Neural Space and Biomechanical Integrity of the Developing Cervical Spine in Compression

Study Design. A factorial study design was used to examine the biomechanical and neuroprotective integrity of the cervical spine throughout maturation using a postmortem baboon model. Objective. To investigate changes with spinal development that affect the neuroprotective ability of the cervical spine in compressive loading. Summary of Background Data. Child spinal cord injuries claim and debilitate thousands of children in the United States each year. Many of these injuries are diagnostically and mechanistically difficult to classify, treat, and prevent. Biomechanical studies on maturing spinal tissues have identified decreased stiffness and tolerance characteristics for children compared with adults. Unfortunately, while neurologic deficit typically dictates functional outcome, no previous studies have examined the neuroprotective role of the pediatric cervical spine. Methods. Twenty-two postmortem baboon cervical spines across the developmental age spectrum were tested. Two functional spinal unit segments (Oc–C2, C3–C5, and C6–T1) were instrumented with transducers to measure dynamic changes in the spinal canal. These tissues were compressed to 70% strain dynamically, and the resultant mechanics and spinal canal occlusions were recorded. Results. Classic injury patterns were observed in all of the specimens tested. The compressive mechanics exhibited a significant age relationship (P < 0.0001). Furthermore, while the peak-percent spinal canal occlusion was not age dependant, the percent occlusion just before failure did demonstrate a significant decrease with advancing age (P = 0.0001). Conclusions. The neuroprotective ability of the cervical spine preceding failure appears to be age dependent, where the young spine can produce greater spinal canal occlusions without failure than its adult counterpart. The overall percent of the spinal canal occluded during a compression injury was not age dependent; however, these data reveal the neuroprotective ability of the child spine to be more sensitive as an injury predictor than the biomechanical fracture data.