Abstract
Purpose: The acromiohumeral interval (AHI) is an index used for the diagnosis of rotator cuff tear. We measured the AHI in subjects with shoulder pain with limited range of motion of the shoulder joint, and examined the correlation between AHI and limited range of motion of the shoulder joint to examine the effectiveness of AHI measurement in patients with scapulohumeral periarthritis.
Method: Fifteen shoulders of 15 patients in whom the contralateral shoulder joint was on the healthy side who were underwent treatment for scapulohumeral periarthritis participated in the study. The range of motion of both shoulders, the AHI from the frontal view of the shoulder joint, and the ratio of AHI to the caput humeri maximum diameter (A/H ratio) were examined, and the correlation of the range of motion of the shoulder joint and AHI・A/H ratio were examined (p < 0.05).
Results: As a result of measuring the AHI of the shoulder joint of the affected side, the AHI was 9.6 ± 2.6 mm. There was the negative correlation between A/H ratio of the affected side and differences of flexion and abduction angles in healthy and affected shoulder joint.
Conclusions: Between the subacromial surface and the caput lies the second shoulder joint and, when elevating the upper extremity, the caput humeri must passes under the lower part of the acromion. The AHI is equal to the measurement of the fissure distance of the upper portion of the second shoulder joint, and we thought that for obtaining normal ranges of motion in patients with scapulohumeral periarthritis, a sufficiently wide AHI is required to incorporate the caput humeri. This study suggested functional meaning for A/H ratio determination in patients with scapulohumeral periarthritis.
