scholarly journals Effect of static foot posture on the dynamic stiffness of foot joints during walking

2018 ◽  
Vol 62 ◽  
pp. 241-246 ◽  
Author(s):  
E. Sanchis-Sales ◽  
J.L. Sancho-Bru ◽  
A. Roda-Sales ◽  
J. Pascual-Huerta
Keyword(s):  
Dynamic Stiffness ◽  
Foot Joints ◽  
Foot Posture

Variability of the Dynamic Stiffness of Foot Joints: Effect of Gait Speed

2019 ◽  
Vol 109 (4) ◽  
pp. 291-298 ◽  
Author(s):  
Enrique Sanchis-Sales ◽  
Joaquín Luis Sancho-Bru ◽  
Alba Roda-Sales ◽  
Javier Pascual-Huerta
Keyword(s):  
Sample Size ◽  
Gait Speed ◽  
Dynamic Stiffness ◽  
Mean Value ◽  
Comparative Analyses ◽  
Foot Joints ◽  
Foot Posture ◽  
The Central Nervous System ◽  
Midtarsal Joint ◽  
Metatarsophalangeal Joints

Background: Comparison of dynamic stiffness of foot joints was previously proposed to investigate pathologic situations with changes in the properties of muscle and passive structures. Samples must be controlled to reduce the variability within groups being compared, which may arise from different sources, such as gait speed or Foot Posture Index (FPI). Methods: Variability in the measurement of the dynamic stiffness of ankle, midtarsal, and metatarsophalangeal joints was studied in a controlled sample of healthy men with normal FPI, and the effect of gait speed was analyzed. In experiment 1, dynamic stiffnesses were obtained in three sessions, five trials per session, for each participant, taking the mean value across trials as representative of each session. In experiment 2, five trials were considered at slow, comfortable, and fast velocities. Results: Similar intersession and intrasession errors and intraparticipant errors within sessions were found, indicating the goodness of using five trials per session for averaging. The intraparticipant and interparticipant variability data provided can be used to select the sample size in future comparative analyses. Significant differences with gait speed were observed in most dynamic stiffnesses considered, with a general rise when gait speed increased, especially at the midtarsal joint, this being attributed to an active modulation produced by the central nervous system. Conclusions: Differences with gait speed were higher than intrasession and intersession repeatability errors for the propulsion phases at the ankle and midtarsal joints; comparative analyses at these phases need more exhaustive control of gait speed to reduce the required sample size.

Dynamic Flexion Stiffness of Foot Joints During Walking

2016 ◽  
Vol 106 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Enrique Sanchis-Sales ◽  
Joaquin L. Sancho-Bru ◽  
Alba Roda-Sales ◽  
Javier Pascual-Huerta
Keyword(s):  
Dynamic Stiffness ◽  
Three Dimensional ◽  
Joint Stiffness ◽  
Metatarsophalangeal Joint ◽  
Foot Joints ◽  
Linear Relationships ◽  
Flexion Moment ◽  
Analysis System ◽  
Propulsion Phase

Background: Dynamic stiffness can be used for studying foot pathologic abnormalities and for developing prostheses and orthoses. Although previous works have studied the role of ankle joint stiffness during gait, other foot joints have not yet been analyzed. We sought to characterize the dynamic stiffness of the ankle, midtarsal, and metatarsophalangeal joints during normal walking. Methods: Kinematics and contact data from four healthy individuals during walking were registered with a three-dimensional motion analysis system and a pressure platform. Stance phases with flexion moment-angle linear relationships were identified, and dynamic stiffnesses were calculated from the slope of their linear regressions. Intraparticipant repeatability was analyzed using analyses of variance, and interparticipant variability was checked through the SD of averaged participant stiffnesses. Results: Flexion moment-angle linear relationships were identified (R2 > 0.98) during the early and late midstance phases and the propulsion phase at the ankle (2.76, 5.23, and 3.42 N·m/kg/rad, respectively) and midtarsal (15.88, 3.90, and 4.64 N·m/kg/rad, respectively) joints. At the metatarsophalangeal joint, a linear relationship (R2 > 0.96) occurred only during the propulsion phase (0.11 N·m/kg/rad). High dynamic stiffness variability was observed during the late and early midstance phases at the ankle and midtarsal joints, respectively. Conclusions: These results may serve as a basis for future studies aimed at investigating the role of dynamic stiffness identified herein in different foot disorders. The importance of properly controlling the samples in such studies is highlighted. Study of the dynamic stiffnesses identified might be used in the design of prostheses, orthoses, and other assistive devices.

