Why Do My Knees Cave In When I Squat?

What is dynamic knee valgus?

Dynamic knee valgus is when your knees collapse inward during movement, most obviously during a squat, a lunge, or when landing from a jump. It is different from structural knock knees, which is a fixed bone position. Dynamic valgus happens only when you load the joint. It may look like a small wobble or a dramatic inward cave, depending on the cause.

This movement pattern increases stress on the inner side of the knee, the kneecap, and the ligaments that hold the joint stable. Over time, repeated valgus loading can contribute to knee pain, patellofemoral problems and even injury.

How do I know if my knees are caving in?

You may spot it yourself in a mirror, or someone else may point it out. These are the most common signs.

What causes knees to cave in during a squat?

Several factors can make your knees collapse inward, and most people have more than one at play. The causes fall into two groups: soft tissue (muscles and tendons) and structure (the shape of your bones).

Stance width and cueing also matter. A very narrow squat stance or simply not knowing where your knees should track makes valgus more likely. As load or fatigue increases, even people with good technique can lose control.

Why does the whole leg matter, not just the knee?

Your body is a connected chain from your feet to your head. A problem at one level makes another level compensate. Knee valgus rarely starts at the knee itself. It is usually driven from above (the hip) or below (the ankle and foot).

This is why a scan of just the knee often misses the real issue. It might show the joint looks normal, while the reason for your pain, perhaps a rotational pattern in the hip or poor alignment through the whole leg, stays hidden.

Lying-down imaging relaxes the muscles and removes gravity. A knee that collapses inward only when standing and loaded will look perfectly fine on a scan taken while you are flat on your back. Standing imaging captures what actually happens under your own body weight.

How does a standing EOS scan help with knee valgus?

An EOS scan captures your full leg alignment, from the hip joint down through the knee and ankle, in a single standing image. Because you are upright and weight-bearing, it shows the alignment your body actually uses, not the relaxed position that appears when you lie down.

The scan uses about 90% less radiation than a standard X-ray, around ten times less. It takes seconds to capture and requires no special preparation.

With ScanAlign standing EOS imaging, a specialist radiographer assesses the relationship between your hip rotation, knee angle and ankle position in one view. This can reveal whether the valgus pattern is driven by bone shape, by soft-tissue factors, or by a combination of both.

What helps stop knees collapsing inward?

Addressing knee valgus usually means working on the areas that cause it, not the knee itself. Common approaches recommended by physiotherapists and strength coaches include the following.

• Glute medius strengthening. Exercises such as banded side-walks, clamshells and single-leg work build the hip muscles that control inward rotation of the thigh.
• Ankle mobility drills. Improving dorsiflexion lets you squat deeper without the knee compensating.
• Cueing and technique. Thinking "knees out" during a squat, or using a light resistance band around the knees as a reminder, helps retrain the movement pattern.
• Stance width adjustment. A slightly wider stance with toes turned out can reduce the demand on ankle mobility and make it easier to keep the knees tracking well.
• Foot support. If foot pronation is a factor, appropriate footwear or insoles may help control the chain reaction from the ground up.

These strategies work well when the cause is muscular. But if a structural issue, such as the way your thigh bone or shin bone is shaped, is contributing, exercises alone may not fully resolve it. That is where imaging becomes important, so you and your clinician know exactly what you are dealing with before deciding on a plan. You can book a leg alignment scan to get a clear picture of your structure.

Frequently asked questions