Viscosupplementation - its origins and development

Viscosupplementation is a medical procedure used primarily to treat osteoarthritis (OA), a degenerative joint disease most often affecting the knees. It involves injecting hyaluronic acid, a naturally occurring substance in the synovial fluid of joints, directly into the affected joint. The goal is to improve the viscoelasticity of the synovial fluid, enhancing lubrication and shock absorption, and thereby alleviating pain and improving joint function.

The origins of viscosupplementation date back to research on the role of hyaluronic acid in joint health. In the 1970s, scientists began investigating hyaluronic acid’s potential in replenishing the diminishing fluid in arthritic joints. The first clinical trials of viscosupplementation began in the late 1980s and early 1990s, primarily focusing on knee osteoarthritis. It was approved by the U.S. Food and Drug Administration (FDA) for knee OA treatment in 1997. Since then, its usage has expanded globally, and ongoing research continues to explore its effectiveness for other joints such as the hip, ankle, and shoulder.

Viscosupplementation has become a widely accepted treatment option for managing osteoarthritis, especially for patients who have not responded to other forms of conservative care, such as nonsteroidal anti-inflammatory drugs (NSAIDs), physical therapy, or lifestyle changes. Some of the notable positive effects include:

1. Pain Relief: Hyaluronic acid injections can reduce pain in the joint by improving lubrication and reducing the friction between cartilage surfaces.
2. Improved Joint Function: Enhanced synovial fluid quality improves movement within the joint, leading to better mobility and decreased stiffness.
3. Delay in Surgical Intervention: For patients not yet ready or suitable for joint replacement surgery, viscosupplementation can delay the need for surgical interventions like knee replacement.
4. Fewer Side Effects Compared to Oral Medications: Unlike systemic medications such as NSAIDs or corticosteroids, hyaluronic acid injections are localized, leading to fewer systemic side effects.
5. Minimal Invasiveness: The procedure is relatively non-invasive compared to surgical options, requiring only injections rather than surgery or more invasive procedures.

Viscosupplementation is primarily used to treat osteoarthritis in the knee, but studies have explored its benefits for other joints affected by OA. It is particularly useful in cases where other treatment modalities have failed or in patients who want to avoid or delay surgery. The main uses include:

• Knee Osteoarthritis: The most common application of viscosupplementation, it is used when conservative treatments like physiotherapy, NSAIDs, or weight management have proven inadequate.
• Hip Osteoarthritis: Though less commonly performed, viscosupplementation is also used for hip OA, though access to the joint makes the procedure more complex.
• Shoulder Osteoarthritis: The shoulder, being another weight-bearing joint, is a potential candidate for viscosupplementation in cases of severe OA.
• Ankle Osteoarthritis: Patients with OA in the ankle can also benefit from the lubricating effects of hyaluronic acid injections.

Cortisone injections are another common treatment for osteoarthritis. While both viscosupplementation and cortisone injections aim to reduce joint pain and improve function, they work in distinct ways and have different benefits and drawbacks:

• Mechanism of Action: Cortisone is a corticosteroid that reduces inflammation in the joint by suppressing the immune response, which provides immediate relief from swelling and pain. Viscosupplementation, on the other hand, works by restoring the quality of synovial fluid, offering more long-term improvement in joint function.
• Duration of Relief: Cortisone injections provide rapid relief, often within a few days, but the effects may last for only a few weeks to a couple of months. In contrast, viscosupplementation has a delayed onset (up to several weeks for full effect) but can offer relief for six months to a year.
• Frequency: Cortisone injections are generally limited to three to four times a year because repeated use can weaken tendons and cartilage. Viscosupplementation can be administered in a series of injections (usually 3-5 injections over a few weeks) and can be repeated if necessary after a gap of six months or a year.
• Side Effects: Cortisone injections carry the risk of joint damage with repeated use, while viscosupplementation is associated with fewer long-term risks, making it a safer option for patients requiring ongoing treatment.

While viscosupplementation is considered safe, like all medical procedures, it is not without risks or potential downsides:

1. Delayed Onset of Relief: Unlike cortisone, which provides almost immediate relief, it may take several weeks to experience the full benefit of viscosupplementation.
2. Limited Efficacy: Some studies suggest that viscosupplementation may be less effective in patients with advanced osteoarthritis where the cartilage is severely damaged. In these cases, the treatment may provide minimal or no relief.
3. Infection: As with any injection, there is a small risk of infection at the injection site, though this is rare.
4. Swelling and Pain: Some patients may experience temporary swelling or pain following the injections.
5. Cost: Viscosupplementation can be expensive, and not all insurance plans cover the procedure, especially when it is administered for joints other than the knee.
6. Not a Permanent Solution: While viscosupplementation can delay the need for surgery, it is not a cure for osteoarthritis. Patients may eventually require more invasive treatments like joint replacement.

Viscosupplementation involves a series of injections administered directly into the affected joint. The process typically includes:

• Preparation: The affected joint is cleaned, and a local anesthetic may be applied. If there is excessive fluid in the joint, it is often drained before the hyaluronic acid is injected.
• Administration: A syringe containing hyaluronic acid is injected into the joint space. Most treatment protocols involve 3 to 5 injections over the course of several weeks, though single-injection formulations are available.
• Recovery: Following the injection, patients are usually advised to rest the joint for 24-48 hours. Light activities can often be resumed quickly, though strenuous activities should be avoided.

Hyaluronic acid supplements are available in oral or topical forms, often marketed for joint health. However, the effectiveness of these supplements is debated, and they are generally considered less effective than injections for treating osteoarthritis. Some key points about viscosupplementation supplements include:

• Absorption Issues: Oral hyaluronic acid is often broken down by the digestive system before it reaches the joints, leading to questions about its efficacy.
• Topical Use: Hyaluronic acid is widely used in skincare products due to its moisturizing properties, but topical forms are unlikely to penetrate deep enough to affect joint health.
• Supplementing Injections: Some patients use oral hyaluronic acid supplements to complement injection therapy, though the benefits of doing so remain unclear.

Viscosupplementation offers an important option in the treatment of osteoarthritis, especially for individuals seeking to avoid surgery or those not responding well to traditional treatments. By restoring joint lubrication, it helps reduce pain and improve mobility over the long term. Although not without its limitations—such as delayed relief, potential swelling, and cost—it provides a less invasive alternative to joint replacement and is considered safer than repeated cortisone injections. With ongoing advancements, viscosupplementation may continue to play a key role in joint health management.