scholarly journals Numerical Modeling of Shockwave Treatment of Knee Joint

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7678
Author(s):  
Galina Eremina ◽  
Alexey Smolin
Keyword(s):  
Numerical Modeling ◽  
Knee Joint ◽  
Fluid Pressure ◽  
Threshold Value ◽  
Optimal Level ◽  
Acoustic Stimulation ◽  
Compressive Stresses ◽  
Computer Aided ◽  
Energy Flux Density ◽  
Shockwave Loading

Arthritis is a degenerative disease that primarily affects the cartilage and meniscus of the knee joint. External acoustic stimulation is used to treat this disease. This article presents a numerical model of the knee joint aimed at the computer-aided study of the regenerative effects of shockwave treatment. The presented model was verified and validated. A numerical analysis of the conditions for the regeneration of the tissues of the knee joint under shockwave action was conducted. The results allow us to conclude that to obtain the conditions required for the regeneration of cartilage tissues and meniscus (compressive stresses above the threshold value of 0.15 MPa to start the process of chondrogenesis; distortional strains above the threshold value of 0.05% characterized by the beginning of the differentiation of the tissues in large volumes; fluid pressure corresponding to the optimal level of 68 kPa to transfer tissue cells in large volumes), the energy flux density of therapeutic shockwave loading should exceed 0.3 mJ/mm2.

Partial Meniscectomy Changes Fluid Pressurization in Articular Cartilage in Human Knees

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
M. Kazemi ◽  
L. P. Li ◽  
M. D. Buschmann ◽  
P. Savard
Keyword(s):  
Articular Cartilage ◽  
Knee Joint ◽  
Relaxation Times ◽  
Fluid Pressure ◽  
Partial Meniscectomy ◽  
Loading Conditions ◽  
Support Mechanism ◽  
Fluid Pressurization ◽  
Creep Loading ◽  
Intact Knee

Partial meniscectomy is believed to change the biomechanics of the knee joint through alterations in the contact of articular cartilages and menisci. Although fluid pressure plays an important role in the load support mechanism of the knee, the fluid pressurization in the cartilages and menisci has been ignored in the finite element studies of the mechanics of meniscectomy. In the present study, a 3D fibril-reinforced poromechanical model of the knee joint was used to explore the fluid flow dependent changes in articular cartilage following partial medial and lateral meniscectomies. Six partial longitudinal meniscectomies were considered under relaxation, simple creep, and combined creep loading conditions. In comparison to the intact knee, partial meniscectomy not only caused a substantial increase in the maximum fluid pressure but also shifted the location of this pressure in the femoral cartilage. Furthermore, these changes were positively correlated to the size of meniscal resection. While in the intact joint, the location of the maximum fluid pressure was dependent on the loading conditions, in the meniscectomized joint the location was predominantly determined by the site of meniscal resection. The partial meniscectomy also reduced the rate of the pressure dissipation, resulting in even larger difference between creep and relaxation times as compared to the case of the intact knee. The knee joint became stiffer after meniscectomy because of higher fluid pressure at knee compression followed by slower pressure dissipation. The present study indicated the role of fluid pressurization in the altered mechanics of meniscectomized knees.

NUMERICAL MODELING OF VIBRATED BEDS

1993 ◽  
Vol 07 (09n10) ◽  
pp. 1839-1858 ◽  
Author(s):  
Y-h. TAGUCHI
Keyword(s):  
Numerical Modeling ◽  
Numerical Model ◽  
Anomalous Diffusion ◽  
Side Wall ◽  
Convective Motion ◽  
Threshold Value ◽  
Linear Feature ◽  
Non Linear ◽  
Dynamical Features ◽  
First Time

I propose a numerical model which describes the dynamical features of vibrated beds. It succeeds in reproducing convective motion in vibrated beds which was observed by Faraday for the first time in 1831. In addition to this, this modeling can explain threshold value of instability and surface fluidization. Moreover, I numerically show vibrated bed without side wall can exhibit strong non-linear feature like turbulence or anomalous diffusion.

