Why Your Knee Pain Might Be a Hip Problem

The knee is a hinge with very little control of its own in the side-to-side direction. What it does under load is largely decided above and below it.

What the hip actually controls

Gluteus medius and minimus stop the pelvis dropping and stop the thigh falling inward when you stand on one leg.

The deep external rotators stop the thigh rotating inward at the same time.

When both are working, the knee tracks over the middle of the foot. When they are not, the knee drifts in toward the midline.

That inward drift is called dynamic valgus, and it is visible from across a room once you know to look for it.

Why the knee minds

The kneecap runs in a groove at the end of the thigh bone. If the thigh bone rotates inward underneath it, the contact pressure between the two shifts and concentrates.

That is a plausible and well-studied mechanism for anterior knee pain, and it explains why the pain shows up on stairs, squatting and prolonged sitting rather than at rest.

The same inward collapse increases tension along the outside of the knee, which is part of the iliotibial band story.

And it changes the loading at the medial knee, which matters in people who already have arthritis there.

The test

Stand on one leg. Bend the knee to about thirty degrees. Watch what happens.

Three things to look for: the knee drifting inward over the big toe, the opposite side of the pelvis dropping, and the trunk leaning toward the standing side.

Any of the three suggests the hip is not controlling the position, and all three together make it obvious.

Doing it in front of a mirror, or filming it on a phone, is worth more than any description. Most people are surprised by the difference between what they think is happening and what is.

The evidence, honestly stated

Hip strengthening reduces pain and improves function in patellofemoral pain, and the trials supporting that are reasonably consistent.

Adding hip work to knee work outperforms knee work alone in several of them, and in some, hip work alone performs comparably.

What is less settled is whether the weakness causes the pain or results from it. Prospective studies are mixed.

That uncertainty does not change the practical answer much: the strengthening helps either way, and it is safe, cheap and useful for other reasons.

What weakness looks like on testing

Hip abduction strength measured against resistance, compared side to side. Differences of ten to twenty percent are common in people with one painful knee.

Hip external rotation strength, tested the same way.

Single-leg squat quality, which integrates both and is closer to what actually happens in life.

And single-leg bridge endurance, which tells you about the posterior chain that supports all of it.

The program

Start with side-lying abduction and clamshells if the hip is genuinely weak, which is a starting point rather than a program.

Progress quickly to loaded, upright, single-leg work: step-downs, split squats, single-leg deadlifts, banded lateral walks with real resistance.

The reason upright work matters is specificity. The problem shows up standing on one leg, so the strengthening eventually has to happen standing on one leg.

Two to three sessions a week, twelve weeks, with load that progresses. Six weeks is where most people notice, and stopping there is the usual error.

What about the foot

The other end of the chain. Excessive or poorly controlled pronation rotates the shin inward, which contributes to the same knee position from below.

Calf and foot intrinsic strength matter, and single-leg heel raises are worth including for that reason alone.

Orthoses help some people, particularly in the short term, and the evidence is moderate rather than compelling.

In practice I look at both ends and load both. Neither is a complete explanation on its own.

The pain that comes on while sitting

Anterior knee pain after twenty minutes in a cinema or a car is characteristic enough that it has a nickname, and it is one of the more useful pieces of history.

The mechanism is sustained compression of the kneecap against the groove with the knee bent and the quadriceps inactive.

It tells you the problem is patellofemoral rather than something inside the joint, and it responds to the same hip and quadriceps work as the rest of it.

In the meantime, straightening the leg periodically is a legitimate management strategy rather than fidgeting.

Why one side and not the other

Almost everyone has a side difference in hip strength, and most people have no pain at all. Weakness is a contributor, not a verdict.

What usually decides which knee complains is the load history: which leg leads on stairs, which side you push off from, an old ankle injury that changed how you land.

A previous injury on that side is the most common finding in the history and the most commonly forgotten by the person giving it.

So when I ask about an ankle sprain from ten years ago, it is not idle curiosity. The compensations set up then are frequently still in place.

Where the knee still needs treating

Quadriceps strength is reduced in almost every painful knee, and it needs addressing directly. Hip work does not replace it.

A knee with mechanical symptoms — locking, giving way, a genuine block to extension — needs assessment in its own right.

Acute swelling after an injury changes the whole picture and warrants prompt review.

So the argument is not that the knee is innocent. It is that treating the knee alone leaves the mechanism that loaded it in place.

Running, specifically

Dynamic valgus at the moment of foot contact is visible on video and is associated with several running injuries, not just knee pain.

Increasing cadence by about five to ten percent reduces load at the knee and is one of the few running changes that is both easy and evidence-supported.

Strength work off the road matters more than form cues on it, because the collapse is a capacity problem before it is a technique problem.

And volume, as always. Most running knee pain arrives after an increase in training, not out of nowhere.

Stairs, which is where people notice

Descending stairs loads the knee more than ascending, and it demands more control from the hip.

If descending hurts and ascending does not, that is a control and capacity finding rather than a structural one.

Practicing controlled step-downs from a low step, watching the knee stay over the foot, is a genuinely useful exercise and a decent daily test.

Progress it by height and by load, and it doubles as the thing you were struggling with.

What to do about a leg that will not fire

Some people cannot feel the side of the hip working at all, which is a coordination problem rather than a strength one and it needs a different starting point.

Lying on your side with the back against a wall, keeping the top leg slightly behind the line of the body, usually produces the sensation that a standing attempt does not.

Once you can feel it, progress out of lying and into standing quickly. Lying work is a teaching tool, not a program.

If several weeks of that produces nothing, the assessment needs widening. Persistent inability to activate a muscle group is worth investigating rather than drilling.

What good looks like at the end

Single-leg squat with the knee tracking over the foot, on both sides, held under control rather than snatched.

Stairs in both directions without thinking about it, at normal speed.

Hip abduction strength within about ten percent of the other side, measured rather than estimated.

And the activity you came in for, done at full volume, with two maintenance sessions a week keeping it there.

Timeframes

Four to six weeks for a noticeable change in symptoms.

Twelve weeks for meaningful strength change, because that is how long muscle takes.

Longer for people who have avoided loading the leg for a year, which is common by the time anyone gets assessed properly.

The strength gains hold if you keep doing something twice a week. They fade if you stop entirely, and so does the improvement.

A reasonable first step

Film your single-leg squat from the front on a phone. Ten seconds, both legs.

Compare them. If the painful side drops or drifts and the other does not, you have found something worth working on.

Start with step-downs and banded lateral walks, and give it six weeks.

If nothing changes, or if the knee swells, locks or gives way, that is the point to have it assessed rather than to keep going.