scholarly journals Knee loading in OA subjects is correlated to flexion and adduction moments and to contact point locations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ali Zeighami ◽  
Raphael Dumas ◽  
Rachid Aissaoui
Keyword(s):  
Contact Force ◽  
Contact Point ◽  
Frontal Plane ◽  
Knee Adduction Moment ◽  
Poor Correlation ◽  
Lateral Direction ◽  
Contact Points ◽  
Lateral Contact ◽  
Flexion Moment ◽  
Point Trajectories

AbstractThis study evaluated the association of contact point locations with the knee medial and lateral contact force (Fmed, Flat) alterations in OA and healthy subjects. A musculoskeletal model of the lower limb with subject-specific tibiofemoral contact point trajectories was used to estimate the Fmed and Flat in ten healthy and twelve OA subjects during treadmill gait. Regression analyses were performed to evaluate the correlation of the contact point locations, knee adduction moment (KAM), knee flexion moment (KFM), frontal plane alignment, and gait speed with the Fmed and Flat. Medial contact point locations in the medial–lateral direction showed a poor correlation with the Fmed in OA (R2 = 0.13, p = 0.01) and healthy (R2 = 0.24, p = 0.001) subjects. Anterior–posterior location of the contact points also showed a poor correlation with the Fmed of OA subjects (R2 = 0.32, p < 0.001). Across all subjects, KAM and KFM remained the best predictors of the Fmed and Flat, respectively (R2 between 0.62 and 0.69). Results suggest different mechanisms of contact force distribution in OA joints. The variations in the location of the contact points participate partially to explains the Fmed variations in OA subjects together with the KFM and KAM.

scholarly journals An Electronic Force Sensor for Medical Jet Injection

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Nickolas P. Demas ◽  
Ian W. Hunter
Keyword(s):  
Contact Force ◽  
Mean Absolute Error ◽  
Force Sensor ◽  
Absolute Error ◽  
Jet Injection ◽  
Lateral Direction ◽  
Normal Contact ◽  
Normal Contact Force ◽  
Force Magnitude ◽  
Lateral Contact

In medical jet injection, a narrow fluid drug stream is propelled at high velocity into skin without a needle. Previous studies have shown that the volume delivered is highly dependent on a number of factors. This paper details the development of an electronic force sensor for medical jet injection and shows that the normal contact force exerted on the tissue by the nozzle is an additional factor affecting volume delivered. Using this sensor, we measure the forces at the nozzle tip in the normal direction with a sensitivity of 18 μN, calibrated over a range from 1 N to 8 N with a mean absolute error of 8 mN, and a maximum overload of 300 N. We further measure forces at the nozzle tip in the lateral direction with a sensitivity of 8 μN, calibrated over a range from 0.1 N to 7 N, with a mean absolute error of 101 mN for lateral contact force magnitude and 1.60 deg for lateral contact force direction. Experimental validation confirms that the force sensor does not adversely affect the accuracy and precision of ejected volume from the jet injector. We use this setup to examine the effect of normal contact force on volume delivered into postmortem porcine tissue. Experimental results demonstrate that volume delivered with normal contact force between 4 N and 8 N is significantly more accurate and precise compared to volume delivered with normal contact force between 0 N and 3.9 N.

LOWER EXTREMITIES BIOMECHANICS OF REGULAR STAIR CLIMBING: SLIM VERSUS OBESE

2015 ◽  
Vol 27 (04) ◽  
pp. 1550036
Author(s):  
Sami Almashaqbeh ◽  
Bahaa Al-Sheikh ◽  
Wan Abu Bakar Wan Abas ◽  
Noor Azuan Abu Osman
Keyword(s):  
Knee Joint ◽  
Force Plate ◽  
Three Dimensional ◽  
Frontal Plane ◽  
Stair Climbing ◽  
Knee Adduction Moment ◽  
Obese People ◽  
Gait Characteristics ◽  
Flexion Moment ◽  
Analysis System

