Blount’s disease is progressive pathologic genu varum centered at the tibia
Bowing of one or both legs that may
Blount's disease occurs in young children and adolescents. The cause is unknown but is thought to be due to the effects of weight on the growth plate. The inner part of the tibia, just below the knee, fails to develop normally, causing angulation of the bone.
Unlike bowlegs, which tend to straighten as the child develops, Blount's disease is progressive and the condition worsens. It can cause severe bowing of the legs and can affect one or both legs. This condition is more common among children of African ancestry. It is also associated with obesity, short stature, and early walking.
The exact cause of Blount’s disease is unknown. Children with infantile Blount’s disease are typically early walkers (prior to 12 months) and are often overweight. Adolescent Blount’s disease may be related to rapid weight gain or obesity. There is also believed to be a genetic component. Blount’s disease tends to run in families.
Blount’s disease is diagnosed by physical exam and X-ray. If Blount’s disease is suspected, your pediatric orthopaedic specialist will order an X-ray. X-rays may demonstrate the deformity in the bone and may also show abnormalities at the growth plate.
X-ray of a patient with Blount’s disease that demonstrates an abnormality near the growth plate called metaphyseal beaking.
Lower extremity deformities in Rickets can closely mimic those produced by Blount's disease. To differentiate between Rickets and Blount's disease it is important to correlate the clinical picture with laboratory findings such as calcium, phosphorus and alkaline phosphatase. Besides the X-ray appearance. Bone deformities in Rickets have a reasonable likelihood to correct over time, while this is not the case with Blount's disease. Nevertheless both disorders may need surgical intervention in the form of bone osteotomy or more commonly guided growth surgery. Osteochondrodysplasias or genetic bone diseases can cause lower extremity deformities similar to Blount's disease. The clinical appearance and the characteristic radiographic are important to confirm the diagnosis
For young patients with infantile Blount’s disease, bracing can be effective. The goal of bracing is to guide the legs into a straighter position as the child grows. An improvement is usually noticed within 12 months of treatment. If the deformity is not corrected by the age of 4, surgery may be needed.
The goal of treatment for Blount’s disease is to correct the deformity and improve overall alignment of the legs.
Surgery may be recommended if bracing doesn’t produce desired results. Children with severe deformities and those who are no longer candidates for bracing may also need surgery. Several surgeries are available to treat Blount’s disease, including osteotomies and hemiepiphysiodeses.
An osteotomy is a procedure that involves cutting and realigning the bone to put it in a more normal position. This type of surgery usually corrects the deformity immediately.
A hemiepiphysiodesis, on the other hand, corrects the deformity over time. It involves placing plates or staples on one side of the growth plate to stop the growth on that side. The plate guides the growth of the bone into a straighter position while the nonplated side continues to grow.
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.
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.