Chin-on-chest deformity is a disabling manifestation of ankylosing spondylitis. Surgical treatment consists of extension osteotomy at the cervicothoracic junction. The purpose of this study was to characterize the clinical presentation of this deformity and to determine the long-term functional and radiographic outcomes of treatment.

The medical records and radiographs of all twenty-six patients treated with cervicothoracic extension osteotomy by one of us between 1976 and 2001 were retrospectively reviewed. Three patients died during the two-year-minimum follow-up period. The remaining twenty-three patients were followed for an average of 4.5 years (range, two years to twenty-one years and ten months).

The mean sagittal correction was 38 degrees. Delayed union in two patients and additional cervical trauma in two others resulted in partial loss of the initial correction. Quadriplegia developed in one patient, who died as a result of subluxation at the osteotomy site. Five patients had irritation of the eighth cervical nerve root postoperatively.

Extension osteotomy can reliably improve sagittal alignment and horizontal gaze as well as decrease neck pain, eating difficulties, and neurologic abnormalities. Internal fixation is recommended to prevent subluxation, delayed union, nonunion, loss of correction, or neurologic injury. There is a risk of death or catastrophic neurologic injury from the procedure.