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Biomechanics

In Biomechanics, Multibody Dynamics, Research

Surface Modification and Software Design of Customized Knee Joint

Surface Modification and Software Design of Customized Knee Joint

Chin YU Wang, Chien Fen Huang, Yi-Lin Liou, Life Science Journal, December 2014, Volume 11, Number 12, Article 137.

Abstract

This paper used the medical image of a patient’s knee joint as basis to assemble a complete human knee through geometric software. Because this model can’t precisely align the position, local contact will occur which would cause stress concentration. It should undergo the tension adjustment of the ligaments to adjust the relative positions of the cartilage of the femoral condyle, the meniscus and the femoral cartilage to the minimal relative position of the contact stress to comply with the lowest energy or stress allowed by the law of nature for our body needs. First, this study used the spring simulation in the ligament tension and used the software, RecurDyn, to find the relative position of the minimum contact stress of the knee system. Second, the customized man-made knee was imported in the biomechanical software called LifeMod to build muscles and the ligaments system to simulate the ligament tensions of the artificial knee under a variety of sports. Aside from being the basis for the spring coefficient setting of the human knee, the tension can also select the specific posture of the knee in the model and then convert it into a file of ANSYS stress analysis software to complete a more accurate stress analysis. Finally, we can retest the human and artificial knee joints under different postures in the above steps to know the changes in the patterns between contact stress and contact area to obtain customized artificial knee prosthesis closest to the patient’s original human knee joints. The concept is the same if the original denture tooth shape is kept, we can be able to organize the most stable and compatible peripherals, prolong the life of the prosthesis and reduce its possibility of loosening.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is used to perform dynamic simulation of an artificial knee. The geometry of the artificial knee is imported into RecurDyn from a CAD program. Accurate data from physical testing can be limited and difficult to obtain. RecurDyn provides an easy way to test if design parameters are within an acceptable performance range.

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In Biomechanics, Multibody Dynamics, Research

Influence of Bundle Diameter and Attachment Point on Kinematic Behavior in Double Bundle Anterior Cruciate Ligament Reconstruction Using Computational Model

Influence of Bundle Diameter and Attachment Point on Kinematic Behavior in Double Bundle Anterior Cruciate Ligament Reconstruction Using Computational Model

Oh Soo Kwon, Tserenchimed Purevsuren, Kyungsoo Kim, Won Man Park, Tae-Kyu Kwon, Yoon Hyuk Kim, Computational and Mathematical Methods in Medicine, January 2014, Volume 2014, Article ID 948292, 8 pages.

  • Abstract

    A protocol to choose the graft diameter attachment point of each bundle has not yet been determined since they are usually dependent on a surgeon’s preference. Therefore, the influence of bundle diameters and attachment points on the kinematics of the knee joint needs to be quantitatively analyzed. A three-dimensional knee model was reconstructed with computed tomography images of a 26-year-old man. Based on the model, models of double bundle anterior cruciate ligament (ACL) reconstruction were developed. The anterior tibial translations for the anterior drawer test and the internal tibial rotation for the pivot shift test were investigated according to variation of bundle diameters and attachment points. For the model in this study, the knee kinematics after the double bundle ACL reconstruction were dependent on the attachment point and not much influenced by the bundle diameter although larger sized anterior-medial bundles provided increased stability in the knee joint. Therefore, in the clinical setting, the bundle attachment point needs to be considered prior to the bundle diameter, and the current selection method of graft diameters for both bundles appears justified.

    How Multibody Dynamics Simulation Technology is Used

    RecurDyn provides nonlinear force entities to model tissues such as ligaments, as well as contact modeling capabilities needed to simulate the movement of ligaments around bone and cartilage boundaries.

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In Biomechanics, Multibody Dynamics, Research

Simulation of extension, radial and ulnar deviation of the wrist with a rigid body spring model

Simulation of extension, radial and ulnar deviation of the wrist with a rigid body spring model

S. Fischli, R.W. Sellens, M. Beek, Dr. Pichora, Journal of Biomechanics, Kingston, June 2009, Volume 42, Issue 9, pp 1363-1366.

Abstract

A novel computational model of the wrist that predicts carpal bone motion was developed in order to investigate the complex kinematics of the human wrist. This rigid body spring model (RBSM) of the wrist was built using surface models of the eight carpal bones, the bases of the five metacarpal bones, and the distal parts of the ulna and radius, all obtained from computed tomography (CT) scans of a cadaver upper limb. Elastic contact conditions between the rigid bodies modeled he influence of the cartilage layers, and ligamentous structures were constructed using nonlinear, tension-only spring elements. Motion of the wrist was simulated by applying forces to the tendons of the five main wrist muscles modeled. Three wrist motions were simulated: extension, ulnar deviation and radial deviation. The model was tested and tuned by comparing the simulated displacement and orientation of the carpal bones with previously obtained CT-scans of the same cadaver arm in deviated (451 ulnar and 151 radial), and extended (571) wrist positions. Simulation results for the scaphoid, lunate, capitate, hamate and tri quetrum are presented here and provide credible prediction of carpal bone movement. These are the first reported results of such a model. They indicate promise that this model will assist in future wrist kinematics investigations. However, further optimization and validation are required to define and guarantee the validity of results.

How Multibody Dynamics Simulation Technology is Used

The high performance and robust contact modeling capabilities in RecurDyn are needed to simulate the complex interactions of bones in the wrist during the transition to various postures.

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