Bow Legs, Knock-knees: Are They “Normal?”

Few people have perfect-shaped legs. In fact, there may be no consensus on what a “perfect” leg shape actually is. Two curvatures of the leg are so common that they have been given names: bowlegs, officially called “genu varus,” in which the legs give the appearance of a bow–and knock-knees, or “genu valgus,” so-named because the knees curve inward and appear to “knock” together, while the lower part of the legs splay outward.

You may wonder whether these conditions can, or should, be treated in order to straighten them or prevent orthopedic problems later in life. But orthopedists say the two conditions are usually normal variations.

Most babies are born with curved or bowed legs. This is usually a result of the way they were “packaged” in the uterus. When children start walking, the bones in the legs start to slowly reform, and by age 2 or 3, most will have straighter legs. Discuss the situation with your doctor if your child’s bowlegs are severe or only involve one of the legs.

Bowlegs, especially if the condition is one-sided, can also be caused by other medical problems, including trauma to the growing bones, infection, skeletal problems, tumors, and rickets (a severe lack of vitamin C in the diet)—but these conditions are rare. Some people simply “inherit” bowlegs. Adults can also have bowlegs, which is usually due to arthritis and progressive deformity of the knees.

Knock-knees are less common. Even severe degrees of curvature usually correct spontaneously by age 9, but sometimes knock-knees can persist and cause knee pain.

An orthopedic surgeon can determine whether your child’s (or your own) bowlegs or knock-knees are normal or if treatment is required. If your child’s condition is severe, one-sided, or runs in the family, correction may be recommended. This is usually done with splints, braces, and sometimes surgery. If the condition is normal, time is the best treatment.

SOURCES: ChildNet and Merck Manual of Medical Information