Osteoarthritis (OA) is the most common form of arthritis and affects more than 20 million Americans. It is a condition that adversely affects hyaline articular cartilage, the smooth tough gristle that caps the ends of long bones.

Hyaline cartilage consists of two components: a matrix made up of a combination of proteoglycans (complexes of proteins and sugars), and chondrocytes. Chondrocytes are cartilage cells that manufacture matrix under normal healthy circumstances. They are responsible for nourishing the matrix as well.

With the development of OA, a distinct change in the joint environment occurs. Chondrocytes begin to elaborate destructive enzymes causing cracks and fissures in the cartilage. These are called “fibrillations.”

One of the most common joints affected by osteoarthritis is the knee.

This is not a surprise since OA preferentially attacks weight-bearing joints.

In a previous article I discussed the use of corticosteroid (“cortisone”) injections. In this article I will discuss the use of hyaluronan (hyaluronic acid) injections.

Hyaluronic acid is a normal constituent of synovial fluid, the naturally produced lubricant found inside joints. Synovial fluid is produced by cells that line the joint. Hyaluronic acid is what gives the synovial fluid the viscous properties that contribute not only to the lubricating properties but also aid in the shock absorbing capacity of the joint.

One of the dysfunctional characteristics of the OA joint is that the synovial fluid loses much of its shock absorbing capacity, presumably due to the loss of hyaluronic acid. By injecting an outside source of synthetic hyaluronic acid, there is improvement in synovial fluid viscosity that leads to better function and amelioration of pain.

To date, viscosupplements are FDA approved only for use in knee OA. There have been anecdotal reports as well as clinical trials evaluating the effectiveness in other joint such as the ankle, shoulder, and hips. While promising, there is still insufficient evidence from the FDA’s perspective to grant approval.

Viscosupplements are used in patients who still have pain that adversely affects their activities of daily living and who have failed other measures including corticosteroid injections. They are also useful for patients in whom surgical options are not viable. They can also be used to “buy time” for patients awaiting knee replacement.

There are five commercially available viscosupplements: Hyalgan, Supartz, Euflexxa, Orthovisc, and Synvisc. Each has a different injection schedule. Some viscosupplements are given as a five injection course and there are some where only one injection is used. I personally feel the five injection supplements such as Supartz and Hyalgan work better than the ones that require fewer injections.

A course of viscosupplementation should last at least six months. One very important point: Every injection should be administered using ultrasound guidance.

Risks include a post-injection flare of pain in the first 24-48 hours after a shot. One preparation, Synvisc, has been reported to cause “pseudoseptic” reactions where the knee becomes acutely inflamed after an injection.

Another potential problem is allergic reactions in patients who are sensitive to bird or egg products. (The reason is that some of the preparations are made from rooster combs).

By and large, though, they are safe.

Viscosupplements, like corticosteroids, are only palliative. They provide pain relief only. They do not restore cartilage. Patients who fail viscosupplements are usually a candidate for mesenchymal stem cell procedures. Total knee replacement should be considered a last resort.

Nathan Wei, MD FACP FACR is a board-certified rheumatologist and nationally known arthritis authority and expert. For more info: Arthritis Treatment and Arthritis Treatment Center

Nathan Wei, MD FACP FACR is a board-certified rheumatologist and nationally known arthritis authority and expert. For more info: http://www.arthritis-treatment-and-relief.com/arthritis-treatment.html Arthritis Treatment and Arthritis Treatment Center

Author Bio: Nathan Wei, MD FACP FACR is a board-certified rheumatologist and nationally known arthritis authority and expert. For more info: Arthritis Treatment and Arthritis Treatment Center

Category: Medicines and Remedies
Keywords: arthritis treatment, osteoarthritis knee, viscosupplements, rooster comb, stem cells