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Cervical Deformity and Treatment Algorithms


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  • Chapter Synopsis

  • Cervical deformity is disruption of normal cervical alignment. This chapter focuses on the different causes of cervical deformity, normative data, and deformity evaluation and examination and presents various treatment options for the proper management of these debilitating conditions.

  • Important Points

  • Disruption of normal cervical lordosis can result in loss of horizontal gaze and resulting mechanical neck pain.

  • Main etiologic factors in cervical spine deformity can be divided into primary, inflammatory, degenerative, and iatrogenic causes.

  • Careful history and examination and thorough imaging are important for the assessment, diagnosis, and surgical planning in patients with cervical spine deformities.

  • Surgical treatment may be indicated in patients with severe mechanical neck pain, neurologic compromise, and progressive deformity causing significant disability such as dysphagia or loss of horizontal gaze.

  • Considerations for anterior, posterior, and/or combined circumferential procedures are based on the patient’s pathologic process and the surgeon’s familiarity with and preference for the surgical techniques.

Normal Cervical Lordosis

To understand cervical spine alignment and deformity treatment properly, several basic concepts must be understood:

  • 1.

    The significant mass of the head is supported by the cervical spine, and significant deviation from normal alignment increases cantilever loads and muscular activity.

  • 2.

    The flexible, mobile cervical segment is connected to the relatively fixed thoracic spine.

  • 3.

    The T1 inclination determines the amount of subaxial lordosis required to maintain the center of gravity of the head in a balanced position.

  • 4.

    The T1 inclination varies depending on global spinal alignment as measured by the sagittal vertical axis (SVA) and by inherent upper thoracic kyphosis.

  • 5.

    The radiographic parameters that affect health-related quality of life scores are not well defined compared with global and pelvic parameters in thoracolumbar deformity. Chin-brow to vertical angle (CBVA), cervical SVA (C2 SVA), and regional cervical lordosis should all be considered in preoperative planning strategies involving standing 36-inch radiographs in which the external auditory canal (approximation of head center of mass) to the femoral head is visible.

In asymptomatic normal volunteers, cervical standing lordosis is greatest at C1 to C2, and little lordosis exists in the lower cervical levels ( Table 15-1 ). Approximately 75% of total cervical lordosis is taken at C1 to C2. Mean total cervical lordosis is approximately −40 degrees, with, on average, the occiput-C1 segment being kyphotic ( Fig. 15-1 ). Only 6 degrees (15%) occurs at the lowest three cervical levels (C4 to C7) (see Table 15-1 ). Furthermore, no difference is noted between asymptomatic men and women in total cervical lordosis, and a positive correlation exists with cervical lordosis and increasing age. The average odontoid-C7 plumb line distance ranges from 15 to 17 ± 11.2 mm (see Table 15-1 ).

Table 15-1
Normal Cervical Spinal Values in Asymptomatic Adults from the Literature ∗
Segmental Cervical Angles C2-C7 Lordosis
Level Angle (Degree) Age Group (yr) Men (Degree) Women (Degree)
C0-C1 2.1 ± 5.0 20-25 16 ± 16 15 ± 10
C1-C2 −32.2 ± 7.0 30-35 21 ± 14 16 ± 16
C2-C3 −1.9 ± 5.2 40-45 27 ± 14 23 ± 17
C3-C4 −1.5 ± 5.0 50-55 22 ± 15 25 ± 11
C4-C5 −0.6 ± 4.4 60-65 22 ± 13 25 ± 16
C5-C6 −1.1 ± 5.1
C6-C7 −4.5 ± 4.3
C2-C7 −9.6
Total (C1-C7) −41.8

Cervical Sagittal Vertical Axis
Odontoid marker at C7 15.6 ± 11.2 mm
Odontoid marker at sacrum 13.2 ± 29.5 mm

∗ Values presented as the means ± SD and the negative sign indicates lordosis in the segmental values.

FIGURE 15-1, Cervical standing lateral radiograph displaying the cervical lordosis angles in asymptomatic normal adults. OD, Odontoid.

Anatomically and biomechanically, the cranium and cervical spine are placed over the thoracic inlet, a fixed bony circle that is composed of the T1 vertebral body, the first ribs on both sides, and the upper part of the sternum. The sagittal balance of the cranium and cervical spine may possibly be influenced by the shape and orientation of the thoracic inlet to obtain a balanced, upright posture and horizontal gaze, similar to the pelvic incidence in the pelvis. The authors have found linkage of significant correlation from the thoracic inlet angle to the cranial offset and craniocervical alignment. The ratio of the C0-C2 to C2-C7 angles to total cervical lordosis was 77%:23%, and the ratio of cervical to cranial tilting to T1 slope was 70%:30% in asymptomatic individuals.

Neck tilting was maintained at approximately 45 degrees to minimize energy expenditure of the neck muscles. These results indicate that a small thoracic inlet angle makes the small T1 slope to maintain physiologic neck tilting and makes the small cervical spine lordotic angle, and vice versa. According to the study, the thoracic inlet angle and the T1 slope may be used as parameters to evaluate sagittal balance, predict physiologic alignment, and guide deformity correction of the cervical spine.

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