腱板断裂における肩関節荷重位正面像(“push-up view”)の有用性について

第1報

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If the size of the rotator cuff tear can be predicted, the surgeon can prepare alternatives for the operation. The acromiohumeral interval (AHI) on plain roentgenograms less than 5to 6 mm has been considered a sign of rotator cuff tear.
However, this measurement can vary even in t h e same subject depending on the arm position in which the X-ray is taken. We found that paraplegic patients with rotator cuff tears revealed reproducible AHIs on the antero-posterior projections which were taken with the patients on crutches. This paper discusses the usefulness of a new roentgenographic projection in the rotator cuff tears which we called the “push-up view”.
Materials & Methods: 35 rotator cuff tears were classified in to three groups. Group A consisted of 7 massive rotator cuff tears which were verified operatively, group B,11 massive rotator cuff tears diagnosed arthrographically and group C,17 full thickness supraspinatus tears and incomplete thickness tears verified operatively. The “push-up view”, which was an antero-posterior projection of the bilateral shoulders on a large cassette with the patient in an arm chair lifting himself a little off the seat, was taken in all cases preoperatively. The shoulder bears a load of from one third to one half of the body weight in the “push-up view”. The “push-up AIH”, which was measured on the “push-up view”, was compared with the “standing AHI”, which was measured on conventional antero-posterior projection with the patient standing.
Results: The “standing AHI” and the “push-up AHI” were from 0 to 9 mm, mean value 4.1 mm, and from-8 to 6 mm, mean value 0.8 mm in groups A and B which consisted of massive tears.
The “ standing AHI” and the “push-up AHI” were from 7 to 12 mm, mean value 9.4 mm, and from 6 to 10 mm, mean value 8.4 mm in group C which consisted of small and partial tears.
Discussion: In previous reports, the lowest value of the normal AHI has been discussed, but the positions of the subjects were not clearly described. In our series, “standing AHI” was 7 mm and more in 4/18 (22%) of massive cuff tears. But “push-up AHI” was 6 mm and less in all those cases. In one case of massive tear with rupture of the tendon of the long head of biceps, the “push-up AHI” was 8 mm while the “standing AHI” was 7 mm. It is clear that “standing AHI” does not reflect the conditions of the rotator cuff or the long head of the biceps.
Conclusions: 1. The acromiohumeral interval in a conventional shoulder roentgenogram is unreliable.2. The AHI in the “push-up view” is reproducible and a massive cuff tear is suspected if it is 6 mm or less.3. The “push-up view” is proposed for the screening of massive rotator cuff tears.