外転外旋位 MRI による下関節上腕靱帯の機能的評価：
鏡視下 Bankart 修復術前後での変化

抄録

Background: The arm position of abduction and external rotation (ABER) is widely used to evaluate the function of the inferior glenohumeral ligament-labral complex (IGHL-LC). The purpose of this study is to compare between pre- and postoperative conditions of IGHL-LC by ABER MRI.
Methods: We utilized the pre- and post-operative ABER MRI in the patients with anterior shoulder instability (23 shoulders of 22 patients, 20 males and 2 females). The attachment of IGHL-LC was classified into 3 categories: Type A; the attachment of IGHL-LC was mainly on the glenoid face, Type B; more than half of its attachment was on the glenoid neck, Type C; its attachment was on the glenoid neck only. The inclination of the IGHL-LC against the glenoid neck and the antero-posterior translation of humeral head against the glenoid were measured and compared between pre- and post-operative conditions.
Results: The inclination of IGHL-LC decreased significantly from 16.5 +/- 10.5 degrees before the surgery to 7.1 +/- 5.4 degrees after the surgery. The humeral head center was shifted from +2.1 +/- 13.4% before the surgery to -6.7 +/- 7.7% after the surgery (the positive values mean anterior translation). 13, 4 and 3 shoulders were classified into type A, B and C of the postoperative attachment of IGHL-LC, respectively. 3 shoulders were unable to be classified. The humeral head center of type C was located more anteriorly than those of other types.
Conclusion: The IGHL-LC ran sharply from the glenoid face and the humeral head was translated more posteriorly after the surgery in ABER views of MRI.