Complex deformities of the cervical spine.

Cervical deformities arise from a multitude of causes, including genetic, congenital, inflammatory, degenerative, and iatrogenic etiologies. They often require surgical intervention for treatment of pain, progressive structural decompensation, and neurologic deterioration. Although congenital and hereditary causes of cervical deformity require specialized attention to particular clinical features and operative considerations, postsurgical (iatrogenic) cervical deformity after surgery is the most common single cause. Appropriate treatment involves careful selection of conservative and aggressive measures and familiarity with advanced surgical techniques that allow for the safe correction of these challenging deformities. Flexible deformities can be managed with single-staged procedures, whereas fixed deformities require two-staged or even three-staged procedures. Staged surgery for fixed cervical deformities can achieve up to 28 degrees of angular correction and 31% translational correction.