Bowlegs

Bowlegs is a condition where the knees point away from the center of the body. Many young children normally have bow legs that correct around age 2. This is referred to as physiologic bowlegs.

However, there are two conditions in which bowlegs do not correct in young children: infantile Blount’s disease and rickets. Both of these problems can be diagnosed with an X-ray. If your child still has bow legs by age 2, it is important to have him or her evaluated for underlying conditions that may be causing the bowlegs.

Infantile Blount’s Disease (Infantile Tibia Vara)

Infantile Blount’s disease is the most common reason for a bowlegged deformity. In this disease, the growth plate stops growing on the upper, inner portion of the tibia bone. This results in a bowleg deformity that gets progressively worse. Blount’s disease is usually diagnosed around age 2.

Infantile Blount’s disease is thought to be a developmental problem rather than a congenital one. This means it is not something a child is born with, but a condition he or she develops over time. This is because Blount’s disease is never seen in children younger than 1 year of age, and rarely in children younger than 2 years of age. Risk factors for developing Blount’s disease include:

  • Walking at an early age
  • Being ​African American
  • Being female
  • Being overweight

Infantile Blounts

Blount’s disease can be diagnosed with a combination of a physical exam and X-rays. During the physical exam, your child’s doctor will watch how your child walks to see how severe the bowleg deformity is. On the X-ray, the doctor will look for an abnormality in the bone called “beaking,” which suggests early stages of infantile Blount’s disease. Beaking typically looks like an unusual, pointed piece of bone around the growth plate.

If your child is diagnosed before age 3, your doctor may recommend a special brace that is worn from the ankles to the thighs. The brace is worn all day. We know it can be extremely difficult to place a 2-year old in long braces, but if the braces are made and worn correctly, they can often correct the problem.

Unfortunately, Blount’s disease does not get better on its own. If your child is diagnosed after age 3, or if his or her condition is not improving with the braces, your child’s doctor may recommend corrective surgery. If your child is younger and the deformity less severe, your doctor may suggest placing a small plate on the outer portion of the growth plate and allow the inner portion to continue growing. For children who are older or have a more severe deformity, it is often necessary to cut the bone to straighten it. These details should be discussed with your child’s surgeon prior to surgery.

Adolescent Blount’s Disease (Adolescent Tibia Vara)

Adolescent Blount’s disease, also known as juvenile Blount’s disease, is very different from infantile Blount’s disease. While infantile Blount’s is diagnosed soon after walking, adolescent Blount’s is usually diagnosed when the child is age 10 or older. Children who are diagnosed with adolescent Blount’s have normal-appearing limbs when they are younger, but they develop bowlegs as they become older. While the disease often affects both sides, one side may be more severely bowlegged than the other. In adolescent Blount’s, the initial bowlegged deformity tends to be less severe than infantile Blount’s, but it has the potential to become just as severe if left untreated. Although some patients with adolescent Blount’s may be normal weight, the majority of children with this condition are overweight or obese.

Just as with infantile Blount’s, adolescent Blount’s is diagnosed with a physical exam and X-rays.

Unfortunately, brace treatment cannot help correct adolescent Blount’s and surgery is usually needed. Surgeries are based on the severity of the deformity. For less severe deformities, your child’s surgeon may recommend placing a plate on the outer portion of the tibia bone. More severe deformities may require cutting the bone and straightening it out. Sometimes, one operation can correct the deformity, but in some cases your child’s surgeon may recommend using an external fixator to gradually correct the deformity. Your child’s surgeon can describe all of these different treatment options prior to surgery.

Rickets

Rickets is a childhood condition where bones lack certain minerals. Although they all look the same on X-rays, there are several different types of rickets. The type depends on which mineral is deficient – either calcium, phosphorus, or the enzyme that helps create the mineral portion of bone, alkaline phosphatase.

Calcium deficiency

The most common cause of calcium deficiency in bone is a lack of vitamin D, not a lack of calcium in the diet. This is because vitamin D allows the body to absorb calcium. If the body does not have enough calcium in the blood, then it will take the calcium out of bone instead. If this cycle continues, bones can become weaker. This can lead to a child developing physical signs of rickets, such as bowed legs or other bone deformities.

Phosphorus deficiency

Phosphates support the growth and repair of bones and teeth. The most common reason for a phosphorus deficiency in bone is an inherited disorder known as X-linked hypophosphatemic rickets. This disorder is caused by a defect in the PHEX gene, which regulates the movement of phosphate compounds from the kidney. Normally, the kidney sends phosphates to the bone through the blood. The PHEX gene defect causes the kidney to get rid of the phosphate instead of sending it through the blood, leading to a phosphorus shortage in the blood. Similar to low calcium in the blood, when the body recognizes there is not enough phosphorus in the blood, it will remove it from the bone instead. This genetic defect may also prevent the kidneys from processing vitamin D, which is necessary for the body to absorb calcium. Women are twice as likely as men to have the X-linked hypophosphatemic disorder.

When there is less calcium or phosphorus in bone, the bone and the bone’s growth plate become weak. This weakening of bone can lead to slow growth. In severe cases, children can have seizures from calcium deficiencies or develop fractures in weakened bone.

Treatment for rickets depends on which mineral deficiency your child has. This may require the assistance of an endocrinologist. Once your child’s doctor determines the mineral deficiency, treatment involves replacing the mineral – whether it is calcium, vitamin D, phosphorus, or a combination of these. In many cases, the bone changes that happen with rickets get better with time. In more severe cases, children may continue to have slowed bone growth and bones that are somewhat crooked. Occasionally, bones become so crooked that they require surgery to correct.