Knock knees is a term that describes the appearance seen when the lower legs bend outwards, so that when the knees are touching, the ankles are spread apart. The medical name for knock knees is genu valgum.
Between the ages of 2 and 7 years, knock knees is a normal process of development and hence is very common. The legs usually straighten as your child grows. In these ‘normal’ cases, the knock knees are symmetrical (the same on both sides).
One way of assessing the problem is to ask your child to stand up straight with his or her knees touching and measure the distance between the bones at the inside of the ankles. This distance should decrease as your child grows.
Because knock knees usually straighten on their own, exercises, shoe inserts or wearing splints at night are not recommended.
Occasionally there is a medical cause for a child having knock knees. In these cases the deformity is usually greater, not the same on both sides and becomes more obvious with time. Causes include fractures and other injuries, developmental abnormalities and nutritional problems such as rickets.
In very rare cases when the knees do not straighten on their own, treatment may be needed in adolescence.
2. Childrenâ€™s Hospital Westmead; Sydney Childrenâ€™s Hospital; Kaleidoscope Childrenâ€™s Health Network. Fact sheet: bowlegs and knock-knees (updated 10 July 2012). http://kidshealth.schn.health.nsw.gov.au/fact-sheets/bowlegs-and-knock-knees (accessed Feb 2013).