Bursae are fluid-filled sacs in areas of the body that facilitate movement by reducing friction and creating a cushion between two structures. The knee has several bursae around the patella, tendons, and ligaments.
The body’s musculoskeletal system enables humans to move. It involves structures like skin, tendons, muscles, joints, and bones moving over one another.
Several bursae lie around the knee joint.
This article discusses bursae in the knee, common issues, symptoms, causes, and more.
A bursa is a fluid-filled sac that produces small amounts of synovial fluid.
Bursae facilitate movement by providing a gliding surface for structures moving over each other. They also cushion soft tissues to reduce friction between the structures.
Common areas for bursae include spaces between:
- tendons and bone
- skin and bone
- tendons and joints
There are several bursae in the knee. Some of the major bursae in the knee include:
- Prepatellar bursa: This bursa lies between the patella and its overlying subcutaneous tissue.
- Superficial and deep infrapatellar bursa: The superficial infrapatellar bursa is located between the tibial tubercle and the overlying skin. The deep infrapatellar cushions the patellar tendon’s back (posterior) part against the tibia.
- Suprapatellar bursa: This bursa lies between the thigh bone and the quadriceps muscle.
- Pes anserine bursa: This bursa lies between the hamstring tendons and the superficial to the medial collateral ligament.
- Iliotibial bursa: This is the largest bursa in the body and protects the iliotibial band’s farther (distal) end against its bony insertion in the tibia.
Below are some of the issues people can experience with bursa.
Septic or infectious bursitis
Infection can also spread from distant sites and reach the bursa.
If a person does not receive appropriate initial treatment, they may develop chronic septic bursitis. This can lead to complications such as:
- continuous pain
- weakness or rupture of overlying ligaments and tendons
A ruptured bursa occurs when there is a tear in the bursa, causing inflamed or infected synovial fluid to leak into the joint and surrounding tissue. It can lead to the spread of infection in the body (sepsis) and septic shock.
Calcific bursitis happens when calcium deposits collect within the bursae. It can occur in people with longstanding untreated bursitis.
The symptoms of knee bursitis may vary depending on the bursa in question. Acute bursitis may cause the following symptoms:
- pain during motion
- limited movement
Crystal or bacterial-induced bursitis may also cause redness, pitting edema, warmth, and pain in the area around the bursa.
In contrast, chronic bursitis is
- repetitive motion, such as constant kneeling
- trauma from direct pressure
- infection from a direct penetration such as those from invasive procedures
- autoimmune conditions such as rheumatoid arthritis (RA), osteoarthritis, gout, scleroderma, and systemic lupus erythematosus (SLE)
People with diabetes may also have an increased risk of developing bursitis.
Cases of knee bursitis specifically can be due to:
- prolonged or constant kneeling
- improper training, such as forgetting to stretch, a sudden increase in workout intensity, or excessive uphill running
- tight muscles
- postural issues such as out-toeing (duckfooted) and genu valgum (knock knees)
- rheumatoid arthritis
Doctors diagnose most types of bursitis by checking for signs of swelling and pain that worsen with movement.
They may also use imaging techniques such as ultrasound and MRI to confirm the diagnosis when they suspect a deep bursa problem. This can also help exclude other possible conditions.
When there are signs of redness, swelling, and warmth, the doctor
A person may take over-the-counter (OTC) pain medicines to relieve pain. Cortical injections may offer symptomatic relief for the inflammation of deeper bursae.
If an underlying condition is causing bursitis, it is essential to get treatment for the underlying condition.
Doctors typically give oral antibiotics to people with septic bursitis.
If bursitis keeps recurring, a doctor may suggest removing it surgically through arthroscopy.
Other lifestyle changes that a person
- avoiding movements that can worsen the condition by using proper ergonomics
- using padding to protect superficial bursae
- performing stretching and core strengthening exercises
The following may help prevent knee bursitis:
- avoiding prolonged kneeling
- stretching and strengthening the thighs (quadriceps and hamstrings)
- avoiding deep knee bends
- avoiding running downhill
- wearing properly fitting shoes with good arch support
- changing shoes every 3 months
- avoiding wearing shoes with cleats
Knee bursitis is a very common condition that tends to resolve on its own. People with bursitis do not usually require hospitalization.
While people with bursitis generally have a good outcome, those who continue with the same activities and do not avoid the triggers may have recurring bursitis.
Below are some answers to questions people ask about the bursae.
What does the pain feel like in bursitis?
Acute bursitis may cause dull pain and tenderness in the affected area. However, chronic bursitis may cause no pain.
Will the pain go away?
Bursitis often improves within days to a few weeks.
How serious is knee bursitis?
Knee bursitis is rarely a serious condition. It is often a short-term irritation that does not cause long lasting damage unless a person continues to overuse or injure the area.
Knee bursitis is a common condition that happens because of knee bursa inflammation. This inflammation is often short-lived and lasts for several days to weeks.
Rest and lifestyle modifications can help relieve symptoms. However, symptoms tend to recur if they are due to repetitive movements a person performs at their job or during hobbies.
A person can prevent bursitis by identifying which motions and activities cause irritation and avoiding them.