Knee bursitis occurs when there is irritation or inflammation in one of the knee bursa. Bursa are small fluid filled sacs that reduce the friction between two surfaces. They are found all over the body, and sit between bones and muscles, a bit like ball bearings. They allow the muscles to move freely as they contract and relax without being subjected to too much strain or friction.
Bursitis is usually caused by either repetitive friction on the area from movements such as jumping/kicking or muscle tightness, or from a sudden injury to the knee. It results in pain and swelling, most commonly just below or behind the knee.
Here, we will look at the common causes, symptoms and types of knee bursitis as well as how to prevent it.
Bursitis of the knee usually arises when there is excessive pressure and friction on the bursa. There are two main causes of this. Repeating the same movements over and over such as kneeling or squatting can cause the bursa to swell and become inflamed. Alternatively, if a muscle is tight it tends to push down on the bursa and squash it, which can lead to irritation and inflammation.
Knee bursitis can also develop after an injury such as a sharp blow to the knee. Alternatively, if there is swelling in the knee from wear and tear e.g. arthritis, or from inflammation e.g. gout this excess fluid can seep into the bursa, causing it to swell.
The most common symptoms of bursitis of the knee are pain and swelling. This tends to come on gradually over time and symptoms often come and go and aren't always consistent. If the bursitis of the knee was caused by an injury, symptoms will however come on very rapidly.
Sometimes you can feel a squashy lump where the bursa has swollen. This is most common behind the knee, known as a Bakers Cyst.
There are approximately eleven bursa located around the knee and bursitis can develop at any one of the bursa knee locations.
The most common types of knee bursitis are:
1) Prepatellar Bursitis: This is found at the front of the knee, just below the kneecap. It is a common problem for people who spend long periods kneeling e.g. carpet layers/roofers. Irritation here is known as Housemaids Knee causing pain and swelling just below the knee
2) Infrapatellar Bursitis: This occurs just below the kneecap and is often referred to as Clergyman's knee. There are two types of infrapatellar bursitis. The superficial infrapatellar bursa sits between the skin and the patellar tendon and the deep infrapatellar bursa sits further in behind patellar tendon cushioning it from the shin bone behind.
3) Pes Anserine Bursitis: This occurs on the inner side of the knee. The pes anserine bursa sits between the medial collateral ligament and the conjoined medial knee tendons of the gracilis, sartorius and semitendinosus muscles. Pes Anserine bursitis usually develops from overuse and most commonly affects runners.
4) Semimembranosus Bursitis: This is found at the back of the knee and is a common problem associated with arthritis. The semimembranosus bursa sits between one of the hamstring tendons (semimembranosus) and the gastrocnemius calf muscle. Irritation here is known as a Bakers Cyst or popliteal cyst causing swelling and pain behind the knee.
5) Iliotibial Bursitis: This occurs on the outer side of the knee. The iliotibial bursa sits between the iliotibial band and the outer shin bone, just below the knee. It is often misdiagnosed as iliotibial band syndrome.
The two most common types of bursitis of the knee are Housemaids Knee and a Bakers Cyst. You can find out more about these conditions, including simple knee bursitis treatment techniques by choosing from the links.
With any problem, prevention is better than cure. The best things you can do to avoid knee bursitis are to:
1) Ensure there is no muscle imbalance in the leg (weakness or tightness)
2) Wear Gel knee pads if kneeling for prolonged periods
Knee stretches ensure the muscles aren’t putting the bursa under any extra strain, and strengthening exercises ensure the forces go through joint correctly without putting extra pressure on the bursa. There are easy to follow exercises that can help you avoid bursitis of the knee, just click on the links above.
Gel Knee Pads reduce the forces going through the joint when kneeling and eliminate friction on the bursa.
If this isn't sounding quite like your problem, visit the knee pain diagnosis section for helping working out what is wrong.