Gel injections, technically known as viscosupplementation, treat knee pain caused by osteoarthritis. This condition thins the natural lubricating and shock-absorbing synovial fluid in the joint, leading to discomfort and stiffness. The injection delivers a gel-like substance, typically hyaluronic acid, directly into the knee joint to supplement the depleted fluid. Hyaluronic acid is a natural lubricant and cushion. Patients often worry about the pain associated with receiving a shot directly into the joint.
The Sensation During the Procedure
The immediate sensation during the gel injection is brief and is better described as pressure than sharp pain. Patients first feel a quick pinch as the needle punctures the skin, similar to any standard injection. Clinicians often minimize this initial feeling by using a very thin needle or applying a small amount of local anesthetic to the skin.
Once the needle is correctly positioned, the viscous hyaluronic acid is slowly administered into the joint space. Most patients notice the gel entering the joint, describing it as a sensation of fullness or internal pressure. This transient pressure results from the volume of gel introduced into the confined joint capsule. The entire injection process is quick, usually lasting only moments, which limits the duration of discomfort.
Steps Taken to Minimize Discomfort
Medical professionals employ techniques to ensure the injection process is comfortable. A common practice involves using local anesthetics, such as lidocaine, which are injected into the skin or mixed with the gel to numb the tissues. This significantly reduces the discomfort associated with needle entry.
Many practitioners use image guidance, such as ultrasound or fluoroscopy, to precisely direct the needle tip into the narrow joint space. This visual guidance ensures optimal placement of the gel, preventing unnecessary contact with sensitive tissues and minimizing the need for multiple needle adjustments.
If the knee has accumulated excess fluid due to inflammation, the clinician may first perform a joint aspiration (arthrocentesis) to remove this fluid. Removing the fluid before injection reduces the pressure inside the joint, lowering the likelihood of discomfort when the new volume of gel is introduced.
Managing Post-Injection Soreness
After the procedure, it is common to experience localized soreness, swelling, or stiffness at the injection site. This is a normal reaction to the needle and the introduction of the new substance, typically resolving within 24 to 48 hours. Occasionally, patients may experience an acute, temporary flare-up of pain and inflammation.
For managing this expected post-injection discomfort, patients are advised to rest the knee for one to two days and avoid strenuous activities like jogging or heavy lifting. Applying a cold compress or ice pack to the area for 10 to 15 minutes can help reduce local swelling and mild pain. Over-the-counter pain relievers, such as acetaminophen, are recommended for managing discomfort.
It is important to differentiate between this expected soreness and signs of a more serious, though rare, complication like an infection. While mild redness and swelling are normal, increasing pain, significant warmth, spreading redness, or a fever should prompt immediate contact with a healthcare provider. The temporary post-injection pain should gradually improve, and any persistent or worsening pain requires medical attention.