Knee osteoarthritis often causes significant pain, leading many to seek non-surgical interventions when conservative treatments are no longer effective. Viscosupplementation, frequently called “gel injections,” is one common option. This treatment involves injecting a substance directly into the knee joint to improve mobility and reduce discomfort associated with osteoarthritis. Understanding the process, from the initial consultation to the expected long-term outcomes, can help ease uncertainty. This article details the full experience of receiving these injections, outlining the gel’s composition, the procedure steps, immediate aftermath, and the typical timeline for achieving pain relief.
Understanding Viscosupplementation
The substance injected during viscosupplementation is hyaluronic acid (HA), a naturally occurring complex sugar molecule found throughout the body. In a healthy knee, HA is a major component of the synovial fluid, lubricating joint surfaces and absorbing mechanical shock during movement. In knees affected by osteoarthritis, the concentration of native HA is often reduced, leading to increased friction and deterioration of the cartilage and underlying bone.
By injecting an engineered form of HA directly into the joint space, the treatment aims to temporarily restore the fluid’s natural properties. This restoration is intended to improve joint mechanics, reduce pain signals, and potentially offer a protective effect to the remaining cartilage. The HA used in treatment is derived either from bacterial fermentation or rooster combs, though modern products rely heavily on non-animal sources to minimize allergic reactions.
Viscosupplementation is generally considered a second-line treatment, reserved for individuals whose knee pain persists despite using conventional methods. These methods typically include over-the-counter pain relievers, prescription anti-inflammatory drugs, and physical therapy programs. The injections are often positioned as an intermediate step for patients who are not yet ready for joint replacement surgery or who have underlying health conditions preventing major surgery.
The Procedure: Preparation and Execution
Before the appointment, patients may receive specific instructions regarding their regular medications, particularly if they are taking blood thinners such as warfarin or antiplatelet agents. Stopping these medications is sometimes advised briefly beforehand to minimize the risk of bleeding or bruising within the joint capsule. Patients should also arrange for transportation home, as activity restrictions are often recommended immediately following the injection, and wear loose-fitting clothing that allows easy access to the knee.
The procedure is performed in a clean, clinical setting, typically in an orthopedic office or specialized injection suite. The skin around the knee is meticulously cleaned with an antiseptic solution to reduce the chance of introducing bacteria into the joint space. A small amount of local anesthetic is often injected into the skin and underlying tissues to numb the area where the needle will pass.
If significant joint swelling or effusion is present, the clinician may first perform an arthrocentesis. This involves using a separate needle to withdraw the excess fluid before injecting the HA. This step can improve the effectiveness of the viscosupplementation and reduce immediate pressure within the joint.
To ensure the medication is delivered precisely into the synovial space, most clinicians use image guidance. The use of imaging significantly increases the accuracy of the injection placement compared to using anatomical landmarks alone, which is important for the treatment’s efficacy. This guidance typically involves either fluoroscopy (continuous X-ray imaging) or ultrasound technology to visualize the needle tip in real-time. Once the needle is confirmed to be in the correct location, the hyaluronic acid solution is slowly pushed into the joint capsule. While the local anesthetic minimizes sharp pain, patients commonly report a sensation of pressure or fullness as the gel enters the joint space, but this feeling is usually brief and tolerable.
Immediate Recovery and Managing Side Effects
Following the injection, patients are generally instructed to take it easy for the remainder of the day to allow the gel to settle within the joint capsule. It is advisable to avoid high-impact activities, such as running, jumping, or heavy lifting, and to limit prolonged standing or walking for at least the first 24 to 48 hours. Using the knee gently is acceptable, but excessive loading can potentially lead to the rapid migration of the newly injected substance away from the target area.
The most frequent reaction experienced is localized discomfort or soreness directly at the injection site, which resembles a mild bruise. Some individuals may also notice minor, temporary swelling, warmth, or a slight redness around the knee joint. These symptoms are typically transient and represent a localized inflammatory response to the needle insertion or the presence of the new substance.
Management of these common side effects usually involves applying an ice pack to the area for short intervals and using over-the-counter pain relievers, such as acetaminophen, if necessary. It is generally recommended to avoid non-steroidal anti-inflammatory drugs (NSAIDs) immediately following the injection if they were discontinued beforehand, but a physician can provide specific guidance. The mild localized reactions should begin to subside completely within two to three days.
While rare, patients must monitor for signs of a more significant complication, such as a joint infection, which requires immediate medical attention. Symptoms that warrant an urgent call to the treating physician include a high fever, severe pain that rapidly increases instead of decreasing, or extensive, spreading redness and warmth that goes far beyond the injection puncture site.
Timeline for Results and Treatment Duration
Unlike pain relief injections that contain corticosteroids, the therapeutic benefits of viscosupplementation are not immediate. Patients should understand that it may take several weeks following the procedure before a noticeable reduction in pain and improvement in joint function begins. If the treatment involves a series of injections, often spaced one week apart, the full effect is generally not felt until after the final dose has been administered.
The duration of pain relief varies widely, but the average effectiveness typically lasts between four to six months. Newer, higher molecular weight HA products are often formulated for a single-shot regimen, delivered in one appointment. Older molecular structures may still require the traditional series of three to five weekly injections. Patients can discuss the possibility of repeat injections with their physician once the initial effects wear off.