A 3D Biphasic Finite Element Model of the Human Knee Joint for the Study of Tibiofemoral Contact and Fluid Pressurization

2013 ◽  
Author(s):  
Hongqiang Guo ◽  
Suzanne A. Maher ◽  
Robert L. Spilker
Keyword(s):  
Finite Element ◽  
Fluid Flow ◽  
Knee Joint ◽  
Contact Problem ◽  
Finite Element Model ◽  
Soft Tissues ◽  
Fluid Pressure ◽  
Element Model ◽  
Human Knee Joint ◽  
Biphasic Finite Element

Biphasic theory which considers soft tissue, such as articular cartilage and meniscus, as a combination of a solid and a fluid phase has been widely used to model their biomechanical behavior [1]. Though fluid flow plays an important role in the load-carrying ability of soft tissues, most finite element models of the knee joint consider cartilage and the meniscus as solid. This simplification is due to the fact that biphasic contact is complicated to model. Beside the continuity conditions for displacement and traction that a single-phase contact problem consists of, there are two additional continuity conditions in the biphasic contact problem for relative fluid flow and fluid pressure [2]. The problem becomes even more complex when a joint is being modeled. The knee joint, for example, has multiple contact pairs which make the biphasic finite element model of this joint far more complex. Several biphasic models of the knee have been developed [3–9], yet simplifications were included in these models: (1) the 3D geometry of the knee was represented by a 2D axisymmetric geometry [3, 5, 6, 9]; (2) no fluid flow was allowed between contact surfaces of the soft tissues [4, 8] which is inconsistent with the equation of mass conservation across the contact interface [10]; (3) zero fluid pressure boundary conditions were inaccurately applied around the contact area [7].

Determination of amputation level in ischaemic limbs using tcPO2 measurement

VASA ◽  
2005 ◽  
Vol 34 (2) ◽  
pp. 108-112 ◽  
Author(s):  
Poredos ◽  
Rakovec ◽  
Guzic-Salobir
Keyword(s):  
Threshold Value ◽  
Optimal Level ◽  
Invasive Procedures ◽  
Clinical Criteria ◽  
Amputation Level ◽  
Non Invasive ◽  
Below The Knee ◽  
Healing Wound ◽  
Primary Healing

Background: Determination of the optimal amputation level is essential for patients, morbidity and rehabilitation. Various non-invasive procedures have been proposed to determine the optimal level of amputation. There is no consensus on the minimal tcPO2 level that is required to predict the healing of the stump. Therefore we aimed to rank the probability of primary wound healing at the most distal level and to answer the question if there is a lower limit of tcPO2 below which healing cannot occur. Patients and methods: 56 consecutive patients undergoing amputation below the knee for ischaemic gangrene of limbs were prospectively enrolled in the study. 39 were men (18 of whom were diabetics) and 17 women (8 diabetics) whose ages ranged from 45 to 87 years (mean 73 years). The total of 71 amputations was performed on the 56 patients: 39 below-knee with primary healing and, in 16 patients the above-knee reamputation was performed, due to the non-healing wound on the below-knee stump. The level of the amputation (below or above the knee) was in all cases decided solely on clinical grounds. TcPO2 was measured on each patient prior to amputation, on the dorsum of the foot and 10 cm below the knee. Results: The median tcPO2 value on the dorsum of the foot of diseased legs before amputation was 12 mm Hg (range from 0 to 22 mm Hg). At the anticipated level of the amputation of the shank, the median value of tcPO2 was 28 mm Hg (8–56 mm Hg). Patients with primary healing of postoperative wounds had significantly higher values of tcPO2 than patients with failure to heal (37mm Hg; range15–56mm Hg vs.18 mm Hg; range 8–36 mm Hg, p < 0.01). The success rate increased with higher tcPO2 values at the level of amputation. The 15% prevalence of reamputations was obtained for tcPO2 values between 25 and 36 mm Hg (median value 33 mm Hg) and the threshold value of tcPO2 below which the stump failed to heal was 15 mm Hg. Conclusions: Our study showed that tcPO2 is a reliable indicator of local ischemia. The integration of this parameter with other personal clinical criteria may be a valuable help to the surgeon in decision making.