Repeatability vs. multiple-trait models to evaluate shell dynamic stiffness for layer chickens

2017 ◽  
Vol 95 (1) ◽  
pp. 9 ◽  
Author(s):  
A. Wolc ◽  
J. Arango ◽  
P. Settar ◽  
N. P. O’Sullivan ◽  
J. C. M. Dekkers
Keyword(s):  
Dynamic Stiffness ◽  
Multiple Trait ◽  
Layer Chickens

scholarly journals Review of the Upright Balance Assessment Based on the Force Plate

2021 ◽  
Vol 18 (5) ◽  
pp. 2696
Author(s):  
Baoliang Chen ◽  
Peng Liu ◽  
Feiyun Xiao ◽  
Zhengshi Liu ◽  
Yong Wang
Keyword(s):  
Postural Balance ◽  
Force Plate ◽  
Assessment Method ◽  
Balance Assessment ◽  
Experimental Conditions ◽  
Methodological Research ◽  
Assessment Tests ◽  
Wide Range ◽  
Foot Posture ◽  
Plate System

Quantitative assessment is crucial for the evaluation of human postural balance. The force plate system is the key quantitative balance assessment method. The purpose of this study is to review the important concepts in balance assessment and analyze the experimental conditions, parameter variables, and application scope based on force plate technology. As there is a wide range of balance assessment tests and a variety of commercial force plate systems to choose from, there is room for further improvement of the test details and evaluation variables of the balance assessment. The recommendations presented in this article are the foundation and key part of the postural balance assessment; these recommendations focus on the type of force plate, the subject’s foot posture, and the choice of assessment variables, which further enriches the content of posturography. In order to promote a more reasonable balance assessment method based on force plates, further methodological research and a stronger consensus are still needed.

scholarly journals FRI0415 BODY MASS INDEX AND STATIC FOOT DISORDERS IN GONARTHROSIC PATIENTS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 806.3-806
Author(s):  
K. Maatallah ◽  
M. Hfaidh ◽  
H. Ferjani ◽  
W. Triki ◽  
D. Kaffel ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Demographic Data ◽  
Navicular Bone ◽  
Hindfoot Alignment ◽  
Knee Oa ◽  
Postural Changes ◽  
Flat Feet ◽  
Foot Posture ◽  
Hindfoot Deformities

