Bone, cartilage and synovial fluid: an integrated approach to joint health

What is synovial fluid?

Synovial fluid is synthesised by the synovial membrane. The synovial membrane is a coating that lines the inside of the joint capsule, except the cartilage surface. Its most notable feature is the absence of epithelial cells and a basement membrane. It consists of a layer just 1 to 3 cells deep, freely distributed over a matrix of mucopolysaccharides.

Synovial fluid is synthesised as plasma crosses the synovial membrane. The resulting ultrafiltrate has very low protein and cell content. In the body, hyaluronic acid, which is an ingredient in the Advance Articular Care Diet, is synthesised in the synovial membrane by type B synoviocytes before combining with the plasma ultrafiltrate. Hyaluronic acid lends synovial fluid its high viscosity and is essential for all of its functions.

Functions of synovial fluid

The main functions of synovial fluid include:

• It provides the joint cartilage with nutrition.
• It removes waste that accumulates as a result of using the joint.
• Protective function: its high viscosity reduces friction between cartilage, lubricating the joint and cushioning it during movement.

Synovial fluid is readily accessible and its analysis can help in the diagnosis of both local and systemic diseases. Synovial fluid analysis should occupy a more central role in routine clinical practice.

The indications for synovial fluid analysis are:

• Inflammation of one or more joints
• Radiological signs suggestive of degenerative joint disease
• Possible  polyarthritis (gait disturbance, intermittent limp, nonlocalised pain), especially associated with systemic clinical signs such as fever, elevated neutrophils, leukocytosis or anorexia.
• Cyclic fevers of unknown origin.

It is important to emphasise that joint health depends on the health of each joint’s individual components. It does not depend solely on cartilage degeneration. The condition of the bone and synovial fluid are just as important.

The Advance Articular Care Diet features hyaluronic acid among its ingredients to improve the protective capacity of the synovial fluid and therefore reduce joint pain. Other components of the diet that improve joint health are:

• Glucosamine and chondroitin sulphate, which inhibit cartilage degradation and calcification, thereby improving the joint’s ability to absorb compressive forces.
• Hydrolysed collagen contains the amino acids needed to synthesise collagen from the cartilage matrix.