Estimation of geometric properties of cortical bone in spinal cord injury.

OBJECTIVE To evaluate structural and geometrical properties of the tibia shaft in subjects with spinal cord injury (SCI) and subjects without SCI and to estimate the potential usefulness of a multimodal approach to diagnosing osteoporosis in SCI. DESIGN A cross-sectional study of randomly selected SCI and non-SCI subjects. METHODS Measurements of bone geometric indices by computed tomography, and calculated bending stiffness with a biomechanical testing method. SETTING An SCI center hospital. SUBJECTS Ten men without known orthopedic or neurologic impairments (controls), 10 men with SCI who had a history of lower extremity pathologic fracture since SCI, and 10 men with SCI who had never had lower extremity pathologic fracture. RESULTS Analysis of geometric and structural indices of subjects' tibias found a significant difference in all geometric indices between controls and the SCI subjects with pathologic fracture history. Between the controls and the SCI subjects with no fracture history, however, differences were found only in cross-sectional area and calculated bending stiffness. CONCLUSION Structural analysis of leg bone, combined with measurement of bone density, may improve the ability to assess fracture risk in patients with SCI.