Joint fluid enhancement, also known as hyaluronic acid injections, involve injecting a gel-like substance into the knee joint of patients suffering from osteoarthritis. The substance acts as a lubricant and shock absorber in the knee joint.

How does Viscosupplementation Work?

The natural lubricating fluid or synovial fluid in the knee joint becomes thin and loses its cushioning ability as osteoarthritis progresses. Joint fluid enhancement involves injecting a gel-like substance called hyaluronic acid (HA) into the knee joint. HA is a natural substance found in the synovial fluid and cartilage throughout the body. The injected HA mimics the natural synovial fluid and serves to lubricate and cushion the knee joint. It absorbs shock and provides lubrication, helping reduce pain and improve movement.

Types of Hyaluronic Acid Products

There are several FDA approved HA products available for joint fluid enhancement. They differ in molecular weight, concentration and source - animal or non-animal. Some common HA products used are:

- Hyalgan/Supartz/Orthovisc: These are lower molecular weight HA products derived from rooster combs. They are administered as a series of 3-5 weekly injections.

- Synvisc/Synvisc-One: These are high molecular weight HA gels. Synvisc is given as 3 weekly injections while Synvisc-One requires only a single injection as it releases HA gradually over 3 months.

- Euflexxa: It contains high molecular weight cross-linked HA. A course of 3 weekly injections is recommended.

- Gel-One/Monovisc: Single injection products containing high molecular weight non-animal stabilized HA.

- Durolane: A single injection of ultra-high weight HA derived from bacteria fermentation. Its effects can last 6 months or longer.

Patient Selection and Pretreatment Evaluation

Joint fluid enhancement is generally considered for patients with mild to moderate osteoarthritis of the knee. The patients should have symptoms of knee pain with activities that aggravate the knee like walking or climbing stairs. X-rays are done to confirm osteoarthritis and its stage. Other blood tests may be done to rule out any underlying inflammatory arthritis or infection. Patients are advised to try conservative treatments like physical therapy, weight loss and medications before joint fluid enhancement.

Procedure and Post Treatment Care

The procedure is done on an outpatient basis under sterile conditions. Local anesthesia is used to numb the area before injecting the HA product into the knee joint using an ultrasound or x-ray guidance. Patients may feel some discomfort during and after the injection which can be managed with over-the-counter painkillers. applying an ice pack. Strenuous activities are avoided for 2-3 days. Minor swelling, pain or stiffness post injection is common but resolves within a few days. Completing the recommended course of injections is important to obtain maximum benefits.

Effectiveness and Duration of Relief

Studies have found HA injections provide effective pain relief and functional improvement for around 6 months on an average in properly selected patients with osteoarthritis of the knee. However, the benefits may last shorter or longer depending on the individual and product used. Joint fluid enhancement works best in combination with other conservative therapies like exercises rather than as a standalone treatment. While the effects are temporary, HA injections when combined with lifestyle modifications can delay knee replacement surgery in some cases.

Safety Profile

Overall, HA injections are considered very safe with minor and temporary side effects. Since it is derived from natural substances present in the body, allergic reactions are rare. The injections are not recommended during pregnancy or in patients with knee infections or bleeding disorders. Rare potential risks include increased pain, swelling or warmness at the injection site. As with any injection, there is a very small risk of infection.

When to Consider Other Options

Joint fluid enhancement may not work or provide sufficient relief in cases of end-stage osteoarthritis, severe malalignment or deformity of the knee. For advanced cases with bone-on-bone contact and significant disability, options like knee replacement surgery should be explored instead. Patients not getting adequate relief after 1-2 complete courses of HA injections may need to reconsider their treatment plan in consultation with an orthopedist.

Conclusion

Viscosupplementation offers a non-surgical option for temporary relief of knee pain caused by osteoarthritis. When used appropriately along with lifestyle changes as part of a comprehensive osteoarthritis treatment plan, it can significantly improve knee function and quality of life without major health risks. While not a cure forOA, HA injections enable many patients to delay or potentially avoid knee replacement surgery.