knee swelling

What is knee swelling?

Knee swelling is sometimes referred to as "water on the knee." The medical term for this condition is knee effusion. Water on the knee can result from an injury, chronic overuse, or disease.

Swelling in a knee joint may limit knee flexibility and function. For example, a person may find it difficult to fully bend or completely straighten a swollen knee, and the joint may naturally bend 15 to 25 degrees while the leg is at rest.1

Depending on the underlying condition, the swollen knee may exhibit no other symptoms or it may be painful, red, and/or difficult to put weight on.

Whether water on the knee is mildly annoying or painfully debilitating, a patient will want to identify the likely cause and treat the symptoms to help mitigate future problems. Chronic or long-standing swelling may lead to joint tissue damage, cartilage degradation, and bone softening, therefore treatment is usually recommended.


-Knee swelling may be caused by infectious processes including:

  • Abscesses
  • Cellulitis (infection of the skin and subcutaneous tissue)

-Knee swelling can be caused by inflammatory diseases that may also affect multiple joints within the body including:

  • Ankylosing spondylitis (inflammation of joints between the vertebrae of the spine)
  • Bursitis (inflammation of a bursa sac that cushions a joints)
  • Gout (type of arthritis caused by a buildup of uric acid in the joints) and pseudogout
  • Osteoarthritis
  • Psoriatic arthritis (arthritis associated with psoriasis of the skin)
  • Rheumatoid arthritis (chronic autoimmune disease characterized by joint inflammation)
  • Septic arthritis (infectious arthritis)
  • Systemic lupus erythematosus (disorder in which the body attacks its own healthy cells and tissues)

-Knee swelling can arise due to trauma or injury. Traumatic causes include:

  • Bite and sting injuries
  • Fracture of bone
  • Fragments of bone or cartilage within joint space
  • Hematoma (collection of blood in body tissue)
  • Sprains and strains
  • Torn meniscus

-Tumors that may cause knee swelling

Both benign and malignant tumors of the skin, soft tissues, or bone can cause a swollen knee.

Risk factors

By Mayo Clinic Staff

  • Water on the knee tends to happen more often in people older than age 55.
  • Sports participation.People who participate in sports that involve sudden changes of direction, such as basketball, are more likely to experience the types of knee injuries that cause water on the knee.
  • Excess weight puts added stress on the knee joint, contributing to the wear-and-tear damage that may lead to water on the knee. This increases your risk of osteoarthritis, one of the more frequent causes of water on the knee.


By Mayo Clinic Staff

If left untreated, water on the knee can severely limit your mobility. If the swelling is Pain medications and procedures to remove fluid from the knee joint reduce the symptoms of water on the knee. Treatment varies for diseases and conditions causing water on the knee, but depending on the severity of the swelling and your medical history, options may include:


If the cause of the knee swelling is a fracture, your doctor may recommend a cast or splint to keep it immobilized until the bone is healed.

  • Sprained knee ligaments are treated with cold or ice packs to reduce inflammation and pain as well as with medication such as painkillers and anti-inflammatory drugs
  • In case of torn ligaments and tendon ruptures, surgical repair is often necessary.
  • Procedures to reduce dislocation such as popping the patella back in place may be required.
  • Chronic swelling of the knee caused by arthritis is treated with over-the-counter painkillers and anti-inflammatory medications.
  • There is a new brand of anti-inflammatory medication known as biologics. These drugs specifically target the substance that causes the inflammation in cases of rheumatoid arthritis.

PRICE is what you should remember when it comes to treating a swollen knee. PRICE stands for protection, rest, ice, compression, and elevation.

Protect –Wear a kneepad to prevent repetitive stress injury.

