The biomechanical evaluation of calcium phosphate cements for use in vertebroplasty.
OBJECTIVE
The authors evaluate the biomechanical properties of vertebral bodies (VBs) stabilized with calcium phosphate (CaP) cements for use in vertebroplasty in comparison with polymethylmethacrylate (PMMA).


METHODS
In the first phase of the study, 73 VBs (T3-L2; thoracic region [T3-8] and thoracolumbar region [T9-L2]) were collected from seven fresh human cadavers. Compression tests were performed before and after vertebroplasty using PMMA (compression strength 80 MPa) and three kinds of CaP cements-CaP1 (5 MPa), CaP2 (20 MPa), and CaP3 (50 MPa). The authors compared the maximal compression loads (MCLs) and stiffness before and after vertebroplasty in each of the four cement groups. In the second phase of the study, 18 paired spinal units (PSUs) were collected from three fresh human cadavers, and the authors injected two types of cement selected from the first phase of the study into the lower level of six PSUs. They compared the MCLs of the untreated and two treated groups (there were six PSUs in each type of group) to analyze the tendency of inducing compression fractures in the upper level of the PSUs. The MCLs of the PMMA-injected vertebrae were significantly increased after vertebroplasty. The MCL levels of the CaP3-injected vertebrae and the CaP2-injected thoracolumbar vertebrae were decreased from those of untreated vertebrae without being significant. The MCLs of CaP1-injected vertebrae and CaP2-injected thoracic vertebrae were significantly decreased after vertebroplasty. The stiffness of all cement groups was decreased after vertebroplasty compared with initial stiffness, significantly so in all three thoracic CaP groups. In the second compression test with PSUs, the MCLs of the CaP2- and CaP3-injected PSUs were not significantly different from those of the untreated control PSUs.


CONCLUSIONS
The CaP3-injected vertebrae restored the MCLs of human vertebrae closer to their initial levels than the PMMA-injected vertebrae did. The CaP2- and CaP3-injected PSUs showed no tendency to induce compression fractures in adjacent VBs.
Hong
Suk-Joo
SJ
Department of Radiology, Guro Hospital, Korea University College of Medicine.
Park
Youn-Kwan
YK
Kim
Jung Hyuk
JH
Lee
Soon Hyuck
SH
Ryu
Kyung Nam
KN
Park
Cheol Min
CM
Kim
Yeon Soo
YS
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000627:therapeutic use*; D002102:Cadaver; D002130:Calcium Phosphates / Q000008:administration & dosage / Q000627:therapeutic use*; D019245:Compressive Strength; D005260:Female; D050815:Fractures, Compression / Q000628:therapy*; D006801:Humans; D007593:Joint Instability; D008159:Lumbar Vertebrae; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D013904:Thoracic Vertebrae
D001843:Bone Cements; D002130:Calcium Phosphates; C020243:calcium phosphate