A New Technique to Increase Reliability in Measuring the Axis of Bone

Measuring bone angles is an important method for diagnosing disease and predicting the prognosis in orthopedics. Traditionally, the angle is measured using lines drawn manually and adjusted by the naked eye. The purpose of the present study was to propose new methods to measure the bone angles formed by the axes of the calcaneus with good reliability and low operational error. The 2 new methods used linear regression analysis of the points inside and on the "envelope" line. The traditional method used the vector of the lines drawn for calculation. Digital radiographs of the lateral view of the feet from 51 patients were collected, and the angles were measured using these 3 methods. Next, we analyzed the reliability, differences, and correlations of these 3 methods. The intra- and interobserver comparisons revealed significant differences between the results of the 2 new methods and those of the traditional method. In addition, the new methods had greater reliability and better intra- and interobserver correlations than did the traditional method. We suggest that these 2 new methods to measure bone axis should be added to the Picture Archiving and Communication System to obtain more reliable and standardized data in clinical practice and for future research purposes.