PRE-OPERATIVE PLANNING WITH CT SLICES CAN INDUCE INTERNAL-ROTATED POSITION OF THE FEMORAL COMPONENT IN TOTAL KNEE ARTHROPLASTY

IntroductionRadiographs and computed tomography (CT) images are used for the preoperative planning in total knee arthroplasty (TKA), however, these two-dimensional (2D) measurements are affected easily by limb position and scanning direction relative to three-dimensional (3D) bone model analyses. The purpose of our study was to compare these measurements to evaluate the factors affecting the difference.Patients and MethodsA total of 75 osteoarthritis knees before primary TKA were assessed. The full-length weight-bearing anteroposterior radiograph and CT slices were used for the 2D measurement. Three-dimensional measurement used 3D bone model reconstructed from the CT data and the coordinate system as the previous reports (Figure 1). We measured FVA (femoral valgus angle), CRA (the angle between the posterior condylar line and the clinical epicondylar axis ), and SRA (the angle between the PC-L and the surgical epicondylar axis ). Intra- and inter-observer reliabilities were assessed by in...