Abstract
Purpose of the study
Monitoring of scoliosis is traditionally done with radiographs which can be associated with an increased risk of cancer secondary to multiple exposures over many years. This study investigates whether lateral asymmetry (LA) from ISIS2 surface topography can predict radiographic cobb angle, to provide an alternative non- invasive means of monitoring scoliosis patients.
Methods
A total of 72 untreated patients with scoliosis (77 curves) with a Cobb angle of 55 degrees or less were included in the study. They had clinical assessment, cobb angle measurement taken from a standard radiograph and surface topography done on the same day. The cobb angle were measured by single surgeon using digital PACS system. The surgeon was unaware of the LA score. Lateral asymmetry was measured using ISIS2 surface topography done by a research nurse who was also unaware of the cobb angle as previously described. Lateral asymmetry was calculated using the standard ISIS2 software. A comparison of cobb angle and LA was performed.
Linear regression analysis was performed to define an equation predicting Cobb from LA. The predicted Cobb angles were then compared with the measured radiographic Cobb angles using Bland-Altman analysis. All statistical analysis was carried out using R.
Results
The regression equation is: Predicted Cobb = 1.04∗LA + 9.972 with a Pearson correlation coefficient of 0.85 for Cobb angles less than 55 degrees. Bland-Altman analysis of the difference between radiographic Cobb and predicted Cobb from LA gave a mean difference of 0.08 degrees, standard deviation of 6.71 degrees and 95% limits of agreement of −13.3 to 13.5 degrees.
For cobb angle less than 55 degrees on radiograph, ISIS2 was able to predict the cobb angle within 13 degrees
Conclusion
Cobb angles themselves display poor reliability, estimates ranging from 3 degrees to 10 degrees. Even so, the 95% confidence limits on the prediction of Cobb angle from ISIS2 LA are too wide to use it alone for monitoring spinal curvature. Whether or not LA is capable of monitoring change in curvature will be investigated as more longitudinal data is built up.
Ethics approval: None
Interest Statement: None
