How are knock knees different from bow legs?

Key points in 30 seconds

1. Knock knees are a shape where the knees touch and the ankles are apart, the opposite of bow legs.
2. They're usually found not by the leg shape but through knee pain or frequent ankle sprains.
3. Knock knees at age three or four are part of growing, so we usually watch and wait.
4. If they're still clear after age seven, get them checked once.
5. Treatment starts not at the knees but at the pelvis and feet.

What we often hear

• "I was told I have knock knees. How is that different from bow legs?"
• "My knees bump into each other."
• "The inside of my knee hurts when I walk."

How are knock knees different from bow legs?

It's a shape where the knees touch but there's a gap between the ankles. It's the opposite of bow legs, and so is the reason people come in — usually not because of how it looks, but because it hurts.

People who come in for bow legs usually say first, "people keep commenting on the shape of my legs." Knock knees are different. Most people come in saying "the inside of my knee hurts" or "I keep spraining my ankle and falling," and the leg shape is found while examining them.

In medicine, knock knees are called "genu valgum," and bow legs "genu varum."

How can I tell at home?

Stand at attention in front of a mirror. If your knees touch but there's a gap of a fist or more between your ankles, you lean toward knock knees.

Bow legs are the opposite: the ankles touch, but there's a gap between the knees. The two go in opposite directions, so the places treated are opposite too.

If it's a child, can we leave it alone?

It depends on age. A knock-knee stage is a normal part of growing, so knock knees at that stage are usually watched.

Most children go through this process. At birth the legs are slightly bowed, they straighten around age two, then at three or four they turn the other way into a knock-knee shape. Then around six or seven they straighten out again.

So if knock knees are still clearly there after age seven, it's a good idea to get them checked. It means the period when they straighten on their own has passed.

As for why they don't straighten: when knock knees form at three or four, if the inside and outside of the knee take different amounts of force, the growth plates get different stimulation too. If that difference remains, the legs can't straighten when they should.

Why does it hurt?

Because strain concentrates on the ligament that holds the inside of the knee, and the foot arch drops at the same time. So symptoms come from both the knee and the foot.

The knee has a ligament on the inside and one on the outside that hold it from the side. With knock knees, the inner ligament keeps getting strained in the direction of stretching. Often only the inside hurts at first, and later people say the whole knee hurts.

The feet go along with it. As the ankle tilts inward, the arch drops and the foot becomes like a flat foot. In that state, the feet get tired after even a short walk, and you trip over your own legs or sprain your ankle often.

How do you treat it?

We work not on the knees but on the pelvis and feet. With knock knees, the pelvis is often tilted forward, and the foot arches have dropped.

When the pelvis tilts forward, the abdominal muscles and the muscles at the back of the thighs weaken, while the lower back muscles and the muscles at the front of the thighs shorten. If this is left as it is and only the knees are treated, it doesn't last long.

So along with Chuna, we give exercises that loosen what has shortened and get the weakened parts working. If the arches have dropped, we support them with insoles, and we also look at how you walk.

But not everyone has this pattern. Some people with knock knees have a pelvis tilted backward, and some have arches that are too high rather than flat feet. If someone doesn't fit the common pattern, where we work changes. That's why we check first.

When should I see another doctor first?

If one side is especially severe, it keeps getting worse as the child grows, or the legs are bent and the child is much shorter than peers, see an orthopedic doctor first.

Sometimes the cause is a problem with the bone itself, damage to a growth plate, or another condition. That's not something we check. It's the same as we said about bow legs — when the bone itself is bent, it's beyond what correction can do.

What are the limits of this assessment?

We don't have numbers on how much straighter the legs become. What we aim for is less about the shape and more about relieving the spots where strain concentrates.

One more note. We don't promise to straighten the legs by a certain number of degrees. What's possible differs greatly depending on how bent the bones are, age, and how long it has been this way.

We start by seeing which way the knees are pulled. Knock knees and bow legs bend in opposite directions, so the muscles that need strengthening are opposite too.

If you're not sure which type your legs are, come in and get measured. It doesn't take long.

What's possible differs from person to person depending on how bent the legs are and age.