Biomechanical properties and patterns of injury in the human cervical spine

The nonlinear load-displacement response and strength of the mid- (C2-C5) and lower-cervical (C5-T1) regions of the spine were determined for combinations of sagittal loads in vitro. A multiaxial testing apparatus was designed and constructed for this purpose. In tests of nineteen segments, it was found that all specimens were more stiff in compression than in tension, and more stiff in posterior shear than in anterior shear. The mid-cervical region was more still in compression than the lower cervical region. In tests to failure, six of seven mid-cervical specimens failed from flexion alone, while combined compression-flexion was required to fail five of eight lower cervical specimens. Post-test dissections revealed no regional differences in patterns of failure. Data suggest that consideration of three regions of the cervical spine should facilitate the assessment of the risk and the diagnosis of injury.<>