Experimental study of adjacent vertebral refracture after vertebroplasty on embalmed specimens

Abstract

Objective To study the causes of fractures in untreated adjacent vertebraes after vertebroplasty. Methods Twelve spinal segements (four T9-T10, four T12-L2, and four L3-L5) from four embalmed human cadavers were divided into groups A and B (n=6/group). In group A, experimental vertebral compression fractures were created at middle vertebraes (T10, L1, L4), and these middle vertebraes were augmented with polymethymethacryclate. Then all spinal segements were compressed until a new fracture occured at any vertebrae, and the location of fractured vertebrae, maximum veritical load, and stiffness were investigated. Results There was statistically significant difference in the maximum vertical load between groups A and B (t=-2.267, P=0.047). The maximum veritical load in group A was, on average, 15% lower than that in group B [(3 048±403), (3 586±418) N, respectively]. There was no significant difference in stiffness between the two groups (t=-0.542, P=0.600). In the group A, new fractures following percutaneous verteoplasty (PVP) occurred at T9 in 2 specimens, T12 in 2, and L3 in 2. All new fractures occurred in the superior vertebrae in the group A. In the group B, the fractures occurred at T9 in 1 specimen, T10 in 1, T12 in 1, L1 in 1, and L3 in 2. Conclusion The failure strength of spinal segments can be decreased by vertebroplasty, which will increase the risk of adjacent vertebral body fracture, especially the superior vertebrae. Key words: Vertebroplasty; Adjacent vertebral body refracture; Bone cement; Maximum veritical load; Stiffness