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Intraoperative Halo Application for Severe Cervical Flexion Deformity: A Case Report

Parent-Weiss, Nicole M. CO, OTR, FAAOP; Graziano, Gregory P. MD; Weiss, David B. MD

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JPO Journal of Prosthetics and Orthotics: October 2005 - Volume 17 - Issue 4 - p 129-134
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Ankylosing spondylitis (AS) is a type of inflammatory systemic arthritis that primarily affects joints in the spine. AS is a disease within the group of conditions that affect the spine classified as seronegative spondyloarthropathies. AS is otherwise known as Marie-Strumpell disease or Bechterew disease. AS has also been described as “rheumatoid spondylitis,” but technically they are diseases with different serology. AS occurs more often in men than women and is more commonly associated with afflictions of the spine and major joints. Clinical manifestations of AS occur in 0.2 to 0.3 of the general population.1 AS can be further defined as an autoimmune disease that affects collagen structures, specifically the joints between the vertebrae of the spine. It may also affect other joints in addition to the spine, including peripheral joints of the arms and legs. In contrast to rheumatoid arthritis, which attacks the synovial membrane, AS attacks enthuses, the insertion point of tendons, ligaments, fascia, and fibrous joint capsules. Enthesopathy, the process of progressive fibrosis and ossification of the periarticular soft tissues, eventually leads to bony ankylosis of the joint.2 Ankylosing spondylitis is a system disease, which also may have extra-articular manifestations, such as iridocyclitis,3 aortitis,4 cardiac conduction abnormality,3 arachnoiditis,5 cauda equina syndrome,6,7 muscle diseases, and spinal stenosis.8 It has been associated with ulcerating colitis,9 regional enteritis,9 psoriasis,9 multiple sclerosis,10 Reiter syndrome,9 and Behçet syndrome.9

Chronic and severe inflammation of the spinal joints can progress to development of a complete bony fusion of the spine (ankylosis). Although the pain in the autofused area will decrease, there will be a complete loss of spinal mobility. Once the spine is fused, it becomes exceptionally brittle and vulnerable to fracture. The term “bamboo spine” is used to describe this advanced radiological picture of severe ankylosing spondylitis (Figures 1 and 2).

Figure 1.:
Radiograph showing bamboo spine.
Figure 2.:
Radiograph of a normal cervical spine.

Chronic AS can cause increased forward curvature of the thoracic spine (normal thoracic kyphosis is between 20° and 40°). In some cases, increased forward curvature can also occur in the normally lordotic cervical spine. In a small but significant number of patients, the cervical spine is the primary location of the deformity. In cases in which severe AS affects the cervical spine, a flexion deformity occurs, carrying with it significant functional limitations.11 “Chin-on-chest” deformity (Figure 3) limits the ability of an individual to achieve a forward gaze and attain an upright posture (Figure 4). This leads to considerable difficulty with ambulation. With progression, it may also limit the patient’s ability to open his or her mouth and maintain the integrity of the skin on the chest, as well as lead to dyspnea, dysphonia, and dysphagia.12 Pressure sores and infections associated with this are also potential complications.1 Nutritional deficits may also occur because of the position of the chin, causing difficulty managing food intake. Chin-brow to vertical angle measurement can be used as a preoperative measurement of deformity. The chin-brow to vertical angle is the angle measured from a line from the brow to the chin to the vertical when the patient stands with his hips and knees extended. This is a measure used to quantify and record the flexion deformity in ankylosing spondylitis (Figure 5).12

Figure 3.:
Radiograph of chin-on-chest deformity.
Figure 4.:
Chin-on-chest deformity limits the ability to achieve a forward gaze and attain upright posture.
Figure 5.:
Measurement of chin-brow to vertical angle.

For supple progressive deformity, cervical traction and spinal fusion can be used to gain correction.13 An Ilizarov apparatus has also been described to address cervical traction treatment when attached to a cast.14,15 However, if the deformity is rigid, an osteotomy is required for correction. Surgical intervention includes posterior C7–T1 extension osteotomy/fusion with midprocedure halo placement. Urist16 described the C7/T1 level as the optimal level for osteotomy/fusion because the interspace is the most receptive to surgical correction in the cervical spine. The procedure is performed under local anesthesia with the patient in a sitting position as recommended by Urist in 1958. This protocol facilitates the patient’s ability to provide verbal feedback for neurologic monitoring throughout the procedure by indicating any paresthesia or discomfort during decompression. This enables confirmation of the location of the C8 nerve root canal and level of the root.1

Significant risks and potential complications exist with this procedure. Risks include neurologic injury, root injury, central cord syndrome, vascular injury, pulmonary air embolism, intraoperative cardiac arrest, perforated ulcer, myocardial infarction, and death. Other potential complications include nonunion, loss of correction, and neurologic or aortic injury.17,18 Simmons12 reported a small incidence of C8 paresthesia, pain, and transient weakness. Other neurologic manifestations included central cord syndrome, 9th and 10th cranial nerve dysfunction, and Horne’s syndrome. All resolved gradually with time.12


Two to 3 days before surgery, the patient is placed in a well-padded rigid plaster thoracolumbosacral (TLSO)-style cast. Care is taken to allow the patient to sit, stand, and lie supine in the cast to ensure there is no movement within the cast or any slipping or migration of the cast. Trimming the cast or padding as necessary during a period of 2 days while the patient is in the hospital addresses potential cast problems. Anterior and posterior halo brackets are incorporated with plaster into the cast (Figure 6). There is generally some difficulty in positioning the anterior bracket because the chin-on-chest deformity prevents ideal placement of the bracket high enough on the chest. Therefore, the anterior bracket is molded into the cast as high as possible. The less-than-ideal position of the anterior bracket is compensated for with extra-long anterior uprights for the superstructure of the halo (may need as much as a 22″ height when specially made vs. 14″ to 16″ for standard upright height). Longer uprights should be available for the procedure in 2-inch increments from 16″ to 22″. Various combinations may be used (i.e., shorter on the back or longer on the front). Different length uprights may even be used on the two anterior placements if torticollis or other rotary deformity is present to some degree after surgery or if cast height could not be made even, secondary to preoperative position. Having all sizes available facilitates interchange of sizes midapplication, as needed.

