Magnetic resonance imaging of traumatic anterior instability of the shoulder

The diagnostic capability of MRI in depicting abnormalities in traumatic anterior instability of the shoulder (TAI) was evaluated with special attention to MR arthrogram enhanced by joint effusion or saline solution. Sixty five shoulders with TAI and 19 control shoulders were scanned using the field gradient echo method (STAGE technique) on axial plane with a 1.0 or 1.5 Tesla system. MR arthrogram was obtained in 36 shoulders with TAI (Group A) and 11 control shoulders (Group C). Conventional MRI was obtained in 29 shoulders with TAI (Group B) and 8 control shoulders (Group D). Abnormalities in Bankart lesion were assessed according to signal intensity and labral shape. Abnormal signal was obtained in 8 shoulders (27.6%) in group B. Changes in shape were seen in 35 shoulders (97.2%) in group A and 18 (62.1%) in group B. Interruption of the anterior capsule was suspected in 3 (8.3%) in group A. Hill-Sachs lesion was suspected in 60 shoulders. Shoulders in the control group showed no abnormal change. Details of Bankart lesion confirmed by subsequent arthroscopy were diagnosed correctly in all of 14 shoulders on MR arthrogram and 8 of 16 shoulders on conventional MRI. These results show that MRI, MR arthrogram in particular, is useful for depicting abnormalities in TAI. (author)