Manubriosternal Joint

symphysis manubriosternalis

The manubriosternal joint is a fibrocartilaginous symphysis between the inferior margin of the manubrium and the superior margin of the sternal body at the level of the second costal cartilage, forming the sternal angle (angle of Louis). It may ossify in later life, becoming a synostosis. The sternal angle is a key surface landmark at the level of the T4-T5 intervertebral disc.

Region: Chest

Clinical Relevance

Clinical Notes

The sternal angle formed at this joint is a critical anatomical landmark used to locate the second intercostal space for chest auscultation and rib counting, count from the clavicle in counting ribs, and identify the level of the aortic arch, tracheal bifurcation, and superior mediastinum. Dislocation of this joint is rare but can occur in chest trauma, producing localised pain and palpable step deformity. Inflammatory arthritis, particularly ankylosing spondylitis and rheumatoid arthritis, can involve this joint.

Pathology

Common Injuries & Conditions

Manubriosternal Dislocation

A rare complication of chest trauma or CPR where the manubrium displaces relative to the sternal body, producing a painful palpable step and requiring CT to assess for underlying mediastinal injury.

Manubriosternal Arthritis

Inflammatory involvement in ankylosing spondylitis or SAPHO syndrome produces anterior chest pain and tenderness directly at the sternal angle, often preceding or accompanying sacroiliac and spinal inflammation.