External rotation immobilization for primary shoulder dislocation: a randomized controlled trial.

BACKGROUND: The traditional treatment for primary anterior shoulder dislocations has been immobilization in a sling with the arm in a position of adduction and internal rotation. However, recent basic science and clinical data have suggested recurrent instability may be reduced with immobilization in external rotation after primary shoulder dislocation.

QUESTIONS/PURPOSES: We performed a randomized controlled trial to compare the (1) frequency of recurrent instability and (2) disease-specific quality-of-life scores after treatment of first-time shoulder dislocation using either immobilization in external rotation or immobilization in internal rotation in a group of young patients.

METHODS: Sixty patients younger than 35 years of age with primary, traumatic, anterior shoulder dislocations were randomized (concealed, computer-generated) to immobilization with either an internal rotation sling (n = 29) or an external rotation brace (n = 31) at a mean of 4 days after closed reduction (range, 1-7 days). Patients with large bony lesions or polytrauma were excluded. The two groups were similar at baseline. Both groups were immobilized for 4 weeks with identical therapy protocols thereafter. Blinded assessments were completed by independent observers for a minimum of 12 months (mean, 25 months; range, 12-43 months). Recurrent instability was defined as a second documented anterior dislocation or multiple episodes of shoulder subluxation severe enough for the patient to request surgical stabilization. Validated disease-specific quality-of-life data (Western Ontario Shoulder Instability index [WOSI], American Shoulder and Elbow Surgeons evaluation [ASES]) were also collected. Ten patients (17%, five from each group) were lost to followup. Reported compliance with immobilization in both groups was excellent (80%).

RESULTS: With the numbers available, there was no difference in the rate of recurrent instability between groups: 10 of 27 patients (37%) with the external rotation brace versus 10 of 25 patients (40%) with the sling redislocated or developed symptomatic recurrent instability (p = 0.41). WOSI scores were not different between groups (p = 0.74) and, although the difference in ASES scores approached statistical significance (p = 0.05), the magnitude of this difference was small and of uncertain clinical importance.

CONCLUSIONS: Despite previous published findings, our results show immobilization in external rotation did not confer a significant benefit versus sling immobilization in the prevention of recurrent instability after primary anterior shoulder dislocation. Further studies with larger numbers may elucidate whether functional outcomes, compliance, or comfort with immobilization can be improved with this device.

LEVEL OF EVIDENCE: Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.