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Knock knees

Definition

Knock knees are condition in which the knees touch, but the ankles do not touch. The legs turn inward.

Alternative Names

Genu valgum

Causes

Infants start out with bowlegs because of their folded position while in their mother's womb. The legs begin to straighten once the child starts to walk (at about 12 to 18 months). By age 3, the child becomes knock-kneed. When the child stands, the knees touch but the ankles are apart.

By puberty, the legs straighten out and most children can stand with the knees and ankles touching (without forcing the position).

Knock knees can also develop as a result of a medical problem or disease, such as:

  • Injury of the shinbone (only one leg will be knock-kneed)
  • Osteomyelitis (bone infection)
  • Overweight or obesity
  • Rickets (a disease caused by a lack of vitamin D)

Exams and Tests

A health care provider will examine your child. Tests will be done if there are signs that knock knees are not a part of normal development.

Treatment

Knock knees are not treated in most cases.

If the problem continues after age 7, the child may use a night brace. This brace is attached to a shoe.

Surgery may be considered for knock knees that are severe and continue beyond late childhood.

Outlook (Prognosis)

Children normally outgrow knock knees without treatment, unless it is caused by a disease.

If surgery is needed, the results are most often good.

Possible Complications

Complications may include:

  • Difficulty walking (very rare)
  • Self-esteem changes related to cosmetic appearance of knock knees
  • If left untreated, knock knees can lead to early arthritis of the knee

When to Contact a Medical Professional

Call your provider if you think your child has knock knees.

Prevention

There is no known prevention for normal knock knees.

References

Demay MB, Krane SM. Disorders of mineralization. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 71.

Kliegman RM, Stanton BF, St. Geme JW, Schor NF. Torsional and angular deformities. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 675.

Review Date:12/9/2016
Reviewed By:Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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Outcome Data

No data available for this condition/procedure.

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