Biomedical subjects

Chengtao Wang

Publications and source records attributed to Chengtao Wang.

At least 19 recordsLinked to original sources

PubMed2006

[Accuracy of femur mechanical axis in computer-assisted total knee replacement].

The location of the center of the femoral head and the mechanical axis of femur were obtained by using optical tracking localizer in computer-assisted total knee replacement (TKR). The 3-D reconstruction model of femur was used firstly in the accuracy verification of mechanical axis of femur. The results showed that the accurate mechanical axis of femur can be defined by tracking the reference frame pinned at the distal femur. Compared to the intramedullary rods locating, this method introduces mechanical axis error less that 1 and the accuracy and repeatability of mechanical axis definition have been improved greatly.

Arthroplasty, Replacement, Knee↗

PubMed2006

[A mechanical model of knee joint in sagittal plane].

A sagittal plane model of knee joint based on crossed-four-bar-linkage-based tibiofemoral joint model has been developed using geometric and force equilibrium constraints. The model predicts and explains the movement of contact point on the patella and femur, variation of patellar and patellar tendon angle, variation of patellar mechanism angle and variation of patellofemoral contact force and patellar tendon force. The computed results agree well with the published experimental results.

Biomechanical Phenomena↗

PubMed2006

[A rapid prototype fabrication method of dental splint based on 3D simulation and technology].

The conventional design and fabrication of the dental splint (in orthognathic surgery) is based on the preoperative planning and model surgery so this process is of low precision and efficiency. In order to solve the problems and be up to the trend of computer-assisted surgery, we have developed a novel method to design and fabricate the dental splint--computer-generated dental splint, which is based on three-dimensional model simulation and rapid prototype technology. After the surgical planning and simulation of 3D model, we can modify the model to be superior in chewing action (functional) and overall facial appearance (aesthetic). Then, through the Boolean operation of the dental splint blank and the maxillofacial bone model the model of dental splint is formed. At last, the dental splint model is fabricated through rapid prototype machine and applied in clinic. The result indicates that, with the use of this method, the surgical precision and efficiency are improved.

Computer-Aided Design↗

PubMed2006

[Study of biomechanical effects on the reconstruction of mandible defect with autogenous bone grafts].

The biomechanical effects of the reconstructed mandible with autogenous bone grafts were analyzed and evaluated, under simulated mechanical environment of occlusion. Based on anatomical feature of the human skeleton, muscle system and the clinical B, BS"S" and RB"S"defect patterns, the modularized model of mandible and the three finite element models of the fibula grafts and iliac crest grafts reconstruction mandible were made. The stress state calculations under bite force were also processed. The findings are as follows: Along the right connection area to left connection area (corresponding to far-end of the molar teeth alveolar ridge and the chin section respectively), the stress state on the various grafted bone all changes from compression stress to tensile stress. There is obvious change on the stress distribution between the fibula type reconstruction mandible and normal one. The stress on the grafted bone which is mainly made up of cortical bone is approximately 5 times higher than that of normal, which indicates the obvious stress shielding effect; the stress distribution of the iliac crest type reconstruction mandible is close to the normal mandible, the iliac crest used is mainly made up of cancellous. Therefore, the mechanical properties of the reconstructed mandible with iliac crest are more similar to normal mandible, which is beneficial to wound healing and further functional reconstruction.

Bone Transplantation↗

PubMed2006

[Visualization and real-time tracking of the instruments in surgical navigation system].

In order to realize the visualization and real-time tracking of the instruments in surgical navigation system, we use the CAD solid model of the instruments directly or by reverse engineering, and transform the solid model to surface model. Then, the instruments, which are fixed with locator, are characterized and tested their precision. After registration between the CT model and the patient site in intra-operation, the system accurately displays the STL model of the instruments according to the tracked site and orientations. The model construction of the instruments is the base of the surgical navigation and is important to improve the security and precision of operation.

