Sex-specific differences of subacromial space width during abduction, with and without muscular activity, and correlation with anthropometric variables

The objectives of this study were to determine sex-specific differences of the subacromial space width during active and passive arm abduction and to analyze the correlation of this space with general and regional anthropometric variables. Fourteen healthy subjects (7 men, 7 women) were examined with an open magnetic resonance system at 30° and 90° of abduction (with and without muscle activity). After 3-dimensional reconstruction, the minimal acromiohumeral distance, the glenoid size, and the humeral head radius were determined. At 30° of abduction, a significant difference of the acromiohumeral distance was observed between men (8.18 ± 1.0 mm) and women (6.98 ± 0.75 mm) (P <.05), but not at 90° (6.7 ± 2.0 mm versus 5.9 ± 1.0 mm) or under muscle activity (4.9 ± 2.4 mm versus 3.5 ± 2.1 mm). Significant correlations between the acromiohumeral distance and anthropometric variables were found at 30° of abduction (r = 0.48 to 0.72), but not at 90°, with or without muscle activity (r = 0.21 to 0.55). The results demonstrate that at physical rest, the subacromial space width is dependent on sex, but the interindividual variability increases substantially during abduction and under muscle activity. (J Shoulder Elbow Surg 2001;10:129-35.)