Volumetric quantitative computed tomography of the proximal femur: relationships linking geometric and densitometric variables to bone strength. Role for compact bone |
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Authors: | V Bousson A Le Le Bras F Roqueplan Y Kang D Mitton S Kolta C Bergot W Skalli E Vicaut W Kalender K Engelke J-D Laredo |
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Institution: | 1. Service de Radiologie Ostéo-Articulaire, H?pital Lariboisière, 2, rue Ambroise Paré, 75010, Paris, France 2. Laboratoire de Radiologie Expérimentale, CNRS UMR 7052, UFR Lariboisière-Saint-Louis, Paris, France 3. Laboratoire de Biomécanique, ENSAM-CNRS, Paris, France 4. Institute of Medical Physics, University of Erlangen, Erlangen, Germany 5. Service de Rhumatologie, H?pital Cochin, Paris, France 6. Université René Descartes, Paris, France 7. Unité de Recherche Clinique, H?pital Fernand-Widal, Paris, France
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Abstract: | Introduction In assessing cervical fractures of the proximal femur, this in vitro quantitative computed tomography (QCT) study had three
objectives: to compare QCT to dual-energy X-ray absorptiometry (DXA) for predicting the failure load of the proximal femur,
to compare the contributions of density and geometry to bone failure load, and to compare the contributions of cortical and
trabecular bone to bone failure load. A novel three-dimensional (3D) analysis tool medical image analysis framework (MIAF-Femur)]
was used to analyze QCT scans.
Methods The proximal ends of 28 excised femurs were studied (1) using QCT to separately measure bone mineral density (BMD) and geometric
variables of trabecular and cortical bone, (2) using mechanical tests to failure in a stance configuration, and (3) using
DXA to measure BMD. The variables were described with mean, standard deviation, and range. Correlation matrix and multivariate
linear models were computed.
Results Among correlations, cortical thicknesses of the femoral neck were significantly correlated with femoral failure load, especially
of the inferoanterior quadrant (r
2=0.41; p<0.001), as was cortical volume at the “extended neck“ (r
2=0.41; p<0.001). Femoral failure load variance was best explained by a combination of QCT variables. Combining densitometric and geometric
variables measured by QCT explained 76% of femoral failure load variance compared with 69% with the DXA model. Geometric variables
(measured by QCT) explained 43% of femoral failure load variance compared with 72% for densitometric variables (measured by
QCT). A model including only trabecular variables explained 52% of femoral failure load variance compared with 59% for a model
including only cortical variables.
Conclusion The QCT-MIAF reported here provides analysis of both geometric and densitometric variables characterizing cortical and trabecular
bone. Confirmation of our results in an independent sample would suggest that QCT may better explain failure load variance
for cervical fracture than the gold standard DXA-provided BMD.
This work was supported in part by grants from EU, contract number: QLK6-CT-2002-02440-3DQCT |
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Keywords: | Bone mineral density Cortical bone Hip Osteoporosis Quantitative computed tomography (QCT) |
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