Acromiohumeral distance changes with posture in healthy adults and patients while wearing a shoulder abduction brace

[Purpose] To examine the humeral head positions while wearing an abduction brace in the sitting and supine positions in healthy adults and patients who have been operated on for shoulder joint diseases. [Participants and Methods] Thirty participants were included in the study, of which 15 were healthy adults (without any orthopedic diseases) and 15 had shoulder diseases (post-arthroscopic repair of a rotator cuff tear). The acromion and humeral head were observed on ultrasound. The acromiohumeral distance was measured once in two different positions while wearing the brace: edge sitting and supine. [Results] The mean acromiohumeral distance in the healthy group was 7.9 ± 1.1 mm while sitting and 7.2 ± 1.0 mm in the supine position. In the disease group it was 7.6 ± 0.9 mm while sitting and 6.3 ± 1.1 mm in the supine position. Multiple logical regression revealed that the acromiohumeral distance was not affected by the participant's age, height, or weight. [Conclusion] The acromiohumeral distance was significantly reduced in the supine position despite the use of an abduction brace. Therefore, patients must use a pillow/towel to support the shoulder joint to prevent unnecessary stress while the cuff tendons are healing.