What is a joint aspiration (arthrocentesis)?
A joint aspiration is a procedure whereby a sterile needle and syringe are used to drain synovial fluid from a patient's joint. Joint aspiration is typically performed by a doctor or ancillary health care provider as an office procedure or at the bedside of hospitalized patients. Joint aspiration is sometimes called joint drainage and is medically referred to as arthrocentesis.
How do patients prepare for a joint aspiration (arthrocentesis), and does it cause pain?
Patients do not need any special preparation before a joint aspiration. The aspiration is easily performed in a doctor's office as an outpatient procedure. Pain is minimized by topical or local anesthetics applied onto the patient's skin or just beneath the skin. Usually, there is a momentary, slight amount of pain as the needle is inserted into the patient's joint space. Withdrawal of the fluid into the syringe does not typically cause pain. Injection of medication into the joint does not typically cause pain. There is very slight pain sometimes as the needle is withdrawn from the joint. Any pain is reduced by topical or local anesthetics that block pain sensation.
What is the purpose of joint aspiration (arthrocentesis), and when is it performed?
Joint aspiration can be both used for diagnosis and medical treatment of arthritis of a joint. Joint aspiration is used to obtain fluid from the patient's joint for examination in the laboratory. Analysis of joint fluid can help the physician to define causes of joint swelling (joint effusion) or arthritis, such as infection, gout arthritis, and rheumatoid disease. Fluid from the joint can be tested for white cell count, crystals, protein, glucose, as well as cultured to detect infection. Each of these laboratory parameters can be helpful in defining the cause of a particular form of arthritis, particularly in distinguishing inflammatory from non-inflammatory forms of arthritis. The result can be key to identifying various potential rheumatology diseases and musculoskeletal conditions.
Joint aspiration can also be a helpful treatment in relieving joint swelling and pain. Removal of synovial fluid from the joint that is inflamed can also remove the white blood cells within that are sources of enzymes that can be destructive to the joint. This treatment can more rapidly restore the health of the joint. Bursa aspiration procedure and indications for bursitis are analogous to joint aspiration for arthritis, except the bursa is the target instead of the joint (intra-articular). The result and analysis of the fluid (aspirate) is similarly evaluated for various diseases and conditions in the laboratory.
What is a joint injection?
A joint injection is a procedure whereby a medicine is injected into the joint space with a needle and syringe. Occasionally, cortisone (an anti-inflammatory medication) or hyaluronic acid derivatives (a synthetic joint lubricant, approved for pain relief of the knee in degenerative arthritis) are injected into the joint during the joint aspiration. Cortisone injection can rapidly relieve joint inflammation and further reduce symptoms. Simultaneous joint aspiration followed by joint injection can often be done by changing the aspiration syringe with the syringe for the injection (such as for steroid injection). In this way, the joint injection does not need to be done as a separate procedure.
How is joint aspiration (arthrocentesis) performed?
The skin over the joint is cleaned by the health care professional using a liquid, typically an iodine solution (Betadine). Local anesthetic is used in the area of the joint; either by injection, a topical liquid coolant, or both. A needle with a syringe attached is inserted within the joint (joint injection) and joint fluid is drawn back under suction (aspirated) into the syringe. For certain diseases and medical conditions, the health care professional will also inject medicine into the joint after fluid removal. The needle is then removed and a Band-Aid or dressing is applied over the entry point.
Who performs a joint aspiration (arthrocentesis)?
Joint aspirations can be performed under medical guidelines by qualified doctors, including general physicians, internists, orthopedic surgeons, rheumatologists, interventional radiologists, emergency room physicians, as well as nurse practitioners and physician assistants.
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Knee Bursitis Treatment
Joint Aspiration (Arthrocentesis)
The treatment of any bursitis dependson whether or not it involves infection. Aseptic prepatellar bursitis can be treated with ice compresses, rest, and anti-inflammatory and pain medications. Occasionally, it requires aspiration of the bursa fluid. This procedure involves removal of the fluid with a needle and syringe under sterile conditions and can be performed in the doctor's office. Sometimes the fluid is sent to the laboratory for further analysis. Noninfectious knee bursitis can also be treated with an injection of cortisone medication into the swollen bursa. Cortisone injections are sometimes done at the same time as the aspiration procedure.
Who should not undergo joint aspiration (arthrocentesis)?
There are few health contraindications to a joint aspiration. People who are taking blood-thinning medicines (anticoagulants such as warfarin [Coumadin]) for underlying health reasons can have bleeding into the joint. The risk of this is extremely low, unless the level of blood thinner is too high (making the blood very thin), in which case the procedure may need to be temporarily delayed. The risk of bleeding into the joint is minimized when the physician uses the thinnest needle possible and applies cold packs after the procedure. If the skin over a joint is infected, the joint should not be aspirated, in order to prevent the infection from spreading into the joint.
What are complications of joint aspiration (arthrocentesis)?
Medical complications of joint aspiration are uncommon. Possible complications of the aspiration procedure include a reaction to the local anesthetic, local bruising or, minor bleeding into the joint. If cortisone is used, there may be loss of pigment in the skin (a light-colored spot may develop). A rare but serious complication of the procedure is infection of the joint (septic arthritis).
With corticosteroid injections, additional uncommon complications include inflammation in the joint as a result of the medication crystallizing, shrinkage (atrophy) or loss of pigment of skin at the injection site, increased blood sugar (worsening of diabetes mellitus), and aggravation of preexisting infection elsewhere in the body. If multiple injections with corticosteroids are given too frequently, it is possible to develop systemic side effects (side effects throughout the body), such as weight gain, puffy face and trunk, and easy bruising. Injection of hyaluronic acid derivatives may cause local inflammation and swelling of the joint due to a reaction to the medication. Hyaluronic acid injections into the knee joint for pain relief are generally given no more frequently than every six months.
What is the recovery time for joint aspiration (arthrocentesis)?
There is no recovery time required after joint aspiration. Doctors typically will suggest avoiding stressful activity with the joint for at least 24 hours, especially if medication (such as steroid injection) has been injected by joint injection. If pain increases after the procedure while at home, the doctor should be notified.
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Firestein, Gary S., et al. Kelley's Textbook of Rheumatology, 9th Edition. Philadelphia, PA: Saunders, 2013.