Natural History of Adult Scoliosis

Purpose: A retrospective analyse of the progression of adult scoliosis.

Methods: We selected the charts and radiographs of 51 adults who had a progressive scoliosis. The mean follow-up was 27 years. The radiographs were measured by two senior physicians. We made for each patient a diagram with the Cobb angle on the Y axis and the age on the X axis. We noted the age (AR) and Cobb angle (CR) of the 1st radiograph demonstrating a rotary subluxation and the age of menopause. We used linear regression and the Anova test.

Results: The mean number of radiographs was 6 (min.4, max.12). The linear test was significant in 46 patients. The diagram illustrated two types : type A is an scoliosis which continues to progress regularly after skeletal maturity, whereas type B appears or progresses late. There were 13 type A and 20 type B of which 11 demonstrated progression around menopause. 13 were unclassified because of the insufficient number of x-rays. Significant differences were noted between group A and B regarding:

- loss of body height (A : 5 cm; B : 9,5 cm p<0 .001)

- rate of progression in L and TL (A:0,82°/year; B: 1,64°/year; p<0 .004)

- Cobb 1st radiograph (A:37°; B:20°; p<0 .0001)

- AR : A: 42 year; B: 56 year; p<0 .0001

- CR : A: 52°; B: 30°; p<0 .0001

Discussion: Our study compared the 2 different types of adult scoliosis. 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. The originality of our study is the diagram. We demonstrated that the rate of progression was linear and hence, this allowed us to establish an individual prognostic.