Unilateral C-1 lateral mass sagittal split fracture: an unstable Jefferson fracture variant

Object. The object of this study was to describe an unusual fracture subtype within C-1 injuries with a propensity to result in late deformity and pain. Most patients with C-1 injuries are nonsurgically treated using external immobilization unless there is an injury of the transverse atlantal ligament. The authors describe an unusual variant involving a unilateral sagittal split with a high tendency to late deformity and pain. They also review the literature and treatment of C-1 fractures. Methods. A retrospective review of 12,671 CT scans from a Level I trauma center over a 6-year period yielded 54 patients with C-1 fractures. Among these patients, 6 had an unusual unilateral lateral mass sagittal split, which resulted in a late cock-robin deformity in all survivors and thus a surgical deformity correction with occipital-cervical instrumented fusions. Patient charts and radiographs were reviewed, this fracture subtype is described, and its treatment discussed. Results. Radiographic studies in 6 patients with C-1 fractures demonstrated a unilateral sagittal split of the lateral mass but an intact transverse atlantal ligament. In the 3 surviving patients, a late cock-robin deformity, significant loss of neck rotation, and severe neck pain developed. Vertebral artery occlusion, as revealed on CT angiography, occurred in I patient. All patients were placed in traction and underwent successful occipital-cervical fusion and deformity correction. At the final follow-up, all patients had satisfactory pain relief and improved head alignment. Conclusions. Patients with a unilateral sagittal split of the C-1 lateral mass have unstable injuries and must be carefully monitored, with a low threshold for surgical reconstruction or prolonged traction. Patients with late deformity can be successfully treated with occipital-cervical instrumented fusions. (DOI: 10.3171/2009.1.SPINE08708)