Diagnosing Blount Disease in Children

The orthopedics team at Hassenfeld Children’s Hospital at NYU Langone has extensive experience in diagnosing Blount disease, a condition that makes bones in the lower leg curve outward, or bow.

Because of the way a developing child is positioned in the womb, most babies and toddlers have some bowing of the legs below the knee until they begin walking, when the legs gradually straighten. In children with Blount disease, the growth plate at the top of the shinbone—an island of cartilage that allows the leg below the knee to lengthen—bears more weight or pressure than it can handle as the child grows.

This compression of the inner part of the growth plate prevents it from making new bone. But as the outer part of the growth plate continues to make more bone, the shinbone grows unevenly. This uneven growth can cause curvature and rotation in the leg, which is not usually painful.

Blount disease is more common in children younger than age four who began walking early and in adolescents who are overweight or obese. The risk of developing Blount disease is higher in girls and in those with a family history of the condition. Blount disease often affects both legs in young children but, for unknown reasons, only one leg in adolescents.

Blount disease can be difficult to distinguish from the usual bowing of the legs seen in infants and toddlers. If you and your doctor suspect that your child may have this condition, our specialists can conduct a comprehensive physical exam and order imaging tests to guide diagnosis.

Physical Exam

During a physical exam, the doctor may ask if you have a family history of Blount disease or if your child began walking at age 10 months or younger, which may have put excessive pressure on the growth plates. The doctor may look for other signs of Blount disease, including walking with difficulty or discomfort, walking with the feet pointed inward instead of straight ahead, and a difference in limb length. Blood tests may be used to rule out rickets—a deficiency in vitamin D, phosphorus, or calcium, another cause of bowing.

X-rays

X-rays of the lower legs enable your doctor to see if the bones and growth plates have been damaged and to measure the degree of curvature in your child’s legs.

Our specialists use information from these diagnostic tests to develop a treatment plan to realign your child’s leg bones, allowing them to straighten and grow.