[Immobilization in external rotation after primary shoulder dislocation]

The standard method of treating acute primary dislocation of the glenohumeral joint is immobilization of the arm in adduction and internal rotation with a sling. The recurrence rate for anterior instability after nonoperative treatment in young active patients is extremely high (up to 90%) and well reported. A new method of immobilization with the arm in external rotation improves the position of the displaced labrum on the glenoid rim. With the use of control MRI before and after immobilization in external rotation, a study on this new repositioning of the labrum is evaluated.

Ten patients (mean age 30.4 years) with primary anterior dislocation of the shoulder and Bankart lesion as shown on MRI but with no hyperlaxity of the contralateral side were immobilized in 10-20 degrees of external rotation for 3 weeks. Scans with MRI were taken in internal and external shoulder rotation post trauma and in internal rotation after 6 weeks. All patients were reevaluated after 6 and 12 months.

Dislocation and separation of the labrum were both significantly less with the arm in external rotation due to the tension of the anterior capsule and the tendon of the subscapularis muscle. In the MRI taken in internal rotation 6 weeks post trauma, all Bankart lesions were fixed in reposition after three weeks of immobilization in external rotation. At 12-month follow-up, the average Constant Score was 96.1 points (range 63-100), and the Rowe Score was 91.5 points (range 25-100). One patient had traumatic redislocation after 8 months.

After primary shoulder dislocation, immobilizing the arm in 10-20 degrees external rotation provided stable fixation of the Bankart lesion in an anatomic position. First long-term indications from an ongoing prospective study of recurrence rates after immobilization in external rotation are promising.