Fracture and Viscoelastic Characteristics of the Human Cervical Spine,
BETH ISRAEL HOSPITAL BOSTON MASS
Pagination or Media Count:
Cervical spine segments were tested both nondestructively and destructively to determine the load-displacement relationships and vertebral strength. For this study, a servo-hydraulic multi-degree of freedom material testing machine was designed and constructed. This new system, called the Planar Testing Apparatus PTA, was used to generate motions needed to characterize the sagittal response of spine segments. A study of the viscoelastic properties of two vertebrae lumbar spine segments was conducted following the completion of the PTA to check and demonstrate the test system. The results from seven lumbar specimens were also included in this report. The cervical spine segments consisted of three vertebrae and their interconnecting soft tissue, discs, and ligaments. A noninvasive electro-mechanical displacement measuring apparatus was constructed to monitor the six degree of freedom motion of the middle vertebral body as it moved relative to the two adjacent vertebrae during the mechanical tests. Results for cervical spine specimens indicated that a low displacement rates less than 5 mmsec or 5 degsec there was no dependence of spinal segment stiffness on displacement rate. Curves for load vs. displacement both axila and shear and moment vs. sagittal bending displayed large regions of small load and low slope as displacements increased. All specimens were stiffer in compression that in tension. All specimens displayed soft tissue failure before bony fracture for loading in flexion.
- Anatomy and Physiology
- Stress Physiology