My inner knee aches. Is it because of my bow legs?

If the outside of your knee feels fine but the inside keeps aching

Key points in 30 seconds

1. When the legs curve outward, every step puts your weight more on the inside of the knee. This may be why the inside hurts while the outside feels fine.
2. In research that followed thousands of knees over time, bow-legged alignment raised the risk of developing arthritis on the inside of the knee by about 1.5 times, and the risk of it getting worse by about 3.6 times.
3. The load on the inside of the knee is close to "how curved × how heavy." The angle of the curve is hard to change, but your weight can change.
4. That said, inner knee pain has several possible sources, such as a worn joint, the tendon attachment just below the joint, or a meniscus injury, so we first sort out where exactly it hurts and when.
5. If the knee is swollen and warm, hurts at night, locks or gives way, or started hurting after an injury, checking the joint comes first.

What we often hear

• "My legs have always been a bit curved, but lately the inside of my knee has started to ache."
• "The outside is fine. Why is it always just the inside that hurts?"
• "The first few steps after I get up in the morning are the stiffest."
• "I've put on some weight over the last few years. Could that have something to do with it?"

Your legs have always curved a little. You thought of it as just a matter of looks. Apart from pants not fitting quite right, it never bothered you.

But at some point, the inside of your knee started to ache. After a long walk, going down stairs, taking the first few steps in the morning. The outside is fine. It's always just the inside.

Could it be connected to your curved legs? Quite possibly. And once you know that, it becomes clearer what to do.

Why the inside, of all places?

When the legs are straight, each step sends your weight through the middle of the knee, split fairly evenly between the inside and the outside.

When the legs curve outward, things change. The path the weight travels shifts toward the inside of the knee. The inside ends up carrying more of the weight the whole knee should be sharing. It's a bit like a seesaw with someone always sitting on just one end.

This imbalance repeats thousands of steps a day, and builds up over decades. In large follow-up studies, bow-legged alignment raised the risk of new arthritis on the inside of the knee by about 1.5 times, and the risk of existing arthritis getting worse by about 3.6 times. These numbers confirm that the side where the weight concentrates is the side that wears first.

What multiplies it: body weight

The load on the inside of the knee is close to "how curved" multiplied by "how heavy." Even with legs curved at the same angle, if your weight goes up, the load on the inside goes up with it.

Have your legs looked the same for years, but your inner knee started to hurt as your weight went up over the last few years? If so, the timing may not be a coincidence.

There's good news, too. The angle of the curve is hard to change, but the other side of this multiplication can change. What happens to the knee when you lose weight is covered separately in the weight-loss article.

The same "inner knee" pain can have different causes

Not all inner knee pain is caused by bow legs. There are three main types.

Pain from a worn joint. It hurts at the level of the joint line, the gap that forms when you bend your knee. It often hurts and feels stiff after a long walk, going down stairs, or with the first step in the morning. This is the type most directly linked to bow legs.

Pain a little below the joint, where tendons attach. It hurts when you press on the inside about two or three finger-widths below the joint line. It aches when climbing stairs or getting up from a chair. This may be a problem with the tendons around the joint, which calls for a different approach.

An injured meniscus inside the knee. If the knee catches or locks, gives a sharp pain when you twist it, or swells, this needs to be checked.

These distinctions are only a rough guide, not a diagnosis.

Knees that need checking before we talk about bow legs

If any of the following apply, we look at the joint first.

• The knee is swollen and feels warm
• It hurts at night, even at rest
• The knee suddenly locks or gives way
• The pain started after an injury

In that case, we check the joint first, in partnership with the radiology clinic on the 2nd floor of the same building.

The angle may stay the same, but the inner knee can hurt less

First, reduce one side of the multiplication. If the time your weight went up overlaps with the time the pain started, managing your weight is a direct treatment for your knee. Skipping meals doesn't last and costs you muscle too. We aim for a pace your knee can handle.

Second, build the muscles that support the knee. The muscles at the front of the thigh absorb the impact that reaches the knee with every step. The muscles on the side of the hip keep the knee from collapsing inward. The side-lying leg raise and slowly standing up from and sitting back down on a chair, introduced in the bow-leg exercise article, are exactly the moves that build these muscles.

Third, don't stop walking. Change how you walk. If you walk less because it hurts, your thighs weaken first, and then the same step hurts your knee more. Splitting up your walks, how to use stairs, and what to do on painful days are covered in the knee and walking article.

How we look at it

First, we sort out where it hurts and why. We ask exactly where and when it hurts, and examine the knee. We see which of the three types above it's closest to, and if needed, check the joint with the 2nd-floor clinic.

Second, we measure both values in the multiplication. We check how curved the legs are with the X-body posture analysis, and weight with the InBody test. This step confirms in numbers why this knee is taking extra load on the inside.

Third, we treat to share the load. We manage pain with acupuncture and pharmacopuncture (herbal acupuncture), and use Chuna (Korean manual therapy) to fine-tune how the pelvis and hip joints move. We set your muscle exercises down to the method and number of reps, and if weight is involved, we set a goal together. At the next visit, we compare how much the pain has gone down and how much longer you can walk against where you started. We don't promise to change the angle of your legs.

What changes

A morning when you don't have to calculate "how far can I walk today?" before heading out. A day when your legs are still curved, but the inside of your knee stays quiet.

What we aim for is a knee that walks comfortably, even with curved legs.

How much and how quickly things improve differs from person to person, depending on the joint, alignment, weight and muscle strength.

Today's takeaway

Inner knee pain may be a load created by both the curve of your legs and your weight. Even if the angle stays the same, weight and muscle can lighten that load.

Check just three things today.

1. Point to where it hurts with one finger. Is it at the level of the joint line, the gap that forms when you bend your knee, or a little below it?
2. When does it hurt most? Your first steps in the morning, after a long walk, going up stairs, or going down?
3. Did your weight change around the time the pain started?

If you write down these three lines and bring them, we can tell much faster which type of inner knee pain you have. We're open until 8:30 p.m. on weekdays, and on weekends and public holidays too.

The original research on bow legs and knee arthritis is summarized in the bow-leg evidence article.

For questions or appointments, message us in English through the messenger at the bottom right of the page, or call +82-53-716-1175.