Harris or axis ring: an aid in diagnosing low (type 3) odontoid fractures.

OBJECTIVE

To present our experience of diagnosing fractures of the odontoid process on lateral radiographs of the cervical spine that show the Harris (axis) ring.

DESIGN

Retrospective study.

SETTING

Teaching hospital, Belgium.

SUBJECTS: 12 patients with multiple injuries, including cervical spine, 8 of them unconscious or uncooperative.

INTERVENTIONS: Cross table lateral view of the cervical spine.

MAIN OUTCOME MEASURE: Identification of otherwise hidden type 3 axial fractures.

RESULTS

Diagnosis of low odontoid fractures in all cases.

CONCLUSION

The Harris ring is disrupted in low odontoid fractures and intact in fractures of the odontoid process. Awareness of this sign will allow diagnosis of otherwise hidden axial fractures.