• Burden of disease
• Natural history
• Symptoms affecting various bodily systems associated with the conditions are as follows:

Burden of disease

Adolescent idiopathic scoliosis (AISAdolescent idiopathic scoliosis (AIS) is a condition with a prevalence worldwide that ranges from 0.35% to 13%, depending on ethnicity, gender, and screening methods, with the condition being more common among females than males. In Thailand, a survey conducted in some schools found a prevalence of 0.91% to 4.62%, while a study in schools within the Bangkok metropolitan area, involving 1,818 girls aged 11-13 years, reported a prevalence of 4.62%.

If left untreated, the condition can lead to increased curve progression, severe back pain, and an increased risk of spine degeneration, which can affect cosmetic appearance, social and psychological well-being, and, in severe cases, lung function. Early detection and treatment are crucial for reducing the likelihood of significant curve progression and the need for surgical intervention.

Natural history

Adolescent idiopathic scoliosis and its causes are still not fully understood, but factors that may contribute to the development of the condition include:

1. Genetics: Studies have shown a genetic predisposition to scoliosis within females of the same family, with an incidence of 11% among first-degree relatives and lower percentages among second and third-degree relatives. A study into monozygotic twins found a higher likelihood of developing scoliosis, with a rate of up to 75%, compared to heterozygous twins with a rate of approximately 33%.
2. Connective tissue abnormality: There is a correlation between scoliosis and connective tissue diseases, such as Marfan syndrome.
3. Thrombocyte abnormalities: Abnormalities in thrombocytes (blood platelets) and proteins controlling intracellular calcium-binding (calmodulin) and melatonin hormone have been implicated in the development of scoliosis.
4. Growth and biomechanical theories: Growth during the rapid growth phase is considered a significant factor in curve progression, and the cessation of progression occurs after skeletal maturity. However, these factors are still under investigation. In terms of biomechanics, it has been observed that cartilage on the concave side of the curve is subject to excessive weight-bearing that can inhibit growth, which is believed to result in an asymmetrical load that may lead to vertebral wedging and a vertebral deformity.

Symptoms affecting various bodily systems associated with the conditions are as follows:

1. Back pain The Iowa long-term series was a 50-year study which showed that individuals with scoliosis may experience back pain even after reaching skeletal maturity. X-ray results from this research project showed that up to 91% of patients had signs of spinal joint degeneration, including minimal osteophyte formation, mild disc space narrowing, or moderate facet joint sclerotic changes. However, the majority of back pain cases were not directly correlated with the degeneration of spinal joints, except in certain positions where there was a translator shift in the thoracic-lumbar and lumbar curves. There were also three Swedish long-term studies conducted over more than 30 years that found more than 90% of scoliosis patients experienced some degree of low back pain, which improved with rest and varied in terms of pain location, although it was not found to be related to the location or magnitude of the curve.
2. Pulmonary function A relationship has been found between the magnitude of the thoracic curve and pulmonary function, whereby pulmonary function decreases when the curve angle exceeds 60-70 degrees, while forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) are reduced by 20% when there is a curvature of around 100 degrees. Weinstein also observed significant limitations in FVC with curves of 100-120 degrees, particularly in cases of thoracic hypokyphosis.
3. Mortality;Patients with thoracic curves exceeding 100 degrees have an increased risk of mortality due to cor pulmonale and right ventricular failure.
4. Psychosocial effects Scoliosis can result in a severe cosmetic deformity, especially in cases with severe curves where rib prominence exceeds 3 centimeters. However, there seems to be no link between the location or magnitude of the condition on the severity of psychosocial effects.
5. PregnancyResearch by Nachemson suggests that multiple pregnancies before the age of 23 may increase the risk of curve progression. Betz et al. reported that the age at onset of the first pregnancy, number of pregnancies, or curve stability do not increase the risk of scoliosis curve progression, while the Iowa long-term study found that mild-moderate scoliosis did not affect pregnancy or delivery outcomes.

Article by Dr. Pritsanai Pruttikul
Specialist in orthopedics and spinal surgery