DEAR DR. DONOHUE: Our 9-year-old son plays all sports with passion and a skill beyond his years. This winter he has been on a basketball team. Last week, I noticed him limping. I asked if he hurt himself and he said no, but his left leg hurt and he pointed to his hip area. I took him to our doctor, who ordered X-rays. They showed he has Legg-Calvé-Perthes disease. We have some unanswered questions. He’s in a cast put on by an orthopedic doctor. How long will he stay in it? Will he ever play sports again? – R.H.

ANSWER: Legg-Calvé-Perthes disease is not an unexpected diagnosis in children between the ages of 2 and 12 who develop a limp and hip pain.

For reasons unknown to anyone, the blood supply to the topmost part of the thigh bone, the part that makes the hip joint, is suddenly cut off. That part of the bone begins to crumble. The process is called avascular necrosis, and in a slightly different form, it can happen to adults too.

In time, the blood supply is re-established and new bone forms.

While the process is going on, the goals of therapy are to relieve pain and the muscle spasms that contribute to the pain. The orthopedic doctor put a cast on the thigh to preserve the hip’s range of motion and to make certain that the new bone fits snugly into the hip socket.

How long the cast remains on depends on how long it takes for new bone to form. Your child was treated early, so healing is likely to be relatively quick. Quick here can mean a year or so. He might not have to be in a cast that long, but he probably won’t be able to play sports until then.

Most children return to full athletic activities. A small percentage develop arthritis in early adulthood.

DEAR DR. DONOHUE: I would love to be rid of calluses on the heels of my feet. Sometimes they are so bad that I take a pair of nail clippers and start clipping. After that, I start picking and peeling the skin off until it starts to bleed. Then I take a pumice stone to smooth it out.

The calluses always come back no matter how much of my foot I end up removing. What can I do? – K.A.

ANSWER: If you treated someone else’s calluses the way you treat yours, you could be accused of cruel and unusual punishment. The Eighth Amendment to the Constitution forbids that.

A callus is the body’s way of protecting itself against pressure. Something is irritating your heels. It most likely is your shoes. Or your feet might be hitting the ground in a peculiar and abnormal way.

To get rid of calluses, put away the nail clippers and stop the picking and peeling. Soak your feet in warm, soapy water for at least 15 minutes. Then with an emery board or a pumice stone, gently rub the hard skin off the callus. The emphasis is on “gently.” Do this every day until the calluses are gone.

To solve the recurring callus problem, you have to relieve the pressure on your heels. Most likely that will mean investing in new shoes with heels that fit your feet perfectly.

DEAR DR. DONOHUE: While dancing a fast disco, I was twirled and landed on the floor. I quickly got up and continued dancing. The next day I felt sore on my right side. Three weeks later, it still hurt, and I saw the family doctor, who ordered X-rays. I have a fractured right rib. My workout buddies, mostly male, say there is nothing to do for a rib fracture. I am not in pain. Should I exercise the upper body, or should I see another doctor? – E.W.

ANSWER: Either you’re the world’s greatest stoic or your fracture is not a bad one. Yes, you should see another doctor. No, you shouldn’t exercise the upper body until the rib is healed, and that takes four to six weeks.

Your friends are right. There is nothing extraordinary to do for a rib fracture other than pain relief and making sure the two broken ends are aligned.

DEAR DR. DONOHUE: After numerous tests, a pediatric gastroenterologist reluctantly diagnosed my 14-year-old son with intestinal lymphangiectasia. I say “reluctantly” because she felt that the illness was so rare that the likelihood of his having it was remote. A second opinion confirmed the diagnosis, however.

Is this condition permanent? Is there any medicine for it? His low-fat diet helps – when he stays on it. – N.S.

ANSWER: Your son does have an unusual condition. Lymphatics – lymph vessels – are similar to arteries and veins, but they’re part of a separate circulatory system, the lymph system. Lymph is fluid that oozes out of blood vessels, percolates around tissues and cells, brings them nourishment and flushes away waste material. The lymphatic vessels are open-ended hoses that suction up lymph fluid and return it to the primary circulation.

Your son was born with lymphatics that are stretched out of shape. Lymphatics are the vessels that fats take to enter the general circulation when they are absorbed by the intestine. Dilated lymphatics don’t absorb fat normally. The result is diarrhea, stomach pain and weight loss. Often, people with this condition also lose body protein.

Your son’s condition is unpleasant and serious, but it must not be so bad that it has bothered him from birth or has stunted his growth. You didn’t mention either one. That’s something in his favor.

There is no medicine that can correct the problem, and it doesn’t get better with time. But a diet that eliminates the kind of fat that is difficult for these people to absorb can generally eliminate the diarrhea and the stomach pain.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.