MUSC Children's Health Offers Time-Sensitive Corrective Treatments for Blount's Disease

By Vitria Adisetiyo

 

It wasn't until Amani was eight years old that Sade White and her fiancé Antonio Governor started to notice their daughter's legs were bowing outward at the knees. Yet, Amani never complained.

"I wasn't concerned at first," recalls Ms. White. "I didn't know anything about Blount's disease and everyone I knew who was bowlegged never got it checked out and just went about their lives."

But things changed after Amani fell on her right leg while playing. She started to complain about leg pain. Teachers started to voice concern about the extensive bowing of Amani's right leg, as did Ms. White, who immediately reached out to MUSC Children’s Health. She did so just in time.

Blount's disease, also known as tibia vara or bowleggedness, is a disorder of the growth plate around the knee in the tibia (shin bone). In young children, physiologic leg bowing is common and often resolves by three years old. However, bowleggedness beyond that age may signal one of three types of Blount's disease: Infantile Blount's disease (children less than four years old who tend to be early walkers), Juvenile Blount's disease (children between ages four to ten), or Adolescent Blount's disease (children older than ten years). Once a child reaches skeletal maturity (when the bones stop growing), the leg bowing will remain unchanged. However, if left untreated, Blount's disease can cause medial compartment osteoarthritis (arthritis of the inner knee), which is a source of pain and disability that may require early joint replacement. Fortunately, Blount's disease can be fully corrected, especially if caught early.

"Age at presentation affects treatment," explains Sara Van Nortwick, M.D., the pediatric orthopaedic surgeon who treated Amani. "It's ideal to catch Blount's disease when a child is still growing. This allows the surgeon to take advantage of the patient's remaining growth to correct the problem. Amani presented with growth remaining so a relatively simple procedure was able to fully straighten her legs."

While the causes are not well understood, Blount's disease is thought to be related to stress overload on the inner side of the tibial growth plate, which is the area of new bone growth in children and teens. This overload likely hinders bone growth on the inner side of the growth plate while normal growth occurs on the outer side, resulting in leg bowing. Risk factors include early walking, obesity, and being of Hispanic or African American decent.

Diagnosis is confirmed by a physical exam, low dose x-rays of the legs, and review of family and medical history to account for other potential causes. The treatment for Blount's disease depends on two factors: the severity of bone deformity and the bone age of the patient, specifically how much bone growth is remaining, as determined by x-rays.

Younger patients who are still growing and have mild deformity will initially be treated with a leg brace and monitoring of growth correction. For cases where the leg brace is ineffective and for older patients who are still growing and have moderate to significant deformity, the treatment is an outpatient surgery called growth modulation. In this procedure, a small, 1-inch-long incision is made in the outer side of the knee and a screw is inserted. This screw stops bone growth on the outer side of the knee, which allows growth in the inner side of the knee to catch up and straighten the leg. The surgery takes half an hour to complete and when both legs are affected, both legs can be treated at the same time. Patients can go home the same day and will have no post-operative activity restrictions. Follow-up visits occur every three to six months to monitor growth correction with x-rays. Once the leg is anatomically aligned, the screw is removed during an outpatient procedure. Follow-up monitoring will continue until the child reaches skeletal maturity to ensure there is no recurrent bowing, which can happen if the patient is still growing.

"Amani's case was fairly typical," says Van Nortwick. "Her legs were significantly bowed but growth modulation was able to fully correct the problem as she continued to grow. There are other cases when the patient is nearly done growing and a full correction cannot be achieved by placement of a single screw across the growth plate."

For those cases and for patients who have reached skeletal maturity or have severe bone deformity, the treatment is a more complex inpatient surgery called high tibial osteotomy. In this procedure, the leg is fully corrected by cutting the bone at the area of deformity and securing the new leg position with plates, screws, and a bone graft. This surgery takes approximately two hours to complete and only one leg can be addressed at a time because the patient cannot put any significant weight on the leg for four to six weeks while the bone cut is healing. If both legs need to be corrected, two separate surgeries are required.

Today, Amani is nearly finished with her treatment. Her legs are straight, and soon she will have her implants removed through the same small incision used to place the screws.

"You can't even tell Amani had surgery," says Mr. Governor. "She's doing the things she did before and then some. Now she can live her life and do the activities she loves, like dancing, all without discomfort."

"I'm glad that when we caught it, we didn't let it linger," adds Ms. White. "We got more information and had the surgery done. It makes me feel good that we did something right for her."

Dr. Van Nortwick understands that talking about surgery can be scary for families. "If you have a concern, it's important to get it evaluated. We're here to explain the disease and treatment process and make sure we come up with a plan that's best for your child."

To refer patients for evaluation or treatment of Blount's disease, visit musckids.org or call 843-876-0111.