The Stabilizing Effects of Different Orthoses in the Intact and Unstable Upper Cervical Spine: A Cadaver Study

BACKGROUND: Although cervical orthoses are frequently used in prehospital stabilization and in the definitive treatment for lesions of the cervical spine, there is little information about the control of extension-flexion, lateral bending, and rotation given to individual segments by different designs. METHODS: In an experimental in vitro study with four fresh frozen cadavers, the halo vest was compared with the soft collar, prefabricated Minerva brace, and Miami J collar. The controlling effects for the segments C1-2 and C2-3 were tested for all four devices in the intact and the unstable spine with an Anderson type II fracture of the odontoid. RESULTS: All four orthoses reduced the range of motion at both C1-2 and C2-3 of the intact spine significantly, although none of the three semirigid devices provided a halo-like immobilization in the intact spine. The osteotomy of the odontoid increased the range of motion in the segment C1-2. The soft collar did not give any clinically relevant stability to the unstable spine. Miami J and Minerva brace provided a similar moderate control in the sagittal plane but a much better control of "torque" in the upper cervical spine. The halo vest did not allow any measurable motion in any plane with our experimental external loading. CONCLUSION: The halo vest seems to be the first choice for conservative treatment of unstable injuries of the upper cervical spine, although pin track problems, accurate fitting of the vest, and a lack of patient compliance lead to clinical failures.