Prognostic reliability of the Hawkins sign in fractures of the talus.

OBJECTIVE

To determine the prognostic reliability, sensitivity, and specificity of the Hawkins sign. The Hawkins sign is a subchondral radiolucent band in the talar dome that is indicative of viability at 6 to 8 weeks after a talus fracture. It is visible in the anterior-posterior view, but seldom appears on lateral radiographs.

DESIGN

Retrospective study.

SETTING

University hospital.

PATIENTS AND

METHODS

Between January 1995 and December 2000, a total of 41 patients (13 female, 28 male) with displaced talar fractures were operated on in our hospital. Thirty-four patients with a mean age of 35 years (range 12-60) were followed for more than 36 months (range 36-52). The prognostic reliability of the Hawkins sign was studied in 31 of these patients using a two-by-two table. The Ankle-Hindfoot scale of the American Orthopaedic Foot and Ankle Society (AOFAS) was used as an outcome measure.

RESULTS

No Hawkins sign was found in the five patients who developed avascular necrosis (AVN) of the talus. In the remaining 26 patients who did not develop AVN, a positive (full) Hawkins sign was observed 11 times, a partially positive Hawkins sign 4 times, and a negative Hawkins sign 11 times. The Hawkins sign thus showed a sensitivity of 100% and a specificity of 57.7%. The Hawkins sign (if present) appeared between the 6th and the 9th week after trauma. Mean [range] AOFAS scores were: Pain, 31 [10-40] out of 40; Function, 39 [14-50] out of 50; and Alignment, 7 [0-10] out of 10. The clinical results were satisfactory.

CONCLUSION

The Hawkins sign is a good indicator of talus vascularity following fracture. If a full or partial positive Hawkins sign is detected, it is unlikely that AVN will develop at a later stage after injury.