The most commonly utilized external bracing following cervical surgery are the cervical collar (rigid or soft) and the halo orthosis. Other braces are available, including the cervicothoracic orthosis, sternal occipital mandibular orthosis, and Minerva brace, but are used less frequently and are not discussed extensively. The biomechanical properties of different cervical orthoses are discussed elsewhere in this text. In general, halo orthoses provide the best stability of the upper (occiput to C2) cervical spine, whereas cervicothoracic braces restrict motion in the mid and lower cervical spine better than rigid collars. Semirigid collars provide better restriction of flexion and extension than lateral bending (2, 3 and 4). Because they are less cumbersome, easier to apply, and more cosmetically pleasing, however, collars tend to be utilized more than cervicothoracic orthoses. Soft cervical collars provide the least stability but are the most comfortable (2).

One consideration in the decision to brace postoperatively is the goal of the surgical procedure as well as the expected benefit of bracing. If the goal of surgery is decompression only (e.g., posterior foraminotomy) or if the procedure does not involve significant disruption of bony or soft tissue structures, the objective of bracing may simply be to keep the patient comfortable, and a soft cervical collar may suffice. If, on the other hand, the goal of surgery is to obtain a solid fusion, a more rigid brace may be appropriate. Again, there is a striking lack of literature comparing clinical outcomes of cervical procedures based on the type of collar utilized.

Another concern is the surgeon’s assessment of the overall stability of the surgical construct and the likelihood of obtaining fusion. Multilevel ventral cervical fusions have a higher rate of pseudarthrosis than single-level procedures, particularly with the use of allograft (5, 6 and 7). This alone may justify the addition of external immobilization in the surgeon’s mind. Bone quality is another concern; in patients with osteoporotic bone, fixation of instrumentation may be less than ideal. With ventral procedures, there is an increased risk of graft settling into osteoporotic bone.

Although fast becoming the standard, not all surgeons utilize internal fixation for ventral cervical fusions. In the absence of plate fixation, postoperative bracing is recommended. Similarly, a surgeon may find that he or she is in a situation that allows less than ideal fixation. For example, a unilateral vertebral artery injury (iatrogenic or otherwise) may preclude bilateral lateral mass fixation, and a collar may be chosen for added support postoperatively.

Surgical treatment of disorders involving the upper cervical spine has undergone a transformation over the past two decades. Treatment of occipitocervical instability has evolved from the use of noninstrumented or wired-in bone grafts to the currently available fixation systems consisting of occipital plate-screw constructs connected to the cervical spine with rigid segmental instrumentation. Surgical treatment of atlantoaxial instability, whether due to traumatic injuries or metabolic conditions (e.g., rheu-matoid arthritis), has also evolved from the use of dorsal wiring constructs to the placement of rigid screw-based instrumentation (dorsal C1-C2 transarticular fixation, C1 lateral mass and C2 pedicle fixation, odontoid screw). Earlier methods of fixation did not provide a high degree of inherent stability and required external immobilization, frequently in a halo orthosis. Newer techniques allow post-operative immobilization in a collar. There are no clinical studies that compare outcomes of patients undergoing upper cervical fixation either with or without postoperative bracing.

When needed, halo orthoses provide the greatest stability for the upper cervical spine. Richter et al. (8) compared the efficacy of four different orthoses in both an intact and unstable cervical spine cadaveric model. In the intact spine, the soft collar, Miami J semirigid collar, Minerva brace, and halo all restricted C1-C2 motion compared to the unbraced spine, although the halo provided the greatest stability and the soft collar the least. After creating an odontoid fracture, the Miami J and Minerva orthoses provided similar restriction of flexion/extension and torque, the soft collar had little effect, and the halo demonstrated only minimal sagittal motion and no torque (8).

DiPaola et al. (9) recently reported on stability differences between a conventional halo (with skull pin fixation) and a noninvasive halo device. In a cadaveric model that included C1-C2 instability and (separately) C5-C6 instability, the conventional device stabilized the C1-C2 junction better than the noninvasive halo with regard to mediolateral translation and also provided superior stabilization of C5-C6 in axial translation and lateral bending. The noninvasive halo, however, provided similar stability in all other planes of testing (9). The use of a noninvasive halo, therefore, may provide additional external stability without the need for skull fixation (and pin site complications) in patients who have undergone upper cervical surgery with rigid instrumentation.