Osteoarthritis (OA) of the knee is a common condition causing chronic pain, stiffness, and reduced mobility. This degenerative disease involves the gradual breakdown of the joint’s protective cartilage, severely limiting daily activities. When initial conservative treatments like physical therapy and over-the-counter pain relievers fail, patients often explore non-surgical options. One intervention used to manage symptoms is “gel injections,” formally known as viscosupplementation.
Understanding Viscosupplementation
Viscosupplementation involves injecting a gel-like substance directly into the knee joint space. The primary component of this material is hyaluronic acid (HA), a naturally occurring molecule found in the body. In a healthy joint, HA is a major component of synovial fluid, providing both lubrication and shock absorption.
In a knee affected by osteoarthritis, the natural concentration and quality of HA are diminished, compromising the fluid’s ability to protect the joint. The scientific rationale for viscosupplementation is to restore the viscoelastic properties of the synovial fluid. Supplementing the joint with external HA enhances joint lubrication, reduces friction between the bones, and may provide an anti-inflammatory effect.
The Injection Procedure and Logistics
The procedure for receiving a gel injection is typically quick and performed in a clinical setting. The injection is administered by a qualified healthcare professional, which may be an orthopedist, rheumatologist, or pain management specialist. To ensure precise placement into the joint space, many providers utilize imaging guidance, such as ultrasound or fluoroscopy (a type of X-ray).
Before the HA is injected, the area is cleaned and a local anesthetic may be used to minimize discomfort. If there is excess fluid buildup, the physician may drain this fluid before proceeding. Treatment involves either a single, high-volume injection or a series of three to five smaller injections given weekly over several weeks. Following the procedure, patients are advised to limit strenuous activity for about 48 hours, though light walking is permitted.
Determining Treatment Success
The central question for many patients is whether these gel injections truly provide relief from knee pain. Efficacy data suggest that the response to viscosupplementation is highly individualized and variable. Clinical success is measured by a patient’s reduction in pain and improved functional ability, such as walking or climbing stairs.
The treatment appears more effective for individuals with mild to moderate stages of knee osteoarthritis; those with advanced disease are less likely to benefit. For responders, the onset of pain relief is not immediate; benefits often begin several weeks after the injection series is completed. The pain relief typically lasts for approximately six months, though some patients report sustained benefits for up to a year.
While the U.S. Food and Drug Administration (FDA) has approved various HA products, some clinical guidelines show conflicting recommendations, acknowledging the treatment’s variability. Many studies show that a significant percentage of patients experience pain reduction and functional improvement superior to a placebo injection. If helpful, the treatment can be safely repeated every six months to maintain the effect.
Who Qualifies and Potential Complications
Gel injections are typically reserved for patients who have not achieved adequate relief from initial conservative strategies. This includes individuals whose knee pain persists despite using treatments like physical therapy, weight loss, and oral pain medications such as NSAIDs. The goal is to provide an effective, non-surgical option that may delay the need for joint replacement surgery.
Contraindications include an active infection in or near the knee joint, or a known allergy to hyaluronic acid preparations. The procedure carries a low risk of side effects, which are usually minor and localized. The most common issues are temporary pain, warmth, mild swelling, or stiffness at the injection site, which typically resolve within a few days.
Rarely, a more serious reaction known as an injection flare or pseudo-sepsis can occur, which involves significant, acute swelling and pain in the joint. Any procedure that breaks the skin also carries a small risk of introducing bacteria, potentially leading to a severe joint infection (septic arthritis). Patients are monitored for signs of fever or disproportionate pain following the treatment.