ABSTRACT
PURPOSE: To measure and to analyze the relationships among the rotational axes of the distal femoral region by means of 3-dimensional (3D) computed tomographic (CT) images taken perpendicularly to the mechanical axis and a 3D rendering program. MATERIALS AND METHODS: Fifty cases involving the lower extremity were included in this study, which used 3D computed tomographic angiograms. CT images of the perpendicular cross-sections to the mechanical axis of the femur were obtained by processing 3D recombinant images using Aquaris NET(R). The following anatomical angles were obtained from axial imaging using the 3D reconstructed bone model: transepicondylar axis, surgical transepicondylar axis, anteroposterior axis, and real posterior condylar axis. RESULTS: In the tomographic images, the angles to the real posterior condylar axis formed by the anatomical femoral transepicondylar axis, the anatomical femoral transepicondylar axis, and the anteroposterior axis were 6.34+/-1.23degrees, 2.43+/-1.56degrees, and 96.52+/-1.77degrees, respectively. The angles to the anatomical femoral transepicondylar axis formed by the anteroposterior axis and the surgical femoral transepicondylar axis were 90.19+/-1.61degrees and 3.91+/-0.90degrees, respectively. In the recombinant 3D femur model, the angles to the real posterior condylar axis formed by the anatomical femoral transepicondylar axis and the anteroposterior axis were 6.29+/-1.86degrees, and 93.33+/-3.76degrees, respectively. And, the angle for anteroposterior axis from anatomical transepicondylar axis was 87.04+/-4.11degrees. CONCLUSION: The method of measuring the rotational axes of the distal femur using the CT image taken perpendicularly to the mechanical axis is considered reproducible. In particular, the measurement method using the anatomical transepicondylar axis is more accurate than that using the anteroposterior axis.