The Geometry of the Knee in the Sagittal Plane

1989 ◽  
Vol 203 (4) ◽  
pp. 223-233 ◽  
Author(s):  
J J O'Connor ◽  
T L Shercliff ◽  
E Biden ◽  
J W Goodfellow
Keyword(s):  
Sagittal Plane ◽  
Geometric Model ◽  
Contact Point ◽  
Contact Forces ◽  
Cruciate Ligaments ◽  
Constant Length ◽  
Articular Surfaces ◽  
Parasagittal Plane ◽  
Four Bar Linkage ◽  
The Relationship

A geometric model of the tibio-femoral joint in the sagittal plane has been developed which demonstrates the relationship between the geometry of the cruciate ligaments and the geometry of the articular surfaces. The cruciate ligaments are represented as two inextensible fibres which, with the femur and the tibia, are analysed as a crossed four-bar linkage. The directions of the ligaments at each position of flexion are calculated. The instant centre, where the flexion axis crosses the parasagittal plane through the joint, lies at the intersection of the cruciates. It moves relative to each of the bones during flexion and extension. The successive positions of the flexion axis relative to a fixed femur and to a fixed tibia are deduced. The shapes of articular surfaces which would allow the bones to flex and extend while maintaining the ligaments each at constant length are calculated and are found to agree closely with the shapes of the natural articular surfaces. The calculated movements of the contact point between the femur and the tibia during flexion also agree well with measurements made on cadaver specimens. The outcome is a geometric simulation of the tibio-femoral joint in the sagittal plane which illustrates the central role played by the cruciate ligaments in the kinematics of the knee and which can be used for the analysis of ligament and contact forces.

Investigation of Material Properties and Force of 6-Year-Old Children Lumbar FEM

2012 ◽  
Vol 548 ◽  
pp. 433-437
Author(s):  
Jesse Ruan ◽  
Ao Yang Yu ◽  
Wei Zhao ◽  
Hai Yan Li
Keyword(s):  
Static Load ◽  
Sagittal Plane ◽  
Geometric Model ◽  
Metal Plate ◽  
Fe Model ◽  
Engineering Software ◽  
Articular Surfaces ◽  
Biomechanical Response ◽  
Lumbar Segment ◽  
Cadaveric Experiment

The purpose of this study was to investigate injury mechanism and injury biomechanical response of children lumbar segment L4-L5. Firstly, the geometric model of lumbar segment at L4-L5 was extracted from CT scan images of a healthy 6-year-old child for from repairing and refining by reverse engineering software Geomagic to finite element (FE) pre-processing by Hypermesh. The FE model was calculated by LS-Dyna under the conditions given by cadaveric experiments, in which a static load was applied to the center of lumber segment at L4-L5 by a metal plate. The static load was subsequently moved forward and backward 10mm in sagittal plane, respectively. The interfacial force between articular surfaces was the objective to investigate for the comparison between the simulation and the cadaveric experiment as well as the simulation by adult FE model. The simulated results showed that the displacement between L4 and L5 of children was, to some extent, smaller than that of adults. The ratio of calculated force between articular surfaces of L4-L5 of children to the applied force moreover was, to a great extent, smaller than that of adults. Children are much easier to be rendered injury at L4-L5 than adults are, because articular surfaces of children relatively more slightly contribute to distributing the force that nucleus pulposus undergoes than those of adults do. Hence, the current study could be perceived as a theoretical basis for the product design toward vehicle safety.

Analysis and Visualization of the Contact Force Solution Space for Multi-Limbed Mobile Robots With Three Feet Contact

2003 ◽  
Author(s):  
Dennis W. Hong ◽  
Raymond J. Cipra
Keyword(s):  
Contact Force ◽  
Dimensional Space ◽  
Contact Point ◽  
Solution Process ◽  
Solution Space ◽  
Contact Forces ◽  
Static Equilibrium ◽  
Equilibrium Equations ◽  
Force Components ◽  
The Relationship

A new analytical method for determining, describing, and visualizing the solution space for the contact force distribution of multi-limbed robots with three feet in contact with the environment in three-dimensional space is presented. The foot contact forces are first resolved into strategically defined foot contact force components to decouple them for simplifying the solution process, and then the static equilibrium equations are applied to find certain contact force components and the relationship between the others. Using the friction cone equation at each foot contact point and the known contact force components, the problem is transformed into a geometrical one to find the ranges of contact forces and the relationship between them that satisfy the friction constraint. Using geometric properties of the friction cones and by simple manipulation of their conic sections, the whole solution space which satisfies the static equilibrium and friction constraints at each contact point can be found. Two representation schemes, the “force space graph” and the “solution volume representation,” are developed for describing and visualizing the solution space which gives an intuitive visual map of how well the solution space is formed for the given conditions of the system.

