We have +150 bursae throughout our bodies. They’re distributed in different joints, reducing the friction between tissues. But, how many bursa in the knee do we have specifically?
Well, most people have +10 bursae in the knee joint. Impressive, right? (1)
The majority of our knee bursae are small. They’re under layers of skin, muscles, and tendon, making it hard for them to have bursitis.
But, other knee bursae aren’t so lucky. Their location increases their risk of having bursitis. Those are the ones we’ll talk about below.
Here’s what you’ll learn about in detail:
- Basic knee anatomy
- Prepatellar bursa
- Infrapatellar bursae
- Pes anserine bursa
- Iliotibial bursa
- Other bursae
- How to treat bursitis
- Bursitis prevention
Knee bursae prone to knee bursitis
Let’s start with the basics – a little about human anatomy.
The knee joint is the biggest joint of the body. It’s the point of connection between several bones (2):
- The femur, or thigh bone.
- The tibia, or shin bone.
- The fibula, or calf bone.
- The patella, or knee cap.
There are several tissues between and around those bones.
We have two menisci between the femur and the tibia. They act as shock absorbers, protecting the bones.
Also, we have four ligaments inside and around the joint. They keep it stable.
Synovial fluid is a liquid inside the joint that lubricates it. It also nurtures the other tissues to keep them healthy.
The knee joint also has blood vessels, nerves, and muscles.
As you can see, large joints like the knee have a lot going on. And, it’s a tight space.
They need something to reduce friction between tissues.
That’s why knee bursae exist.
A bursa is a fluid-filled sac. It reduces friction between bones, muscles, and/or skin.
Our movements are smoother thanks to healthy bursae.
A bursa can have swelling due to excessive friction or prolonged pressure. This is called bursitis.
Now, there are different types of knee bursae. We name them after their locations:
1) Prepatellar bursa
The prepatellar bursa is located at the front of the knee. Between the top of the knee cap and the overlying skin.
It’s the most commonly injured bursa on the knee, due to its location.
Prepatellar bursitis often occurs after kneeling on hard surfaces for long periods. (3)
It’s common in certain occupations. Thus, why this type of bursitis is also called:
- Housemaid’s knee.
- Carpet layer’s knee.
- Carpenter’s knee.
Prepatellar bursitis causes anterior knee pain and swelling. It makes the knee look like a balloon. Bending the knee can be painful.
Also, this type of bursitis has a high risk of infection.
This is known as “septic prepatellar bursitis.” The treatment will depend on whether the bursa is infected or not.
More about it further down!
2) Infrapatellar bursae
The patellar tendon connects the kneecap to the shin bone. It’s a strong, thick band that helps us straighten our knees.
It has two bursae (4):
- The superficial infrapatellar bursa. On top of the tendon, under the skin.
- The deep infrapatellar bursa. Between the patellar tendon and the shin bone.
The superficial bursa has a higher risk of bursitis. Compared to the deep infrapatellar bursae.
Infrapatellar bursitis commonly occurs after prolonged kneeling. Like with prepatellar bursitis.
But, this type of bursitis is known as “clergyman’s knee.”
The clinical presentation of infrapatellar knee bursitis includes (5):
- Knee swelling and pain.
- A big lump under the kneecap. It can be tender to the touch.
- The person can have a fever if it’s septic bursitis.
3) Pes anserine bursa
This bursa is located between the tendons of:
- The semitendinosus, one of the hamstring muscles;
- The gracilis;
- And the sartorius muscles.
They form the “pes anserine” area, on the inner side of the knee. Their bursa reduces the friction between those muscles.
A direct hit in the area can cause pes anserine bursitis. Also, excessive friction due to overuse.
That’s why it’s a common injury in certain sports. Mostly, running and jumping sports. (6)
What does pes anserine bursitis feel like, you ask?
Well, you may feel swelling and pain on the inner side of the knee. Often while rising from a chair or crossing your legs. (6)
This bursa is unlikely to develop septic bursitis, though.
This is because it isn’t as superficial as the prepatellar or infrapatellar bursae.
4) Iliotibial bursa
The iliotibial band goes from the outer side of the hip to the knee. It’s a thick tissue that stabilizes our hip and leg.
The IT band has a bursa under it, close to the knee. This is the iliotibial bursa. (4)
Due to its location, iliotibial bursitis is common in runners.
The IT band rubs on the bursa constantly during running. This can cause inflammation on the bursa – IT knee bursitis.
People with this type of knee bursitis may need a sports physiotherapist.
They will help you improve your running pattern to reduce friction.
5) Other knee bursae
The suprapatellar bursa is above the kneecap, under the quadriceps tendon.
Suprapatellar bursitis is one of the less common types of bursitis. It can happen after a direct hit or excessive friction. (4)
We also have a bursa under the medial collateral ligament – the MCL.
This ligament is on the inner side of the knee. It’s a vertical band going from the thigh bone to the shin bone.
This location makes it the most commonly injured ligament in the knee. (7)
The MCL bursa can develop bursitis after a sprain of the ligament. Its symptoms are like those of a sprain, so it’s easy to confuse them. (7)
Treatment for knee pain due to bursitis
The treatment depends on whether the bursitis is septic or not.
If it is, the treatment is antibiotics. But, if it’s not, there are several treatments:
Treating acute bursitis is easy. If there’s no infection, most cases of knee bursitis resolve on their own.
