Bursitis
A bursa is a slim, fluid-filled sac whose purpose is to reduce friction and pressure wherever needed, such as between bones and surrounding soft tissues (e.g. muscles, tendons, ligaments, and skin).
You have around 160 of them, ranging in size from millimetres to five or six centimetres, depending on location.
They are good at their job, but sometimes even the structures designed to cushion and lubricate can get a bit overwhelmed. When this happens, you get inflammation (you may remember that is what the ending -itis means) and hence a bursitis.
You have around 160 of them, ranging in size from millimetres to five or six centimetres, depending on location.
They are good at their job, but sometimes even the structures designed to cushion and lubricate can get a bit overwhelmed. When this happens, you get inflammation (you may remember that is what the ending -itis means) and hence a bursitis.
These images show the location of some of the bursae around the shoulder and knee, for example. As you can see, they are plentiful. However, because of their location and the forces they have to deal with, some bursae are more likely to develop issues than others. The prepatellar bursa lies just in front of the kneecap, and can be irritated by too much kneeling on hard surfaces. It used to be called (the now-dated) 'housemaid's knee'. The one just below the kneecap (infrapatellar bursa) gave rise to (the arrestingly specifically-named) 'clergyman's knee'. Nowadays, it is just as likely (if not more!) to be a tiler or other tradie who suffers from these conditions rather than cleaners and priests. |
The trochanteric bursa lies between the bony prominence on the outside of the hip area, at the top of the thigh. Trochanteric bursitis can be caused by tight gluteal (buttock) muscles, and weakness or degeneration of these muscles and their tendons is a big predisposing factor towards this issue. Trochanteric bursitis may also mimic low back pain, and send pain radiating down the outside of the thigh.
The subacromial bursa can be seen in the picture to the right, on the top of the shoulder joint, and underneath the bony shelf that lies above it. This bursa gets compressed when we lift our arms straight out to the side, and its bursitis is often associated with rotator cuff and other shoulder problems.
The olecranon bursa is on the bony point of the elbow, and can be irritated by leaning on this point too much.
Anyway, I don't want to list all 160-odd bursae and the quirky historical names for their bursitides (the plural for 'bursitis'); but they are worth bearing in mind as a source for your undiagnosed pain.
You can get more information on some of the specific bursae and how they cause issues in our blogs on rotator cuff shoulder pain and common causes of knee pain.
The subacromial bursa can be seen in the picture to the right, on the top of the shoulder joint, and underneath the bony shelf that lies above it. This bursa gets compressed when we lift our arms straight out to the side, and its bursitis is often associated with rotator cuff and other shoulder problems.
The olecranon bursa is on the bony point of the elbow, and can be irritated by leaning on this point too much.
Anyway, I don't want to list all 160-odd bursae and the quirky historical names for their bursitides (the plural for 'bursitis'); but they are worth bearing in mind as a source for your undiagnosed pain.
You can get more information on some of the specific bursae and how they cause issues in our blogs on rotator cuff shoulder pain and common causes of knee pain.