Upper Limb Biomechanics Modelling And Research On Typical Motion

Human being is a very complex system. Due to the differences between individuals, diversity of human musculoskeletal system and limitation of experiment condition in vivo, it is very difficult to develop researches on human body biomechanical characteristics. At the same time, the demand of living quality improves with the improvement of living standard. How to prevent sport injuries and improve the effect of medicine implants are becoming an important task for relative biomedical researchers.This dissertation is based on the key project"Mechanical Virtual Human of China"supported by National Natural Science Foundation, and two projects cooperated with RenJi Hospital. Firstly, the 3D geometrical model and biomechanical model of human upper limb"skeleton-muscle"system were built. Based on the model, upper limb kinematic and kinetic simulation models were established. Then forearm flexion was chosen as the typical movement to be simulated.Using motion capture system, forearm flexion motion path was obtained. The muscle forces of relative movement muscles were predicted. The stress distribution of humerus was analysis with the muscle forces assigned as the boundary condition during elbow flexion. Finally, biomechanical experiment was used to verify the predicted muscle forces. The main contents can be included in:(1)The model of human upper limb musculoskeletal system was established based on cryosectional image data. In order to extract the outline of the bone and muscle as possible as precision, we utilized the image segmentation and B-spline curve approximation. The established anatomical upper limb model includes humerus, ulna, radius, scapula and clavicle. Based on anatomical knowledge, muscle line model was built by connecting muscle origins and terminations. Some pennate muscles were simulated by a cluster of line.(2)Upper limb kinematic and kinetic models were built. The kinematic model included three bones and seven degree of freedom, which can simulate all kinds of upper arm and forearm motion. The motion information obtained by the NDI motion capture system was input into the kinematic model. Then the kinematic parameters of all skeletons can be calculated, such as displacement, velocity and acceleration. Based on those parameters kinetic parameters can be achieved using kinetic model, such as joint force and joint torque. Muscle forces in the movement were predicted using EMG assisted method.(3)Finite element model of upper limb was established. According to the relationship of CT Hounsfield value and Young's modulus, the mean Young's modulus of upper bone were calculated. The material property of soft tissue was assigned based on published article. The model was verified by two joint contact analyses, humeral external rotation and elbow flexion. The static stress-strain distribution of humerus was analyzed with the boundary conditions resulted from the kinetic simulation, such as muscle force and joint force.(4)A testing device was established to perform elbow flexion in vitro. Biceps, brachialis, brachioradialis and triceps can be loaded to simulate active elbow flexion. A variable ratios loading scheme based on kinetic simulation and three constant ratios loading were chosen to simulate elbow flexion. Muscle force and motion path were recorded and compared in seven degrees,30°,45°,60°,75°,90°,105°and 120°.(5)Based on three-dimensional computed tomography scanning data, computer models of the proximal humerus of 180 Chinese people were built. Anatomical parameters including the total length of humerus, the diameter of medular, the diameter in coronal plane , the diameter in sagittal plane, the curvature diameter of the head, the head height, the inclination, the retroversion, the medial offset, and the posterior offset were measured using the software in these three-dimensional proximal humerus models. Statistic results were compared with the geometrical parameters of MVHC standard human. Then the averages of four anatomical parameters (the curvature diameter of the head, the head height, the inclination, and the retroversion) were compared with four commonly used anatomical prostheses parameters.A human upper limb biomechanics analysis platform was built, which included the 3D geometrical model, the kinematics model, the kinetic model and the finite element model of human upper limb. The platform can be widely used to biomechanical analysis, for example, evaluation the biomechanics of shoulder arthroplasty which can guide the prosthetic design and then heighten the use life.