Correction of Posture Deviations in the Sagittal Plane Using the Pilates Method

2019 ◽  
pp. 3-13
Author(s):  
Alexandru Cîtea ◽  
George-Sebastian Iacob
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Postural Control ◽  
Human Body ◽  
Sagittal Plane ◽  
The Body ◽  
Lower Limbs ◽  
Low Back ◽  
Pilates Method ◽  
The Relationship

Posture is commonly perceived as the relationship between the segments of the human body upright. Certain parts of the body such as the cephalic extremity, neck, torso, upper and lower limbs are involved in the final posture of the body. Musculoskeletal instabilities and reduced postural control lead to the installation of nonstructural posture deviations in all 3 anatomical planes. When we talk about the sagittal plane, it was concluded that there are 4 main types of posture deviation: hyperlordotic posture, kyphotic posture, rectitude and "sway-back" posture.Pilates method has become in the last decade a much more popular formof exercise used in rehabilitation. The Pilates method is frequently prescribed to people with low back pain due to their orientation on the stabilizing muscles of the pelvis. Pilates exercise is thus theorized to help reactivate the muscles and, by doingso, increases lumbar support, reduces pain, and improves body alignment.

scholarly journals Slipping–rolling transitions of a body with two contact points

2021 ◽  
Author(s):  
Mate Antali ◽  
Gabor Stepan
Keyword(s):  
Rigid Body ◽  
Contact Point ◽  
Static Friction ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Friction Forces ◽  
Contact Points ◽  
Body Dynamics ◽  
Coulomb Model ◽  
Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

TORUS KNOTS EMBODYING CURVATURE AND TORSION IN AN OTHERWISE FEATURELESS CONTINUUM

2011 ◽  
Vol 20 (12) ◽  
pp. 1723-1739 ◽  
Author(s):  
J. S. AVRIN
Keyword(s):  
Elementary Particle ◽  
General Relativity ◽  
Geometric Model ◽  
The Other ◽  
Particle Model ◽  
Torus Knots ◽  
Torus Knot ◽  
The Subject ◽  
Curvature And Torsion ◽  
The Relationship

The subject is a localized disturbance in the form of a torus knot of an otherwise featureless continuum. The knot's topologically quantized, self-sustaining nature emerges in an elementary, straightforward way on the basis of a simple geometric model, one that constrains the differential geometric basis it otherwise shares with General Relativity (GR). Two approaches are employed to generate the knot's solitonic nature, one emphasizing basic differential geometry and the other based on a Lagrangian. The relationship to GR is also examined, especially in terms of the formulation of an energy density for the Lagrangian. The emergent knot formalism is used to derive estimates of some measurable quantities for a certain elementary particle model documented in previous publications. Also emerging is the compatibility of the torus knot formalism and, by extension, that of the cited particle model, with general relativity as well as with the Dirac theoretic notion of antiparticles.

A geometric model of the lumbar spine in the sagittal plane

1993 ◽  
Vol 26 (3) ◽  
pp. 348
Author(s):  
Claude Sicard ◽  
Micheline Gagnon
Keyword(s):  
Lumbar Spine ◽  
Sagittal Plane ◽  
Geometric Model

scholarly journals Increased Foot and Tibial Angles at Footstrike Decrease Vertical Loadrate in Runners

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0048
Author(s):  
Adam Tenforde ◽  
Haylee Donaghe Borgstrom ◽  
Steve Jamison ◽  
Irene Davis
Keyword(s):  
Injury Risk ◽  
Loading Rate ◽  
Sagittal Plane ◽  
Video Recording ◽  
Correlation Coefficients ◽  
Group Differences ◽  
P Values ◽  
Source Program ◽  
Running Injuries ◽  
The Relationship

Category: Sports Introduction/Purpose: It is well established that elevated vertical loadrates on footstrike are a risk factor for developing running injuries. Overstriding, or increased foot and tibial angles at footstrike, has been theorized to increase loading rate. Thus, it is often suggested that runners shorten their stride to reduce their injury risk. However, the relationship between landing alignment and loadrates has not been well established in current literature. Thus, we aimed to investigate the relationship between sagittal plane foot angle (FA) and tibial angle (TA) with vertical loadrates in both healthy and injured forefoot (FFS) and rearfoot strike (RFS) runners. It was hypothesized that as FA and TA increased, loadrate would increase for all runners. Methods: This is an ongoing study with 52 healthy runners (35 RFS, 17 FFS) and 24 injured runners (14 RFS, 10 FFS) for a total of 76 runners (51 M, 25 F; age34.3±11.4 yrs). Vertical average loadrate (VALR) and vertical instantaneous loadrate (VILR) were obtained while running at 2.68 m/s on an instrumented treadmill. All runners reported 0/10 pain during the assessment. Sagittal plane FA and TA at footstrike were measured from video recording using an open-source program. Positive FA designated RFS. Positive TA was defined as ankle anterior to the knee. Between-group differences were evaluated using paired two-tailed t-tests. Correlation coefficients (r) were computed for FA and TA with VALR and VILR (p=0.05; trend: p =0.10). Results: Healthy RFS - FA and TA were negatively correlated with VALR and VILR. Injured RFS – There was a trend toward negative correlation between TA and both VALR and VILR. Healthy FFS – TA was negatively correlated with both loadrates. Injured FFS – There were no significant correlations. Correlation coefficients, slopes, and p values are presented in Table 1. VALR and VILR were higher in RFS vs FFS runners (56±20 vs 40±10, 69±25 vs 54±12 BW/s, p<0.01), but were not significantly different for healthy vs injured runners (52±19 vs 56±26, 63±21 vs 67±27 BW/s, p=0.4). Conclusion: In contrast to current thought, preliminary results suggest that increasing FA and TA at footstrike are associated with decreasing vertical loadrates. This relationship was strongest for FA in the healthy RFS runners and weakest for FA in both the healthy and injured FFS runners. With increased FA, load attenuation may be due to increased eccentric activity of the tibialis anterior as well as increased knee flexion excursion and eccentric quadriceps activity with increased TA.

