The Anatomical Explanation
The most common cause of bursitis is the same thing that causes pain in your body and your relationships, friction. In all seriousness, the friction that the bursa is designed to absorb and reduce is often the very same thing that causes its own affliction.
When two parts of your body have a bursa sac between them they use it as a buffer a glide surface so they do not irritate each other. The bursa sac is filled with a slick, viscous liquid called synovial fluid. This liquid lets the opposing sides of the bursa sac rub against themselves as the body parts they are protecting rub on the outsides without building up much friction.
If you take a small beach ball and start to blow it up but then you stop putting air into it when you can still squish it down to about a third of its full height you'd have a good comparison to a bursa sac. If you then put that underinflated beach ball between your hands and press them together you will see how a bursa sac works.
Move your hands back and forth and watch the walls of the beach ball stay on your hands while the beach ball sac deforms and slides against the air inside. You actually have a large range of motion while it is underinflated. Now put some more air into the beach ball. You can't move the ball back and forth in your hands as far. If you inflate the ball until it is full you can't move your hands much at all.
This happens in a bursa sac as well. In a healthy bursa sac there isn't that much fluid in the sac so there is a great deal of motion available. However if there is significant repetitive stress or overuse of the bursa sac the body may respond by providing extra synovial fluid to the bursa sac to increase the cushion between the body parts using it. If this continues the excess fluid can cause inflammation directly or the reduced movement capability of the bursa sac can cause friction to build up resulting in the irritation and inflammation of the bursa sac that is bursitis.
This inflammation is commonly caused by repetitive motion or overuse that strains the bursa sac. However an acute trauma or injury may cause the same bodily response leading to bursitis. In these cases, and sometimes with repetitive stress, all of the fluid swelling the bursa is not synovial fluid, but foreign fluids such as blood, edema or others.
Another way that acute trauma can cause bursitis is when the space that the bursa sac occupies becomes deformed or changes somehow and now the bursa does not fit in the space correctly.
A form of bursitis called Septic Bursitis is actually caused by an infection in the bursa sac. In Septic Bursitis the infection causes swelling and inflammation of the bursa sac resulting in the same symptoms as regular bursitis with the addition of a fever as your body fights off the infection. If you have a fever in conjunction with bursitis you should seek medical treatment.
Your physical health factors into bursitis. Maintaining a healthy weight and staying hydrated are keys to preventing repetitive stress injuries. Also important is your flexibility. If you are not flexible than any activity may be enough to cause bursitis. Failing to adequately stretch before and after exercising may cause bursitis for much the same reason.
Having bad posture may cause bursitis. If your posture is bad you may be putting undo stress on your joints and pressure on the related bursae. This can lead to bursitis. Maintain a good, balanced and strong posture for whatever activity you are performing.
Know More: The Basics of Good Posture
The typical body is balanced and symmetrical. Among other things (such as making you more attractive) the symmetry of your body helps balance and distributes stress evenly throughout your joints. If you have some asymmetrical anatomy this distribution could be thrown out of whack. Say you have one of your lower leg bones is half an inch longer than the other. This introduces a shift throughout your entire body that must be compensated for through unbalanced muscle loading and affects to your posture. Now you have got all kinds of added stress on some of your joints. And this additional stress can easily over-stress and inflame a bursa sac.
Anatomical asymmetry may be genetic and you have had it since birth or it could be the results of a severe injury such as a broken bone. It can even be the result of arthritis in your joint. Once identified you may be able to compensate for it with orthotic inserts in your shoes or other postural aids.
Some conditions and ailments may cause enough stress on a bursa sac for bursitis to develop, especially inflammatory conditions. Rheumatoid arthritis and psoriatic arthritis, thyroid disorders and gout are common culprits.
Age can also play a role in causing your bursitis. As you age your tissue loses some of its elasticity. Everything gets stiffer as you get older and that includes your bursae and tendons. And when your tendons lose elasticity they can not handle stress as well. So what might have been a normal level of activity at 40 years of age can become a repetitive stress or a period of overuse at 60.
Repetitive Motion Activities that May Cause Bursitis
Like with most repetitive stress injuries sports can be a likely cause of bursitis. Sports provide a lot of repetitive motion to joints as well as impacts that can cause micro traumas. Larger traumas as well as commonly flexing joints to the extremes of their range of motion are also common place. Some sports that see a high occurrence of bursitis in one or more joint areas are:
- Tennis and other racquet sports
- Baseball (throwing and pitching)
Workplace activities as well as active hobbies can provide the same sources of repetitive motion and micro traumas that sports can. Activities that require the use of strength from your legs through your back while flexing your waist, back and arms are particularly troublesome for developing bursitis. Additionally knee bursitis is common in those who work a lot while on their knees. Some of these activities are:
- Typing/Computer Use
- Yard Work (Shoveling, raking, etc.)
- Wood working
- House cleaning, especially hard scrubbing while standing or on your knees
- Construction work
When it comes down to it even sitting can cause bursitis. Bursitis in the buttocks can be caused from the constant pressure placed on them from sitting on hard surfaces for long periods of time.
Clothing and Conditions
There are two types of repetitive stress that can cause bursitis, repetitive motion and constant, excessive pressure on a joint. Restrictive clothing that puts constant pressure on a joint or conditions that affect your posture and apply continuous pressure on your body can cause bursitis just as surely as ten hours of tennis a day.
The most common form of bursitis caused by restrictive clothing is a bunion. If your shoes are too tight at the toes the bug toe may be constantly pushed inward. This can irritate the bursa sac at the big toe's knuckle resulting in a painful and tender "growth" on the outside of the big toe knuckle. This is often actually just an inflamed bursa sac.
Conditions that can lead to bursitis are things like have to hunch over while working in a mine, traveling in confined spaces and things of that nature which hold your joints in awkward and unnatural positions for long periods of time.
Bursitis can be caused by many things. If you avoid repetitive stress and prolonged pressure on joints and are reasonably healthy you may never develop bursitis. However if you do develop bursitis it is beneficial to identify the cause of it for your diagnosis as well as modifying your behavior so you won't get again in the future.