Knock Knees Genu Valgum

Overview

Knock knees — doctors call it genu valgum — is when a person stands with their knees together and their ankles stay apart. The lower legs angle outward, so the knees point inward and touch while the feet do not. A small gap between the ankles is very common and often normal, especially in young children. When the gap is large, or appears suddenly, or comes with pain, a doctor may want to look into why.

Yes, it is very common. Almost all children go through a stage of knock knees between about 2 and 6 years old as their legs change shape during growth. In most of them it settles by itself. Knock knees that first appear or get worse in older children, teenagers, or adults are less common, and those cases are the ones doctors usually look at more closely.

It affects children most often — typically between the ages of 2 and 6 — and is slightly more common in girls during growth. It can also affect teenagers during a growth spurt, and adults, especially people who are overweight, people with arthritis of the knee, and people who have had a knee injury or infection. Some people are simply born with a shape that runs in their family.

Symptoms

Common symptoms

• Knees that touch or nearly touch when standing, with a visible gap between the ankles
• Lower legs that angle outward, so the feet point slightly apart
• Walking that looks a little awkward or 'waddling'
• Feet that turn in or flat feet that seem more noticeable
• Tired legs or mild knee discomfort after a lot of walking or running
• Knees that look different from one side to the other

Symptoms in children

• Knock knees that appear around age 2 to 6 and slowly improve as the child grows
• Tripping or falling a bit more than other children of the same age
• Complaining of tired legs after play
• Clumsiness or a slightly stiff-looking run
• In most children, no pain at all — the shape is simply part of normal growth

Symptoms in older adults

• Knee pain that gets worse with walking, stairs, or standing for long periods
• Stiffness, especially first thing in the morning or after sitting
• Swelling around the knee
• A knee that feels unstable or gives way
• Gradual change in the shape of the legs, sometimes making shoes wear unevenly
• Difficulty with activities like getting out of a chair or walking long distances

Causes

Main causes

• Normal growth: most children pass through a knock-knee stage as their legs change shape between toddlerhood and about age 7
• Family traits: the shape of your hips, knees, and ankles often runs in families
• Vitamin D or calcium deficiency, which can soften growing bones (a condition called rickets)
• Being overweight, which puts extra load on growing knees
• Previous injury, fracture, or infection near the growth area of the knee
• Arthritis of the knee in adults, especially osteoarthritis, which wears down the inner side of the joint
• Rarely, inherited conditions that affect how bones and cartilage grow
• Rarely, a benign growth or tumour near the knee growth plate in a child

Risk factors

• Age between 2 and 6 years (for the normal childhood stage)
• A family history of knock knees or bow legs
• Low vitamin D levels or limited sun exposure, or a diet low in calcium
• Being overweight or gaining weight quickly
• A past knee injury, broken leg bone, or joint infection
• Knee arthritis or other joint conditions in adults
• Being very active in high-impact sports during a growth spurt
• Certain rare genetic conditions affecting bone growth

When to see a doctor

See a doctor urgently if:

• Knock knees that appear suddenly or get much worse over a few weeks
• Knock knees affecting only one leg
• A child who is limping, refuses to walk, or has pain that wakes them at night
• Knee pain with fever, redness, or swelling
• A knee that locks, clicks painfully, or gives way
• Numbness, tingling, or weakness in the leg or foot

Book a routine appointment if:

• Your child's knock knees are still clearly present after about age 7 or 8
• The gap between the ankles is large enough to catch your eye, or your child is tripping often
• Your child has knock knees along with being shorter than expected or growing slowly
• An adult notices knee pain, stiffness, or a change in leg shape
• You are worried about how the legs look, or your child is being teased about it
• You have questions about whether treatment is needed

Diagnosis

A doctor or physiotherapist can usually tell by watching you or your child stand and walk. They will look at the shape of the legs, check the hips, knees, and ankles, and measure the gap between the inner ankles while the knees are together. They will ask about growth, diet, family history, pain, and how well you or your child can run, jump, and play. Often that is all that is needed. If something seems unusual — such as knock knees in only one leg, a very large gap, pain, or a child who is not growing as expected — the doctor may arrange tests to look for an underlying cause.

Tests that may be done

• Physical examination and measurement of the ankle gap (sometimes called the intermalleolar distance)
• Checking how your child walks and stands, and comparing both legs
• Reviewing growth charts and height over time
• X-rays of the knees or legs, usually only if the shape is unusual, one-sided, or painful
• Blood tests to check vitamin D, calcium, and other bone-related levels if a deficiency is suspected
• Sometimes an X-ray of the wrist or hand to check bone age in a growing child
• Rarely, scans such as an MRI if a growth or joint problem is suspected

What to expect at your appointment

The visit is usually quick and gentle. Your child will be asked to stand still with their knees together and then to walk a few steps. The doctor may measure the space between the ankles with a ruler or tape. You may be asked to come back in a few months so the doctor can see whether the legs are straightening as your child grows — this 'watch and see' step is common and does not mean anything is wrong. If tests are needed, they are usually simple and can be done the same day.

Treatment

Treatment depends on your age, how big the gap between the ankles is, whether there is pain, and whether anything else is going on. Most young children need no treatment at all — just regular check-ups to make sure the legs are straightening as expected. Older children and adults may benefit from physiotherapy, activity changes, and treating any underlying cause. Surgery is only considered in a small number of people, usually when the shape is severe, causing pain, or not improving as expected.

