Viscosupplementation for the treatment of osteoarthritis of the knee

Description

A wide variety of treatments for osteoarthritis of the knee are possible. Guidelines have been drawn up by the American College of Rheumatology (ACR) and the European League against Rheumatism (EULAR). 1 In a first group, known as the non-pharmacological interventions we find treatments such as education, exercise, life style changes and physical therapy. 2 A second group comprises the pharmacological treatments like pain killers and non-steroidal anti-inflammatory drugs (NSAIDs). 1 2 Intra-articular corticosteroid injections are also an option and are often used for transient symptom relief. When the more conservative measures fail, there is another option when surgery is to be avoided: viscosupplementation. 1 2 Viscosupplementation belongs in the category of localized therapy, more precisely intra-articular pharmacological therapy. 3

Viscosupplementation is actually the injection of Hyaluronic Acid (HA). 2 HA is a major component of the synovial fluid and of the cartilage and is one of the most important components of the extracellular matrix.1 HA is a high-molecular-weight glycosaminoglycan composed of repeating disaccharides of glucuronic acid and N-acetylglucosamine. 2 4

When a person has osteoarthritis of the knee, the quality of the synovial fluid decreases, but also the concentration and Molecular Weight of HA. 1 This can lead to pain and loss of function in the joint of the knee.2 Therefore, hyaluronic acid is injected so that de concentration, molecular weight characteristics in the extracellular matrix and the visco-elasticity of the synovial fluid can recover.1 This results in improved pain control, articular function and mobility. 4

There are different hyaluronic acid preparations and we can classify them in two categories: low molecular weight and high molecular weight. Two examples of hyaluronic acid products are naturally occurring hyaluronan (Hyalgan) and synthetic hylan G-F 20 (Synvisc). 4 2 5