title: Adjacent vertebral failure after vertebroplasty: a biomechanical study of low-modulus PMMA cement.
abstract: PMMA is the most common bone substitute used for vertebroplasty. An increased fracture rate of the adjacent vertebrae has been observed after vertebroplasty. Decreased failure strength has been noted in a laboratory study of augmented functional spine units (FSUs), where the adjacent, non-augmented vertebral body always failed. This may provide evidence that rigid cement augmentation may facilitate the subsequent collapse of the adjacent vertebrae. The purpose of this study was to evaluate whether the decrease in failure strength of augmented FSUs can be avoided using low-modulus PMMA bone cement. In cadaveric FSUs, overall stiffness, failure strength and stiffness of the two vertebral bodies were determined under compression for both the treated and untreated specimens. Augmentation was performed on the caudal vertebrae with either regular or low-modulus PMMA. Endplate and wedge-shaped fractures occurred in the cranial and caudal vertebrae in the ratios endplate:wedge (cranial:caudal): 3:8 (5:6), 4:7 (7:4) and 10:1 (10:1) for control, low-modulus and regular cement group, respectively. The mean failure strength was 3.3 +/- 1 MPa with low-modulus cement, 2.9 +/- 1.2 MPa with regular cement and 3.6 +/- 1.3 MPa for the control group. Differences between the groups were not significant (p = 0.754 and p = 0.375, respectively, for low-modulus cement vs. control and regular cement vs. control). Overall FSU stiffness was not significantly affected by augmentation. Significant differences were observed for the stiffness differences of the cranial to the caudal vertebral body for the regular PMMA group to the other groups (p < 0.003). The individual vertebral stiffness values clearly showed the stiffening effect of the regular cement and the lesser alteration of the stiffness of the augmented vertebrae using the low-modulus PMMA compared to the control group (p = 0.999). In vitro biomechanical study and biomechanical evaluation of the hypothesis state that the failure strength of augmented functional spine units could be better preserved using low-modulus PMMA in comparison to regular PMMA cement.
authors: AO Research Institute, Clavadelerstrasse 8, 7270, Davos Platz, Switzerland. andreas.boger@aofoundation.org
authors: Andreas
authors: A
authors: Boger
authors: Paul
authors: P
authors: Heini
authors: Markus
authors: M
authors: Windolf
authors: Erich
authors: E
authors: Schneider
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000009:adverse effects / Q000592:standards*; D002102:Cadaver; D019245:Compressive Strength; D005260:Female; D006801:Humans; D008297:Male; D010024:Osteoporosis / Q000150:complications*; D019904:Polymethyl Methacrylate / Q000009:adverse effects / Q000592:standards*; D011183:Postoperative Complications / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control; D016103:Spinal Fractures / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D013131:Spine / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D017211:Treatment Failure; D054854:Vertebroplasty / Q000009:adverse effects / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate
references: Bone. 2000 Feb;26(2):169-73
references: 10678412
references: Eur Spine J. 2000 Oct;9(5):445-50
references: 11057541
references: Clin Biomech (Bristol, Avon). 2005 Jan;20(1):25-31
references: 15567533
references: J Orthop Res. 1999 Jan;17(1):67-72
references: 10073649
references: J Bone Joint Surg Br. 2002 Jul;84(5):748-52
references: 12188498
references: Neuroradiology. 2002 Nov;44(11):950-4
references: 12428134
references: BMJ. 1992 Jun 20;304(6842):1634-5
references: 1385749
references: J Biomed Mater Res B Appl Biomater. 2008 Aug;86(2):474-82
references: 18288697
references: Orthopade. 2004 Jan;33(1):22-30
references: 14747907
references: Comput Methods Biomech Biomed Engin. 2003 Apr;6(2):133-9
references: 12745427
references: Rheumatology (Oxford). 2000 Dec;39(12):1410-4
references: 11136886
references: Bone. 1999 Aug;25(2 Suppl):23S-26S
references: 10458269
references: J Bone Miner Res. 2002 Sep;17(9):1621-8
references: 12211432
references: Spine (Phila Pa 1976). 2003 May 15;28(10):991-6
references: 12768136
references: Eur Spine J. 2003 Aug;12(4):421-6
references: 12687437
references: Bone. 1996 Mar;18(3 Suppl):179S-183S
references: 8777085
references: Spine (Phila Pa 1976). 2000 May 1;25(9):1061-4
references: 10788848
references: Radiology. 2003 Jan;226(1):119-24
references: 12511679