Osteoarthritis is the progressive, irreversible breakdown of joints from wear and tear, and approximately 50 million people have osteoarthritis (or OA) in the United States. OA becomes more common with increasing age, though young patients can develop osteoarthritis, especially after injury. OA affects the cartilage and bone of joints like the knee and the hip. Symptoms may include: joint pain, stiffness, swelling, a feeling of joint instability, and difficulty walking. These symptoms may negatively impact daily life.
Initial treatment for OA is weight loss and exercise, followed by acetaminophen and oral or topical anti-inflammatory medications. For patients who have difficulty despite these treatments, joint injection is often the next step, and this may include viscosupplementation.
Viscosupplementation is the injection of hyaluronic acid into the arthritic, painful joint, usually the knee, and it can decrease pain and increase function for patients with mild to moderate osteoarthritis. Hyaluronic acid is a natural gel-like substance found in joint fluid and cartilage which helps joints move smoothly and acts as a shock absorber. Patients with OA have less hyaluronic acid than normal in their joints. Injectable hyaluronic acid is made in a lab or collected from animal tissue (rooster comb).
This injection is performed in the doctor’s office. The patient should discuss current treatments and medications with the doctor prior to the procedure. The patient typically lies flat on their back with their knee extended. If the joint is swollen with fluid, the fluid is often removed with a needle. The hyaluronic acid is then injected through the same needle, sometimes with ultrasound guidance to ensure the medication enters the joint. A band-aid is applied to the injection site. Depending on the type of hyaluronic acid chosen by the doctor, the patient may need to return for a few more injections over several weeks.
It may take a few weeks for patients to notice improvement in their symptoms, which is an important difference from steroid injections, which can improve pain within days. Relief continues for months for many patients. It is difficult to predict which patients will have the most benefit from viscosupplementation. If effective, viscosupplementation can be repeated, usually after six months. If ineffective, next steps may include a different type of injection or surgery, such as joint replacement.
Side effects such as local pain, slight swelling, and skin redness are uncommon but can occur immediately after injection. Ice and over-the-counter pain medication can help. Rare serious side effects include intense pain with a large amount of joint swelling, warmth, and stiffness. The patient should contact a medical provider immediately if this occurs. Side effects may be more common with the second or third injection, as the body may sensitize to the fluid, but it is not predictable who will have this response.
For at least 48 hours after the injection, patients should focus on rest and gentle activities like walking. Patients are recommended to avoid high intensity or grueling weight-bearing activities like prolonged standing, jogging, or heavy lifting. After 48 hours, patients gradually return to activity using pain as their guide.