Genu valgum (Knock knees) : Causes, Symptoms, Diagnosis, Treatment

What is Genu valgum Deformity?

Genu valgum or genu valgus is also known as “knock knees”. Genu valgum is a deformity in which both the knee turns inward or knock each other.

The word Genu came from the Latin word which means ‘knee’ and valgum means ‘bent outward’. But in this distal portion of the knee joint will bend outwards while the proximal portion of the knee joint will bends inward.

knock knees is a deformity in which the patients can not make their feet touch against each other.

Image showing genu valgum (knock knees)

Knock knees in children

Normally from birth bow legs are present in babies and this bowing disappears when the child reaches 2 years of age. And after that, the knees start turning inwards and the alignment of knee changes to valgum (knock knees) at around 3 years of age.

This knocking will nearly get corrected by the age of 6 or 7 years this is called physiological genu valgum. And around 8 to 10 years of age the normal knee alignment is usually achieved.

Knock knees in adults

In very rare cases adults will acquire bow legs. Like in case of osteoarthritis or rheumatoid arthritis or if tibia got fractured and left untreated. Poor bone healing may lead to knocking knees on the injured leg.

You can remember it by making a mnemonic like when you pronounce the word “valgum” there comes the word ‘Gum’ which means your knees get to stick together.

Genu valgum Causes 

Genu valgum is of two types –

Unilateral (single leg) – The main causes of unilateral genu valgum include-

  • Trauma
  • osteomyelitis
  • Tumor

Bilateral (in both the legs) – The main causes of Bilateral genu valgum are –

  • Physiological genu valgum – The alignment of knee changes to valgum at around 3 years of age. This knocking will nearly get corrected by the age of 6 or 7 years this is called physiological genu valgum
  • Pathological genu valgum – If the knock knees not get corrected or get worsen after the age of 7 years It is called pathological genu varum. The main causes of pathological genu varum can be post-traumatic, obesity, growth plate deformity, metabolic (rickets), degenerative or inflammatory arthritis, flat feet, etc.

Post Trauma/Injury 

Due to previous injury or trauma, you had developed an abnormal walking pattern. But you are ignoring it by considering it normal for your body for an extended period.

Therefore by regularly hurting yourself in the past, you may have developed a full-on case of knock knees.


Due to overweight, you are placing a lot of stress on your knees as your knees can only handle a limited amount of load. So now this extra amount of load will place too much pressure on your knees. And this extra stress will force your knees into knock-knees position.

Growth plate deformity 

The role of the growth plate is to grow the bone. And if it gets injured it can lead to unequal growth of any one side of growth plate either of lower femoral epiphysis or upper tibial epiphysis.

Metabolic disorders

Lack of Vitamin D and calcium can lead to a disease called Rickets. The role of vitamin D is to transports the calcium into bones. Insufficient exposure to sunlight can lead to a lack of vitamin D.

Arthritis in knees 

Arthritis in knees can also lead to genu valgum, And if this valgum deformity doesn’t get treated on time. Then it will place an extra amount of stress on the articular cartilage, bones, and the ligaments of the knee joint which will increase the progression of knee osteoarthritis.

Flat feet –

Sometimes flat feet can lead to knock knees and after sometime flat feet get worsen along with knock knees.

Related Article – Bow legs (Genu varum) 

Genu valgum Symptoms

Genu valgum is a frontal plane deformity because when you look at someone from the front you will get a kind of sense of there deformity.

Their legs will look asymmetric as there will be a gap of 3 inches between both the ankles and the knees will come close to each other. The gait pattern of the patient will be affected and it can lead to –

  •  Pain in knees
  •  Ankle, feet, and hip will be painful
  •  The person will not able to stand properly
  •  There will be stiffness in joints
  •  Walking will be difficult, a person will walk like he/she is having a limp.

Genu Valgum Risk Factors 

If Genu valgum not treated on time, an individual may also suffer from

  • Lower back pain in later stage
  • Osteoarthritis in knee
  • Chronic pain in the foot
  • Early knee degeneration
  • Plantar fasciitis

Genu Valgum Diagnosis 

It becomes very difficult to diagnose genu valgum at an early age of life like up to 5 or 6 years of age because the alignment of the knee changes to valgum (knock knees) at around 3 years of age.

