My mother had a total shoulder replacement six months ago. Six weeks later she started having all kinds of problems with that arm. The doctor says it's a condition called CRPS. Can you tell me what this is and what causes it?

CRPS stands for complex regional pain syndrome. It's a group of symptoms with no real known cause. It usually occurs after surgery or trauma. Women are affected more often than men. Children can get CRPS, but it occurs more often in adults. Symptoms occur in the arm or leg that's been injured or operated on.

The patient often has pain that can be very severe. Changes occur in the skin. It can become dry and flaky or smooth and shiny. Sometimes the patient loses the hair on the arm or leg that's affected. Other times hair grows more on the involved limb.

There are ways to treat this problem, though symptoms come back in about half of all patients. Ask your mother's doctor about treatment options. Physical therapy and medications are usually tried first. Surgery may be needed if these don't work.