Most young children have their legs bowed from the position in the womb.
This curvature remains until the muscles in the lower back and legs are strong enough to hold them upright.
A small amount of bowing is quite normal for young babies, and as most children begin to walk, between the ages of 1 and 2, their legs gradually straighten.
During normal development, the infantile tibia vara follows as part of a sequence that is then gradually corrected.
Because the physiologic tibial rod present at birth disappears in the first to second year of life, the varus angulation seen after 2 years of age is generally considered abnormal.
There is no need for treatment for this normal stage of development. But it is not always clear at this age whether the variant of the tibia is physiological (normal variation) or pathological (Blount’s disease).
Causes of Blount’s disease
The tibia vara is a medial angulation of the tibia in the proximal metaphyseal region as a result of an alteration of growth on the medial aspect of the proximal tibial epiphysis.
In the infantile type, the child is usually an obese early walker, for his age, and will develop pronounced bowls during the first year of life.
As the child walks, repeated stress and compression from the added weight suppresses (slows) or stops the growth of the developing bone.
When only one side of the tibia stops growing, there are abnormal changes in bone alignment that result in this curvature of the bone.
Black females are particularly at risk for severe deformity.
In the adolescent variety, onset occurs during late childhood or early adolescence, and the deformity is usually unilateral and milder.
Although reinforcement can be effective in childhood cases diagnosed in the first 2 years of life, correction of severe deformity generally requires surgical intervention.
There may be other causes of bow legs in young children such as metabolic disorders, vitamin D deficiency causing rickets.
Currently many foods are fortified with vitamin D to prevent this problem.
In a small number of children, vitamin D deficiency occurs as a result of a genetic abnormality. The child cannot absorb or metabolize vitamin D.
Juvenile or adolescent Blount’s disease is usually caused by obesity (being overweight), but can be the result of an infection or trauma that disrupted the medial growth plate.
Symptoms of Blount’s disease
The young child may not feel any symptoms. However, patients with adolescent tibia varum generally complain of pain along the medial side of the knee.
The arched appearance of the lower legs may be the first obvious sign.
In infants (under three years of age). The tibia vara is usually bilateral (both legs are affected at the same time). The bones begin to angle and turn inward.
The child may have trouble walking without stumbling. The way the child walks may not seem normal.
Children push the leg out of the other leg when walking on the affected leg.
It is often associated with internal tibial torsion, there is a leg length discrepancy, and there is usually no restriction of movement.
Diagnosis of Blount’s disease
Visual observation is the first diagnostic method. The family or doctor sees the problem when they look at the child or watch the child walk.
The distance between the knees is measured with the child standing with the feet together. If the space between the knees is more than two inches, additional tests are needed.
Bowing of the bones can be seen more clearly on x-rays.
The radiologist will see an acute varus angle and other changes in the metaphysis, and there is often widening of the growth plate.
Some orthopedists believe that X-rays are not necessary in a child of normal height with an examination consistent with the physiological inclination and that these children can be managed with periodic examinations.
There are six stages of tibia varum seen on X-rays and named after the physician (Dr. Langenskiold) who first described them.
- Stage I (observed in children up to 3 years) : characterized by the middle and distal blow of the metaphysis and the irregularity of the entire metaphysis.
- Stage II (seen in children aged 2½ to 4 years) : is characterized by an acute lateromedial depression in the line of ossification of the medial wedge-shaped metaphysis. Complete restoration is common at this stage.
- Stage III (seen from the ages of 4 to 6 years) : is characterized by the deepening of the metaphyseal peak, which gives the appearance of a step in the medial metaphysis.
- Stage IV (seen from ages 5 to 10 years) : is characterized by enlarged epiphysis, occupying the medial metaphyseal depression. Restoration is still possible at this stage.
- Stage V (seen from ages 9 to 11) : is characterized by a slit in the epiphysis, which gives the appearance of a double epiphysis; The articular surface of the medial tibia is deformed, sloping distally and medially from the intercondylar region.
- Stage VI (seen from 10 to 13 years of age) : is characterized by the closure of the medial proximal tibial physis, with a normal lateral physis.
Langenkiöld described his findings based on his observations of Finnish children, changes in African American children tend to occur at a younger age.
Treatment depends on the age of the child and the stage of the disease. For the obese child, weight loss is helpful but often difficult.
Most of the time this condition resolves on its own with time and growth.
No specific treatment is needed unless the problem persists after two years.
Severe bowing before the age of three is reinforced with a hip-knee-ankle-foot orthosis or knee-ankle-foot orthosis.
Shoring is recommended to be used 23 hours a day. As the bone is straightened with bracing, the orthosis is changed approximately every two months to correct the position of the bowl.
A physical therapist will work with the family to teach them how to put on and take off the brace.
Inspection and skin care is very important and will be included in the instruction.
The child may need help with gait training (learning to walk properly).
The therapist will help the child learn to use any assistive devices (eg, walker, crutches) that he may need.
If the tibia vario deformity is not corrected early, permanent damage to the growth plate and growing bone often occurs. Later, joint degeneration may occur.
In general, in cases where a child’s booster treatment has not been effective in correcting leg tilt, or where the condition is identified in children older than 3 or 4 years, with a more severe tilt surgery is recommended.
The most commonly used operation is called an osteotomy, in which a very small wedge is removed from the tibia (shin), and sometimes also the fibula, in an effort to realign the lower leg to a straighter position.
A plate is placed at the osteotomy site and may need to be removed 1 to 2 years after surgery.
Other surgical treatments include performing a small operation, in which the growth plate (epiphysis) is removed or tied off with the use of small plates to stop abnormal growth of the tibia and correct its alignment.
An osteotomy is also used followed by the placement of an external fixator device, in which a device is attached to the outside of the leg for several months with small metal pins, which help the newly aligned tibia to heal properly.
Blount’s disease (tibia vara) can require some difficult adjustments for parents and their child with the condition.
Frequent visits to the doctor, the use of braces or casts, and a surgical operation at an early age can present 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 who are treated for this disease reach childhood or adulthood without abnormalities or restrictions in their activities and abilities, from walking every day to demanding and competitive sports.
If the leg can be placed in the proper position, the outlook is good, even the leg should function properly and appear normal.