ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

(a) (b)
Figure 1. original femur and sliced femur (a) original tibia and sliced tibia (b).
Therefore, the 3D CAD model was modified by an orthopedic surgeon who sliced both
femur and tibia in MIMICS as shown in Fig. 1. The steps required to obtain a CAD
model from the CT images is represented in Fig 2(a). The 3D CAD model of both femur
and tibia are also given in Fig.2 (b). The final 3D CAD model was generated by
assembling a mobile bearing-type prosthesis received from Sistem Ortopedi® (Sistem
Ortopedi Inc., Konya, TURKEY) and cement models .
In order to obtain a realistic 3D model for both femur and tibia, the femur and tibia
model were obtained having cortical and trabecular bones, rather than having one single
body for femur or tibia. The following steps were carried out in order to get the
trabecular model, and are shown in Fig. 3.
A closed region formed on the CT slices, comprising the boundaries of the
cortical bone (Fig.3 a)
A new mask is assigned, considering the limit HU values for the trabecular
bone (Fig 3.b)
Figure 2: Steps required to get a 3D model from CT scans (a), 3D model of femur and
tibia (b).
3