The kinematic and kinetic differences between obese and slim people when climbing a staircase at their self-selected speed are compared. A four-step wooden stair instrumented with two force plates were used as the action platform whilst the kinematic and kinetic recordings were collected and analyzed using a six-camera and two-force plate three-dimensional motion analysis system. Ten obese adults, six males and four females, and ten lean adults, six males and four females, volunteered for the study. The results showed that the obese people are able to reduce the knee joint flexion moment when climbing stair compared to the normal slim people. In the frontal plane, no significant differences were found in the knee adduction moment. Moreover, obese individuals have identified some kinematics adaptations including slower velocity and longer stance phase, compared to slim individuals. The obese individuals might adjust their gait characteristics in response to their heavy bodies to reduce or maintain the same load on the knee joint as slim individuals.

scholarly journals Effects of Toe-Out and Toe-In Gaits on Lower-Extremity Kinematics, Dynamics, and Electromyography

2019 ◽  
Vol 9 (23) ◽  
pp. 5245
Author(s):  
Weiling Cui ◽  
Changjiang Wang ◽  
Weiyi Chen ◽  
Yuan Guo ◽  
Yi Jia ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Contact Force ◽  
Repeated Measures ◽  
Joint Pain ◽  
Knee Flexion ◽  
Reaction Force ◽  
Contact Forces ◽  
Knee Adduction Moment ◽  
Positive Effects ◽  
Lateral Contact

Toe-in and toe-out gait modifications have received increasing attention as an effective, conservative treatment for individuals without severe osteoarthritis because of its potential for improving knee adduction moment (KAM) and knee flexion moment (KFM). Although toe-in and toe-out gaits have positive effects on tibiofemoral (TF) joint pain in the short term, negative impacts on other joints of the lower extremity may arise. The main purpose of this study was to quantitatively compare the effects of foot progression angle (FPA) gait modification with normal walking speeds in healthy individuals on lower-extremity joint, ground reaction force (GRF), muscle electromyography, joint moment, and TF contact force. Experimental measurements using the Vicon system and multi-body dynamics musculoskeletal modelling using OpenSim were conducted in this study. Gait analysis of 12 subjects (n = 12) was conducted with natural gait, toe-in gait, and toe-out gait. One-way repeated measures of ANOVA (p < 0.05) with Tukey’s test was used for statistical analysis. Results showed that the toe-in and toe-out gait modifications decreased the max angle of knee flexion by 8.8 and 12.18 degrees respectively (p < 0.05) and the max angle of hip adduction by 1.28 and 0.99 degrees respectively (p < 0.05) compared to the natural gait. Changes of TF contact forces caused by FPA gait modifications were not statistically significant; however, the effect on KAM and KFM were significant (p < 0.05). KAM or combination of KAM and KFM can be used as surrogate measures for TF medial contact force. Toe-in and toe-out gait modifications could relieve knee joint pain probably due to redistribution of TF contact forces on medial and lateral condylar through changing lateral contact centers and shifting bilateral contact locations.

Analysis of Insertion Force in Elastic/Plastic Mating

1990 ◽  
Vol 112 (3) ◽  
pp. 192-197 ◽  
Author(s):  
S. E. Yamada ◽  
H. Ueno
Keyword(s):  
Contact Force ◽  
Contact Point ◽  
Friction Angle ◽  
Electronic System ◽  
Insertion Force ◽  
Elastic Plastic ◽  
Contact Points ◽  
Force Direction ◽  
System Interconnection ◽  
Insertion Process

A simulation of an insertion of a solid pin into a slot between two opposing compliant beams is attempted. As a particular feature, the elastic-plastic deformation of the slot during the insertion is incorporated, as such a situation often occurs in electronic system interconnection. Each instance of the insertion process is considered as a static equilibrium of the insertion force and the contact force (including the frictional force). The equilibrium position of the deflected beams and the pin can be obtained as the point satisfying the following two conditions: 1) at the contact point, the contact force direction is offset from the normal direction to the contact points by the friction angle and, 2) the present positions of the contact points (one on the beam and the other on the pin), and their tangent angles must coincide exactly with each other. The simulated insertion force and depth relation agrees well with the real measurement.

