A 3D Kinematics Measurement of Knee Joint Using X-Ray Projection Images(Mechanical Systems)

Abstract

Most of previous studies about joint kinematic analysis using X-ray image needed totally clear outline bones. However, to obtain the clear outline is not easy in clinical because X-ray image of knee often overlaps with bones. In this study, the method of kinetic analysis that uses the outline, which was not totally clear, was proposed. In order to achieve the aim, P type Fourier Descriptor that can be used in an open curve was applied. And, the library database was preliminary selected using feature vectors which were based on shape feature, initial point and terminal point of the outline. After an outline of the object was divided in three parts, template pattern matching was performed. In results, the standard deviation of errors of patella were θ_x=1.00±0.84 deg, θ_y=0.55±0.65 deg and θ_z=0.62±0.12 deg. As to femur, tibia and patella, a part of divided outlines influenced the accuracy of our proposal method. This result shows that, even if all outline of bone is not clear on X-ray image, 3D kinematic analysis can be carried out.