Femoral anteversion measurement : evaluation of inter- and intraobserver reliability.

ABSTRACT

The aim of this study was to evaluate the inter- and intraobserver reliability of a CT-based femoral anteversion measurement. 17 CT scans showing an abnormal anteversion on one side were presented to 6. Three measurements of all scans were obtained two bilateral measurements and a third measurement with a flipped CT scan. Interobserver correlation results using the spearman test for left, right and anteversion difference had a mean of respectively 0.918, 0.760 and 0.757. Intraobserver correlation had a maximum of respectively 0,99, 0,89 and 0,94. Correlation coefficients were consistently higher for the second measurement. The lower correlation boarder of 0,8 was often exceeded. Intraobserver correlation was higher than interobserver correlation. As we evaluated a high variance in interobserver reliability, we recommend an accurate and objective measurement of the anteversion angle. A personal measurement and comparison to the radiological protocol is necessary.