Dr. Aparna Krishnan, MD, MPH

Both injection and aspiration are techniques that involve inserting a needle connected to a syringe directly into the joint. Aspiration involves the removal of excess fluid, and injection is the placement of medication directly into the joint space via the needle. Both procedures may be performed at the same time. In both cases a local anesthetic may be used, the skin will be cleaned and disinfected, and then the needle will be inserted. In some cases, especially if the injection or aspiration is in a large and deep joint such as the hip or spine, ultrasound may be used to guide the needle to the exact location desired.

In some cases, irritation to the joint can cause fluid to build up so significantly that the joint hurts and can no longer move well. Aspiration removes some of the excess fluid and relieves the pressure. In addition, aspiration can be used to provide a sample of joint fluid if it needs to be examined microscopically for the presence of white blood cells, bacteria, or crystal formations.

Certain injuries and diseases that affect joints are inflammatory in nature, such as rheumatoid arthritis, tendonitis or gout. These diseases may be helped by the local injection of anti-inflammatory medications directly into the affected joint. In this case, corticosteroids such as methylprednisone are usually used. Relief from the pain may be felt right away and may last for weeks or even months.

In some cases, such as with osteoarthritis, the cartilage buffer between the two bones wears down and pain comes from bones rubbing against each other. In this case, injection of a lubricating agent such as hyaluronic acid may be beneficial. It provides a slippery cushion between the bones to relieve pain that can last for months.