Can surface topography replace radiography in the management of patients with scoliosis?

Introduction Scoliosis is a three-dimensional deformity of the spine and trunk, which during adolescence, can be effectively treated conservatively. Scoliosis patients are exposed to multiple Xray investigations during treatment. One can reduce the need for X-rays during the regular follow-ups when clinical measurements are taken (angle of trunk rotation, surface topography); however, as indications and follow-ups of treatment still rely on the measurement of the Cobb angle (CA) on a full-standing X-ray, the exposure of children and adolescents with scoliosis cannot be avoided. Claims have been made recently that surface topography can predict the CA satisfactorily. The aim of this report is to analyse patients from our centre to test the repeatability of the results from that previously reported using the Diers Formetric ® system. Materials and methods Twenty-five patients (four males and 21 females) with adolescent idiopathic scoliosis (AIS) had a Formetric ® scan and an anteroposterior X-ray of the spine at the time they presented for having their first brace in the office of the senior author. The average age was 12.9 years (10–14 years), average CA was 38.2°. The CA as measured on the X-ray was correlated to the scoliosis angle (SA) as provided by the Formetric ® system. Results Correlation was relatively high (r = 0.84), and the differences between the two series of measurement were not significant (P = 0.08). However, only 9/25 measurements were in the range of technical error (±5°). In 12/25 patients, the Formetric ® SA measurements were six or more degrees too low (maximum 38°). In 4/25 patients, the Formetric ® SA measurements were six or more degrees too high (maximum 8°). Conclusion Although the correlation between X-ray and surface measurements was comparable with that published before, we cannot conclude that the device can be reliably used in the surveillance of patients with AIS, as the differences in one case were as high as 38°. Currently, there is no proof that surface measurement devices can reduce the need for X-rays.