebrae filled with bone cement, which increases stress concentration on the adjacent verte-brae and raises the likelihood of fracture.

Biomechanics, Finite Element Method, Vertebral Compression Fracture, Balloon Kyphoplasty, Mechanical Analysis

Takano, H. , Yonezawa, I. , Todo, M. , Mazlan, M. , Sato, T. and Kaneko, K. (2016) Biomechanical Study of the Effects of Balloon Kyphoplasty on the Adjacent Vertebrae. Journal of Biomedical Science and Engineering, 9, 478-487. doi: 10.4236/jbise.2016.910043.