Risk Factors and Natural History of De Novo Degenerative Lumbar Scoliosis in a Community-Based Cohort: The Miyama Study.

Study Design: A prospective study of de novo degenerative lumbar scoliosis in a community-based cohort.

Objectives: To investigate risk factors and natural history of de novo scoliosis in the elderly.

Summary Of Background Data: Most previous studies have focused on the risk of progression with greater curve magnitude, which often manifests with serious clinical symptoms. There have only been a few reports regarding the etiology of de novo scoliosis.

Methods: Subjects (n = 400) were selected by sex and age from a list of 1,543 district residents, born from 1910 to 1949; 50 men and 50 women were selected from each age decade. Radiographic examinations of the lumbar spine in anteroposterior and lateral views were performed in 1990 and repeated in 2005 and 2008. De novo scoliosis was defined as newly developed scoliosis (a Cobb angle of 10° or greater and an increase in Cobb angle 5° or greater) in 2005 or 2008.

Results: Evaluation of radiographic surveys was completed for 200 of the 400 participants in 2005 and for 154 in 2008. De novo scoliosis was found in 33 inhabitants in 2005 and 24 in 2008. The scoliotic angles were less than 30°. During the follow-up period, significant asymmetric intervertebral disc degeneration developed, especially in the upper lumbar spine (p < .03), and lumbar coronal imbalance was significantly increased (p = .016). Logistic regression analysis, which was performed with the occurrence of scoliosis as an objective factor, identified L3 rotation as a significant risk factor (odds ratio, 13.95; 95% confidence interval, 4.05-52.34; p < .0001).

Conclusions: This epidemiological study using radiography of the lumbar spine suggests that patients with asymmetric intervertebral disc degeneration and rotation of L3 in initial radiography without scoliosis should be closely followed up to observe the occurrence of scoliosis. Although the incidence of de novo scoliosis increases with age, scoliosis is usually benign.