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Sternocostal joint

The sternocostal joints are the articulations between the costal cartilages of the first seven ribs and the lateral borders of the sternum. These joints provide stability and flexibility to the anterior thoracic cage during respiration. The first sternocostal joint is a primary cartilaginous joint (synchondrosis), while the second to seventh sternocostal joints are synovial plane joints reinforced by surrounding ligaments. They allow limited gliding movements that accommodate chest wall expansion during breathing.

Synonyms

  • Costosternal joint

  • Rib-sternum articulation

  • Anterior thoracic wall joint

Function

  • Connects the costal cartilages of ribs 1–7 to the sternum

  • Provides stability to the anterior chest wall

  • Permits slight gliding movement to facilitate respiration

  • Acts as a load-transmitting joint during chest wall motion and upper limb activity

MRI Appearance

T1-weighted images:

  • Costal cartilage appears low-to-intermediate signal

  • Bone marrow of adjacent sternum and ribs is high signal compared to cartilage

  • Joint space is narrow, sometimes not distinctly visible

T2-weighted images:

  • Cartilage appears intermediate  signal

  • Synovial fluid in joints (2nd–7th) appears bright hyperintense

  • Degenerative changes appear as irregular signal with subchondral changes

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, highlighting inflammation, edema, or synovitis

  • Useful for detecting costochondritis, arthritis, or infection

  • Pathology appears as bright hyperintensity in cartilage or bone marrow

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal joints show minimal enhancement

  • Inflammation, infection, or arthritis shows enhancing synovium and perichondral tissues

CT Appearance

Non-contrast CT:

  • Visualizes costal cartilages as intermediate density and sternum/rib bone as hyperdense

  • Joint space is narrow, may be poorly defined in normal cases

  • Detects calcification, fractures, or joint irregularities

Contrast-enhanced CT (CECT):

  • Highlights soft tissue involvement in cases of infection or neoplasm

  • Useful for identifying erosions, sclerosis, or masses extending into the sternocostal region

MRI image

Sternocostal joint anatomyMRI coronal image -img-00000-00000

CT image

Sternocostal joint anatomy CT AXIAL image -img-00000-00000