Natural history of progressive adult scoliosis

A retrospective analysis of the progression of adult scoliosis.

To establish an individual prognosis.

Most studies have investigated the adolescent scoliosis after skeletal maturity, but the results are discordant.

Two senior physicians measured all the radiographs of 51 adults who had a progressive scoliosis. The mean delay between the first and last radiograph was 27 years. For each patient, a diagram was established with the Cobb angle on the y-axis and the corresponding age on the x-axis. We noted the age and Cobb angle of the first radiograph showing a rotatory subluxation and the age of menopause. We used linear regression and the analysis of variance test.

The mean number of radiographs per patient was 6. The linear test was significant in 46 patients. Two main types exist. Type A is an adolescent scoliosis that continues to progress after skeletal maturity, whereas type B appears or progresses late. There were 13 type A and 20 type B of which 11 progressed around menopause. Significant differences were noted between groups A and B regarding loss of body height (group A, 5 cm and group B, 9.5 cm; P < 0.001), rate of progression in lumbar single and thoracolumbar single curves (group A, 0.82 degrees/y and group B, 1.64 degrees/y; P < 0.004), Cobb first radiograph (group A, 37 degrees and group B, 20 degrees; P < 0.0001), age rotatory subluxation (group A, 42 years and group B, 56 years; P < 0.0001), and Cobb rotatory subluxation (group A, 52 degrees and group B, 29 degrees; P < 0.0001).

The originality of our study is the diagram. We demonstrated that the rate of progression was linear, and it can be used to establish an individual prognosis. The diagrams visualized 2 main distinct types. There was a significantly faster rate of progression in type B. In type A, rotary subluxation occurs during progression of the curvature. In type B, it seems to be the initial event. Menopause is a period of deterioration in type B.