Open MR imaging of the unstable shoulder in the apprehension test position: description and evaluation of an alternative MR examination position

The aim of this study was to describe and evaluate an alternative MR assess ment procedure for analysis of unstable shoulders. Twelve patients with uni lateral recurrent anterior shoulder dislocation had both shoulders examined . Magnetic resonance imaging was performed with an open-MR system in the ap prehension position with the shoulder in 90 degrees of abduction and maximu m tolerable external rotation. Contrast enhancement was achieved with intra venous gadolinium. Correlations were made to the findings at operation. In 10 of 12 unstable shoulders the inferior glenohumeral ligament labral compl ex (IGHLLC) was detached from the glenoid as seen on MR and later verified during surgery. In one shoulder MR unable to show a capsulolabral detachmen t that was verified at surgery, whereas in one shoulder both MR and surgica l assessment revealed no soft tissue detachment (accuracy 92%). A Hill-Sach s lesion was visualized and verified in all unstable shoulders, whereas the stable controls revealed normal IGHLLC and no Hill-Sachs lesion. Open-MRI evaluation of the shoulder in the apprehension test position may become a u seful tool for the evaluation of anterior shoulder instability.