Self-care at home

• Keep active: walking, swimming, and cycling help keep the muscles around the knees strong without overloading them
• Choose supportive, well-fitting shoes with a little cushioning
• If one activity hurts, try shorter sessions or swap to something gentler rather than stopping everything
• Keep to a healthy weight — this takes strain off the knees
• For sore knees, a cold pack wrapped in a cloth for a short time can ease discomfort
• Build strength gently: a physiotherapist can show you safe exercises for the hips, thighs, and calves
• Make sure children get plenty of outdoor play and a balanced diet with calcium-rich foods
• Keep a note of any pain, limping, or changes so you can share them at your check-up

Medical treatments

There is no single pill that reshapes a leg. Instead, treatment focuses on the cause and the symptoms. If a vitamin or mineral deficiency is found, your doctor may suggest a supplement and a change in diet — always follow their advice, and check with a pharmacist before giving a child any supplement. Overweight is often addressed with dietitian support and gentle, steady activity changes. Physiotherapy can improve strength, balance, and walking style. Painful knees may be helped with simple pain relief recommended by a pharmacist or doctor, alongside exercises and activity changes. Some children are given shoe inserts or insoles by a physiotherapist or podiatrist, although the evidence for these is mixed. Regular check-ups are a normal part of care so everyone can see whether things are improving.

When is surgery considered?

Surgery is uncommon and is only discussed when the shape is marked, is getting worse, is one-sided, causes real pain or difficulty, or does not improve as a child grows. In growing children, a small operation on the growth plate (sometimes called guided growth) can gently correct the angle while the leg continues to grow. In older teenagers and adults, surgery to realign the bone may be considered, and in adults with severe arthritis, joint replacement may be an option. Your specialist team would talk through the benefits, the risks, and the recovery time with you before any decision.

Living with this condition

Most people with knock knees live completely normal lives — they play sports, walk, work, and get around without thinking about it. If you or your child do have discomfort, a little planning helps: pace longer walks, use handrails on stairs, choose comfortable shoes, and build in rest after busy days. For children, keep the focus on fun and movement rather than on how the legs look. If your child is being teased, let their teacher or club leader know so they can help.

Lifestyle tips

• Stay active in ways you enjoy — swimming and cycling are kind to the knees
• Warm up before sport and cool down afterwards
• Take breaks from long periods of standing or sitting
• Eat a varied diet with calcium-rich foods such as milk, yoghurt, cheese, leafy greens, and fortified alternatives
• Get regular safe sun exposure, and ask your doctor or pharmacist about vitamin D if you think you may be low
• Aim for a healthy weight for your height and age
• Wear shoes that fit well and offer some support
• For children, encourage running, jumping, and outdoor play to build strong bones

Diet and exercise

Bones and joints do best with a steady supply of calcium, vitamin D, and protein, plus regular movement. Dairy foods, fortified plant milks, tinned fish with bones, tofu, and leafy greens are good calcium sources. Oily fish, eggs, and safe sunshine help with vitamin D — ask your pharmacist or doctor if you are unsure whether you or your child needs a supplement. For exercise, aim for a mix: something that gets the heart pumping, something that builds strength (like climbing stairs, cycling, or body-weight exercises), and gentle stretching. Children should be encouraged to move every day. If an activity causes pain, reduce it rather than pushing through, and ask a physiotherapist for guidance.

Mental health and emotional wellbeing

How legs look can affect how people feel about themselves, especially during the teenage years. Being teased or feeling different can cause worry, low mood, or shyness about sport and swimming. These feelings are valid and worth talking about. For parents, it helps to listen without dismissing concerns, praise what the body can do, and avoid commenting on appearance. If low mood, anxiety, or distress is affecting daily life, please speak to a doctor or counsellor — support is available. If you or someone you know is having thoughts of self-harm or suicide, contact your local emergency number or a crisis support service right away.

Prevention

You cannot prevent the normal knock-knee stage of childhood growth — and you would not want to, because it is part of healthy development. Some causes can be reduced, though. Making sure children get enough vitamin D and calcium, keeping weight in a healthy range, and treating knee injuries and infections promptly all help protect growing bones and joints. Adults can look after their knees by staying active, keeping muscles strong, and maintaining a healthy weight.

Vaccines

There is no vaccine for knock knees. Keeping up to date with routine childhood vaccinations is still important for general health.

Screening programmes

There is no routine screening programme for knock knees. Instead, they are usually noticed during ordinary health checks for babies and children, such as growth and development reviews. If you have any concerns between check-ups, you can raise them at any appointment — you do not need to wait for a scheduled review.

Complications

If left untreated

• Knee, hip, or ankle pain later in life if the angle stays large
• Extra strain on the knee joint, which may speed up wear and tear (osteoarthritis)
• A knee that feels less stable, or a kneecap that slips out of place
• Difficulty with running, jumping, or long walks
• A greater chance of trips and falls
• In a small number of children, the shape gets worse rather than better, and needs treatment
• Self-consciousness or low mood about appearance, especially in teenagers

Long-term outlook

The outlook is generally very good. For most young children, knock knees straighten naturally as they grow, with no lasting effects and no need for treatment. When a cause is found — such as low vitamin D or extra weight — addressing it often makes a real difference. For adults with knee pain or arthritis, physiotherapy, weight management, and activity changes usually help a lot, and surgery is available for the small number of people who need it. Whatever your situation, there is support available, and seeing a healthcare professional early gives you the best chance of a smooth path ahead.

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