Computer Simulation↗

PubMed2005

Effects of acupuncture on heart rate variability in normal subjects under fatigue and non-fatigue state.

The objective of this study was to assess the effects of acupuncture applied at Hegu (LI 4) points and Neiguan (PC6) points on heart rate variability (HRV) in normal subjects under fatigue and non-fatigue states using power spectral analysis. Twenty-nine normal male subjects were randomly divided into three groups. Subjects in Group A and Group B performed a simulated driving task for 3 h and acupuncture needles were then inserted perpendicularly into the LI 4 points in the middle of the dorsal thenar muscle and PC 6 points situated between the tendons of the palmaris longus and carpi radialis muscles for 15 min for Group A but inserted subcutaneously to the acupuncture points for Group B as a control. Acupuncture needles were directly inserted perpendicularly into the LI 4 points and PC 6 points for 15 min for Group C. Stimulations of the acupuncture points induced a significant decrease in heart rate (HR), HRV total power (TP), low frequency (LF) power and ratio of low frequency to high frequency (LF/HF), and a significant increase in the HF power in normalized units (NU) during the post stimulation period in fatigue state (P<0.05). Stimulation of acupuncture points resulted in a significant increase both in the LF power and HF power in absolute units (AU) (P<0.05) but no significant change in NU was found during the post stimulation period in non-fatigue state. It was concluded that the modulating effect of acupuncture on heart rate variability not only depended on the points of stimulation such as acupuncture or non-acupuncture points but also on the functional state of the subject, namely whether the subjects are in a state of fatigue or not.

Acupuncture Points↗

PubMed2005

[Three-dimensional finite element analysis of the biomechanical effects of multiloop edgewise archwire (MEAW)].

This study is designed to theoretically evaluate the treatment effects of MEAW with tip back bends on the mandible dentition when used as a finishing archwire without elastic and with long class III elastics respectively, and to compare them with those of stainless-steel wire and shape-memory wire. The finite element analysis (FEA) method was adopted and the findings were as follows: (1) In the case of no elastics, the MEAW rotates the second premolar, the first molar and the second molar distally while rotating other teeth mesially, and depresses anterior teeth. However, the stainless-steel wire and the shape-memory wire rotate molars distally while rotating other teeth mesially. Furthermore, they extrude anterior teeth and depress posterior teeth. (2) The MEAW with tip back bends and long class III elastics inclines and rotates posterior teeth more distally than the MEAW with only tip back bends does. In the case of tip back bends and long class III elastics loaded together, the shape-memory wire inclines teeth in greater strength as compared with the stainless-steel wire. (3) The stress level of tooth root is the lowest with MEAW, the highest with stainless-steel wire, and is middle with the shape-memory wire. From these results, it is suggested that: (1) The MEAW therapy technique is effective for leveling the curve of Spee and regulating tooth respectively. (2) The MEAW therapy technique can transfer therapy force efficiently. (3) The MEAW is considered to be suitable for treating openbite malocclusion to make the posterior teeth upright because it effectively rotates teeth distally through the force of posterior bends and long class III elastics. (4) The loaded force on the teeth is more soft and permanent in the MEAW than in the stainless-steel wire and the shape-memory wire.

Biomechanical Phenomena↗

PubMed2005

[Progress of mechanical model for the study of knee biomechanics].

The mechanical model of knee is a system of constructional elements with specific restrains and material properties, which are deduced from the components of knee based on their functions and junctions. Kinematics and kinetics of knee can be calculated from the mechanical model. A review of some mechanical models of knee are shown in this paper.

Biomechanical Phenomena↗

PubMed2005

[Fabricating facial prostheses using CAD/CAM and rapid prototyping technique].

At present, the treatments of hemifacial microsomia such as the missing of ear and eye still rely on the skill of technician to make the wax model of contralateral apparatus of patient in China. In this paper, CAD/CAM and rapid prototyping (RP) techniques are integrated to successfully create a silastic prosthesis by using the patient's data of CT or laser scanning. The clinical results suggest that a high accuracy has been achieved in shape, size, and protrusion of the facial prostheses, which indicates that the application of RP techniques in conjunction with CAD/CAM is a suitable approach for fabricating facial prosthesis.

Biocompatible Materials↗

PubMed2005

[Synthetic effect analysis of heart rate variability and blood pressure variability on driving mental fatigue].

Driving mental fatigue is a substantial problem and threatens people's health and life. This investigation was made to evaluate the driving mental fatigue based on power spectral analysis of heart rate variability (HRV) and blood pressure variability (BPV) synthetically. Twenty health male subjects (28.8 +/- 4.3 years) were required to perform the simulated driving for 90 min. The frequency domain indices of HRV such as low frequency (0.04-0.15 Hz, LF), high frequency (0.15-0.4 Hz, HF), LF/HF together with the indices of hemodynamics such as blood pressure (BP) and heart rate (HR) of the subjects were calculated and anlyzed after the simulated driving. The results showed that sympathetic activity of the subjects enhanced after the simulated driving while parasympathetic activities decreased. The sympathovagal balance was also improved. Remarkable linear correlations were observed between all the corresponding indices of HRV and BPV (P<0.05). The findings suggested that the evaluation of autonomic activities by means of multi-variable synthetic effect analysis is scientific and objective.

Adult↗

PubMed2005

[Digital geometry processing and its applications in maxilla and mandible reconstruction surgery].

A new method to fabricate exact-fit medical implants is proposed. Medical image processing and digital geometry processing are adopted for bone triangular mesh modeling from CT image series. After geometric operations such as decimation, defragmentation, cutting and mirroring are applied to the original triangular mesh, an RP model of same size as the bone is fabricated with LOM method. RP models are used for manufacturing exact-fit implants and they also serve surgery-guiding purpose. This novel technique has been applied in over 30 clinical cases, and it is proven to be practicable.

Humans↗

PubMed2005

[Rolling friction: a desing of artificial knee joint].

Resorption and osteolysis of periimplant bones resulting from the wear debris of artificial joint will cause long-term loosening. A new type of rolling knee artificial joint without UHMWPE based on the mechanics of rolling friction is designed for alleviating this problem. Because of low friction force, the resistance of extension and flexion is reduced strikingly and the stress on the interface between prosthesis and bone is reduced evidently. In addition, the bio-toxicity caused by the wear debris of UHMWPE will not occur absolutely. In consequence, the rolling artificial joint can prevent the trend of long-term loosening of the prosthesis efficiently.

Animals↗

PubMed2005

[A method for automatic selection of optimal standard hip stems].

In a hip replacement case when a standard hip stem is chosen, it is rough to select hip stems before operation, thus some stand-up standard hip stems should be prepared. The operation time is usually prolonged. In order to solve this problem, this paper presents a method to automatically select optimal standard hip stems by computers. Femoral anatomical data of a patient are acquired from X-ray films. Based on these anatomical data and a database of average cross-sections in proximal femurs, proximal femur of the patient can be reconstructed. This proximal femur model makes it possible to optimally select a standard hip stem. Theory analyses indicate that the method, presented in this paper, is practicable.

Arthroplasty, Replacement, Hip↗

PubMed2004

Effect of different vibration frequencies on heart rate variability and driving fatigue in healthy drivers.

OBJECTIVE: This investigation was to assess the effect of different vibration frequencies on heart rate variability (HRV) and driving fatigue in healthy subjects during simulated driving, by the use of power spectrum analysis and subjective evaluation. MATERIALS AND METHODS: Sixty healthy subjects (29.6+/-3.3 years) were randomly divided into three groups, A, B and C, and the subjects of each group participated in the simulated driving for 90 min with vertical sinusoidal vibration (acceleration 0.05 g) of 1.8 Hz (group A), 6 Hz (group B) and no vibration (group C), respectively. Low-frequency (LF) and high-frequency (HF) components of HRV, reflecting sympathetic and parasympathetic activities, and the LF:HF ratio, indicating sympathovagal balance, were measured throughout all periods. All indices of HRV were calculated in the pre-experiment period, mid-experiment period and end-experiment period, and were analyzed by repeated measures analysis of variance. Subjective responses to a questionnaire were obtained after the simulated task for the three groups. RESULTS: Significant differences in all indices of HRV were observed between different experiment periods and between any two groups. The ratings of subjective fatigue exhibited significant differences between any two groups. CONCLUSION: The drivers' fatigue ratings were associated with vibration frequencies in simulated driving. The study quantitatively demonstrated that different effects on autonomic nerve activities were induced by different vibration frequencies.

Adult↗

PubMed2004

Reducing the effects of driving fatigue with magnitopuncture stimulation.

The purpose of this study was to assess the effects of reducing driving fatigue with magnitopuncture stimuli on Dazhui (DU14) point and Neiguan (PC6) points using heart rate (HR), reaction time (RT) testing, right rate (RR), critical flicker fusion frequency (CFF) and subjective evaluation. Forty healthy subjects were randomly divided into two groups: study and control groups. All subjects were required to be well rested before the experiment. The subjects were engaged in high speed driving at a constant vehicle velocity of 80 km/h continuously for 3h on a test course simulating an expressway. During the driving magnitopunctures (Haci Five Elements Needle, 250 mT, made by Haci Company limited) were applied to the Dazhui (DU14) point and Neiguan (PC6) points for the study group when the subject performed the task for 2.5h, and for the control group magnitopunctures were applied to non-acupuncture points during the same time session. The results of this study show a significant effect of magnitopuncture stimuli on RT, RR and CFF. Subjective evaluation also exhibited significant differences (P < 0.05) between the two groups after the driving task. The findings showed that magnitopuncture stimuli on DU14 point and PC6 points could reduce the effects of driving fatigue.

Acupuncture Points↗

PubMed2004

[Study on the 3D mathematical mode of the muscle groups applied to human mandible by a linear programming method].

Four types of 3D mathematical mode of the muscle groups applied to the human mandible have been developed. One is based on electromyography (EMG) and the others are based on linear programming with different objective function. Each model contains 26 muscle forces and two joint forces, allowing simulation of static bite forces and concomitant joint reaction forces for various bite point locations and mandibular positions. In this paper, the method of image processing to measure the position and direction of muscle forces according to 3D CAD model was built with CT data. Matlab optimization toolbox is applied to solve the three modes based on linear programming. Results show that the model with an objective function requiring a minimum sum of the tensions in the muscles is reasonable and agrees very well with the normal physiology activity.

Bite Force↗

PubMed2004

[Custom design of hip joint prostheses based on X-ray films].

A novel method for the design of hip joint prostheses based on X-ray films is introduced. Only arcs and straight-lines form figures of hip joint prostheses. Because geometrical tolerances of manufacturing hip joint prostheses matching section are usually not strict, hip joint prostheses can be manufactured without CNC machine tool. Three hip joint prostheses for three different femurs were designed through a program which was developed by the present authors. Approximate marrow cavities of these femurs were simulated according to a standard database about femur. These models of femur marrow cavities were used to verify the hip joint prostheses designed. These hip joint prostheses designed were manufactured and implanted into femurs respectively. Experimental results indicate that the novel method for the design of hip joint prostheses is practicable.

Computer-Aided Design↗

PubMed2004

[Digital model of human lower extremity musculature based on CT & MRI].

A new method to reconstruct comparatively complete muscle model of human lower limb from CT and MRI data is presented. Topological structure of more than fourteen muscles is built and the coordinates of origin and insertion points are given. Based on this model, straight-line model and centroid-line muscle model are acquired. Muscle force prediction is discussed according to the model reconstructed, and a multi-objective optimization method is put forward for evaluating muscle forces of human lower extremity.

Humans↗