MODELING THE STRESS STATE OF THE BACKFILLING MASS WITH DIFFERENT PHYSICAL AND MECHANICAL PROPERTIES

2021 ◽  
pp. 7-18
Author(s):  
Mykhailo Petlovanyi ◽  
◽  
Kateryna Sai ◽  
Keyword(s):  
Mechanical Properties ◽  
Numerical Modeling ◽  
Stress State ◽  
Physical And Mechanical Properties ◽  
Practical Significance ◽  
Mining Operations ◽  
Mining Depth ◽  
Compressive Stresses ◽  
A Value ◽  
Backfilled Stopes

Purpose. Analytical researches of the stress state of the backfilling stopes with different physical and mechanical properties using numerical modeling to determine possible zones of stability losses and predict their failure. Methods. Numerical modeling of the formation of stresses around a high stopes was carried out for the conditions of mining iron ore reserves in the depth intervals of 740-1040 m of the Pivdenno-Bilozerske deposit, where mining operations are actively carried out using the finite element method in the SolidWorks 2016 software package with reliable substantiation of the parameters of the developed geomechanical model. Results. Numerical simulation of the stress state of the backfilling mass are carried out at variable values of the modulus of its elasticity and the mining depth. It was found that with the existing actual physical and mechanical properties of the backfilling mass during the development of the Pivdenno-Bilozerske deposit, the danger of its failure is predicted at depths of more than 890 m. In the center of the filling array, the stress values change linearly, and at the junction of the roof with the side of the backfilled stopes – polynomial. It was found that an increase in the modulus of elasticity of the backfilling mass allows to reduce the compressive stresses only at the junction of the roof with the side of the backfilled stopes to a value of 800 MPa. Scientific novelty. With an increase in the depth of development, despite an increase in the elastic modulus of the fill, the values of stresses increase, which eliminates the need to increase it with a decrease in the mining depth it was found. Practical significance. The results obtained make it possible to correct the technology of formation of a backfilling mass in the primary stopes, taking into account the formation of stresses on its contour and, with an increase in the mining depth, to form a backfilling mass with viscoplastic properties.

Mechanical Response of Human Knee Joint to Sinusoidal Compression: Influence of Fluid Pressurization in Soft Tissues

2012 ◽  
Author(s):  
Yaghoub Dabiri ◽  
LePing Li
Keyword(s):  
Knee Joint ◽  
Soft Tissues ◽  
Mechanical Response ◽  
Fluid Pressure ◽  
Joint Modeling ◽  
Loading Frequency ◽  
Human Knee ◽  
Human Knee Joint ◽  
Fluid Pressurization

The mechanical response of the knee joint has been simulated using finite element methods with elastic material models [1–4]. Fluid pressurization in articular cartilage and menisci has not been considered in the anatomically accurate joint modeling until recently [5–7]. We have recently considered stress relaxation and creep behavior of human knees. The objective of the present study was to investigate the mechanics of the femoral cartilage under cyclical knee compression. We are particularly interested in the determination of loading versus unloading patterns for the fluid pressure and flow, as well as the influence of the loading frequency on the fluid pressurization.

scholarly journals Numerical modeling to analysis the abrasion of knee joint by walking pattern

2017 ◽  
Vol 19 (5) ◽  
pp. 3875-3882
Author(s):  
Hong Seok Lim ◽  
Dae Eun Moon ◽  
Sung Min Kim
Keyword(s):  
Numerical Modeling ◽  
Knee Joint ◽  
Walking Pattern
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