What is Blount’s Disease?
Blount’ disease is a growth disorder of the lower leg bone (tibia), commonly called the shin bone, and is characterized by a bowing (pronounced boh-ing) appearance of the leg below the knee joint. One or both legs can be affected. Some children may experience shortening of 1 leg (also called leg length discrepancy), or the turning of 1 or both feet inward.
Blount’s disease is classified into 3 groups based on the age of the child:
Infantile (birth to 3 years of age)
Juvenile (4 to 10 years of age)
Adolescent (11 years and older)
Infantile Blount’s disease occurs in children younger than 3 years of age, who walk early, are large, or are overweight. In these toddlers, the repeated stress and compression of the inside-top part of the shin bone causes the “growth plate” to slow down, or to stop the bone from growing on the inside of the leg, while the outside part continues to grow, causing an exaggeration of the typical bowing of the bone in the lower part of the leg. “Growth plates” are made up of cartilage located at each end of a child’s long bones, making the child grow taller by building bone on top of bone.
Some bowing may always be present in the legs of children and adults. Bowing of the lower leg in infants who are developing normally usually resolves by 2 years of age, when the legs bend slightly the other way and the child becomes “knock-kneed” during the third and fourth years of age. By the age of 7 years, their legs achieve a different shape, with the knees appearing to fall inward slightly. By the age of 12, all children’s legs have grown into their adult shape. The shape of the leg changes very little beyond this stage, although the bones and muscles continue to grow longer and thicker. If the bowing is not typical (doesn’t have the shape of typical infant bowing, is unequal in the 2 legs or is extreme), then Blount’s disease should be suspected. Your physician or physical therapist will help distinguish between normal and abnormal bowing. Seek their advice if you are uncertain.
Juvenile Blount’s disease affects children aged 4 to 10 years.
Adolescent Blount’s disease affects children aged 11 and older.
These forms of the disease affecting older children are less common than the infantile form, and typically affect large teenagers, boys more often than girls, and especially boys with a vitamin D deficiency. The upper and lower bones of the leg are often affected in both these forms of the disease.
The major difference between these two groups (juvenile and adolescent) is the age of the child when the bowing is noted, and how much growth the child has remaining. Physicians are able to use radiographs to estimate the amount of growth remaining.
Signs and Symptoms
Blount’s disease may affect 1 or both legs; the most common symptom is a bowing from just below the knee to the ankle. The bowing will get progressively worse as the child grows. In older children, the thigh bone may be affected in addition to the shin bone.
The child may not feel any symptoms, but adolescents may complain of pain on the inside of the knee joint and down the inside of the leg. The appearance of bowing may be the first noticeable symptom. In addition, the way a child walks will look different; the child may limp or frequently trip.
The major difference in the nature and treatment of the disease is the age of the child when the bowing is noted, and how much natural growth time the child has remaining.
How Is It Diagnosed?
Blount’s disease is diagnosed based on a physical examination by a pediatric orthopedist, and by taking radiographic images of the legs. The physician will examine the child’s body, paying close attention to the legs, and will observe the child walking. The physician may measure the distance between the child’s knees when standing with the feet touching. A wide space between the knees will show a need for further testing.
The physician will order radiographic images because bowing of the bones can be seen more clearly on this type of image. Radiographs will allow the physician to confirm the diagnosis (or disprove it) and assign a number from I to VI to indicate the stage of the disease. Stage I is the mildest form and stage VI is the most advanced form. The physician may also request a blood test to determine the vitamin D level in the blood.
How Can a Physical Therapist Help?
Treatment of Blount’s disease depends on the age of the child and the stage of the disease, but a physical therapist will help during all stages. Brace treatment is always considered first in children younger than 30 months, and in the beginning stage (Stage I) of the disease. The brace prescribed by the physician is called a HKAFO (hip-knee-ankle-foot orthosis), or KAFO (knee-ankle-foot orthosis), and will help to redistribute the forces on the growth plate to foster normal growth.
The braces are typically custom-made by a specialist (orthotist) after casting or computer scanning of the leg to get precise measurements. Your physical therapist will teach you and your child how to put on and take off the brace, and how to protect the skin. Your physical therapist also will help your child learn how to walk and balance with the brace. Assistive devices, such as a child-sized rolling walker or crutches may be needed. Your physical therapist will teach your child how to safely and freely walk with the help of a walker or crutches.
