The degradation of bioactive bone cement for vertebroplasty and kyphoplasty in vivo

Abstract

Objective To observe the degradation of calcium phosphate cements (CPC) and calcium sulfate cement (CSC) in vertebras, and explore the ideal filler for vertebroplasty and kyphoplasty.Methods Bone voids were created in L2-L5 vertebras of 24 female mature sheep. CPC, CSC and polymethylmethacrylate (PMMA) were injected into one bone void randomly, and the remaining voids served as the blank control, and L6 vertebra served as the normal control. Eight sheep were sacrificed at the 2nd,12th and 24th week after operation randomly. Gross observation, biomechanical test and undecalcified bone histology analyses were performed. Results Biomechanical analysis showed that the vertebras could be augmented by CPC and CSC. The mechanical properties of CSC group were decreased from the 2nd to 12th week, and increased from the 12th to 24th week after operation. The mechanical properties of CPC group were increased from the 2nd to 24th week, however, but lower than PMMA group. Histology analysis revealed CSC was mostly absorbed at the 12th week, and the bone voids were repaired only in large part at the 24th week. CPC was absorbed partly at the 24th week, and new bone was formed in contact with the surface of the CPC. Conclusion The vertebras can be augmented instantly by CPC and CSC. As time went on, CSC was absorbed fast and CPC was absorbed very slowly. Key words: Calcium phosphate cement; Polymethylmethacrylate; Vertebroplasty