A Contact Force Solution for Non-Colliding Contact Dynamics Simulation

2006 ◽  
Author(s):  
Inna Sharf ◽  
Yuning Zhang
Keyword(s):  
Rigid Body ◽  
Contact Force ◽  
Contact Point ◽  
Closed Form Solution ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Contact Dynamics ◽  
Dynamics Simulation ◽  
Friction Forces ◽  
Contact Points

Rigid-body impact modeling remains an intensive area of research spurred on by new applications in robotics, biomechanics, and more generally multibody systems. By contrast, the modeling of non-colliding contact dynamics has attracted significantly less attention. The existing approaches to solve non-colliding contact problems include compliant approaches in which the contact force between objects is defined explicitly as a function of local deformation, and complementarity formulations in which unilateral constraints are employed to compute contact interactions (impulses or forces) to enforce the impenetrability of the contacting objects. In this article, the authors develop a novel approach to solve the non-colliding contact problem for objects of arbitrary geometry in contact at multiple points. Similarly to the complementarity formulation, the solution is based on rigid-body dynamics and enforces contact kinematics constraints at the acceleration level. Differently, it leads to an explicit closed-form solution for the normal forces at the contact points. Integral to the proposed formulation is the treatment of tangential contact forces, in particular the static friction. These friction forces must be calculated as a function of microslip velocity or displacement at the contact point. Numerical results are presented for three test cases: 1) a thin rod sliding down a stationary wedge; 2) a cube rotating off the stationary wedge under application of an external moment and 3) the cube and the wedge both moving under application of a moment. To ascertain validity and correctness, the solutions to frictionless and frictional scenarios obtained with the proposed formulation are compared to those generated by using a commercial simulation tool MSC ADAMS.

scholarly journals Towards planning of osteotomy around the knee with quantitative inclusion of the adduction moment: a biomechanical approach

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Margit Biehl ◽  
Philipp Damm ◽  
Adam Trepczynski ◽  
Stefan Preiss ◽  
Gian Max Salzmann
Keyword(s):  
Gait Analysis ◽  
Measurement Data ◽  
Frontal Plane ◽  
Medial Compartment ◽  
Knee Adduction Moment ◽  
In Vivo Measurement ◽  
Force Ratio ◽  
Leg Alignment ◽  
Alignment Angle

Abstract Purpose Despite practised for decades, the planning of osteotomy around the knee, commonly using the Mikulicz-Line, is only empirically based, clinical outcome inconsistent and the target angle still controversial. A better target than the angle of frontal-plane static leg alignment might be the external frontal-plane lever arm (EFL) of the knee adduction moment. Hypothetically assessable from frontal-plane-radiograph skeleton dimensions, it might depend on the leg-alignment angle, the hip-centre-to-hip-centre distance, the femur- and tibia-length. Methods The target EFL to achieve a medial compartment force ratio of 50% during level-walking was identified by relating in-vivo-measurement data of knee-internal loads from nine subjects with instrumented prostheses to the same subjects’ EFLs computed from frontal-plane skeleton dimensions. Adduction moments derived from these calculated EFLs were compared to the subjects’ adduction moments measured during gait analysis. Results Highly significant relationships (0.88 ≤ R2 ≤ 0.90) were found for both the peak adduction moment measured during gait analysis and the medial compartment force ratio measured in vivo to EFL calculated from frontal-plane skeleton dimensions. Both correlations exceed the respective correlations with the leg alignment angle, EFL even predicts the adduction moment’s first peak. The guideline EFL for planning osteotomy was identified to 0.349 times the epicondyle distance, hence deducing formulas for individualized target angles and Mikulicz-Line positions based on full-leg radiograph skeleton dimensions. Applied to realistic skeleton geometries, widespread results explain the inconsistency regarding correction recommendations, whereas results for average geometries exactly meet the most-consented “Fujisawa-Point”. Conclusion Osteotomy outcome might be improved by planning re-alignment based on the provided formulas exploiting full-leg-radiograph skeleton dimensions.

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.

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