Bursitis is inflammation of a bursa. A bursa is a thin, slippery piece
of tissue that protects tendons, usually from bones inside a joint. It allows
the tendon to glide easily over the bone. The bursa reduces friction between the
tendon and the bone.
There are many bursae in the body protecting underlying tendons. Bursitis most
often occurs in the following joints:
- Shoulder
- Elbow
- Knee
- Hip
- Ankle
Causes
Acute
Bursitis may be caused by:
- A blow to an area containing a bursa
- Overexertion of a joint (for example: swimming a long distance or throwing
a ball many times)
Chronic bursitis is usually caused by long-term overuse of one muscle-tendon
unit, for example a joint. The repeated motion of that muscle-tendon unit causes
friction in the bursa. As the activity continues, the bursa becomes inflamed and
may fill with fluid. The bursa thickens and does not function well. Both bursa
and tendon may become irritated.
Risk Factors
A risk factor is something that increases your chance of getting a disease or
condition.
- Repetitive motion activities when done to an extreme (such as swimming,
running, or tennis)
- Contact sports
- Sporting gear that does not fit well
Diagnosis
The doctor will ask about your symptoms and your physical activities, and
examine the painful area.
Tests may include:
- X-ray
- Magnetic resonance imaging (MRI) - rarely