Synovial fluid

Joint.svg

Synovial fluid is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its egg white-like consistency, synovial fluid reduces friction between the articular cartilage of synovial joints during movement.

Composition

Synovial fluid is composed of hyaluronic acid, lubricin, proteinases, and collagenases. The fluid is secreted by the synovial membrane and contains phagocytic cells that remove microbes and debris from the joint cavity.

Function

The primary functions of synovial fluid include:

• Lubrication: It reduces friction between the articular cartilages of synovial joints.
• Shock Absorption: It acts as a shock absorber, distributing the load across the joint.
• Nutrient and Waste Transport: It supplies oxygen and nutrients to, and removes carbon dioxide and metabolic wastes from, the chondrocytes within the articular cartilage.

Clinical Significance

Changes in the volume or composition of synovial fluid can indicate joint disorders. For example:

• Arthritis: Inflammatory conditions such as rheumatoid arthritis and osteoarthritis can alter the properties of synovial fluid.
• Gout: The presence of uric acid crystals in the synovial fluid is a hallmark of gout.
• Infection: Septic arthritis is characterized by the presence of bacteria in the synovial fluid.

Diagnostic Use

Synovial fluid analysis, also known as arthrocentesis, is a diagnostic procedure used to assess joint disorders. The analysis includes:

• Physical examination: Assessing the color, clarity, and viscosity of the fluid.
• Chemical analysis: Measuring glucose, protein, and uric acid levels.
• Microscopic examination: Identifying crystals, cells, and microorganisms.

Related Topics

• Synovial joint
• Synovial membrane
• Articular cartilage
• Arthritis
• Rheumatoid arthritis
• Osteoarthritis
• Gout
• Septic arthritis
• Arthrocentesis

See Also

• Joint
• Cartilage
• Ligament
• Tendon