Adjacent Vertebral Body Fracture Following Vertebroplasty With Polymethylmethacrylate or Calcium Phosphate Cement Biomechanical Evaluation of the Cadaveric Spine

Study Design. A biomechanical study using human cadaveric thoracolumbar spinal columns. Objective. To compare the effect of treatment by vertebroplasty (VP) with polymethylmethacrylate cement and VP with calcium phosphate cement on the creation of adjacent vertebral body fracture following VP. Summary of Background Data. Adjacent vertebral body fractures have been reported as a complication followingVP. Methods. Twenty-four spinal columns (T10-L2) from human cadavers were subjected to dual energy radiograph absorptiometry to assess bone mineral density. They were divided into the P group and C group, and experimental vertebral compression fractures were created at T12 vertebrae. T12 vertebrae were augmented with polymethylmethacrylate and calcium phosphate cement in the P group and C group, respectively. Each spinal column was compressed until a new fracture occurred at any vertebra, and the location of newly fractured vertebra and failure load was investigated. Results. There was no significant difference in bone mineral density at each level within each group. In the P group, a new fracture occurred at T10 in 2 specimens, T11 in 8, and L1 in 2. In the C group, it occurred at T10 in 1 specimen, T11 in 2, L1 in 1, and T12 (treated vertebra) in 8. The failure loads of the spinal column were 1774.8 +/- 672.3 N and 1501.2 +/- 556.5 N in the P group and C group, respectively. There was no significant difference in the failure load of the spinal column between each group. Conclusion. New vertebral fractures occurred at the vertebra adjacent to augmented vertebrae in the P group and in the augmented vertebrae in the C group. The difference in the fractured site may be because of the difference in strength between the 2 bone filler materials. Therefore, the strength of bone filler materials is considered a risk factor in developing adjacent vertebral body fractures after VP.