Ethnic variance in the epidemiology of scoliosis in New Zealand.

A manual and computerized search of orthopaedic outpatient records over a 10-year period (1990-2000) identified 386 new patients younger than age 20 years with a diagnosis of scoliosis. Patients were grouped according to race and their numbers were compared with predicted values calculated from New Zealand census data. Of the various etiological categories, idiopathic scoliosis and scoliosis secondary to syringomyelia showed significant ethnic variance. For idiopathic scoliosis, higher numbers than predicted were observed in Europeans and lower numbers than predicted were observed in Polynesians. Conversely, for scoliosis secondary to syringomyelia, relatively higher numbers were observed in Polynesians and relatively lower numbers in Europeans and other ethnic groups. The demonstration in this study of a low incidence of idiopathic scoliosis and conversely a high incidence of syringomyelia in Polynesians has led the authors to reconsider the indications for magnetic resonance imaging when patients of this ethnic group are referred with scoliosis that initially appears to be idiopathic.