Precision, Variability, and Accuracy of Femoral Varus Measurement
Alexander C. Robb
Cummings School of Veterinary Medicine at Tufts University
Precision, Variability, and Accuracy of Femoral Varus Measurement Using Radiographic and Computed Tomographic Imaging in Clinically Abnormal Femora
INTRODUCTION: Many skeletal abnormalities have been associated with medial patellar luxation (MPL), and recent focus has centered on femoral malalignment, specifically excessive femoral varus, quantified by measurement of the anatomic lateral distal femoral angle (aLDFA).1,2 In cases with excessive varus, a distal femoral osteotomy can be performed; however, this invasive procedure requires accurate measurement of aLDFA. Recent studies have reported conflicting evidence regarding the ability to measure distal femoral varus in clinically normal bones using both radiographic and computed tomographic (CT) methods.1,3 The purpose of this study was to establish the precision, variability, and accuracy of aLDFA measurement using radiographic and CT imaging, compared to the reference standard of digital photographs of anatomic specimens, in clinically abnormal femora. Our hypothesis was that CT would be more precise, less variable, and more accurate than radiographs for aLDFA measurement.