Imaging of the Unstable Shoulder

Area of Science:

• Orthopedic imaging
• Radiology
• Sports medicine

Background:

• Shoulder instability presents variably, from acute dislocations to chronic instability.
• Effective imaging is key to successful treatment and preventing recurrence.
• Tailoring imaging to the clinical scenario and patient is essential.

Purpose of the Study:

• To outline optimal imaging strategies for shoulder instability.
• To differentiate imaging needs in acute versus recurrent cases.
• To guide the selection of appropriate imaging modalities for precise diagnosis and treatment planning.

Main Methods:

• Radiographs for initial bone defect assessment in acute settings.
• Magnetic Resonance (MR) imaging around 7 days post-injury to visualize soft tissue and bone lesions.
• Magnetic Resonance Arthrography (MRA) and Computed Tomography (CT), including 3D reconstructions, for detailed characterization in recurrent instability.

Main Results:

• In acute settings, radiographs are used for initial bone defect detection, with MR imaging recommended later for labral/ligamentous and bone defects.
• For recurrent instability, MRI (≥1.5 Tesla) is the primary modality, potentially followed by MRA, especially in younger patients.
• CT, particularly 3D reconstructions (PICO method, "en face view"), is valuable for assessing glenoid bone loss and Hill-Sachs lesions.

Conclusions:

• Clinical diagnosis of anterior shoulder instability requires careful interpretation of imaging findings.
• Imaging approaches differ significantly between acute and chronic/recurrent scenarios.
• Appropriate selection of diverse imaging techniques is critical for guiding treatment decisions in shoulder instability.