Magnetic resonance imaging analysis of deep cervical flexors in patients with ossification of the posterior longitudinal ligament and clinical implication

Objective The purpose of this study was to analyze the cross-sectional area (CSA) of deep cervical flexors as measured by magnetic resonance imaging in ossification of the posterior longitudinal ligament (OPLL) patients with neck pain and, by implication, how this may relate to recruitment of the deep cervical flexors and sternocleidomastoid. Design A retrospective case-control study was conducted. All 72 subjects were imaged using plain radiography, computed tomography, and magnetic resonance imaging. Results There was a more limited cervical range of motion in the OPLL group than that in the control group. Cervical lordosis, T1 slope, and thoracic inlet angle values were significantly lower in the OPLL group than in the control group. Bilateral CSAs of the longus colli muscle and longus capitis muscle of the OPLL group were smaller than those of the control group. In addition, bilateral CSAs of the sternocleidomastoid of the OPLL subjects were greater than those of healthy subjects. Conclusions The authors found that the OPLL patients with chronic neck pain had lesser lordotic cervical alignment, smaller deep cervical flexor CSAs, and larger sternocleidomastoid CSAs than the control group did. The authors' theory is that the sternocleidomastoids in these OPLL patients have compensatorily hypertrophied in response to presumably atrophied deep cervical flexors.