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Articular cartilage of glenoid fossa

The articular cartilage of the glenoid fossa covers the concave articular surface of the scapula’s lateral angle, forming the socket of the glenohumeral (shoulder) joint. It provides a smooth, low-friction surface for articulation with the head of the humerus, facilitating wide and stable motion.

The glenoid cartilage is thin, fibrocartilaginous, and non-uniform, being thicker at the periphery and thinner centrally, which optimizes joint congruity and load distribution. It merges peripherally with the glenoid labrum, a fibrocartilaginous rim that deepens the socket and enhances joint stability.

Synonyms

  • Glenoid articular cartilage

  • Glenoid surface cartilage

  • Cartilaginous surface of scapular fossa

Location and Structure

  • Location: Lines the concave glenoid cavity at the lateral angle of the scapula, articulating with the humeral head.

  • Composition: Hyaline cartilage with zones of collagen, proteoglycans, and water arranged in four histologic layers — superficial, transitional, deep, and calcified zones.

  • Thickness: 1–3 mm on average; thickest at the peripheral margin and thinnest centrally.

  • Surface: Smooth and glistening in health; becomes fibrillated and irregular with degeneration.

  • Subchondral bone plate: Underlies the cartilage, continuous with trabecular bone of the glenoid.

  • Periphery: Merges seamlessly with the fibrocartilaginous glenoid labrum, which enhances socket depth and stability.

Relations

  • Superiorly: Supraglenoid tubercle (origin of long head of biceps tendon) and superior labrum

  • Inferiorly: Infraglenoid tubercle (origin of long head of triceps tendon) and inferior labrum

  • Medially: Subchondral bone of scapular body

  • Laterally: Articular surface of the humeral head

  • Anteriorly: Joint capsule and subscapularis tendon

  • Posteriorly: Infraspinatus and teres minor tendons near capsule

Function

  • Smooth articulation: Provides a low-friction surface for glenohumeral movement.

  • Shock absorption: Distributes compressive and shear forces from the humeral head.

  • Load transmission: Spreads load evenly to prevent focal subchondral stress.

  • Joint congruence: Enhances stability when combined with labrum and negative intra-articular pressure.

  • Nutrient diffusion: Supports chondrocyte metabolism through synovial fluid exchange.

Clinical Significance

  • Degenerative changes: Early cartilage wear seen in osteoarthritis or post-traumatic arthropathy.

  • Osteochondral lesions: Focal cartilage defects after shoulder dislocation or repetitive microtrauma.

  • Chondral fissuring and delamination: Common in chronic instability or labral pathology.

  • Glenoid dysplasia or hypoplasia: May cause abnormal load distribution and secondary degeneration.

  • Imaging importance: MRI and CT arthrography crucial for assessing cartilage thickness, defects, and subchondral bone changes.

MRI Appearance

  • T1-weighted images:

    • Cartilage: Intermediate-to-low signal, uniform and smooth.

    • Subchondral bone: Low-signal cortex with bright fatty marrow underneath.

    • Joint fluid: Bright in contrast to the darker cartilage, outlining the surface clearly.

    • Cartilage thinning or loss: Appears as focal low-signal defects with adjacent bone irregularity.

  • T2-weighted images:

    • Cartilage: Intermediate-to-bright signal; well-defined interface with subchondral bone.

    • Joint fluid: Hyperintense, clearly delineating cartilage margins.

    • Pathology:

      • Chondral fissuring — bright linear signals extending from surface.

      • Full-thickness loss — complete absence of signal with exposed subchondral bone (dark).

      • Subchondral edema — bright hyperintensity beneath cartilage.

  • STIR:

    • Normal cartilage: Intermediate-to-dark signal.

    • Pathologic: Bright subchondral marrow hyperintensity indicating edema, fracture, or inflammation.

    • Sensitive for early osteochondral injury.

  • Proton Density Fat-Saturated (PD FS):

    • Normal cartilage: Intermediate-to-dark signal, smooth margins.

    • Abnormal cartilage: Bright focal hyperintensity in fissures, delamination, or surface irregularity.

    • Excellent for detecting early cartilage softening and subtle subchondral marrow changes.

  • T1 Fat-Sat Post-Contrast:

    • Normal cartilage: Minimal or no enhancement.

    • Inflamed subchondral bone or synovium: Enhances vividly.

    • Chondral defects: Peripheral or nodular enhancement around exposed bone, consistent with reactive granulation tissue.

CT Appearance

Non-Contrast CT:

  • Cartilage: Not directly visualized; appears as a low-density space between humeral head and glenoid bone.

  • Subchondral bone: Dense, sharply marginated surface beneath cartilage.

  • Pathology:

    • Detects subchondral sclerosis, cysts, or osteophytes in degenerative changes.

    • Osteochondral fractures and loose bodies well demonstrated.

MRI images

articular cartilage of glenoid fossa axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

articular cartilage of glenoid fossa CORONAL cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000