Are there exercises I can do to strengthen my weak ankles and prevent sprains?

DEAR DOCTOR K: I tend to sprain my ankle fairly often. Are there any exercises that could help me strengthen my ankles and prevent future sprains?

DEAR READER: Your ankles are remarkable joints. They must bear the full weight of your body, yet stay nimble and flexible. Every step, every jump, every move puts your ankles through a surprising range of motion. Even when you stand quietly, your ankles are constantly making minute adjustments to help you stay balanced.

What should I know about playground safety?

DEAR DOCTOR K: Two of my child's friends have hurt themselves playing on the playground recently. What can I do to keep my child safe?

DEAR READER: Kids get exercise, burn off energy and develop their motor skills by running, jumping and climbing on swing sets, monkey bars and other playground equipment. But each year more than 200,000 children in the United States visit emergency rooms for playground injuries. The most common are broken bones, bruises, scrapes and deeper cuts. More serious injuries also occur.

How long should I wait to fly after scuba diving?

DEAR DOCTOR K: I'm planning a diving vacation. A friend told me it's not safe to fly within 24 hours of diving. Why not?

DEAR READER: I'm not a diver myself, so I had to do some research to answer your question. The concern with flying soon after diving (or rising too quickly to the surface of the water after a deep dive) is something called decompression sickness. It's also known as "the bends."

What is an ankle sprain?

DEAR DOCTOR K: I recently sprained my ankle. I know I twisted it and that it hurts when I walk on it, but what exactly happened to my foot?

DEAR READER: Many people use the words "sprain" and "twist" interchangeably. Though you may sprain your ankle by twisting it, the words do not mean the same thing. A sprain is a tear of ligaments, which are the tough bands of fibrous tissue that connect bones to one another at a joint.

My toenail turned black after an injury — what should I do?

DEAR DOCTOR K: I hurt my toe and now the nail has turned black. What can I do?

DEAR READER: Ouch -- I've been there. A couple of years ago I was outdoors and turned around to walk in the opposite direction, and boom! My big toe hit a lamppost. At least my toe got there before my face did. A day or two later the toenail was black and blue, and the day after that it hurt a lot. What I had, and what you probably have, is blood under the nail, a condition called subungual hematoma.

How can I loosen a frozen shoulder?

DEAR DOCTOR K: Is there any way to unfreeze a frozen shoulder?

DEAR READER: The term "frozen shoulder" describes a condition in which pain and stiffness cause a loss of the normal range of motion. Fortunately, a frozen shoulder can usually be unfrozen -- if you have the time, patience and willingness to experience a little pain.

Do I need surgery for a torn ACL?

DEAR DOCTOR K: I tore my ACL. Is surgery inevitable?

DEAR READER: The anterior cruciate ligament (ACL) is a band of tissue that runs through the middle of the knee joint and keeps the shinbone from sliding forward past the thighbone. The ACL can tear during a sudden or awkward twist, turn or stop. More often than not, it's these non-contact injuries that injure an ACL. Between 100,000 and 200,000 ACL injuries occur each year in the United States.

What’s the best way to treat shin splints?

DEAR DOCTOR K: I'm on my high school track team. I've developed painful shin splints. What's the best way to treat them?

DEAR READER: I was on my high school track team, too, but based on where I placed in my races, I'm not sure anyone noticed. Like you, though, I got shin splints. Shin splints commonly occur in runners.