Is external rotation the correct immobilisation for acute shoulder dislocation? An MRI study

Area of Science:

• Orthopedic Surgery
• Radiology
• Sports Medicine

Background:

• Anterior shoulder dislocation is common and frequently recurs.
• Immobilization in external rotation (ER) is suggested to improve outcomes, but evidence is limited.
• The impact of ER on labral and capsular injuries requires further investigation.

Purpose of the Study:

• To evaluate the effect of external rotation (ER) on labral and capsular ligamentous complex lesions after primary shoulder dislocation using MRI.
• To assess the reduction of hemarthrosis, labral displacement, and anterior capsule volume in ER.

Main Methods:

• Prospective MRI study of 23 patients with acute anteromedial shoulder dislocation.
• MRI protocol included acquisitions in both internal and external rotation.
• Analysis of hemarthrosis, ER amplitude, rotator cuff, bone lesions, and labral lesions (Habermeyer's classification, Itoi criteria).

Main Results:

• External rotation (ER) modified hemarthrosis distribution in 75% of cases.
• All labral lesions showed reduction in ER, with 21% complete reduction.
• Anterior joint effusion was reduced in ER, indicating potential for reduced recurrence factors.

Conclusions:

• External rotation (ER) systematically reduces labral separation and anterior capsule volume, key factors in shoulder instability.
• ER demonstrated a positive effect on hemarthrosis, anterior capsule detachment, and labral lesions.
• Further long-term clinical studies are needed to confirm the efficacy of ER immobilization for preventing shoulder instability.