And after that, this knocking will nearly get corrected by the age of 6 or 7 years and around 8 to  10 years of age the normal knee alignment is usually achieved. So if this disease persists or worsens after 6 or 7 years of age then you should consult the doctor.

Your doctor will look for the family’s medical history, a person’s medical history and ask about any previous disease or injury and other prior conditions that might cause knock-knees. The level of distortion is assessed by measuring the inter-malleolar distance.


Your doctor will also ask for –

  • If you are in pain, he will ask about the location of pain, level of pain, what causes it, and what makes it worse.
  • He will check your gait pattern ie how you stand and walk.
  • your doctor will assess the degree of deformity by measuring the inter-malleolar distance, the distance between your ankles.
  • Look for the unbalanced wear structures on the soles of your shoe.
  • He will order X-ray and MRI for a better diagnosis. When you get the radiograph draw a line from the center of the hip to the center of the ankle and now measure the line where it goes comparative to the center of the knee.
  • Compare it with a normal knee and check how much that straight line will move far away from the center of the knee.

Genu Valgum Treatment

Treatment of genu valgum depends on the cause and severity of the condition.

Weight loss

If you are overweight, you are placing a lot of stress on your knees and this extra stress is placing too much pressure on your knee. And it will force your knees into knock knees position.


As gaining more weight will worsen your knock knees. So your doctor will advise you to lose a couple of pounds. Which, in turn, reduces the extra amount of stress placed on your knees.


If Genu valgum is due to rickets your doctor will prescribe vitamin D and calcium tablets to reestablish your levels. If there is pain and swelling your doctor may prescribe NSAIDs like Zerodol-sp.

Orthotics (Splints and braces)

Sometimes a medial shoe raise (3/16 inch) is inserted into the shoes on the shorter side of your leg so that it can equalize your leg length and correct your gait pattern during walking.

If it is due to postural issues, braces and splints are used. They will force your knees to get into their proper positions and proper angles so that they can grow properly and promote proper growth and development.


Your doctor or therapist will analyze your gait and after that, he will suggest a specific type of exercise along with there appropriate dose that will strengthen your legs, knees, hip, and thigh muscles. and also some specific types of stretching exercises that will decrease your symptoms.

As you follow your exercises daily after some days you can also add some weight that will make it more efficient.

Genu valgum Surgery

Surgery for genu valgum is usually recommended in the following cases –

  • When there is no relief from exercises, braces, and weight loss
  • When Genu valgum become severe
  • If the inter-malleolar distance is 10cm or more than 10cm by the age of 4, Supracondylar osteotomy is performed

Generally, there are 2 types of surgery performed for the correction of genu valgum. One is done in younger adults and another is done in older adults.

Guided growth surgery or Hemiepiphysiodesis

It is performed in younger children, in this surgery a small metal plate generally of figure-eight shaped is positioned on the compressed side of the growth plate, generally on the medial side by allowing the other non-compressed side ie lateral side to continue to grow and correct the angle over time.

Your surgeon will use imaging and estimated growth to determine when the plates need to be taken out, once they are removed, your limbs will continue to grow in the normal position. After finally, you will be able to continue your daily life activities.

Distal Femoral osteotomy

It is performed in older adults or if the inter-malleolar distance is 10cm or more than 10cm by the age of 4, In this laminar spreaders are used to distract and open the femur bone on the lateral side. And after that, the opening which was made on the lateral side of the femur bone is done for the correction of valgum deformity and to bring back the knees into correct alignment.

Then metal plates are inserted where the cut has been made to stabilize the osteotomy or femur bone and further screws are used for tightness of that metal plates.

Releated Article – 

Genu Varum (Bow Legs) – Causes, Diagnosis, Symptoms, Treatment

Genu Recurvatum ( Hyperextended knee) – Causes, Symptoms, Treatment

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