The medical term for fluid on and around the right or left knee is knee effusion. There are several medical conditions that can cause it, including various types of inflammation, knee trauma and sexually transmitted diseases. Having a fluid aspiration, which examines the fluid in the joint, helps to determine the diagnosis.
Reactive Arthritis
This form of arthritis is one of the seronegative spondyloarthropathies. It is called "seronegative" because it does not have the antibodies that people with rheumatoid arthritis have. It is a "spondyloarthropathy" because the disease may involve the spine and the joints. People develop reactive arthritis from a bacterial infection. The main bacteria that cause this disease are Chlamydia, Campylobacter, Yersinia, Salmonella and Shigella, according to Roy Altman, M.D., Professor of Medicine at the University of California in "The Merck Manual for Healthcare Professionals." Chlamydia causes a genital infection, while the other bacteria cause intestinal infections. Conjunctivitis, urethritis and arthritis soon follow. Conjunctivitis is an eye inflammation. Urethritis is an inflammation of the urethra of the urinary tract. The arthritis may be severe and involve the entire body, or it may involve just one joint, usually the knee. This will cause fluid around the knee.
Pseudogout
This disease usually affects the elderly. It is an arthritis that mainly involves the knees and the wrists, writes Jeffrey Alderman, M.D., Assistant Professor of Medicine at the University of Oklahoma College of Medicine in "Current Rheumatology Diagnosis & Treatment." It is called "pseudogout" because physicians originally thought that people with this disease were suffering from gout. The attacks of pseudogout come and go. The pain may last for several days, or for as long as two weeks. People will then have a period of time where they do not have any symptoms before the pain starts again. The inflammation in the knee causes fluid around the knee.
Osteoarthritis
In "Current Rheumatology Diagnosis & Treatment," David Felson, M.D. writes that approximately 20 million Americans have osteoarthritis. In this disease, the cartilage in the joint wears away. Bones need cartilage as a buffer. Without it, the bones are irritated and the joints degenerate. Similar to rheumatoid arthritis and pseudogout, osteoarthritis usually affects the knee. The pain gets worse with activity and better with rest. The inflammation can lead to effusion.
Trauma to the Knee
There are several structures that work together to stabilize the knee. Trauma to the knee usually affects two of these structures, the medial collateral ligament and the anterior cruciate ligament. A ligament connects one bone to another. James Roberts, M.D., Vice Chairman at Drexel University College of Medicine, shows a diagram of the ligaments in "The Merck Manual for Healthcare Professionals." The symptoms of a knee sprain may include muscle spasms, pain, tenderness and effusion.
Gonorrhea
Gonorrhea is a sexually transmitted disease. It is caused by a bacterium named Neisseria gonorrhoeae. The people who contract gonorrhea are usually between 15 to 29 years old, according to Brian Schwartz, M.D., Assistant Clinical Professor at the University of California in "Current Medical Diagnosis & Treatment." This disease can infect almost any part of the female reproductive system. An infected man will usually have urethritis, or inflammation of the urethra. Neisseria can also spread through the bloodstream and cause lesions in the skin and conjunctivitis, or an inflammation in the eye. It can also cause arthritis, and usually involves the knee, ankle and wrist.
References
- "Current Medical Diagnosis & Treatment 2010"; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2010
- "Current Rheumatology Diagnosis & Treatment"; John Imboden, M.D., David Hellmann, M.D., John Stone, M.D.; 2007
- The Merck Manual for Healthcare Professionals: Knee Sprains and Meniscal Injuries
- The Merck Manual for Healthcare Professionals: Seronegative Spondyloarthropathies
