Identified by Blount in 1973, infantile tibia vara (ITV) refers to a developmental disorder marked by the abnormal endochondral ossification of the medial aspect of the proximal tibial physis that results in multiplanar deformities of the lower limb.
The suppression in growth caused by excessive pressure on the posteromedial proximal tibial physis results in bowing of legs which could either be physiological or pathological in nature.
Sanjeev Sabharwal, of the Department of Orthopedics at New Jersey Medical School, identifies two clinically distinct forms of Blount disease – early-onset (infantile) and late-onset – depending on whether the limb deformity develops before or after the age of four years.
The author mentions obesity as a contributing factor to the condition with his studies having established a linear relationship between the magnitude of obesity and biplanar radiographic deformities in children with the infantile form of Blount disease.
Children with early-onset Blount disease, irrespective of a lower body mass index, were observed to have more severe varus and procurvatum deformities of the proximal part of the tibia than did adolescents with the same disease.
Treatment strategies formulated for infantile tibia vara need to focus on achieving a normally aligned lower extremity with normal joint orientation and equal limb lengths at skeletal maturity.
While studying the efficacy of an orthotic intervention in the treatment of infantile tibia vara, Raney et al. reviewed patients who received knee-ankle-foot orthosis for genu varum at Shriners Hospital in Tampa, Florida.
The authors reported that 90 percent of the cases were treated successfully with orthoses which were discontinued when neutral clinical and radiographic alignment were obtained; the study supported orthotic interventions as viable early treatment options for patients younger than 3 years with a metaphyseal-diaphyseal angle greater than sixteen degrees.
Among the long-term follow-up studies of patients with Blount disease, as mentioned by Sabharwal, a number of interesting observations were reported – chiefly the onset of arthritis in the knees at an average age of thirty-eight years.
With postural alignment as one of the main goals of treatment programmes for infantile tibia vara, MASS4D® foot orthotics with heel lifts can be used to further treat structural leg length discrepancy of up to 10mm to restore alignment and optimal lumbopelvic biomechanics after the person has reached skeletal maturity.
Excessive pronation on the long leg side can be treated with corrective orthotics in conjunction with heel lifts on the ipsilateral foot, to balance the sacral base and minimise compensatory scoliosis.
By optimally redirecting the mechanical forces acting on the lower extremity, highly customised orthotics such as MASS4D® can also be used to cause a decrease in the pathological loading forces acting on the affected knee, improving gait function in the patient and protecting the musculoskeletal system from any further damage.
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