Bursas are small sacs of membranes that are filled with fluid that act as a friction decreasing structure to decrease friction in different areas of the body. The bursa at the shoulder, hip and knee can commonly get inflamed to cause local pain. These injections are done with a mixture of local anesthetic and steroid, which tend to help the pain immediately.  After the local anesthetic wears off some pain may recur but generally once the steroid activates itself in 2-5 days, significant pain relief is noted, which can be temporary to permanent.  Risks are minimum in appropriately performed injections. The best results are obtained with injections combined with activity modification with or without appropriate rehabilitation.