Our 13-year-old has a severe case of scoliosis. It appeared out of the blue. They tell us it can be genetic. But what makes the spine curve like that?

Scoliosis is a deformity in the spine that causes an abnormal C-shaped (one curve) or S-shaped curvature (two curves). The spine is not straight but curves to one or both sides. There are three types of scoliosis depending on when it develops. Infantile occurs from birth to three years of age. Juvenile scoliosis develops between four and nine years of age.

The type your child has is called adolescent idiopathic scoliosis (AIS). AIS presents between 10 years and when growth is complete. Idiopathic means the cause of scoliosis is unknown. Idiopathic scoliosis is the most common type and affects about two to three per cent of the population. It tends to run in families and is more common in girls than in boys. Most often it develops in middle or late childhood during a rapid growth spurt.

Any part of the spine can be affected by scoliosis including the cervical, thoracic, or lumbar vertebrae. Most often the thoracic and lumbar spine are affected. The vertebrae curve to one side and may rotate, which makes the waist, hips, or shoulders appear uneven. Exactly what causes the spine to start to curve and then rotate remains a mystery even to scientists who have studied this problem for many years.

For a long time, the focus has been on how to treat this problem. Since it's unknown what causes it, efforts to prevent AIS have taken a back burner. Future research may uncover more specific risk factors and/or pathologic mechanisms associated with this condition. Right now, we have more questions than answers about adolescent idiopathic scoliosis.