  • Rest -Keep the weight off your knees. If you need to move around invest in a pair of crutches to keep the weight off the joint.
  • Ice -Apply a cold or ice pack to your knee twice or thrice a day to reduce inflammation and pain. Always place a cloth or towel between your skin and the ice pack to protect the skin. Never use heat or a warm compress on a swollen knee as it will increase the inflammation.
  • Compression – Use an elastic bandage or knee brace to support the knee joint and provide compression. This will help decrease swelling and fluid buildup.
  • Elevate - Keep the knee elevated as often as you can. Prop a pillow under you leg so that the knee is higher than the heart. This encourages any excess fluid collected around the knee joint to drain faster.

Besides these five steps, other steps to reduce any swelling of the knee include:

  • Regular exercise that helps in reducing weight thus preventing injury of the muscles and joints. If you are overweight or have suffered from joint pain and inflammation, ease into an exercise routine slowly. Opt for joint-friendly exercises such as swimming and aqua aerobics rather than running and cycling.
  • Massage is an excellent way to reduce pain and inflammation. Always inform the masseur or therapist about any injury or weakness before hand.
  • Do not smoke as smoking can slow down or impair the healing process.

 A healthy diet can make a huge difference to an already swollen knee. Eating a balanced diet helps reduce obesity, decreases pressure on the joints and improves overall mobility and flexibility of the body. Include foods rich in vitamin C such as berries and citrus fruits as these help increase the production of collagen in the body. Collagen is an important component of bones and cartilages and can prevent pain and swelling as well as improve the healing process.

  • Foods rich in vitamin B such as soy, lean meat, eggs, whole grain cereals and fish can help reduce pain and swelling of the joints as well.
  • An increase in vitamin D rich foods such as fortified cereals and dairy products have proven to help prevent the onset of degenerative diseases such as osteoporosis.
  • A high sodium diet may increase swelling and inflammation of the joints.
  • Research also indicates that omega-3 fatty acids found in foods such as walnuts and oily fish help reduce inflammation and speed up the healing process.

Surgical and other procedures

Minimally invasive surgery and other methods of treating water on the knee and its most common underlying causes include:

  • Joint aspiration (arthrocentesis).Removing fluid from your knee joint can help relieve the pressure of joint fluid buildup. After aspirating joint fluid, your doctor may inject a corticosteroid into the joint to treat inflammation.
  • During this procedure, the surgeon makes a small incision in the skin over your knee joint, then inserts a small, lighted tube (arthroscope) that sends real-time images of the inside of your knee to a video terminal. Your surgeon may also use small, precise tools — sometimes placed in the joint through an attachment to the arthroscope — to remove loose tissue or repair damage in your knee.
  • Joint replacement.If bearing weight on your knee joint becomes intolerable, your doctor may refer you to an orthopedic surgeon for knee replacement.


This condition is usually characterized by severe pain. However, there are several other typical water on the knee symptoms, that can help a person identify what the problem is. Some of the most common water on knee symptoms are:

  • Swelling in the knee, where one knee may also appear larger than the other
  • Puffiness around certain parts of the knee, especially the bony part
  • Stiffness in the knee joint which contains excess fluid
  • Difficulty to bend the knee or even straighten it completely

There may be other water in knee symptoms, which only become evident in severe cases. Some of the water on the knee signs that are a cause for concern are:

  • Lack of relief, even after taking certain medicines and over the counter pain relievers
  • Redness in the knee
  • One knee becoming warmer, as compared to the others


Since water on the knee is usually caused by an underlying health condition or an injury, it is possible to prevent the condition. Water on the knee management usually requires the patient to work with their doctors, as well as their family members and relatives. Hence, the steps for preventing water on the knee are:

  • Getting regular checkups especially for people who suffer from health conditions like gout, rheumatoid arthritis and osteoarthritis
  • Taking medication prescribed by the doctor on a regular basis
  • Wearing a knee brace, in case of an injury
  • Undergoing therapy or performing exercises to strengthen the thigh muscles

It is best for people to engage in exercises that do not put too much pressure on the knees; these exercises include swimming and water aerobics. People suffering from water on the knee problems should preferably hire a professional fitness expert, who can help them while exercising.