Bowed legs, also known as genu varum, are legs that curve outward at the knee. This creates a space between the knees when the feet are together and a child faces forward while standing. The bowing may be in one leg or in both. It is especially noticeable when a child runs. This is very common during the toddler years and is occasionally seen in adolescents, especially those who are overweight.
For children under 2 years of age, bowed legs are normal. Doctors call this type of bowed legs physiologic genu varum. Around 18 months, the bowing should gradually improve. Around ages 3 to 4, the child’s legs should have a normal appearance.
Blount’s disease is another type of bowing of the legs. This bowing is abnormal. The cause is from an irregularity at the growth plate at the top of tibia. Blount’s disease can be seen in toddlers and adolescents. X-rays or other images taken at about age 3 can show problems at the growth plate.
Rickets or Nutritional Rickets
Rickets is another disorder that can cause the legs to bow. Rickets is a disease of the bone in which children do not get sufficient amounts of calcium, phosphorus or vitamin D. Nutritional rickets happens more often in countries where children cannot get enough dairy in their diet. There is another type of rickets that is inherited where a child cannot absorb enough vitamin D.
A doctor will start with a thorough physical exam and past medical history will be taken. If your child is healthy without any other medical problems, the bowing is equal on both sides and they are under 2 years of age, they will most likely not need any imaging tests, like X-rays. If your child has severe bowing, one side is significantly more bowed then the other or if they are older than 2 1/2 years of age, the doctor will likely want to take an x-ray or other imaging test.
If your child has physiologic genu varum, in the majority of cases, the bowing will correct by 3–4 years of age on its own. However, prior to this time, your specialist may want to follow-up with your child every 6 months to evaluate how the bowing is correcting on its own.
If your child has Blount’s disease or rickets that was not treated, the bowing may worsen over time. Your child can also have pain due to abnormal stress placed on their joints.
If your child is diagnosed with rickets, they will be referred to a metabolic specialist who will help develop a plan to ensure your child is getting the right nutrition and will continue to be followed by an orthopedic specialist.
Surgical treatment is extremely rare for physiologic genu varum. If a child has Blount’s disease and bowing progresses, the child will need surgery. Children with rickets may also require both surgical and medical intervention.