A bursa is a small fluid filled sac that sits between tendons and bones (or tendons and skin), preventing abrasive rubbing against bones as muscles contract and relax. Bursae can become inflamed in a condition is known as bursitis.
While there are many bursae over the body, the most important (and most prone to bursitis) are located in the hip (trochanteric) and shoulder (sub-acromial and sub-deltoid). Other areas include the elbow, knee and Achilles tendon.
Typically bursitis is caused by overuse, trauma, inflammatory arthritis (such and Rheumatoid Arthritis and Gout) or infection. It may present as joint pain, tenderness, swelling and redness.
Treatment typically involves ice, rest and avoid aggravating activity in the early stages. In chronic cases rehabilitative exercise is important to prevent muscle wasting. Spinal adjustment and soft tissue techniques may also be useful.