Topic
The acromial end of the clavicle is the flattened lateral extremity of the clavicle that articulates with the acromion of the scapula to form the acromioclavicular (AC) joint. Unlike the sternal end, the acromial end is broad and compressed. Its articular surface is oval, directed downward and medially, and covered with fibrocartilage.
The AC joint is stabilized by the acromioclavicular ligaments (superior and inferior) and reinforced by the coracoclavicular ligaments (conoid and trapezoid), which prevent vertical displacement. Small intra-articular fibrocartilaginous discs may be present.
This region is highly mobile, allowing scapular rotation, gliding, and elevation, which are essential for full shoulder motion. It is clinically significant as a frequent site of degeneration, separation injuries, fractures, and osteoarthritis.
Synonyms
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Lateral end of clavicle
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Acromioclavicular end
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Acromial extremity of clavicle
Function
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Forms the AC joint, connecting the clavicle and scapula
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Transmits forces from the upper limb to the axial skeleton
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Provides attachment for the acromioclavicular and coracoclavicular ligaments
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Enables scapular rotation and stability of the shoulder girdle
MRI Appearance
T1-weighted images:
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Bone marrow: intermediate signal
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Cortical bone: hypointense rim
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AC joint space: visible as a thin hypointense line
T2-weighted images:
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Cartilage: hyperintense
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Joint fluid or effusion: bright signal
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Detects degenerative changes and joint inflammation
PD-FS (Proton Density Fat-Suppressed):
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Enhances visualization of capsule, ligaments, and marrow edema
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AC joint pathology (arthritis, capsular injury, synovitis) appears hyperintense
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Excellent for trauma and subtle instability assessment
STIR:
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Suppresses fat, highlighting marrow edema and soft tissue inflammation
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Useful in acute fractures and ligamentous injuries
T1 Post-Gadolinium (MR Arthrography or contrast-enhanced MRI):
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Highlights capsule, synovium, and ligamentous insertions
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Detects synovitis, capsular tears, and enhancing arthropathy
MRI Non-Contrast 3D Imaging:
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Provides 3D reconstructions of joint morphology, acromial end alignment, and cartilage surface
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Useful in pre-surgical planning for distal clavicle excision or AC reconstruction
CT Appearance
Non-contrast CT:
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Best for cortical detail: fractures, erosions, bone spurs, and joint alignment
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Defines the relationship of the acromial end with the acromion
CT Post-Contrast (CT Arthrography):
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Contrast highlights the AC joint capsule and articular cartilage
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Detects capsular tears, cartilage loss, osteoarthritis, and subtle osseous injury
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3D reconstructions help in planning reconstructive surgery or distal clavicle excision
MRI images
MRI images
CT image
