Quantitative computed tomography-based predictions of vertebral strength in anterior bending.
METHODS
This study examined the ability of QCT-based structural assessment techniques to predict vertebral strength in anterior bending.


OBJECTIVE
The purpose of this study was to compare the abilities of QCT-based bone mineral density (BMD), mechanics of solids models (MOS), e.g., bending rigidity, and finite element analyses (FE) to predict the strength of isolated vertebral bodies under anterior bending boundary conditions.


BACKGROUND
Although the relative performance of QCT-based structural measures is well established for uniform compression, the ability of these techniques to predict vertebral strength under nonuniform loading conditions has not yet been established.


METHODS
Thirty human thoracic vertebrae from 30 donors (T9-T10, 20 female, 10 male; 87 +/- 5 years of age) were QCT scanned and destructively tested in anterior bending using an industrial robot arm. The QCT scans were processed to generate specimen-specific FE models as well as trabecular bone mineral density (tBMD), integral bone mineral density (iBMD), and MOS measures, such as axial and bending rigidities.


RESULTS
Vertebral strength in anterior bending was poorly to moderately predicted by QCT-based BMD and MOS measures (R2 = 0.14-0.22). QCT-based FE models were better strength predictors (R2 = 0.34-0.40); however, their predictive performance was not statistically different from MOS bending rigidity (P > 0.05).


CONCLUSIONS
Our results suggest that the poor clinical performance of noninvasive structural measures may be due to their inability to predict vertebral strength under bending loads. While their performance was not statistically better than MOS bending rigidities, QCT-based FE models were moderate predictors of both compressive and bending loads at failure, suggesting that this technique has the potential for strength prediction under nonuniform loads. The current FE modeling strategy is insufficient, however, and significant modifications must be made to better mimic whole bone elastic and inelastic material behavior.
Buckley
Jenni M
JM
Department of Mechanical Engineering, University of California-Berkeley, Berkeley, CA, USA. jbuckley@me.berkeley.edu
Cheng
Liu
L
Loo
Kenneth
K
Slyfield
Craig
C
Xu
Zheng
Z
D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology; D002102:Cadaver; D003198:Computer Simulation; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008954:Models, Biological; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data*; D016474:Weight-Bearing / Q000502:physiology