Background:Several studies have shown that there is a link between body mass index (BMI) and painful foot imputed to a biomechanical change in foot structure [1].Objectives:Our objective was to study the association between BMI and static foot disorders in gonarthrosic subjects.Methods:It was a prospective descriptive study conducted in the rheumatology department of the Mohamed Kassab Institute of Orthopedics with 60 patients with Gonarthrosis. The socio-demographic data of the patients were studied. BMI was calculated for all patients. Static foot disorders have been studied.Results:Sixty patients were included, 83.3% of whom were female. The average age was 55.2 years [38-78 years]. The disease has been evolving for an average of 6 years [1-13 years]. The lesion was bilateral in 80% of cases, the average body mass index was 30.4 kg / m2 [24-36]. Knee arthritis was classified as stage I, II and III according to the Kellgren and Lawrence classification in 18.5%, 55.6% and 25.9% of patients respectively. The foot examination involved 108 gonarthrosic limbs. Examination of the integuments showed hyperkeratosis in 94.4% of the cases (79.6% calluses and 83.3% callosities). Forefoot deformities were Hallux valgus (HV) in 52.8% of cases and overlapping toes in 18.5% of cases. Pronation deformity using the Foot Posture Index (FPI) was found in 51.9% of cases. Abnormal lowering of navicular bone was noted in 51.9%. The podoscopic impression revealed flat feet in 73.2% of the cases.A statistically significant association was found between BMI and the presence of calluses (31.21 ± 2.897 vs26.83 ± 1.425, p <0.001), with HV (31.37 ± 3.086 vs29.49 ± 2.969, p = 0.002), at the overlap of the toes (33.2 ± 1.361vs29.86 ± 1.130, p <0.001), with the lowering of the navicular bone (31.17 ± 2.885vs29.68 ± 3.304, p = 0.015), FPI (p = 0.003) and flat podoscopic impression (p <0.001).Conclusion:BMI is strongly associated with static feet disorders in gonarthrosic patients by aggravating the postural changes in the foot caused by knee osteoarthritis [2]. Obesity is associated mainly with the existence of flat feet, pronation of the foot, toes deformities and hyperkeratosis.References:[1]Steele JR, Mickle KJ, Munro B. Fat flat frail feet: how does obesity affect the older foot. XXII Congress of the International Society of Biomechanics; 2009[2]Norton AA, Callaghan JJ, Amendola A, Phisitkul P, Wongsak S, Liu SS, et al. Correlation of knee and hindfoot deformities in advanced knee OA: compensatory hindfoot alignment and where it occurs. Clin Orthop Relat Res. 2015;473(1):166-74Disclosure of Interests:None declared

Exact solution by dynamic stiffness method for the natural vibration of porous functionally graded plate considering neutral surface

2021 ◽  
pp. 146442072098817
Author(s):  
Md. Imran Ali ◽  
Mohammad Sikandar Azam
Keyword(s):  
Power Law ◽  
Functionally Graded Material ◽  
Stiffness Matrix ◽  
Natural Vibration ◽  
Dynamic Stiffness ◽  
Functionally Graded ◽  
Neutral Surface ◽  
Functionally Graded Plate ◽  
Dynamic Stiffness Matrix ◽  
Graded Material

This paper presents the formulation of dynamic stiffness matrix for the natural vibration analysis of porous power-law functionally graded Levy-type plate. In the process of formulating the dynamic stiffness matrix, Kirchhoff-Love plate theory in tandem with the notion of neutral surface has been taken on board. The developed dynamic stiffness matrix, a transcendental function of frequency, has been solved through the Wittrick–Williams algorithm. Hamilton’s principle is used to obtain the equation of motion and associated natural boundary conditions of porous power-law functionally graded plate. The variation across the thickness of the functionally graded plate’s material properties follows the power-law function. During the fabrication process, the microvoids and pores develop in functionally graded material plates. Three types of porosity distributions are considered in this article: even, uneven, and logarithmic. The eigenvalues computed by the dynamic stiffness matrix using Wittrick–Williams algorithm for isotropic, power-law functionally graded, and porous power-law functionally graded plate are juxtaposed with previously referred results, and good agreement is found. The significance of various parameters of plate vis-à-vis aspect ratio ( L/b), boundary conditions, volume fraction index ( p), porosity parameter ( e), and porosity distribution on the eigenvalues of the porous power-law functionally graded plate is examined. The effect of material density ratio and Young’s modulus ratio on the natural vibration of porous power-law functionally graded plate is also explained in this article. The results also prove that the method provided in the present work is highly accurate and computationally efficient and could be confidently used as a reference for further study of porous functionally graded material plate.

Design and analysis of a vibration isolation system with cam–roller–spring–rod mechanism

2021 ◽  
pp. 107754632110005
Author(s):  
Yonglei Zhang ◽  
Guo Wei ◽  
Hao Wen ◽  
Dongping Jin ