Biomedical subjects

Jian-Horng Chen

Publications and source records attributed to Jian-Horng Chen.

4 recordsLinked to original sources

PubMed2005

Vertebral axial rotation measurement method.

This study presents a new method for measuring axial rotation of vertebra. Anatomical landmarks of the vertebral body were first recognized in X-ray film. By employing appropriate geometrical relationships, vertebral body shape parameters and a computer iteration method, the rotation angle of vertebra on the transverse plane can rapidly be obtained. A cadaver lumbar spine axial rotation-fixation device was designed to confirm the accuracy of the proposed methodology. Rotation angles on CT images were adopted as the golden standard and compared with analytical results based on X-ray films. Analytical results demonstrated that the proposed method obtained more accurate and reliable results than previous methods.

Algorithms↗

PubMed2004

Computer simulation on fatigue behavior of cemented hip prostheses: a physiological model.

This paper is concerned with the investigation on the fatigue failure of implant fixation by numerical approaches. A computer algorithm based on finite element analysis and continuum damage mechanics was proposed to quantify the fatigue damage rate of cement mantle under physiological conditions. In examining the interfacial debonding effect, the interface elements were introduced at cement-stem interfaces and calibrated with the increase of loading cycles. Current results reveal that the major sites for failure initiation are in the proximal anterior-medial regions and at the distal prosthesis tip, which clearly demonstrate the same failure scenario as observed in clinical studies. Such fatigue failures not only result in the corruption of cement-stem interfaces, but also greatly affect the cement stress distribution and the damage rate in subsequent loading cycles. Another significant result is that the predicted damage rate increases steadily with gait cycles. This trend in damage development is consistent with the findings obtained from fatigue tests available in literature. It is anticipated that presented methodology can serve as a pre-clinical validation of cemented hip prostheses.

Algorithms↗

PubMed2003

The computer simulation of wear behavior appearing in total hip prosthesis.

Computer algorithms are proposed for the estimation of wear appearing in artificial hip joints using finite element analysis based on the modified Archard's wear law, contact features and an analogue wear process. A pin-on-disk plate experiment is reconstructed to assess the efficiency and validity of the algorithms proposed here. Through the successful verification of wear depth and volume loss of the pin-on-disk plate as well as the artificial hip joint, the current algorithms provide significant agreement with experiments, clinical measurements and numerical calculations and are shown to be both valid and feasible. Further investigation into the effect of femoral heads with various sizes suggests that the larger femoral head may induce larger wear volume but gives a smaller wear depth and that wear depth and volume loss are apparently nonlinearly related to the femoral head diameter. It is shown that the current algorithms are useful and helpful in understanding wear behavior for alternative or new designs of artificial hip joints and even for other analogous structures.

Arthroplasty, Replacement, Hip↗

PubMed2002

Measurement of polyethylene wear - a new three-dimensional methodology.

Studies in the field of polyethylene wear of the acetabular cup have been generally discussed using a two-dimensional assumption on the coronal plane; significant errors thus appear. The present study proposes a new, advanced methodology in order to accurately estimate the polyethylene wear. Through the usage of the distance between X-ray focus and film and only one follow-up, anteroposterior (AP) radiograph, a three-dimensional (3D) algorithm is introduced here. Here, 91 primary total hip joint replacements in 67 patients have been examined and three findings are obtained. Results show that the mean rate of 3D linear wear of the polyethylene estimated by the current method is 0.230+/-0.036 mm per year, that of the 2D linear wear is 0.148+/-0.028 mm per year. Moreover, the wear depth of the femoral head on the sagittal plane is 0.173+/-0.043 mm per year by the current method. This study also shows that the adoption of only one AP radiograph in the evaluation of the 3D penetration of femoral head is possible. Furthermore, the methodology proposed here is more convenient than others.

Adult↗