Glossary
Valgus knee (knock knees)
Quick answer
A valgus knee is one where the knees angle inward, so they touch or nearly touch while the ankles stay apart. This alignment loads the outer side of the knee and can affect how the kneecap tracks, explains Doha knee surgeon Dr. Pablo Gelber, who measures leg alignment at Aman Hospital.
What it means
Valgus, or genu valgum, is the opposite of varus. The weight-bearing line from hip to ankle passes towards the outer side of the knee. Some knock-knee is normal in young children and usually corrects by around the age of seven or eight.
In adults it may be inherited, more common in women, linked to wear of the outer compartment, or follow an old fracture or growth plate problem. Doctors also use dynamic valgus for knees that collapse inward when landing or squatting.
Why it matters
A valgus leg puts more load through the lateral compartment, which can lead to outer-knee arthritis. It also pulls the kneecap outward, contributing to front-of-knee pain and kneecap instability.
Dynamic valgus during jumps and cutting is a recognised risk factor for ACL injury, which is why prevention programmes for football, basketball and handball train landing mechanics.
How it is assessed and treated
Examination looks at standing alignment, walking and a single-leg squat. A full-length standing X-ray measures the angle. Hip and core strengthening, landing training and footwear often help. For significant valgus with outer-knee arthritis or kneecap instability, a femoral osteotomy may be considered to realign the leg.
Frequently asked questions
Do knock knees cause knee pain?
Not always, but they can contribute to pain at the front or outer side of the knee, and to kneecap instability in some people.
Can exercises fix knock knees?
Exercises cannot change bone shape, but they can improve control of dynamic valgus, which reduces strain on the knee during sport.
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