Blount's Disease
What is Blount’s disease?
Blount's disease is a rare growth disorder that affects children, causing the legs to bow outwards just below the knees. It is also know as tibia vara. A small amount of bowing is actually quite normal in young infants. However, as most children begin to walk, between the ages of 1 and 2 years old, their legs gradually straighten out.
In children with Blount's disease, the lower legs remain bowed or bow further outwards, which can lead to future problems with walking. Blount’s can be seen in a child less than 4 years of age as well as in early adolescents. Nearly all children who receive early treatment respond very well.
What causes Blount’s disease?
The exact cause of Blount's disease remains unknown. However, scientists believe that it is the combination of several contributing factors including genetic, environmental, and mechanical. It is more common in girls, African American families and those families with a history of Blount’s.
Because most children who develop Blount's disease began walking at an early age, early walking is believed to be another major contributing factor.
Blount's disease is also more common in obese or overweight children; it is felt that the extra weight placed on the tibia in these children leads to the abnormal process in bone growth.
How is Blount’s disease diagnosed?
Blount's disease is often first suspected when bowing of the legs is noticed in a child during a normal visit to a pediatrician, who will generally refer the case to an orthopaedic surgeon. The older a child is when the condition is detected, the more apparent these changes will be on x-ray.
Identification of Blount's disease is made through a careful physical examination, followed by x-rays of the legs. These x-rays will show the abnormal shape of the tibia and possibly the changes in the growth plate of the bone just under the knee.
Orthopaedic surgeons will take measurements from the x-rays of the angles of different segments of the leg, in order to distinguish between normal bone growth and development and Blount's disease, which shows more severe bowing. If the diagnosis of Blount's disease is made, these measurements will allow the surgeon to create the best treatment plan, and to track the correction of the deformity as a result of treatment in the future.
How is Blount’s disease treated?
The treatment of Blount's disease ranges from simple observation to surgery. Decisions about the best treatment for each child depend mostly upon the age of the child at the time of diagnosis and the severity of bowing of the legs.
If mild bowing is detected in a child under 2 years old, the best treatment is most often observation, in which the progression of the condition is monitored by an orthopaedic surgeon. In many cases, the bowing will prove to have been normal growth and development, and will correct itself over the course of about 1 year without any further treatment by a doctor.
However, if the bowing worsens, or is detected in a child 2-4 years old, Blount's disease can be treated with the use of orthotic braces that are fitted by an orthopaedic surgeon and worn on the child's legs. These braces, referred to as KAFO braces, which stands for Knee-Ankle-Foot Orthotic, extend from top of the thigh to the tips of the toes. Several different models of braces exist, but the goal is the same with each to gradually guide the growth of the legs towards a straighter position of the legs, so that the knees and feet are aligned properly, without bowing. Each child's brace is designed specifically for them, which requires the creation of casts of the legs. The ongoing development of the legs with the use of bracing is then monitored by an orthopaedic surgeon, through follow-up exams and x-rays.
In some instances, the best treatment for Blount's disease is a surgical operation. These are generally cases in which a child's bracing treatment has not been effective in correcting the bowing of the legs, or in which the condition is identified in children older than ages 3 or 4, with more severe bowing.
When Blount's disease is diagnosed in adolescents, surgical treatment is almost always the most appropriate treatment. The operation most commonly used is called an osteotomy, in which a very small wedge of the tibia (shinbone), and sometimes the fibula as well, is removed in an effort to realign the lower leg in a straighter position. A plate is placed at the osteotomy site and will likely need to be removed 1-2 years following the surgery.
Other operative treatments include performing small operation, in which the growth plate (epiphysis) is removed or tethered with the use of small plates in order to halt the abnormal growth of the tibia and correct its alignment, or an osteotomy followed by placement of an external fixator, in which a device is attached to the outside of the leg for a number of months with small metal pins, which aides the proper healing of the newly aligned tibia.
Other Considerations
Blount's disease may require some difficult adjustments for parents and their child with the condition. Frequent visits to the doctor, the wearing of braces or casts, and a surgical operation at a young age can represent emotional and physical challenges for children and parents alike. However, early treatment of the condition has proven to be extremely effective, and almost all children that receive treatment for Blount's disease grow into late childhood or adulthood without any abnormalities or restrictions on their activities and abilities, from everyday walking to demanding, competitive sports.