[Direct MR-arthrography of the shoulder with maximum capsular distension for surgical planning]

To evaluate the effectiveness of direct MR arthrography of the glenohumeral joint with maximum distension of the joint capsule in patients with glenohumeral instability for preoperative diagnosis and for determining the method of surgical intervention.

MR arthrography of the shoulder joint was performed on a 1.5 T system in 38 patients. All patients suffered from anterior or bidirectional instability. Using a fluoroscopically guided posterior approach, a 1 % dilution of dimeglumine gadopentetate (5 mmol Gd-DTPA/l) was injected until full capsular stretching was achieved. MR imaging protocol included fat-saturated transversal, oblique-coronal and oblique-sagittal T1-weighted spin-echo, T1-weighted 3-D and transversal T2-weighted Flash-2D.

MR imaging revealed significant capsule distention in 22 patients and ventral capsule defects in 9 patients. Labral lesions were depicted in 25 patients, bicipital tendon lesions in 4 patients and partial ruptures of the rotator cuff in 3 patients. 15 of the 38 patients underwent surgery. Areas of pathologic laxity of the glenohumeral capsule were correctly described in all cases. In 12 of 15 patients, the best method of intervention could be determined prospectively. In 3 of 15 patients, the necessary operation was overestimated. Regarding labral ruptures, MRI had a sensitivity of 88 %, a specificity of 86 %, and a diagnostic accuracy of 87 %.

Direct glenohumeral MR arthrography allows accurate preoperative evaluation of labral and tendinous structures. Judging the capsular laxity allows the determination of the optimal method of surgical intervention. The maximum extent of a stabilizing operation can be predicted preoperatively.