Abstract
Objective This study aimed to compare the accuracy of sternal recumbency caudocranially obtained
radiographs of canine femora to computed tomographic (CT) frontal plane reconstructions
of the same femora for assessing anatomic distal lateral femoral angles (aLDFA).
Study Design Multicentre, retrospective study utilizing 81 matched radiographic and CT studies
of clinical patients undergoing assessment for various issues were reviewed. Anatomic
lateral distal femoral angles were measured, and accuracy assessed with descriptive
statistics and Bland-Altman plot analysis, with CT considered the reference standard.
Sensitivity and specificity of a cut-off for measured aLDFA (102 degrees) were determined
to assess radiography as a screening tool for significant deformity.
Results Radiographs on average overestimated aLDFA by 1.8 degrees compared to CT. Bland-Altman
analysis identified a 15.4 degrees 95% limit of agreement range and a tendency for
greater overestimation at higher average measured value. Radiographic measurement
of aLDFA of 102 degrees or less had a 90% sensitivity, 71.83% specificity, and 98.08%
negative predictive value for the CT measurement being less than 102 degrees.
Conclusion Accuracy of aLDFA measurement by caudocranial radiographs does not demonstrate sufficient
accuracy when compared to CT frontal plane reconstructions with unpredictable differences.
Radiographic assessment is a useful screening tool to exclude animals with a true
aLDFA of greater than 102 degrees with a high degree of certainty.
Keywords anatomic lateral distal femoral angle - femoral varus angle - femoral osteotomy -
radiograph - computed tomography - dog
