Swelling and Tenderness of Knee Joint

• Hyaluronic acid injections, which are routinely injected into the knee to treat arthritis and arthritis-related pain, are an effective treatment designed to increase mobility and range of motion in a diseased knee joint. As with most other forms of medical treatment, side effects can occur. As the medication interacts with the soft tissues in the knee, the most common side effects are inflammation, swelling and tenderness, at least temporarily.
  
  

Heat Sensations

• A feeling of warmth or heat can often be felt in the knee following a hyaluronic acid injection, because the medication elicits an immune system response that can trigger increased blood flow within the knee joint itself.
  
  

Infection

• A rare side effect of a hyaluronic acid injection into the knee is infection. Any time a foreign object is inserted into the knee, no matter how sterile, the chances of an infection developing are present. Certain germs and microbes can be introduced into the knee by way of the injection needle, leading to a low-grade knee infection.
  
  

Numbness and Tingling

• The process of placing a needle into the knee and injecting medication can disturb the delicate nerves and soft tissue within the knee. There can be temporary feelings of numbness or tingling, which normally subsides within 24 hours after the procedure.