I have a toenail fungus that just won’t go away. What can I do?

DEAR DOCTOR K: I have a toenail fungus that just won't go away. What can I do?

DEAR READER: Fungal toenail infections occur when a fungus infects the area under the surface of a toenail. Fungi love warm, damp environments, and the space inside our shoes provides the perfect habitat. As the infection takes hold, it creates a strong, unpleasant odor. The toenail thickens and turns yellowish-brown. Eventually the nail may separate from the nail bed. Fungal infections are notoriously difficult to get rid of, but there are things you can do to stop their spread and improve your toenail's appearance.

What is flexible flatfoot, and does it need to be treated?

DEAR DOCTOR K: At my son's 12-year well-child visit, his doctor said that he may have flexible flatfeet. What does that mean? Is it something that needs to be treated?

DEAR READER: A person is said to be flat-footed when the foot loses the gently curving arch on the inner side of the sole. That's why flatfeet sometimes are called "fallen arches." If the arch is flattened only when standing and returns when the foot is lifted off the ground, the condition is called flexible flatfoot. If the arch is never present, the condition is called rigid flatfoot. (I've put an illustration of flatfoot, below.) How can parents tell if they or their child have flatfeet?

Is there a “correct” way to walk in order to reduce the risk of injury?

DEAR DOCTOR K: I'd like to start walking more for exercise. Is there a "correct" way to walk in order to reduce the risk of injury?

DEAR READER: Walking comes so naturally to most of us that we may not even give a second thought to proper walking technique. But bad walking habits can lead to a host of problems. What could be more natural than walking? We've been doing it since we were toddlers. It is natural, but in fact a complex series of things happens when we walk. First, your heel touches the ground, absorbing the impact of your weight. As the rest of your foot reaches the ground, your weight shifts forward to the ball of your foot and your toes.

Can hammertoe be reversed?

DEAR DOCTOR K: Can hammertoe be reversed?

DEAR READER: The four smaller toes of your feet are composed of three small bones, connected by two joints. Hammertoe develops when tendons and ligaments -- the fibrous tissues that connect muscles and bones to one another -- contract. Instead of lying flat, the toes very slowly start to hump up. A bend develops in the joint between the first and second bones; the tip of the toe starts to curl up. The toe resembles a hammer, hence the name.

What is Morton’s neuroma?

DEAR DOCTOR K: I have something called Morton's neuroma. Can you explain what it is, and what I can do to relieve the pain?

DEAR READER: A neuroma develops when a nerve is compressed, injured or pinched, causing swelling and pain. A neuroma in the area between the third and fourth toes, or between the second and third toes, is known as a Morton's neuroma. Morton's neuroma causes sharp, burning pain and numbness in the toes and foot.

What can I do about swollen legs and ankles?

DEAR DOCTOR K: Why are my legs and ankles swollen? What can I do about it?

DEAR READER: In yesterday's column, I answered the first part of your question. I explained the different causes of leg and ankle swelling (edema) -- some not serious, and others very serious. Today I'll explain what your doctor needs to do to diagnose the cause of the edema, and what you and your doctor can do to reduce the swelling.

Why are my legs and ankles swollen?

DEAR DOCTOR K: Why are my legs and ankles swollen?

DEAR READER: Swelling of the legs from a buildup of extra fluid is known as edema. In addition to the swelling, the skin above the swollen area is stretched and shiny. Your doctor can easily check for edema by gently pressing a finger over your foot, ankle or leg with slow, steady pressure. If you have edema, you will see an indentation where the doctor pressed.

What is the best way to treat blisters?

DEAR DOCTOR K: I wore a new pair of hiking boots on my vacation and now have several painful blisters on my feet. What's the best way to treat them?

DEAR READER: It sounds like you have friction blisters. A friction blister is a soft pocket of raised skin filled with clear fluid, caused by irritation from continuous rubbing or pressure. The irritation -- in your case caused by new hiking boots -- slightly damages the skin. The uppermost layer of skin separates from the layer beneath, and fluid accumulates in the space that's left.

What causes gout?

DEAR DOCTOR K: What caused my gout? Will avoiding certain foods prevent flare-ups?

DEAR READER: Gout is a painful joint condition. I know, because I've suffered from it. I spoke to my Harvard Medical School colleague, rheumatologist Dr. Robert Shmerling, to get the latest information. Gout attacks come on suddenly, with sharp pain, often in a single joint. The big toe is a common target.

What is the best treatment for a painful bunion?

DEAR DOCTOR K: I have a painful bunion. What is the best way to treat it?

DEAR READER: A bunion occurs when two bones in your foot no longer line up properly. Normally, a bone in the foot lines up straight with the first bone in your big toe. With a bunion, the joint where those two bones meet no longer is straight. Instead, there's knobby bone bulging outward at the base of your big toe. And the big toe itself turns inward, bending toward, or even under, the other toes. As a result, the knobby bone at the base of your big toe points outward.