Q: After several months of suffering pain in my right hip, I made an appointment with a rheumatologist, assuming I had arthritis. I found that I do, in fact, have osteoarthritis of my hip but I also found out that it was made worse – and maybe even caused – by Paget's disease of bone. What is that? Is it anything like osteoporosis? I am a 52-year-old man. Isn't this uncommon in men? What can I expect from here on?

A: It's understandable that you are not familiar with Paget's disease of the bone, because it is relatively uncommon.

Named for Sir James Paget, who first described the disease in the 19th century, Paget's disease of the bone occurs when a malfunction in the normal process of bone breakdown and rebuilding leads to excessive and disorganized new bone growth. As a result, the new bone that is produced is highly vascular (meaning, it contains a lot of blood vessels) and is enlarged and softer than normal bone.

The accelerated bone growth along with the resulting changes in bone structure is among the features that differentiate Paget's disease from osteoporosis, another bone disease. In osteoporosis, bone breakdown exceeds bone growth, leading to thin fragile bones. Also unlike osteoporosis, Paget's disease is slightly more common in men. It often begins between the ages of 50 and 70, and people of Western-European descent are more likely than African Americans to be affected.

Although Paget's disease is often painless, some people experience bone warmth and pain. Sometimes the pain comes from the joints. Because Paget's disease tends to affect the bones of the pelvis and legs and because bone changes may alter mechanical structure of the joints, painful osteoarthritis of the hips or knees can occur. Other common sites of Paget's disease are the skull, lower spine and sacrum (the tail bone).

Treatment for Paget's disease is based mainly on its symptoms and extent of involvement. The goal of treatment will be to relieve the pain in your hip. If there is only mild hip-joint damage and a good deal of bony change from the Paget's disease, your physician may want to treat the Paget's disease with one of several types of drugs you may have heard of in connection with osteoporosis. 

These include calcitonin, a parathyroid hormone derived from salmon; and bisphosphonates, including etidronate, pamidronate and the relative newcomer alendronate. There is also a newly approved bisphosphonate called tiludronate disodium. All of these drugs inhibit the process of bone turnover.

Fortunately, Paget's disease rarely spreads from one site to another. If the disease is, in fact, in your pelvis, it's not likely to affect your spine or skull. Also, the disease generally "burns out" in time, causing no additional pain or damage. Any damage the disease has already caused, however, is irreversible. If your hip joint has been damaged and the resulting pain is a problem, replacement may be needed to relieve pain.

You are wise to see a rheumatologist about this problem. Paget's disease is rarely life-threatening, but without proper treatment it can lead to fractures and other problems. In very rare cases, Paget's can transform into a life-threatening cancerous bone disease. With early and proper therapy, you should be able to maintain an active lifestyle and should experience few lasting effects of the disease.

Doyt Conn, MD, Rheumatologist