In most cases, there is no specific cause. Knock knees is slightly more common in girls than boys. Obesity can increase the risk of knock knees, too. In rare cases, rickets or osteomyelitis can contribute to knock knees.

• Knees touch each other while standing, but ankles are spread apart
• Usually no pain

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Progression of knock knees:

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• From birth to the toddler years, bowlegs are common
• Around 18–24 months, the bowing improves
• Around 2–3 years, knees may begin to touch each other (knock knees)
• Knock knees is most common around age 4
• By age 7–8, knock knees usually begin to straighten

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Usually, no treatment is necessary. Almost all children with knock knees can continue to participate in all their activities, including sports. In the past, bracing was sometimes used, but is not any longer. On rare occasions, if knock knees do not improve by age 10 or worsen and the child complains of significant knee pain, has difficulty walking or is unable to perform normal activities, surgery may be considered. Surgery is typically done before the child is done growing and consists of applying metal plates on the inside of the knees and allowing them to grow straighter.