Idiopathic scoliosis in males. A natural history study.

Curve behavior of idiopathic scoliosis in an exclusively male population was investigated, since it has not been previously reported. Fifty males with idiopathic scoliosis satisfied entry requirements for this study: standing posteroanterior (PA) spine radiograph measuring a curve greater than 20 degrees, preoperative observation for greater than 1 year (mean, 4.4 years), and nonoperative patients with greater than 5 years of radiographic follow-up beyond skeletal maturity (mean, 10.7 years). Mean rate of curve progression from presentation to Risser 4 maturation was 3.0 degrees/year. Forty-four percent of the curves progressed 5 degrees or more between Risser 4 and 5. The rate of curve progression following Risser 5 was 0.18 degrees/year. Thoracic curves were associated with a higher degree of curve progression than other curve types (P less than 0.05). There was no statistically significant association between curve progression and family history, vertebral rotation, Risser sign, or curve magnitude. Curve progression secondary to growth usually terminates at Risser 4 in females with idiopathic scoliosis. This study indicated that scoliotic male curves demonstrated clinically significant progression until Risser 5 rather than Risser 4. Thus, the authors conclude that males with idiopathic scoliosis curves greater than 20 degrees should be followed radiographically until Risser 5. In females, scoliosis beyond Risser 4 can be considered as an adult curve; however, in males, scoliosis can be evaluated as an adult curve only after Risser 5. Beyond Risser 5, male curves demonstrate minimal progression.