You can do this at home with some rest and ice.
However, resting is key.
Your bursa needs time to heal. Remember not to push through the pain – you can cause a setback.
Also, ice packs can reduce pain and swelling.
If you have prepatellar bursitis, put the cold pack at the front of the knee. Secure the affected area with compression wrap if possible.
Leave it there for 10 minutes.
This can help: Home remedies for bursitis you can try today.
A physical therapist can be your best ally. They speed up your recovery time.
Physical therapy starts by managing pain, swelling, and other symptoms you may have.
Then, the focus is on strengthening your leg muscles. This will help you get back to your normal life.
A PT also teaches you how to prevent future episodes of knee bursitis. This is known as “patient education.”
That will make the difference between long-term recovery or not
PS: We can connect you with a qualified physical therapist in your area.
Septic bursitis needs antibiotics. Other types of bursitis can improve with anti-inflammatory medication.
But, if it’s not improving after 7-14 days, your doctor may consider doing a corticosteroid injection.
Corticosteroid injections can help bursitis that’s resistant to the treatments above.
These drugs can reduce pain and swelling fast. But, at the risk of introducing bacteria by accident. (1)
Further reading: How long does it take for knee bursitis to heal?
Although rare, some cases of septic bursitis don’t get better with antibiotics. Here, the doctor may consider doing an aspiration. (1)
The surgeon will remove the excess fluid with a syringe. This is a surgical procedure that you shouldn’t do on your own.
The last resort is removing the bursa. This is an option for people with recurrent bursitis. Or, for septic bursitis that doesn’t improve after aspiration.
How to prevent knee bursitis?
There are several ways to prevent knee bursitis.
First, if your job or hobby needs prolonged kneeling, buy knee pads.
They will soften the pressure on the front of the knee. Which can reduce your risk of having knee bursitis.
Also, take breaks from kneeling.
Stand and walk a little to give some rest to your bursa.
Second, return to your athletic activity little by little. Excessive friction causes knee bursitis.
Give your body time to adapt to the exercise. This will prevent not only bursitis but other injuries, too.
Related: How does knee bursitis feel like?
Some health conditions predispose people to knee bursitis.
For some people, preventing knee bursitis isn’t about resting or kneeling.
It’s about keeping a previous health issue under control. (1)
For example, people with rheumatoid arthritis have a higher risk of bursitis.
That’s an autoimmune disease that causes inflammation of the joints. That inflammation can also trigger bursitis.
Other health conditions that can cause knee bursitis include:
- Knee osteoarthritis.
- Psoriatic arthritis.
- A previous knee bursitis.
Which bursa is most commonly injured in the knee joint?
The prepatellar bursa. Followed by the infrapatellar and pes anserine bursae.
How many bursa do we have?
We have between 150 and 160 bursae in our bodies. (1)
What does bursitis of the knee feel like?
The affected bursa is swollen and can be painful. It looks like a bump or a balloon on the knee.
The symptoms tend to worsen with movement. Rest often reduces pain and inflammation.
If the bursitis is infected, you may have a fever as well.
Conclusion: How many knee bursae do we have?
Now you know we have +150 bursae in our bodies! And, more than 10 in the knee alone.
Bursae are fluid-filled sacs that reduce friction between tissues. We need them to move our bodies.
But, excessive friction or pressure on them can cause bursitis.
Prepatellar and olecranon bursitis are the most common types of bursitis.
Prepatellar bursitis affects the bursa on top of the kneecap. It’s the most common type of knee bursitis. People that kneel often are prone to have it.
Some conditions increase the risk of having knee bursitis. Like rheumatoid arthritis, gout, or alcoholism.
Yes, most cases of knee bursitis resolve on their own. But, if you’re having too much knee pain, seek professional medical advice!
- Lohr, Kristine. “Bursitis: Practice essentials.” [Updated 2020 Dec 11]. Medscape. Retrieved on August, 2021 from: https://emedicine.medscape.com/article/2145588-overview
- Kishner, Stephen. “Knee Joint anatomy.” [Updated 2017 Nov 30]. Medscape. Retrieved on August, 2021 from: https://emedicine.medscape.com/article/1898986-overview
- Rishor-Olney C R, Pozun A. “Prepatellar Bursitis.” [Updated 2021 Feb 22]. StatPearls. Retrieved on August, 2021 from: https://www.ncbi.nlm.nih.gov/books/NBK557508/
- Chatra, Priyank S. “Bursae around the knee joints.” The Indian journal of radiology & imaging vol. 22,1 (2012): 27-30. doi:10.4103/0971-3026.95400
- Jain, Mantu et al. “Infrapatellar bursitis presenting as a lump.” BMJ case reports vol. 14,5 e243581. 25 May. 2021, doi: 10.1136/bcr-2021-243581
- Mohseni M, Graham C. “Pes Anserine Bursitis.” [Updated on 2021 Jul 18]. StatPearls. Retrieved on August, 2021 from: https://www.ncbi.nlm.nih.gov/books/NBK532941/
- Schein, Aaron et al. “Structure and function, injury, pathology, and treatment of the medial collateral ligament of the knee.” Emergency radiology vol. 19,6 (2012): 489-98. doi: 10.1007/s10140-012-1062-z