Bursitis of the Knee
Medical Author: William C. Shiel Jr., MD, FACP, FACR
Medical Editors: Dennis Lee, MD, and Melissa Conrad Stöppler, MD
What is bursitis?
A bursa is a closed
fluid-filled sac that functions as a gliding surface to reduce friction between
tissues of the body. Bursae is plural for bursa. The major bursae are located adjacent to
the tendons near the large joints, such as the shoulders, elbows, hips, and
knees. When a bursa becomes inflamed, the condition is known as bursitis.
Most commonly, bursitis is caused by local soft tissue trauma or strain injury, and there is no
infection (aseptic bursitis). On rare
occasions, the bursa can become infected with bacteria. This condition
is called septic bursitis.
What is knee bursitis?
The knee joint is surrounded by three
major bursae. At the tip of the knee, over the kneecap bone, is
the prepatellar bursa. This bursa can become inflamed (prepatellar
bursitis) from direct trauma to the front of the knee. This commonly
occurs when maintaining a prolonged kneeling position. It has been referred
to as "housemaid's knee," "roofer's knee," and "carpet
layer's knee," based on the patient's
associated occupational histories. It can lead to varying degrees of swelling,
warmth, tenderness, and redness in the overlying area of the knee. As compared
with knee joint inflammation (arthritis), it
is usually only mildly painful. It is usually associated with significant pain
when kneeling and can cause stiffness and pain with walking. Also, in contrast
to problems within the knee joint, the range
of motion of the knee is frequently preserved.
Prepatellar bursitis can occur when the bursa fills with blood
from injury. It can also be seen in rheumatoid arthritis and
can occur from
deposits of crystals, as seen in patients with gouty arthritis
and pseudogout. The prepatellar bursa can
also become infected with bacteria (septic bursitis). When this happens, fever
may be present. This type of infection usually occurs from breaks in the
overlying skin or puncture wounds. The bacteria involved in septic bursitis of
the knee are usually those that normally
cover the skin, called staphylococcus. Rarely, a chronically inflamed
bursa can become infected by bacteria traveling through the blood.
Next: How is prepatellar bursitis of the knee treated? »
- Nonsteroidal Antiinflammatory Drugs (NSAIDs) - Describes Nonsteroidal Antiinflammatory Drugs (NSAIDs), which are medications used primarily to treat inflammation, mild to moderate pain, and fever.
- Cortisone Injection - Read about cortisone injection treatment for inflammation, allergic reaction, sciatica and arthritis. Learn about side effects and complications of a cortisone shot.
- Gout - Gout and hyperuricemia are caused by uric acid crystals building up in the body. Read how diet changes--avoiding alcohol and high purine foods--prevent painful attacks and gout pain.
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