Knock knees

Knock knees are an outward angulation of the lower legs, such that when the knees are touching the ankles are separated.

Causes, incidence, and risk factors 
Most children develop a slight knock-kneed stance by the time they are 2 or 3 years old, often with significant separation at the ankles when the knees are touching. This is part of normal development and often persists through age 5 or 6, at which time the legs begin to straighten fully. By puberty, most children can stand with the knees and ankles touching (without forcing the position).

Knock knees can also develop as a result of disease processes. Most often the cause has already been diagnosed and the knock knees are recognized as a symptom of the condition.

Signs and tests 
If a physical examination and review of the child’s medical history indicate a specific cause for the knock knees other than normal development, your health care provider will order the appropriate studies.

Knock knees are usually not treated. Surgery may be considered for knock knees that persist beyond late childhood and in which the separation between the ankles is severe.

Expectations (prognosis) 
Children normally outgrow knock knees without treatment, unless there is an underlying disease. For cases requiring surgery, the procedure provides excellent cosmetic results.


  • Difficulty walking (very rare)  
  • Self-esteem changes related to cosmetic appearance of knock knees

Calling your health care provider 
Call your health care provider to schedule an evaluation if you suspect your child has knock knees.

There is no known prevention for normal knock knees.

Johns Hopkins patient information

Last revised: December 8, 2012
by Brenda A. Kuper, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.