Helgeson, Melvin D.

Study Design. Literature review. Objective. The goal of this study was to provide a comprehensive outline of spinal injuries that may transpire over the course of military service from traumatic to repetitive stress injuries and chronic sequelae. We considered studies that assessed spinal injuries in combat and non-combat settings as reported in the literature over the last 15 to 20 years. Background. Military service places servicemembers under substantial physical demands, while also exposing them to dangerous, unpredictable environments. As a result, servicemembers are at an increased risk of spinal injuries from combat-related trauma and other causes. They may have different care needs and recovery profiles when compared with civilians with spinal disorders. Materials and Methods. We performed a review of the available literature on spinal injuries and spinal care in the Military Health System from 2001 to the present. Results. The studies discussed in this review were primarily focused on the conflicts in both Iraq and Afghanistan from over 10 years ago and do not fully capture the present-day advancements in military technology that may have an impact on the potential for spinal injuries. The long-term effects of sustained military service and the relative influence of high demand versus sedentary military occupations on the development of spinal disorders remain poorly understood. Given the changing nature of military service, both with respect to the demographic in uniform and the ever-evolving nature of modern combat, we believe that only a long-term prospective observational study dedicated to the surveillance of spinal problems could effectively answer these questions. Conclusion. Further research into the present-day characterization of spinal injuries is warranted given the advancements in both military technology and spine care that have occurred over the last 10 years.

Study Design: Controlled Laboratory Study Objective: To compare multilevel posterior cervical fusion (PCF) constructs stopping at C7, T1, and T2 under cyclic load to determine the range of motion (ROM) between the lowest instrumented level and lowest instrumented-adjacent level (LIV-1). Summary of Background Data: PCF is a mainstay of treatment for various cervical spine conditions. The transition between the flexible cervical spine and rigid thoracic spine can lead to construct failure at the cervicothoracic junction. There is little evidence to determine the most appropriate level at which to stop a multilevel PCF. Methods: Fifteen human cadaveric cervicothoracic spines were randomly assigned to 1 of 3 treatment groups: PCF stopping at C7, T1, or T2. Specimens were tested in their native state, following a simulated PCF, and after cyclic loading. Specimens were loaded in flexion-extension), lateral bending, and axial rotation. Three-dimensional kinematics were recorded to evaluate ROM. Results: The C7 group had greater flexion-extension motion than the T1 and T2 groups following instrumentation (10.17±0.83 degree vs. 2.77±1.66 degree and 1.06±0.55 degree, P <0.001), and after cyclic loading (10.42±2.30 degree vs. 2.47±0.64 degree and 1.99±1.23 degree, P <0.001). There was no significant difference between the T1 and T2 groups. The C7 group had greater lateral bending ROM than both thoracic groups after instrumentation (8.81±3.44 degree vs. 3.51±2.52 degree, P =0.013 and 1.99±1.99 degree, P =0.003) and after cyclic loading. The C7 group had greater axial rotation motion than the thoracic groups (4.46±2.27 degree vs. 1.26±0.69 degree, P =0.010; and 0.73±0.74 degree, P =0.003) following cyclic loading. Conclusion: Motion at the cervicothoracic junction is significantly greater when a multilevel PCF stops at C7 rather than T1 or T2. This is likely attributable to the transition from a flexible cervical spine to a rigid thoracic spine. Although this does not account for in vivo fusion, surgeons should consider extending multilevel PCF constructs to T1 when feasible. Level of Evidence: Not applicable.