Arthrocentesis: Arthrocentesis, also known as joint aspiration -a procedure in which a sterile needle and syringe are used to drain fluid from the joint. This is normally done as an outpatient procedure. For specific conditions, medication is put into the joint after fluid removal. The Joint fluid can be analyzed for diagnostic lab testing to determine the cause of the joint swelling, such as infection, gout arthritis, or rheumatoid disease. Arthrocentesis can be effective in relieving joint swelling, and to alleviate pressure and relieve pain, or both.
When a joint causes pain, swells or has a limited range of motion, a physician may recommend using a needle and syringe to remove fluid from the joint.The most commonly aspirated joint is the knee. However, arthrocentesis can be done on other joints, such as the hip, elbow, wrist, ankle, shoulder and the first metatarsophalangeal joint.
Synovial Fluid in Joints
The aspirated fluid is named synovial fluid, or the joint fluid. It is normally slippery and viscous and can be obtained in joints and bursae. The fluid, along with cartilage, promotes smooth joint movement and provides cushioning within the joint’s bones.
Synovial Fluid in Bursae
Thin, slippery sacs in the joints called bursae contain synovial fluid, and they provide cushioning and reduce friction between a joint’s bones and surrounding muscle and ligaments. While a bursa is inflamed, it is described bursitis, and the bursa may swell with excess fluid.
Depending on the conditions, a physician performing arthrocentesis will eliminate fluid from the joint or from a joint’s bursa.
For instance, a joint with osteoarthritis may contain excess fluid and the fluid may be less viscous than standard, while a joint with gout will have sharp, microscopic uric acid crystals in its fluid.
When is Arthrocentesis Done
Arthrocentesis is typically done for the following reasons:
- Relieving pressure in the joint will further relieve pain and discomfort.
- Additional information is needed to make a diagnosis.
- Excess fluid requires to be withdrawn before a therapeutic injection is given.
A physician may suggest arthrocentesis to confirm or rule out a diagnosis if one or more of the following is suspected:
- A joint disease such as gout, pseudogout, or rheumatoid arthritis.
- An infection in the joint.
- Bursitis (either septic or non-septic bursitis).
- Excess fluid is creating pressure and pain in the joint.
- A traumatic injury has made bleeding into the joint space.
The synovial fluid that is collected throughout arthrocentesis may undergo analysis. Information from that analysis can support diagnosis and commencing a course for treatment.
How is the Joint Aspiration or Arthrocentesis Performed
The skin over the joint is cleaned by the health care specialist using a liquid, typically an iodine solution. The local anaesthetic is employed in the area of the joint typically by injection. A needle with a syringe is inserted into the joint and joint fluid is aspirated into the syringe. For certain diseases and medical conditions, the healthcare specialist will also inject medicine into the joint after fluid removal. The needle is then withdrawn and a Band-Aid or dressing is used over the entry point.
Contraindications for Arthrocentesis
A physician may decide not to perform a joint aspiration if the patient has:
- Skin infection or injury at the point of injection.
- A known source of infection at another site.
- Certain bleeding disorders.
Arthrocentesis of the hip may be challenging in obese patients. In these cases, the physician may recommend arthrocentesis in a hospital setting, where real-time X-rays or ultrasound may be practised to assist needle placement.
Who Does Arthrocentesis
Orthopaedic surgeons who specialize in musculoskeletal problems can perform arthrocentesis. Trained rheumatologists and emergency medicine doctors may also perform the procedure.