TY - JOUR
T1 - A method for patient-specific evaluation of vertebral cancellous bone strength
T2 - In vitro validation
AU - Diamant, I.
AU - Shahar, R.
AU - Masharawi, Y.
AU - Gefen, A.
N1 - Funding Information:
This study was supported by Grant No. 5918 from the Foundation of the Chief Scientist of the Israeli Ministry of Health (AG). We also appreciate the help of Ms. Noa Slomka from the Department of Biomedical Engineering at Tel Aviv University, and Mr. Baha Medleg from the Anatomy Department at Tel Aviv University in preparing the cancellous bone specimens for testing.
PY - 2007/3
Y1 - 2007/3
N2 - Background: In the context of osteoporosis, important determinants of the fracture risk are the apparent strength and stiffness of cancellous bone, as well as its brittleness and energy absorption capacity. Standard medical imaging, however, cannot measure these mechanical properties directly. Consequently, an estimation of the risk for fracture is made by correlating relative density or mineral density at a skeletal site with statistics of fracture occurrence, which provides limited and partial indications on fracture risks. A better method for evaluating the patient-specific mechanical properties of cancellous bone is therefore required. Methods: In order to asses the mechanical properties of vertebral cancellous bone, we developed a finite element parametric model of lattice trabecular architecture that, in the future, will be suitable for use with bone imaging modalities. The model inputs are apparent morphological parameters (trabecular thickness and trabecular separation) and the bone mineral density. We conducted uniaxial compression tests on 36 canine vertebral cancellous bone specimens (C7 and L1) to validate model predictions of strength and stiffness in vitro. Findings: Predictions of strength and stiffness matched the experimental results within relative absolute errors of 17.7% and 12.8%, respectively (average of differences between model-predicted and measured values, divided by the average of measured values). We also employed the model for evaluation of strength and stiffness of human L1 and L5 vertebrae and found mean strength of 1.67 MPa (confidence interval 0.42 MPa) and mean elastic modulus of 190 MPa (confidence interval 50 MPa), which are well within the range of previously reported apparent strength and stiffness properties. Interpretation: The present model can be used to improve medical imaging-based evaluation of the spine in osteoporotic individuals by providing more specific information on the individual bone's susceptibility to fracture once clinical bone scans will be able to provide more reliable measures of trabecular thickness and separation.
AB - Background: In the context of osteoporosis, important determinants of the fracture risk are the apparent strength and stiffness of cancellous bone, as well as its brittleness and energy absorption capacity. Standard medical imaging, however, cannot measure these mechanical properties directly. Consequently, an estimation of the risk for fracture is made by correlating relative density or mineral density at a skeletal site with statistics of fracture occurrence, which provides limited and partial indications on fracture risks. A better method for evaluating the patient-specific mechanical properties of cancellous bone is therefore required. Methods: In order to asses the mechanical properties of vertebral cancellous bone, we developed a finite element parametric model of lattice trabecular architecture that, in the future, will be suitable for use with bone imaging modalities. The model inputs are apparent morphological parameters (trabecular thickness and trabecular separation) and the bone mineral density. We conducted uniaxial compression tests on 36 canine vertebral cancellous bone specimens (C7 and L1) to validate model predictions of strength and stiffness in vitro. Findings: Predictions of strength and stiffness matched the experimental results within relative absolute errors of 17.7% and 12.8%, respectively (average of differences between model-predicted and measured values, divided by the average of measured values). We also employed the model for evaluation of strength and stiffness of human L1 and L5 vertebrae and found mean strength of 1.67 MPa (confidence interval 0.42 MPa) and mean elastic modulus of 190 MPa (confidence interval 50 MPa), which are well within the range of previously reported apparent strength and stiffness properties. Interpretation: The present model can be used to improve medical imaging-based evaluation of the spine in osteoporotic individuals by providing more specific information on the individual bone's susceptibility to fracture once clinical bone scans will be able to provide more reliable measures of trabecular thickness and separation.
KW - Biomechanical modeling
KW - Bone mineral density
KW - Finite element method
KW - Osteoporosis
KW - Trabecular architecture
UR - http://www.scopus.com/inward/record.url?scp=33846813822&partnerID=8YFLogxK
U2 - 10.1016/j.clinbiomech.2006.10.005
DO - 10.1016/j.clinbiomech.2006.10.005
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AN - SCOPUS:33846813822
SN - 0268-0033
VL - 22
SP - 282
EP - 291
JO - Clinical Biomechanics
JF - Clinical Biomechanics
IS - 3
ER -