Bursitis is a disease that takes place when a bursa is inflamed. A bursa is a fluid-filled sac that cushions an area of friction between tissues (e.g. tendon and bone). There are about 160 bursae throughout the body and they reduce friction between moving parts of the body such as around the joints of the shoulder, elbow, hip, knee, and near to the Achilles tendon in the heel. Bursae are lined with synovials, which are special cells that secret synovial fluid. The synovial fluid is rich in collagen and proteins and acts as a lubricant when parts of the body move.

Bursitis can be caused by iterative movements (such as repeated throwing of a ball), trauma (e.g. continuous kneeling or hitting the knee on a table), infection, and preexisting rheumatoid conditions.

In case a trauma occurs (continuous injury or direct impact.), inflammatory bursitis may occur causing chronic bursitis or acute bursitis. In case of chronic bursitis a trauma occurs to the shoulder (subdeltoid) bursa due to repetitive motion such as throwing a ball. Also, the front part of the knee can be inflamed (prepatellar bursitis) due to long or repetitive kneeing on a hard surface (scrubbing a floor or lay carpets). Acute bursitis occurs when a direct blow causes blood to leak into the bursa causing inflammation with pain and swelling.

An infection takes place when the bursae close to the surface of the skin has bacteria. This condition is called septic bursitis, it hits men in 85% of the cases and is normally caused by the staphylococcus aureus or staphylococcus epidermis bacterias. High risk persons to develop septic bursitis are people with diabetes, alcoholism, certain kidney conditions, those with supressed immune systems such as from cortisone medications (e.g. steroid treatments) and those with wounds to the skin over a bursa.

Rheumatoid conditions such as gout and pseudogout can develop bursitis from crystal deposits. When these crystals form in a bursa, they cause inflammation leading to bursitis.

Another type of bursitis is called ischial bursitis, which is an inflammation of the bursa that separates the gluteus maximus muscle of the buttocks from the underlying bony prominence of the bone used to sit on (called „ischial tuberosity“). Ischial bursitis is a form of bursitis that is generally caused by prolonged sitting on hard surfaces that press against the bones of the bottom or mid-buttocks.

Preventing bursitis

Bursitis can be prevented in several ways. The first thing to do is to reduce the activity that is causing bursitis for example in case of doing sports or throwing the ball to be catched by your dog. Another way to prevent bursitis is to use protective equipment such as kneepads or cushioning while doing gardening and scrubbing floors. Specially the following professions and other simmilars are highly advised to use knee protection and appropriate shoes or cushion the ankles with pads: roofers, plumbers, carpet layers

Besides, in order to improve flexibility and strengthen muscles dealing with joint motion it is highly recommended to do rehabilitatibe exercise. In case of having iterative bursitis (bursitis that returns) a physical rehabilitation is recommended in order to exercise and strenghten weak muscles.