Figure 1.

(a) Finite element model of two motion segments of the lumbar spine (L3-L5). (b) A central core of elements was selected in L4 vertebral body and material properties of a lytic metastasis and PMMA were successively allocated. (c) Vertebral bulge (VB) is the horizontal line and vertebral height (VH) is the vertical line. VB was calculated by measuring the distance between two standard nodes at the mid-height of the vertebra on the sagittal plane. VH was calculated by measuring the distance between two standard nodes at the center of the inferior and superior endplates on the sagittal plane.