Sternal instability during arm elevation observed as dynamic, multiplanar separation

Aims: The purpose of this study was to describe and measure the motion of the sternal edges in a single case with sternal instability, a complication that can follow a sternotomy for cardiac surgery. Methods: Using proprietary ultrasonography system software, and with a modification whereby the ultrasound unit head was attached to a microphone stand in order to maintain optimal contact with the chest of the seated subject, imaging was performed in the transverse plane during a series of three repeated unilateral arm elevation movements. Findings: Ultrasonography showed that the sternal separation was in both the transverse (10-17.5mm) and sagittal (3.5-18.2mm) planes during arm elevation. Conclusions: Such multiplanar separation of the sternal edges in inoperable sternal instability may explain the degree of discomfort experienced by patients with sternal non-union. Future research on sternal closure methods and the effects of activity and exercise on the healing sternum could lead to new clinical guidelines, which might reduce this discomfort.