Prepatellar bursitis is an inflammation of the prepatellar bursa. A bursa is a pouch containing lubricating and nourishing synovial fluid that is secreted by a thin membrane lining the sac. Bursae are found around joints, where their purpose is to facilitate the smooth movement of skin, muscles or tendons over bones. The prepatellar bursa lies under the skin on top of the kneecap, where it acts as a cushion between the two and prevents friction as the kneecap moves up and down when the knee bends or straightens. The bursa is normally thin and flattened, but when irritated or injured it can fill with fluid, blood or pus, causing painful swelling on top of the kneecap.
Prepatellar bursitis is sometimes known as ‘housemaid’s knee’ as it occurs most frequently in people whose occupations require them to spend extended periods of time on their knees. Chronic irritation caused by repeated small injuries to the bursa can lead to this painful condition.
Other possible causes include:
- Trauma to the kneecap, such as a fall onto the knee, which can damage the tissues of the bursa and lead to it filling with blood. Even after the body has reabsorbed the blood, the bursa may remain thickened and swollen.
- Infection, which may or may not have been caused by an injury to the skin over the patella. In this case the bursa will become filled with pus.
- Pain around the kneecap, worse with movement of the knee and better with inactivity
- Swelling on top of the kneecap
- Tenderness on top and around the kneecap
- Redness and warmth around the knee, particularly if the bursa is infected
- Reduced range of motion of the knee joint due to swelling and pain
- Inability to kneel on the affected knee
- Sometimes small tender lumps can be felt under the skin over the knee. These are areas of thickened bursa.
Your doctor will ask you questions related to your symptoms, your lifestyle, occupation and activities, and any previous injuries to your knee. The physical examination will include a visual evaluation and palpation (touch) of the knee to assess the amount of fluid over the kneecap and areas of tenderness. Your knee will be flexed and extended to determine the amount of mobility there is in the joint.
X-ray or other imaging techniques will probably only be necessary if a fracture is suspected, or initial treatment has failed to manage the problem.
Before your appointment with the doctor, the following measures can be taken to provide some relief from painful symptoms. Usually, prepatellar bursitis will respond to conservative treatment.
Your doctor may drain some or all of the liquid from the bursa, using a needle and syringe. This simple procedure, known as needle aspiration, can be performed in the doctor’s office. It will reduce the swelling and thereby relieve pain, and the fluid can be tested for possible infection. Sometimes your doctor may inject the bursa, at the same time, with cortisone medication to reduce the inflammation, if an infection has been ruled out. If an infection is present, you will be prescribed antibiotics.
- Rest the knee. Avoid kneeling or any activity that aggravates the condition.
- Apply ice, crushed in a bag and covered with a towel, to the knee for as long as possible without causing excessive discomfort, several times a day.
- Use NSAIDs (non-steroidal anti-inflammatory drugs) such as ibuprofen (Advil), naproxen (Aleve) or aspirin.
- Elevate the knee above heart level whenever possible.
- Perform exercises designed to increase range of motion of the knee and flexibility of the quadriceps and hamstring muscles of the thigh.
- Use a kneepad if kneeling is unavoidable.
- Wearing a knee brace, taping the kneecap or wearing orthotic inserts in the shoes may be helpful, depending on your particular circumstances.
If the bursa continues to fill, and symptoms are persistent and painful, your doctor will discuss the possibility of surgery to remove the bursa entirely. After surgery, the body may grow a new bursa in response to the movement of the skin over the patella. This is often a normal bursa so new painful symptoms should not be experienced.
These exercises should be performed twice each day, if possible. They will help to stretch and strengthen your leg muscles. Always exercise both legs.
Lie on your back on the floor, near a doorway, so that you are able to raise one leg and rest it on the wall next to the doorframe. Your other leg should remain straight out in front of you, extending through the doorway. Hold the stretch in the back of your raised thigh for 30 seconds. Repeat 3 times.
Stand facing a wall and place hands on it for support. Lean forwards until a stretch is felt in the calves. Hold for 30 seconds. Bend at the knees and hold for a further 30 seconds. Repeat 5 times.
Standing or lying down, hold the foot of the injured leg and draw it backwards towards the buttocks as far as possible until a stretch is felt in the front of the thigh. Keep the knees together. Hold the stretch for 30 seconds. Repeat 3 times.
Sitting on the floor with your injured leg straight out in front of you and the unaffected leg bent with the foot on the floor, contract the thigh muscles (the quadriceps) of the injured leg by pressing the knee towards the floor. Hold the position for 5 seconds. Repeat 10 times.
Lie on your back on the floor with your legs straight out in front of you and together. Slide the heel towards the buttocks as far as possible. Hold for 5 seconds then straighten. Repeat 10 times.
Brace for prepatellar bursitis:
A kneepad, or knee sleeve that incorporates a pad over the patella, may help to alleviate pain caused by bursitis, and protect the kneecap from further injury.