People mistakenly believe that carrying heavy bags, poor body posture, playing sports or sleeping on one side can cause the spine to curve, but that is not true. In fact, approximately 80% of all scoliosis cases have no known cause. These cases with no known cause are known as idiopathic scoliosis.
While nobody knows what exactly causes idiopathic scoliosis, there are a few risk factors that have been identified and associated with idiopathic scoliosis:
- Age: Most cases occur when a child reaches their growth spurt at the age of 10 and older, during their adolescence. There are also rarer cases that occur earlier in their lifetime, ones that occur at the age of 3 to 9 (juvenile scoliosis) and curves discovered in babies younger than 3 years old (infantile scoliosis).
- Sex: Girls are eight times more likely to develop scoliosis than boys.
- Family History: Scoliosis can be inherited from parents or affect siblings. If scoliosis is discovered in a child, it would be wise to check on the other siblings for scoliosis.
Cases of scoliosis with a known cause are rarer than idiopathic scoliosis cases, occurring in an average of 1 in every 10,000 people. Non-idiopathic scoliosis is often caused by a poorly developed spine or as a side effect of other diseases.
Neuromuscular scoliosis: The second most common type of scoliosis, caused by nerve or muscular disorders such as cerebral palsy, muscular weakness and spinal cord injury. When the back muscles are weakened or paralysed, there is insufficient support from the back muscles to keep the spine straight.
Unlike idiopathic scoliosis, the spinal curves caused by neuromuscular scoliosis are more likely to progress and continue to curve even as the patient grows into adolescence or adulthood.
Congenital scoliosis: Congenital scoliosis is caused by a defect during the baby’s development in the womb where some parts of the spine are not fully formed or absent. The missing segments of the spine result in a curve as the spine continues to develop. Additional curves may also develop as the spine attempts to straighten or correct the scoliosis, forming double curves or increasing the severity of the curve.
A misleading conception about congenital scoliosis is that there is always a curve in the spine at birth, but that is not true. Some defects do not cause a curve until later in a person’s life.
Degenerative scoliosis: The most common form of scoliosis in adults and the elderly, degenerative scoliosis often occurs in the lower back (lumbar) as part of the natural aging process. Loss of bone mass, deteriorating joints, arthritis or previous spine surgery are all factors that can cause the spine to shift sideways.
Like a building’s structure with a weakened base, degenerative scoliosis may progress as a person continues to age and their spine gradually grows unstable over time. Approximately 60% of adults above the age of 60 are suspected to have mild degenerative scoliosis due to aging. When the degeneration is concentrated on one side of the spine more than the other, a curve may form and progress.