Electromagnetic topographical technique of curve evaluation for adolescent idiopathic scoliosis.

STUDY

DESIGN

Diagnostic testing.

OBJECTIVE

The goal of this study is to measure the accuracy and reliability of the Orthoscan (Orthoscan Technologies, Inc.) and to determine whether it can be substituted for radiographs in the surveillance of adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA: AIS is usually followed using scoliosis radiographs, which offer the most reliable way to quantify the curve, but carry the risk of exposure to ionizing radiation. The Orthoscan is a nonradiographic topographic method for measuring spinal curves.

MATERIALS AND

METHODS

There were 5 phases of this study that measured: the accuracy and reliability of the machine when used with a plastic model; the variability with a real patient; the intraobserver variability; the correlation between the measurements of the machine and that of the radiograph; and the correlation between the change in radiograph measurement over time and the change in Orthoscan measurement over time.

RESULTS

In measurement of a static plastic model, the machine measured curves with a standard deviation of +/-1 degrees in trunk rotation and +/-2 degrees in curve measurement. Error increased with a real patient. Thirty-six comparisons in the thoracic spine, and 19 comparisons in the lumbar spine, were made between measurements using the Orthoscan and radiographs. Mean curves in the 2 groups were not significantly different and had poor-to-moderate correlation. Longitudinal evaluation included 47 curves in 28 patients. The Orthoscan predicted the radiograph change within an acceptable range 55.3% of the time.

CONCLUSIONS

The Orthoscan does not accurately predict the scoliosis curve magnitude or the overall change in curve over time. While analysis in groups of patients using this technique reveals group means that begin to look acceptable, if the variability is too great, then this technology is not yet ready to replace the radiograph in the evaluation of a scoliosis curve.