BIOMECHANICAL PROPERTIES OF HUMAN TIBIAS IN LONG-TERM SPINAL-CORD INJURY

Long-term spinal cord injury (SCI) profoundly alters skeletal structur e and function. In this study, the biomechanical; properties of tibias from persons with SCI and from individuals closely matched in age and size but without SCI were quantified at both the structural and mater ial levels. Nondestructive torsion tests were performed to determine a pparent shear moduli for the tibia. The cortical thicknesses and polar moment of inertia were determined numerically, Four-point bending tes ts were performed to determine flexural modulus of elasticity on corti cal bone specimens of the tibia. The apparent shear moduli of the SCI tibias were found to be lower than the non-SCI tibias (p<0.05), The co rtical thicknesses of the SCI tibias were significantly thinner than t he control tibias (p<0.05), while the polar moment of inertia showed n o significant differences between control and SCI tibial cross section s (p>0.5), The flexural modulus of elasticity of the cortical bone spe cimens were lower in the SCI tibias than the controls (p<0.05). These differences suggest that tibias may undergo micro-structural changes a s well as structural adaptation following SCI, which alter their mecha nical properties.