Water On The Knee (Knee Effusion)

What Is Water On The Knee (Knee Effusion)? What Causes Water On The Knee?

Knee effusion, colloquially known as water on the knee, occurs when excess fluid accumulates in or around the knee joint. There are many common causes for the swelling, including arthritis, injury to the ligaments or meniscus, or when fluid collects in the bursa. This condition is known as prepatellar bursitis.

According to Medilexicon's medical dictionary:

Knee effusion is a large bursa between the inferior part of the femur and the tendon of the quadriceps femoris muscle. It usually communicates with the cavity of the knee joint and is pathologically distended with blood or synovial fluid in suprapatellar bursitis ("water on the knee").

A small amount of fluid exists in normal joints. When a joint is affected by arthritis, particularly an inflammatory arthritis such as rheumatoid arthritis (RA), increased abnormal amounts of fluid buildup, the knee appears swollen. The fluid is produced by the tissues that are affected by the arthritis and that line the joint.

What are the symptoms of Knee Effusion?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.

Signs and symptoms of water on the knee depend on the cause of excess fluid build-up in the knee joint. With osteoarthritis, pain occurs when bearing weight. The pain typically subsides with rest and relaxation.

One knee may appear larger than the other. Puffiness around the bony parts of the knee appears prominent when compared with the other knee.

When the knee joint contains excess fluid, it may become difficult to bend or straighten the knee in certain cases.

If an individual has injured his or her knee, he or she may note bruising on the front, sides or rear of the knee. Bearing weight on the knee joint may be impossible and the pain unbearable.

What are the causes of Knee Effusion?

Causes of the swelling can include arthritis, injury to the ligaments of the knee or an accident after which the body's natural reaction is to surround the knee with a protective fluid.

There could also be an underlying disease or condition. The type of fluid that accumulates around the knee depends on the underlying disease, condition or type of traumatic injury that caused the excess fluid. The swelling can, in most cases, be easily cured.

Having osteoarthritis or engaging in high-risk sports that involve rapid cut-and-run movements of the knee, football or tennis for example, means an individual is more likely to develop water on the knee.
In overweight or obese individuals the body places more weight on the knee joint. This causes more wear in the joint. Over time, the body will produce excess joint fluid.

Diagnosing Knee Effusion

An understanding of knee pathoanatomy is an invaluable part of making the correct diagnosis and formulating a treatment plan. Taking a thorough medical history is the key component of the evaluation.

The most common traumatic causes of knee effusion are ligamentous, osseous and meniscal injuries, and overuse syndromes. Atraumatic etiologies include arthritis, infection, crystal deposition and tumor. It is essential to compare the affected knee with the unaffected knee.

Systematic physical examination of the knee, using specific maneuvers, and the appropriate use of diagnostic imaging studies and arthrocentesis establish the correct diagnosis and treatment.

Joint aspiration, also known as arthrocentesis, is a procedure that includes withdrawal of fluid from inside the knee for analysis such as cell count, culture for bacteria, and examination for crystals, such as uric acid or calcium pyrophosphate dihydrate crystals found in gout or pseudogout.

An X-ray is useful to verify that there is no break or dislocation when there is a history of trauma and may show signs of osteoarthritis.

An MRI (Magnetic Resonance Imaging) detects abnormalities of the bone or knee joint, such as a tear in the ligaments, tendons or cartilage.

If the knee is swollen, red and warm to the touch when compared to the other knee, a doctor may be concerned about inflammation due to rheumatoid arthritis or a crystalline arthritis, such as gout or pseudogout, or joint infection. Besides sending the joint fluid to a laboratory for analysis, he or she may request blood tests to determine a white blood cell count, erythrocyte sedimentation rate, and perhaps the level of C-reactive protein or uric acid. If blood tests reveal Lyme's disease antibodies forming, the condition may be attributed to it.

Psoriatic arthritis often undiagnosed cause of joint conditions. Patients with the skin condition psoriasis can also have the related arthritis subtype called psoriatic arthritis. This arthritic condition tends to be overlooked, even in patients with diagnosed psoriasis.

What are the treatment options for Knee Effusion?

Along with any sort of medical care, knee joint effusion responds well to simple self-care measures, such as rest and elevation as well as icing and exercise. As with any sort of injury, ice should be applied to the affected area only for 15 to 20 minutes at a time. With exercise, a series of fitness activities are established by a physical therapist to strengthen the area to support the weakened knee.

Most treatments for knee joint effusion are based on the cause of the condition, making a "standard" approach to care nonexistent. However, many people with water on the knee need to have the excess fluid removed, so one may undergo a procedure known as aspiration.

Finally, one may need a series of corticosteroid injections, non-steroidal anti-inflammatory drugs (NSAIDs) or antibiotics to reduce inflammation or treat an infection. For others, knee surgery or even joint replacement may be necessary.

Preventing Knee Effusion

Avoiding sudden jolting movements and rough running surfaces can help prevent knee injuries. Obesity adds pressure to the vulnerable knee joint, so weight reduction may help.

Exercises considered better for the knees include small (not deep) knee bends and straightening motions done while in supination with most weight on the outside of the foot.

Sports that are easier on the knees include walking, swimming (flutter kicks, knees straight), skating, baseball, cross-country skiing, and, depending on the state of the knee, cycling (seat high, low gear, avoiding hills).

Choose activities to suit your own knee strength and capacity, and remember that sports especially hard on the knees include football, sprinting, soccer, rugby, hockey, squash, volleyball, basketball, downhill skiing, tennis and jogging or anything that pounds, jolts, or twists the knees.