Hyaluronic acid properties

Functions of hyaluronic acid in the joint

Hyaluronic acid (HA) is a biopolymer found naturally in the body. It is a linear polysaccharide (‘many sugars’) with unique physical and biochemical properties such as viscoelasticity and water-binding ability.

A healthy joint contains a constant amount of hyaluronic acid, which has several very important functions:

  • Hyaluronic acid gives the synovial fluid its characteristic viscoelastic properties. It enables the fluid to act as a lubricant, shock absorber and a filter controlling the movement of cells and large molecules within the joint.1,2
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When the joint is at rest, the synovial fluid is thick. However, as the components of the joint move, the synovial fluid becomes less viscous and allows free and easy movement – for example, when walking or running.
 rheuma_diseases_ha_02.jpg
The elasticity of articular cartilage helps to prevent joints from injury when compressive forces are applied to the joint – for example, when running or as a result of a fall.
  • Hyaluronic acid forms a coating over the entire inner surface of the joint, which acts as a viscoelastic shield over the articular cartilage and protects it from mechanical damage.3 This coating also protects the cartilage and synovium from free radicals and other inflammatory factors. In addition, hyaluronic acid protects from pain by masking the local nociceptors.4,5
  • Hyaluronic acid forms the backbone of the proteoglycan aggregates that are essential for the structural and functional integrity of the articular cartilage.6,7
rheuma_diseases_ha_03.jpg

Thus, hyaluronic acid plays a vital role in keeping a synovial joint healthy and mobile. In osteoarthritis, the amount of hyaluronic acid in the joint is reduced and its protective qualities are diminished.

 

 

  1. Balasz EA, Denlinger JL. J Rheumatol 1993;29(Suppl 39):3-9.

  2. Peyron JG. Osteoarthritis Cartilage 1993;1:85-7.

  3. Homandberg GA et al. Osteoarthritis Cartilage 1997;5:309-19.

  4. Gotoh S et al. Ann Rheum Dis 1993;52:817-22.

  5. Miyazaki K et al. Pharmacometrics 1984;28:1123-35.

  6. Hardingham TE, Muir E. Biochem Biophys Acta 1972;279:401-5.

  7. Hascall VC. J Supramol Struct 1977;7:101-20.