Figure 6.:
Anterior and posterior halo brackets are molded into plaster cast.

The posterior halo bracket is placed centered on the posterior cast and may also differ from ideal positioning because of rounded kyphotic deformity of the thoracic spine. Place the bracket slightly higher than the anterior bracket in a position on the cast that is flat enough to allow stable attachment. The ends of the posterior bracket can be built up slightly with plaster to allow flat positioning if necessary. Caution should be used in building up the ends excessively because if the plaster build-up fails under tension after attachment, the position may be compromised.

A standard four-skull pin halo ring or crown is also applied 2 to 3 days before surgery, after cast application. Lock nuts are aggressively secured. A traction bail is applied to the crown or ring; however, there is no preoperative attachment to the plaster cast or halo brackets. The patient is monitored closely for tolerance to both components (TLSO cast and halo crown) (Figure 7).

Figure 7.:
Halo cast and crown are positioned before surgery.

The operative procedure is performed in a sitting position (Figure 8). The patient is leaned forward with his head resting on a table. Ten pounds of traction is applied in this position by connecting the traction bail to a standard pulley traction system. The amount of weight may be variable or surgeon specific. The anterior and posterior vest joints are attached to the halo bracket before surgery. The vest joints must be attached before the superstructure is applied because these are difficult to apply blindly under the sterile drapes. Both the halo clamps and the transverse bars are also attached before surgery in a position to maintain the transverse bar parallel to the crown. The flexion/extension bolt and the translation bolt should be tightened securely before the procedure commences; however, all vest joints should be loose. An incision is made over the spinous processes at the cervicothoracic junction. The spine is then subperiosteally stripped out to the tip of the facet joint at C7 and the first transverse process at T1. The complete spinous process of C7 is removed. A complete laminectomy of C7 is then performed. An osteotomy is used to undercut the pedicles at C7 to allow more room for the eighth rib after closure of the osteotomy and to crack the posterior body at the C7–T1 junction to facilitate closure of the osteotomy. The patient is anesthetized for a brief period. The neck is then carefully extended, closing the osteotomy.

Figure 8.:
Patient is positioned in sitting position in operating room with anterior universal joints, transverse bars, and halo clamps attached to crown.

At this point, the superstructure of the halo must be applied quickly. Care must be taken not to contaminate the sterile field. The anterior uprights are inserted into the vest joints. By feeling for adequate height, the upright may be interchanged for another size or the vest joint may be rotated to add additional height. The anterior universal joints are then connected to the transverse bar. It is crucial that the universal joint move completely freely on the upright to allow ease in matching the height of the transverse bar because the position of the transverse bar is already secured. Once both connections are made, the anterior vest joints and the anterior universal joints are securely tightened. Tightening of the bolts and placement of the uprights must be done with care, as the surgeon who is actively maintaining the position of the newly closed osteotomy must absorb any additional force applied during the halo application. The posterior uprights are attached in a similar fashion. More time is generally spent attaching the anterior uprights because the anterior visual field is obstructed by the sterile drapes and must be done, in effect, blindly. Time to attach the entire superstructure and lock position with the halo should not exceed 5 to 7 minutes, and the patient must be awakened quickly to assess neurologic status. Excessive time applying the halo superstructure is additional time the patient is unable to provide verbal feedback because of sedation during the osteotomy closure. This additional time may lead to increased complications or injury.

After the halo superstructure is quickly and efficiently applied, the patient is immediately awakened. Neurological function is checked and compared to preoperative function. Resected bone is then packed onto each side of C7–T1 over the osteotomy sites, and the skin is closed.

The halo cast is worn for 4 months. Pin torque and pin sites are monitored, and torque is adjusted as necessary. Skin is checked as adequately as possible around the cast at regular postoperative visits. A prefabricated cervicothoracic orthosis is used for two additional months after halo removal.


The postoperative clinical picture includes a markedly improved horizontal gaze and equally improved chin-brow to vertical measurement angle. Significant skin care is often needed for the chin and chest areas that are broken down. Pressure ulcer treatment, including debridement and skin grafting, has been necessary in some cases. Nutritional consultation and treatment are also initiated. Patient satisfaction among patients having undergone this procedure at the University of Michigan is remarkably high, with a significant improvement in the quality of life and functional level (Figure 9). The responsibility of the certified orthotist involved with this procedure is to establish a regimented procedure for superstructure application and a clear understanding and expectation of the environment in which the halo will be applied. Clear communication must be established with the orthopaedic surgeon performing the procedure. A respect for the significant potential risks of this procedure should exist in conjunction with a well-practiced, prepared system for application and potential component failure or complication.

Figure 9.:
Patient position (A) before and (B) after surgery.


The authors recognize the University of Michigan Orthotics & Prosthetics Center, specifically Thomas W. Lucas, RTO, and the Acute Care University of Michigan Hospital team for their substantial contribution to the development of the protocol described. The authors also extend thanks to Edward H. Simmons for his invaluable instruction and dedication to the advancement of surgery in this patient population as well as to Depuy Spine (Raynam, MA) for their flexibility and assistance with component selection.


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ankylosing spondylitis; cervical flexion deformity; cervical osteotomy; halo; osteotomy fusion

© 2005 American Academy of Orthotists & Prosthetists