Swollen knee: what are its symptoms, causes and treatment

A knee swells when excess fluid collects in or around the knee joint. Health care providers may refer to this condition as knee joint effusion.

This condition can be the result of trauma, an overuse injury, an underlying disease, or a medical condition. To find the cause of swelling, the health care provider may need to test a sample of fluid or blood from an injury to check for infection or disease.

Removing some of the fluid can help reduce pain and stiffness from swelling. Once the underlying cause is known, treatment can begin.

Signs and symptoms usually include the following:

Swelling.

The skin around the kneecap can become noticeably swollen, especially when you compare the affected knee to the other.

Rigidity.

When your knee joint contains excess fluid, you may not be able to fully bend or straighten your leg.

Pain.

Depending on the cause of the fluid buildup, the knee can hurt badly, to the point that it’s impossible to support body weight on it.

Consult your health care provider if symptoms do not improve with self-care measures, such as applying ice and rest. Seek immediate medical attention if one knee becomes red and warm to the touch compared to the other knee. It can be a sign of infection in the joint.

Factors that may increase the risk of knee swelling include:

Age.

The likelihood of developing arthritis-related knee swelling increases with age.

Sports.

People who participate in sports that involve knee rotation, such as basketball, are more likely to experience the types of knee injuries that cause swelling.

Obesity.

Being overweight puts extra pressure on the knee joint, contributing to tissue and joint overload and knee degeneration; this can cause swelling in the knee.

Your health care provider will likely start with a detailed history and physical exam. Later, you can have tests to determine the cause of the swelling in your knee.

Imaging tests are used to show where the problem is. Here are some options:

Bone scan.

X-rays can rule out broken or dislocated bones and determine if you have arthritis.

ultrasound.

This test uses sound waves to detect disorders that affect tendons or ligaments.

Magnetic resonance imaging.

Using radio waves and a strong magnetic field, MRIs can detect injuries to tendons, ligaments and soft tissues that are not visible on an X-ray.

A needle is used to remove fluid from inside the knee. Then, we check if this liquid has the following elements:

Blood, which can come from wounds or bleeding disorders Bacteria, which can cause infection Crystals common in gout or pseudogout

Treatment varies depending on the cause of the swollen knee, its severity, and your medical history.

Physical therapy exercises can improve knee function and strength. In some situations, it may be useful to wear a knee brace.

Treating the underlying cause of a swollen knee may involve the following:

Arthrocentesis.

Removing fluid from the knee can relieve pressure on the joint. After removing some of the joint fluid, your doctor may inject a corticosteroid into the joint to treat the inflammation.

Arthroscopy.

A lighted tube (arthroscope) is inserted through a small incision made in the knee joint. Tools that are attached to the arthroscope can remove soft tissue or repair damage to the knee.