How normal are knock knees?
Do a quick survey of all the toddlers you know: do any of them have perfectly straight legs? The answer will almost certainly be no. Most children are born bowlegged (where the legs curve outward at the knees) and stay that way until about age two or three, at which point they develop knock knees – a condition in which the lower legs bend outward, so that when the knees are touching the ankles are spread apart. The medical term for knock knees is “genu valgum,” from the Latin genu (knee) and valgus, which means “bent outwards.” It can occur in one or both knees.
“Knock knees are almost universal in young children during some period of development,” says Dr. David Wong, a pediatrician in Summerside, P.E.I. “It’s very common and quite normal.” The condition can occur in varying degrees, from slight to very exaggerated, but it typically corrects itself over time. It is almost always painless and usually does not pose any physical problems or limitations for the child.
When should a parent be concerned? “If, at any age, the child is having difficulty walking or running, or is limping, or his mobility is affected in any way, he should be seen by a doctor. But even if there are no mobility problems, if the knock knees are still significant after age six, the child should see the family doctor, who might refer him to a specialist to have it checked out.” The specialist will observe how the child walks and measure the angle at which the ankles point outward, and may also order an X-ray if an underlying bone problem is suspected.
While knock knees usually develop as part of normal growth, they may also be due to an underlying problem such as Rickets, a disease in which the body has too little calcium because it lacks the enzyme to convert Vitamin D into the active form. “In Canada Rickets is very rare, but it does occur, especially further north in First Nations children. I have seen it twice in my practice,” says Dr. Wong. An injury to, or infection of the shin bone can also cause a knock knee, if it’s bad enough to impair bone growth. And kids who are overweight are also more prone to knock knees, since their joints and bones may have difficulty supporting their weight.
Knock knees occur more commonly in girls than boys, because they have a wider pelvis and shorter thigh bone than boys, so their knees may naturally come closer together. Untreated, severe knock knees can cause arthritis later in life, or knee, hip or ankle pain from stress on the joints.
“We almost always hold off on intervening, and take a wait and see approach,” says Dr. Wong. “We don’t recommend special shoes or braces or any of those things – they don’t work, and they’re not necessary.” A doctor or physical therapist may recommend exercises to help strengthen and stabilize the knees. In severe cases, surgery may be required when the child is a bit older. Still, says Dr. Wong, if you are at all concerned, get a doctor’s opinion.