The brace must be worn for about 1½ to 2 years to see resolution of the changes in the shape of the shin bone, but some improvement should be seen within the first year. Adjustments to the brace will be made as the child grows. If improvement is not noted within the first 12 months, the brace will be discontinued and surgery will be recommended.
If the disease has advanced, if brace treatment is unsuccessful, or if the child is older than approximately 10 years of age, surgery may be necessary. To keep the leg in proper alignment during the healing phase following surgery, the surgeon will place another type of brace called a fixator on the leg, to be worn for 8 to 12 weeks.
While in the hospital following surgery, a physical therapist will teach your child how to walk using a walker or crutches. The physical therapist will teach your child how to put the right amount of weight onto the foot (called weight-bearing), as prescribed by the physician to avoid injury to the surgical repair of the leg. The physical therapist will also teach you and your child specific exercises to help keep the leg healthy and regain strength and joint movement. Your physical therapist will teach your child how to transfer in and out of bed safely, how to use the bathroom, how to navigate curbs and stairs, and how to get in and out of a car as well as prepare for the return home.
After discharge home from the hospital, most patients will continue to see their physical therapist 2 to 3 times a week at home or in an outpatient clinic. Physical therapy helps to ensure that the surrounding leg tissues remain flexible as the bone heals, muscle strength is maintained, a child is independent with all daily activities, weight-bearing precautions are taken, and a child only bears weight on the leg as allowed by the physician. Often, when the surgeon allows a child to put full weight on the operated leg to help the bone heal, children are hesitant about doing so. Your physical therapist will work with your child to safely increase the amount of weight-bearing on the operated leg in a fun and supportive way.
Physical therapists also provide guidance and help with walking and strengthening for adolescents diagnosed with Blount’s disease. As the adolescent’s natural growth occurs, the deformity may slowly be corrected. If this approach fails, or if the older adolescent does not have enough growth time left to achieve the correction, surgery may be recommended. Physical therapy will help ensure that recovery is safe and effective following surgery.
Can this Injury or Condition be Prevented?
Numerous studies show that children who are obese have a higher chance of developing problems with their legs, such as Blount’s disease.
Physical therapists may help prevent the occurrence of late-onset Blount’s disease by teaching children who are overweight to engage in a regular exercise and fitness regimen.
A weight-loss program for overweight children may also be beneficial. Since a vitamin D deficiency may contribute to the occurrence of Blount’s disease, especially in boys, the family should always ask the physician for a thorough examination during routine visits, to ensure that the child’s vitamin D levels are sufficient.
Real Life Experiences
Kevin is a 16-year-old boy who was diagnosed with Blount’s disease when he was 14 years old. He had bowing of both shin bones, with the right leg more affected than the left. Bracing was used, but the bowing continued to increase despite the braces.
By the time Kevin turned 16, his doctor recommended surgery to correct the condition, 1 leg at a time. Kevin first had surgery on his right leg.
While in the hospital following his first surgery, a physical therapist taught Kevin how to move in and out of bed, and to only put a little weight on his right foot when he took a few steps.
As he gained strength and control, she taught him how to move about using crutches, and how to perform some gentle exercises to strengthen his leg muscles and maintain motion, especially in his knee, ankle, and toes.
He also learned how to navigate stairs, and at the time of his discharge home, how to get in and out of a car.
About 6 months later, Kevin had surgery on his left leg. The doctor placed a circular frame on his leg. At this time, the right leg that was previously operated on became his strong leg, and he was allowed only to bear a slight weight on his left leg when using crutches to walk. The hospital physical therapist taught him exercises and prepared him for his return home, just as she had done following his first surgery.
During his recovery, Kevin saw his local physical therapist. He wanted to work on his leg strength, walk without a limp, and go back to playing basketball after he was cleared by his physician and physical therapist.
Kevin attended physical therapy sessions twice a week to work on increasing the strength in his hip, knee, and ankle muscles. As the doctor allowed him to put more weight on the operated leg, he started to work on improving his standing with more symmetrical weight-bearing through his feet, walking, and stair climbing.
The circular frame on Kevin’s left leg allowed the surgeon to guide the healing and growth of the shin bone to achieve a strong alignment over time. Kevin wore his frame for almost 16 weeks. Although the frame was large and heavy, he was able to walk with a regular gait, go up and down stairs, and attend school.
After the frame was removed, the surgeon said Kevin still needed to use crutches to ensure a safe and strong recovery. Kevin now works with his physical therapist to practice specific sport-related exercises, as he prepares to safely rejoin his basketball team!