The structure of a joint

A joint is a junction between two bones: it enables them to move them in coordination.

NORMAL JOINT:

• Bone 
• Muscle: Stabilizes the joint and helps with movement. 
• Tendon: Links a muscle to a bone. 
• Ligament: Links two bones within a joint and stabilizes the joint. 
• Cartilage: Favours the sliding of bone against one another and thus enables movement. Absorbs shocks. 
• Subchondral bone (= under the cartilage): It serves as a shock-absorber and assists in the nutrition of the cartilage. 
• Joint space: Full of synovial fluids, it enables movement. 
• Meniscus: Allow two bones of different shapes to adjust, it facilitates movement and stabilizes the joint. 
• Capsule: Delimits the joint and contributes to its stabilization. 
• Synovial membrane: Produces synovial fluids. 
• Synovial fluids: Nourishes cartilage and lubricates the joint.

JOINT WITH OSTEOARTHRITIS :

• Osteophyte: Bony outgrowth that forms inside unstable joints. 
• Erosion zone: Results from the imbalance between synthesis and deterioration of cartilage and of the subchondral bone.

CARTILAGE :

Cartilage is for the most part made up of water, cells (chondrocytes), and of a collagen structure and of proteoglycans (proteins, GAGs and hyaluronic acid).