Cervical osteotomy for ankylosing spondylitis: an innovative variation on an existing technique.

Ankylosing spondylitis can produce severe fixed flexion deformity in the cervical spine. This deformity may be so disabling that it interferes with forward vision, chewing, swallowing and skin care under the chin. The only treatment available is an extension osteotomy of the cervical spine. Existing techniques of cervical osteotomy may be associated with risk of neurological injury. We describe a variation on an existing technique, which provides a controlled method of reduction at the osteotomy site, eliminating sagittal translation. The method employs a modular posterior cervical system consisting of lateral mass and thoracic pedicle screws linked to titanium rods. Our technique substitutes the titanium rod with a temporary malleable rod on one side, allowing controlled reduction of the osteotomy as this rod bends and slides through the thoracic clamps. Once reduction is complete definitive contoured rods are inserted to maintain the correction while fusion takes place. This method appears less hazardous by eliminating sagittal translation, and may reduce the risk of neurological injury during surgery. It achieves rigid internal fixation, obviating the need for a halo vest in the postoperative period.