Gel knee injections, formally known as viscosupplementation, are a common medical treatment for knee pain caused by osteoarthritis. This non-surgical procedure involves injecting a gel-like substance into the joint to provide lubrication and shock absorption, improving function and reducing discomfort. Viscosupplementation is typically considered when conservative treatments, such as oral pain relievers and physical therapy, have not provided sufficient relief.
Understanding Viscosupplementation
Viscosupplementation involves injecting hyaluronic acid directly into the knee joint space. Hyaluronic acid is a naturally occurring, thick, viscous substance found in the body, which is a major component of synovial fluid. Synovial fluid normally acts as a lubricant and shock absorber for the joints, allowing smooth movement between the bones.
In a knee affected by osteoarthritis, the concentration of natural hyaluronic acid decreases, leading to thinner synovial fluid and increased friction. Injecting the therapeutic gel supplements the diminished fluid, improving its consistency and mechanical properties. This added lubrication reduces friction between cartilage and bone surfaces, helping to relieve pain and improve joint function.
Minimizing Discomfort During the Injection
The primary concern for most patients is whether the injection itself will be painful, but any discomfort is typically brief and well-managed. Practitioners often use a local anesthetic, such as lidocaine, injected or applied topically to numb the skin before the procedure. This significantly reduces the sensation from the initial needle entry.
The injection of hyaluronic acid is usually felt as pressure or fullness, rather than sharp pain, due to the viscous gel filling the joint space. To ensure precise placement and minimize irritation to surrounding tissues, many providers use imaging guidance, such as ultrasound or fluoroscopy (a type of continuous X-ray).
This guidance ensures the gel is delivered directly into the joint capsule. If the knee is swollen, the provider may first aspirate, or remove, excess fluid from the joint before administering the gel. The entire process is quick, often taking only a few minutes.
Managing Immediate Post-Injection Sensations
Immediately following the procedure, temporary side effects localized to the injection site are common. Patients frequently report mild soreness, warmth, or slight swelling in the knee joint. These normal reactions are typically short-lived, usually resolving within a few days.
A temporary worsening of symptoms, known as a post-injection “flare-up,” may occur, including increased pain and swelling. To manage this, patients are advised to apply ice wrapped in a towel for the first 48 hours. Over-the-counter pain relievers may also be recommended.
Avoid strenuous activities, such as jogging or heavy lifting, for about 48 hours following the injection. Limiting stress allows the gel to settle properly. Monitor the injection site and contact a healthcare provider immediately if severe redness, persistent warmth, or signs of infection like fever occur.
Expected Timeline for Pain Relief
Unlike corticosteroid injections, which provide quick relief within days, viscosupplementation does not offer immediate therapeutic effects. The hyaluronic acid needs time to integrate into the joint fluid and improve mechanical function. Pain relief is typically gradual and often does not become noticeable until several weeks after the injection.
Significant pain relief is usually felt around four to six weeks following the procedure. The full benefit, including improved mobility and reduced pain, can last for up to six months or sometimes longer.
Depending on the product used, treatment may involve a single injection or a series of three to five injections administered weekly. If the initial course is successful and pain returns after several months, the injections can be repeated. Viscosupplementation is a non-surgical option for long-term pain management, particularly for mild to moderate osteoarthritis.