Articular disc of acromioclavicular joint

Looks like

A small wedge of fibrocartilage inside the AC joint, often incomplete.

What it does

Helps fit the joint surfaces together.

Keeping it well

It wears out early in life, which is why this joint commonly shows arthritis on imaging.

Related conditions

• Frozen shoulder (adhesive capsulitis)
• Gout
• Haemophilia & bleeding disorders
• Lyme disease
• Marfan syndrome & connective tissue disorders
• Osteoarthritis
• Polymyalgia rheumatica
• Psoriatic arthritis
• Rheumatic fever & rheumatic heart disease
• Rheumatoid arthritis
• Shoulder dislocation
• Systemic lupus erythematosus
• Temporomandibular joint disorder