抄録
Background: Although subacromial impingement has been well recognized, details such as the location of impingement and the involvement of acromioclavicular joint (ACJ) have not reached an agreement. We studied the quantitative image evaluation of this phenomenon using kinematic analysis by 1.2T open MRI.
Methods: Twenty dominant shoulders of 20 healthy individuals were intended. Ten sequential evenly spaced images of MRI in the scapular plain were taken from 30 degrees abduction to maximum elevation in neutral and internally rotated position. Image findings were noted and the distance between the rotator cuff and both acromion and ACJ were measured.
Results: No one complained of shoulder pain during this study. The mean elevation angle and distance when the acromion and rotator cuff came the closest was 92degrees (63-126) and 1.6mm (0-4), respectively. The acromion and rotator cuff osculated in 5 cases, and the location of interface was 5.8mm (1.4-21.1) away from the greater tuberosity. The mean elevation angle and distance when the ACJ came closest to the cuff was 86 degrees (57-121) and 2.5mm (0-5.1), respectively. Four cases showed complete contact 17.1mm (3.2-36) away from the greater tuberosity. There was no significant difference whether the shoulder was in neutral or internally rotated position.
Discussion: Despite the lack of pain, there were cases with osculation. This indicates the importance of subacromial bursa. Minute change in joint centralization may produce impingement. The fact that the lesion of the cuff differed according to the opponent must be noted. (241 words)
