J Med Assoc Thai 2008; 91 (9):1377

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3D Geometrical Assessment of Femoral Curvature: A Reverse Engineering Technique
Chantarapanich N Mail, Sitthiseripratip K , Mahaisavariya B , Wongcumchang M , Siribodhi P

Objective: Investigate the 2D/3D geometry of femoral curvature and femoral length using the advanced
technique of computerized tomography combined with reverse engineering techniques.

Material and Method:
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.

Results: 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 =
RSagtital + 3.67 with r = 0.987.

Conclusion: 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

Keywords: Femoral curvature, Femoral length, Intramedually canal, Thai femur

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