Focus On Classification of adolescent idiopathic scoliosis

Scoliosis Research Society defined scoliosis deformity as a lateral curvature of the spine on a radiograph of the spine taken in standing position.1 The degree of the curve is measured as the angle between the most inclined vertebral end-plates at each end of the curve (the Cobb angle). There are many causes of scoliosis deformity. It can be structural due to spinal pathologies or non-structural as a result of other skeletal abnormalities, for example leg-length discrepancy and pelvic obliquity. Scoliosis with Cobb angle more than 10°, associated with vertebral rotational deformity, is regarded as structural scoliosis.2 Many conditions can lead to structural scoliosis deformity: neuromuscular diseases like cerebral palsy and polio myelitis causing neuromuscular scoliosis; congenital vertebral abnormalities including hemi-vertebra and unsegmented bar causing congenital scoliosis; syndromal disorders like Marfan syndrome and neurofibromatosis that lead to syndromal scoliosis. Idiopathic scoliosis is a diagnosis of exclusion that can only be made after other causes of scoliosis deformity have been excluded. It is the most common type of spinal deformity and accounts for about 75% of patients with scoliosis. This article focuses on classifications of adolescent idiopathic scoliosis and their clinical applications.