Zachary A. Smith, Saeed Khayatzadeh, Joshua Bakhsheshian, Michael Harvey, Robert M. Havey, Leonard I. Voronov, Muturi G. Muriuki, Avinash G. Patwardhan


June 2016, Volume 25, Issue 7, pp 2155 - 2165 Original Article Read Full Article 10.1007/s00586-016-4409-4

First Online: 01 February 2016

Purpose

Patients with cervical spondylosis commonly present with neck pain, radiculopathy or myelopathy. As degenerative changes progress, multiple factors including disc height loss, thoracic kyphosis, and facetogenic changes can increase the risk of neural structure compression. This study investigated the impact of cervical deformity including forward head posture (FHP) and upper thoracic kyphosis, on the anatomy of the cervical neural foramen.

Methods

Postural changes of 13 human cervical spine specimens (Occiput-T1, age 50.6 years; range 21–67) were assessed in response to prescribed cervical sagittal malalignments using a previously reported experimental model. Two characteristics of cervical sagittal deformities, C2–C7 sagittal vertical alignment (SVA) and sagittal angle of the T1 vertebra (T1 tilt), were varied to create various cervical malalignments. The postural changes were documented by measuring vertebral positions and orientations. The vertebral motion data were combined with specimen-specific CT-based anatomical models, which allowed assessments of foraminal areas of subaxial cervical segments as a function of increasing C2–C7 SVA and changing T1 tilt.

Results

Increasing C2–C7 SVA from neutral posture resulted in increased neural foraminal area in the lower cervical spine (largest increase at C4–C5: 13.8 ± 15.7 %, P 

Conclusion

An increase in thoracic kyphosis (T1 tilt) decreased cervical neural foraminal areas. In contrast, an increase in cervical SVA increased the lower cervical neural foraminal areas. Patients with increased upper thoracic kyphosis may respond with increased cervical SVA as a compensatory mechanism to increase their lower cervical neural foraminal area.


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