Cross-Sensitivity Characteristics of Instrumented Wheelset Associated With Longitudinal Force and Lateral Contact Position

2021 ◽  
Author(s):  
Takatoshi Hondo ◽  
Takayuki Tanaka ◽  
Shoya Kuniyuki ◽  
Mitsugi Suzuki
Keyword(s):  
Measurement Accuracy ◽  
Contact Point ◽  
Fem Analysis ◽  
Longitudinal Force ◽  
Lateral Position ◽  
Contact Forces ◽  
Load Test ◽  
Static Load Test ◽  
Cross Sensitivity ◽  
The Cross

Abstract It is crucial to grasp wheel-rail contact forces in the evaluation of running safety and curving performance of railway vehicles. To measure the wheel-rail contact forces, instrumented wheelset, which has the strain gauges on the wheel surface, is widely used. The purpose of this research is to increase the measurement accuracy of the wheel-rail contact forces by understanding the detailed characteristics of the instrumented wheelset. Although the various researches on the instrumented wheelset have been carried out to increase the measurement accuracy of wheel-rail contact forces, there are few works considering the longitudinal force and the lateral shift of the wheel-rail contact point. However, sometimes the longitudinal force has a non-negligible influence on the measurement accuracy on the instrumented wheelset. In this paper, the authors clarify the cross-sensitivity characteristics of the instrumented wheelset when the longitudinal force is applied to the various lateral position on the wheel tread through the FEM analysis and the static load test. The authors also propose a method to approximate the cross-sensitivity as an analytical function of the lateral and circumferential contact positions.

The Distribution Trend of Boron Atoms in Semiconductor Silicon under High Temperature

2021 ◽  
Vol 871 ◽  
pp. 243-247
Author(s):  
Zhi Huan Zhao ◽  
Zhi Bin Zhao ◽  
Ming Ming Jiang ◽  
Chuan Zhong Chen ◽  
Wei Hai Song ◽  
...  
Keyword(s):  
Geometric Model ◽  
Impurity Distribution ◽  
Diffusion Time ◽  
Internal Dynamic ◽  
Diffusion Test ◽  
Hydrodynamic Parameters ◽  
Whole Process ◽  
Diffusion Temperature ◽  
The Relationship ◽  
And Diffusion

The ProENGINEER software is used to build a geometric model for the whole process cavity and internal structure and conduct the internal dynamic simulation of cavity with different diffusion temperatures of 1,000°C, 1,050°C, 1,100°C and 1,150°C, and different diffusion time of 5 min, 10 min, 15 min and 20 min. Analyze the process control indexes by combining with specific thermal diffusion test, and study the relationship between hydrodynamic parameters and diffusion uniformity, Comprehensively investigate the effects of the diffusion temperature and diffusion time on doping, achieving the requirements of impurity distribution in materials.

KINETOSTATIC ANALYSIS FOR FOUR-BAR LINKAGE MECHANISM OF PROSTHETIC KNEE JOINT

2019 ◽  
Vol 19 (04) ◽  
pp. 1950018 ◽  
Author(s):  
XUHUI LIU ◽  
TIANTIAN GUO ◽  
JIAHAO ZHANG ◽  
GUANG YANG ◽  
LUCHAN SUN ◽  
...  
Keyword(s):  
Knee Joint ◽  
Group Method ◽  
Linkage Mechanism ◽  
Analysis Software ◽  
Prosthetic Knee ◽  
Damping Effect ◽  
D’Alembert Principle ◽  
Prosthetic Knee Joint ◽  
Four Bar Linkage ◽  
The Relationship

In this paper, a mathematical model of four-bar linkage mechanism is built to investigate the prosthetic knee joint, by means of the bar group method, and the motion of the prosthetic knee joint is simulated by motion analysis software. In the state of motion of the four linkage mechanism, to the moving component of the mechanism, the relationship between the moving displacement, velocity and acceleration are obtained. On the basis of the above investigation, dynamic statics analysis for the moving component of four-bar linkage mechanism are completed by the ‘D’Alembert principle. The research results show that, with the change of the rotating angle of the active part, the counter-force of rotating pair and the balance torque on active component are all changeable, which will provide a theoretical basis for the design of prosthetic knee joint mechanism with longer life and better damping effect.

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