Scoliosis is a common spinal condition that involves a sideways curvature of the spine. This article provides information on its prevalence within the United States.
What is Scoliosis?
Scoliosis is characterized by a sideways curvature of the spine, often accompanied by vertebral rotation. A diagnosis is typically made when this spinal curvature, measured using the Cobb angle, is 10 degrees or more. While it can manifest at any age, it is most frequently identified during adolescence, between 10 and 18 years old. This form, known as Adolescent Idiopathic Scoliosis (AIS), represents approximately 80% of all scoliosis cases.
How Common is Scoliosis in the US?
Scoliosis affects an estimated 2% to 3% of the U.S. population, translating to roughly six to nine million people. Among adolescents, 1% to 3% are affected by adolescent idiopathic scoliosis. Some literature suggests a broader range for children and adolescents, between 0.47% and 5.2%.
In adults, prevalence estimates range from 12% to 20%. This rate significantly increases with age, potentially affecting as many as 68% of individuals over 60 years old, often due to age-related degenerative changes in the spine.
Gender plays a role in scoliosis prevalence and progression. While mild curves (10 degrees or more) are found in similar proportions in both males and females during adolescence, girls are considerably more likely to experience progression to more severe curves. For curves measuring 30 degrees or more, females can be 8 to 10 times more likely to be affected than males. In adults, women have approximately twice the prevalence of scoliosis compared to men and are also more frequently diagnosed with degenerative forms.
Why Prevalence Numbers Can Vary
The reported prevalence of scoliosis can differ across sources due to several factors. One factor is the specific definition of a “significant” curve used in studies. While a Cobb angle of 10 degrees or more is the standard diagnostic threshold, studies may report prevalence based on different severity levels, such as curves greater than 20, 25-30, or 40 degrees. These varying thresholds lead to different reported numbers.
Differences in screening practices also influence prevalence data. Historically, school-based scoliosis screenings were common in the U.S., but their implementation and methodologies varied across states and over time. The type of screening method used, such as the Adam’s forward bend test alone or combined with a scoliometer, can impact detection rates. Variations in diagnostic criteria and study populations further contribute to discrepancies in prevalence statistics, as different research designs and methodologies may not be directly comparable.