3D geometrical assessment of femoral curvature: A reverse engineering technique

Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University, Bangkok, Thailand.
Journal of the Medical Association of Thailand = Chotmaihet thangphaet 10/2008; 91(9):1377-81.
Source: PubMed


Investigate the 2D/3D geometry of femoral curvature and femoral length using the advanced technique of computerized tomography combined with reverse engineering techniques.
The present study was performed using reverse engineering technique based on CT data of 99 cadaveric femora. The femur was divided into three segments, proximal, mid-shaft, and distal regions by defining 35% and 65% of the femoral total length as a boundary of each region. The intramedullary canal in the mid-shaft region was mainly extracted to determine the set of circular center, which could consequence to approximate the 3D femoral radius of curvature using the 3D least square best fit. The 3D femoral curvature was then projected into A-P and M-L directions to investigate the correlation of 2D/3D femoral curvature as normal radiographic images.
It was found that the average 3D Thai femoral curvature was 895.46-mm (SD = 238.06) and the average femoral total length is 421.96-mm (SD = 27.61). In addition, the 2D femoral curvature derived from sagittal radiographic image can be used to determine the 3D femoral curvature with this equation: R3D = RSagittal + 3.67 with r = 0.987.
This described technique is a non-destructive method that can effectively assess the internal/ external 3D geometric data of the femur The obtained data is useful to develop a proper design of prosthesis that required inserting into the intramedullary canal. From the present study, it can be concluded that the 2DSagittal femoral curvature derived from standard radiographic image can be represented for the 3D femoral curvature.

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Available from: Kriskrai Sitthiseripratip,
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    • "Other important parameters are the bowing angle and the anterior bowing, which is vital in prosthesis design [22]. Extreme bowing femora influence the stability of the implant especially with the cementless hip stem at distal diaphysis leading to overreaming, which risks more bone loss during surgery to prevent femora fracture [40, 41]. "
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    • "Moreover, the three-dimensional models can be used to simulate the surgical operation prior surgery (Fürnstahl, et al., 2010), subsequently reduce operating time and increase safety of patients. Alternative uses of computed tomography include morphometric study (Chantarapanich, et al., 2008; Mahaisavariya, et al., 2002) and the evaluation the risk of implant usage (Mahaisavariya, et al., 2004; Sitthiseripratip, et al., 2003) The purpose of this chapter is to present and discuss the medical imaging and reverse engineering techniques by means of demonstrating the application in craniometric study. "

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