Measurement of femoral anteversion by biplane radiography and computed tomography imaging: comparison with an anatomic reference.

Abstract

The ability of biplane radiography and standard computed tomography (CT) imaging techniques to measure accurately the human femoral anteversion was evaluated and compared with an anatomic reference: the osteometric method. Femoral anteversion of 10 normal adult cadaveric human femora were determined using a standardized anatomic measurement method (the anatomic reference) and the 2 selected common imaging techniques (biplane radiography and CT). On average, anteversion measurements using biplane radiography were 21/2 times greater in magnitude than measurements using the anatomic reference (absolute mean difference, 13.5 degrees; P = 0.004). In contrast, the discrepancy between CT and anatomic reference measurements was notably less and not statistically significant (absolute mean difference, 2.8 degrees; P = 0.351). In addition, biplane radiography demonstrated greater inter- and intrarater variability than CT imaging for repeated measurements of the same bone specimens. Compared with the anatomic reference, CT imaging was an accurate and valid technique for measuring the femoral anteversion. In contrast, biplane radiography demonstrated significant inconsistencies in the measurement of this anatomic parameter.