‘SUNSET’- A NEW RADIOLOGICAL SIGN OF FOUR PART PROXIMAL HUMERAL FRACTURES

Abstract

Aim: To evaluate the radiographs of proximal humeral fractures in an attempt to define a diagnostic sign as a predictor of four-part fracture. Diagnostic sign The normal humeral head articular surface points towards the glenoid. We describe our ‘sunset’ sign as ‘articular surface of humeral head pointing away from the glenoid and tilted upwards, in the presence of a displaced greater tuberosity fracture’. We postulate that a patient with proximal humerus fracture showing this sign has four-part fracture until proved otherwise.

Materials and Methods: Between 2002 and 2006, 80 consecutive patients underwent open reduction and internal fixation of their proximal humeral fractures in our Shoulder unit. We reviewed their preoperative radiographs and operative notes retrospectively. The AP radiograph was evaluated independently by three observers who were blinded to the operative diagnosis. The presence of ‘sunset’ sign was recorded. A consensus review was performed for evaluation purpose. The findings were then correlated with the operative findings. With 95% confidence interval we calculated the sensitivity, specificity, and positive and negative predictive values for our diagnostic sign.

Results: Thirty patients displayed ‘sunset’sign in their radiograph. Of these 28 had confirmed four-part fractures operatively. The positive predictive value of ‘sunset’ sign in diagnosis of four-part fracture was 93%. The specificity and sensitivity were 95% and 78% respectively. The sensitivity was affected by 8 patients with four part fractures with displaced articular head fragment which had dropped either medially or posteriorly. There were substantial interobserver and intraobserver agreement as measured by kappa coefficient (0.62 and 0.70)

Conclusion: Our results suggest that in patients with proximal humeral fractures, the presence of ‘sunset’sign in the anteroposterior radiograph is a reliable indicator of four-part fracture.