Bursitis of the knee

Bursitis of the knee occurs when fluid fills up the knee, causing the kneecap to become reddened, painful and swollen. In the body, small sacks of fluid called bursae are found around joints to protect and stabilize these important areas. In the knee, there are 11 bursae that cover the kneecap to protect it from damage. When these burst, whether from trauma or overuse, the knee loses mobility and becomes painful to use when walking. 

Anatomy of the knee

The knee is the joint where the thighbone and shinbone meet. It consists of the following:

  • The femur (thighbone)
  • The tibia (shinbone
  • The patella (kneecap)
  • The bursae (small packets of fluid that protect the kneecap from trauma)
  • Articular cartilage
  • Collateral ligaments
  • Cruciate ligaments

The knee acts as a stabilizer for the body. Connecting the top part of the leg with the bottom, the knee has four ligaments that work together to provide stability and mobility, allowing the leg to smoothly bend at the joint so individuals can walk, jump and do other necessary tasks.


There are a few causes of bursitis of the kneecap:

  • Overuse – The most common cause of this injury is overuse, which is how it got the nickname housemaid’s knee or clergyman’s knee. When a person puts excessive pressure on this already very thin and delicate area, it can cause the bursae to become inflamed. This in turn can lead to an infection.
  • Acute trauma – When a person receives acute trauma to his or her knee, bursitis can easily develop. The fluids released after a trauma can easily cause infection in this delicate region. When this occurs, the knee becomes inflamed, which can in turn trigger bursitis of the knee. First, blood will flow from the injured area to the spot of inflammation. Then, a cellular reaction will begin and leukocytes will flow to the area, causing an infection.
  • Disease – Several diseases, such as gout, CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly and telangiectasia) syndrome, diabetes, sarcoidosis, mellitus, alcohol abuse and chronic obstructive pulmonary disease also can cause bursitis of the kneecap.


Bursitis is typically accompanied by pain in the affected area and is aggravated by pressure put on the knee by kneeling or from injury.

The following are common symptoms of bursitis of the knee. Depending on the cause of the condition, symptoms may be different for each person:

  • Swelling over the kneecap
  • Pain in the knee and up the back of the thigh
  • Limited mobility of the knee
  • Red and warm to touch

Bursitis of the kneecap symptoms occur because of bursae that break open and release fluid. This fluid is often considered to be just water in the knee, however it is important to understand the difference between that and other fluids in the affected area. For this reason, any person experiencing these symptoms should see a medical professional for help.


Bursitis of the kneecap can be divided into two main types of injury:

  • Prepatellar (kneecap) – Prepatellar bursitis is the type that occurs most commonly in athletes and people whose professions require them to spend time on their hands and knees. This is the most common form of this injury and is usually called housemaid’s knee, as historically, housemaids have gotten it from their many hours spent on hands and knees while cleaning. The prepatellar area is located beneath the skin in front of the kneecap and usually becomes inflamed or irritated from infections, injury or continuous kneeling. Regularly applying additional pressure to this fragile part of the body increases the risk of the bursa rupturing.
  • Pes anserinus – This occurs on the inner portion of the knee. The bursa in this area can become irritated when people run, have a condition where they knock knees, or if they are overweight. This type of bursitis of the knee typically comes with pain while sleeping or climbing stairs.


Treatment is fairly easy and requires simply rest, ice and compresses to help the bursa recover. However, in some cases, medicine and antibiotics may be required if there is an infection in the area. It is always important to see a doctor to ensure you do not have an infection or require a prescription.

The multidisciplinary team of experts at Northwell Health Orthopaedic Institute treats bursitis of the knee as well as a broad range of conditions that affect the bones.

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