Arthritis Treatment: Treatment of Knee Osteoarthritis With Corticosteroid Injections

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 tough gristle that caps the ends of long bones.

Hyaline cartilage is made up of a matrix consisting 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.

However, when OA develops, a distinct change in the joint environment occurs. Chondrocytes begin to elaborate destructive enzymes causing cracks 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.

The treatment of OA of the knee is primarily symptomatic. Weight loss, exercise, physical therapy, assistive devices (such as canes and walkers), analgesics (pain-relieving medicines), non-steroidal anti-inflammatory drugs (NSAIDS) which also reduce inflammation and pain, as well as thermal modalities such as heat and ice can all be employed.

But what happens when the patient doesn't respond to these?

The next step is injection therapy. There are two main forms of injection therapy used for OA of the knee. The first are corticosteroid injections. The other major type, hyaluronic acid injections will be discussed in another article.

Corticosteroid (another term used is glucocorticoid - I will use these terms interchangeably) or glucocorticoid injections are used to provide rapid short term relief from the pain and inflammation caused by OA of the knee. Corticosteroids - also known as "cortisone" reduce inflammation and theoretically reduce potential damage to the joint. They are administered in combination with a local anesthetic to help provide immediate relief of pain until the corticosteroid has a chance to "kick in." These injections are administered using sterile technique with a local anesthetic. It's critical that ultrasound guidance be used in order to ensure accuracy. If the corticosteroid isn't placed properly in the joint space, it will not provide optimal relief. They should not be administered more often than three times per year since there is evidence that corticosteroids given more often can damage cartilage.

While generally safe, corticosteroid injections can cause some minor side effects such as flushing of the face, elevation of blood sugar in patients with diabetes, skin atrophy at the site of injection, a flare of pain the evening of the steroid injection, and sometimes some local swelling. Infections are rare if proper technique is used.

Caution should be exercised when giving these injections to patients on anticoagulants such as warfarin. Corticosteroid injections provide short term benefit. The length of effectiveness can range anywhere from weeks to several months. On occasion, they will help for a longer period of time.