A bursa is a sack made of thin, slippery tissue that helps reduce friction wherever skin, muscles, or tendons slide over bone. The prepatellar bursa is located between the front of the kneecap (patella) and the overlying skin.
In some cases, a direct blow or a fall onto the knee can damage the bursa. This usually causes bleeding into the bursa sack, because the blood vessels in the tissues are damaged and torn. This can cause the bursa sack to swell up like a balloon. The walls of the bursa may thicken and become tender even after the body has absorbed the blood. This is known as prepatellar bursitis. People who work on their knees, such as carpet layers and plumbers, can repeatedly injure the bursa. Repeated injuries to the bursa can also cause prepatellar bursitis over a long period of time.
The prepatellar bursa can also become infected. This may occur without any warning, or it may be causes by a small injury and infection of the skin that spreads down into the bursa. In this case, instead of blood or inflammatory fluid in the bursa, it fills with pus. The area around the bursa becomes hot, red, and very tender.
Prepatellar bursitis causes pain and swelling in the area around the front of the kneecap. If the condition has been present for some time, small lumps may be felt underneath the skin over the kneecap. These lumps are usually the thickened folds of bursa tissue that have formed in response to chronic inflammation.
The bursa sack may swell and fill with fluid at times. This is usually associated with increased activity levels. People who are frequently on their knees, such as carpet layers, develop very thick bursa, almost like a kneepad in front of the knee.
If the bursa becomes infected, the front of the knee becomes swollen, tender and warm to the touch around the bursa. You may run a fever and feel chills. An abscess, or area of pus, may form on the front of the knee. If the infection is not treated quickly, the abscess may even begin to drain.
If your doctor is uncertain whether or not the bursa is infected, a needle may be inserted into the bursa and the fluid removed. This fluid will be sent to a lab for tests to determine whether infection is present. If infection is found, antibiotics are usually given.
Prepatellar bursitis caused by an injury will normally go away on its own. The body will absorb the blood in the bursa over several weeks. If swelling in the bursa is causing a slow recovery, a needle may be inserted to drain the blood and speed up the process. There is a slight risk of infection in putting a needle into the bursa.
Chronic prepatellar bursitis can be a major problem. The swelling and tenderness causes pain and difficulty when kneeling. Treatment usually begins by trying to control the inflammation. This may include a short period of rest or possibly a brace to immobilize the knee. Medications such as ibuprofen and aspirin may be suggested by your doctor to control inflammation and swelling. A kneepad may also be helpful to ease the pain.
If an infection is found, the bursa will need to be drained several times over the first few days. You will be placed on antibiotics for several days. If the infection is slow to heal, the bursa may have to be drained surgically.
Your doctor may also prescribe rehabilitation. Your physical therapist may suggest the use of heat, ice, and ultrasound to help calm pain and swelling. The therapist may also suggest specialized stretching and strengthening exercises used in combination with a knee brace, taping of the patella, or shoe inserts. These exercises and aids are used to improve muscle balance and joint alignment of the hip and lower limb, easing pressure and problems in the bursa.
Surgery is sometimes necessary to remove a thickened bursa. Surgical removal is usually done because the swollen bursa is restricting your activity. A small incision is made to remove the bursa.
You may need to stay off your feet for several days to allow the wound to begin to heal and to prevent bleeding into the area where the bursa was removed.
The body will form another bursa as a response to the movement of the patella against the skin during the healing phase. If the healing process goes well, the newly formed bursa will not be thick and painful.
Chronic prepatellar bursitis will usually improve over a period of time. The fluid-filled sack is not necessarily a problem, and if it does not cause pain, it is not always a cause for alarm or treatment. The sack of fluid may come and go with variation in activity.
If surgery is required, you and your doctor will come up with a plan for your rehabilitation. You will have a period of rest, which may involve using crutches. You will also need to start a careful and gradual exercise program. Patients often work with a physical therapist to direct the exercises for their rehabilitation program.