Conditions + Treatments

Knock Knees in Children

LIke ThisLIke ThisLIke ThisLIke ThisLIke This

Contact the Lower Extremity Program

  • 1-617-355-6021
  • International: +01-617-355-5209
  • Locations


"Out of all the thousands of kids we see for this condition, maybe one in 1,000 won't straighten naturally. Just about 99 percent of the time, a 3 or 4 year-old with physiologic genu valgum is going to be just fine."

Samantha Spencer, MD, orthopedic surgeon, Boston Children's Hospital

If your child has been diagnosed with knock knees, you’ll have concerns and questions about her health, treatment, recovery and other issues. It may comfort you to know that Boston Children’s Hospital is a world leader in pediatric orthopedics, and we have a wealth of experience helping children with this fairly common condition. We specialize in innovative, family-centered care that supports your child and family every step of the way.

What to know about knock knees

   •   Knock knees are angular deformities at the knee, in which the head of the deformity points inward.
   •   A standing child whose knees touch but whose ankles do not is usually said to have knock knees.
   •   During childhood, knock knees are a stage in normal growth and development (physiologic valgus).*

* Between birth and 18 months, an outward-turning (varus) alignment from hip to knee to ankle is normal. Between about 18 and 24 months, this alignment normally becomes neutral. When the child is between 2 and 5 years old, an inward-turning (valgus) alignment is normal. The alignment returns to neutral as the child grows.

   •   The condition is slightly more common in girls, although boys can develop it, too.
   •   The condition usually becomes apparent when a child is 2 to 3 years old and may increase in severity until
        about age 4.
   •   Knock knees usually correct themselves by the time a child is 7 or 8 years old. Occasionally, the condition
       persists into adolescence.
   •   If the condition doesn’t appear until a child is 6 or older, she may have an underlying bone disease (pathologic
       valgus), and the condition may be more serious.
   •   Obesity can contribute to knock knees—or can cause gait (manner of walking) problems that resemble, but
       aren’t actually, knock knees.

How Boston Children's Hospital approaches knock knees
Doctors at Boston Children's closely monitor your child’s leg development, to make sure that her legs straighten themselves naturally. In the unlikely event that the condition doesn’t self-correct, your child’s doctors may have her wear corrective leg braces. Only children with the most severe cases may need surgery.

Whatever observation or treatment your child needs, you can have peace of mind knowing that as a national and international orthopedics referral center, our Orthopedic Center has vast experience treating children with every kind of developmental condition, some of which few other pediatric hospitals have ever encountered. As a result, we can provide expert diagnosis, treatment and care for every severity level of knock knees.

One of the first programs. Our Orthopedic Center is one of the world’s first comprehensive pediatric orthopedic programs, and today is the largest pediatric orthopedic surgery center in the United States, performing more 5,000 procedures each year. Our program, consistently ranked among the top three in the country by U.S. News & World Report, is the nation’s preeminent care center for children and young adults with developmental, congenital, post-traumatic and neuromuscular problems of the musculoskeletal system.

The world’s most extensive pediatric research enterprise
At Children’s, we’re known for our innovative treatments and a research-driven approach. We’re home to the world’s most extensive pediatric research enterprise, and we partner with elite health care and biotech organizations around the globe. But as specialists in family-centered care, our physicians never forget that your child is precious, and not just a patient.

Among the highest in the nation in children’s orthopedics

We are honored to be recognized as the #1 Children’s Hospital by U.S. News & World Report. Our orthopedic team offers comprehensive care for a wide variety of congenital and acquired disorders. Our Orthopedic Center is known for an outstanding level of clinical innovation, research and leadership. We offer the most advanced diagnostics and treatments—several of which were developed and pioneered by our own researchers and clinicians.

Orthopedic care in lots of places
Boston Children’s physicians provide orthopedic care at locations in Boston, Lexington, Peabody, Waltham and Weymouth.     


Knock knees: Reviewed by Samantha Spencer, MD

© Children’s Hospital Boston, 2011

The future of pediatrics will be forged by thinking differently, breaking paradigms and joining together in a shared vision of tackling the toughest challenges before us.”
- Sandra L. Fenwick, President and CEO

Boston Children's Hospital 300 Longwood Avenue, Boston, MA 02115 617-355-6000 | 800-355-7944