Comparison of acromiohumeral distance in symptomatic and asymptomatic patient shoulders and those of healthy controls.

BACKGROUND: The reduction of the subacromial space has traditionally been linked to rotator cuff pathology. The contribution of this narrowing, both in the development and maintenance of rotator cuff tendinopathy, is still under debate. The objective of the present study was compare the acromiohumeral distance at 0 and 60 degrees of active shoulder abduction in scapular plane, static position, in both symptomatic and contralateral shoulders, between participants with unilateral rotator cuff related shoulder pain, and in asymptomatic participants.
METHOD: This was a cross-sectional observational study. Seventy-six participants with chronic shoulder pain were assessed. Forty participants without shoulder pain were also recruited to compare the acromiohumeral distance with symptomatic participants. The acromiohumeral distance was measured at 0 and 60 degrees of active shoulder abduction in all the groups by ultrasound imaging. Mean differences between symptomatic versus contralateral shoulders, and versus healthy controls, were calculated.
FINDINGS: There were no statistical significant differences (p > .05) in the acromiohumeral distance at 0 degrees of shoulder elevation between the groups. However, significant differences were found at 60° between symptomatic and contralateral shoulder groups (0,51 mm; 95% CI: -0.90 to -0.12). INTERPRETATIONS: Differences in shoulder pain perception at 0° are not attributable to acromiohumeral distance differences. However, treatments focused on increasing AHD at 60° could be prescribed, as a significantly reduced AHD was found in symptomatic shoulders when compared with contralateral shoulders. Further research is needed to determine, not only static differences in AHD, but also dynamic differences.