Bursitis is commonly diagnosed as the cause of pain in many areas of the body; you may have heard of it when people discuss their shoulder or hip. However, the condition is often not well understood and so I will explain here what bursitis is and why your might get pain referring from the bursa. A bursa is a sac of fluid often found close to joints in the body. It is thought that we have around 160 bursae within the body meaning there are often several around each major joint. Each bursa helps to minimise fricti.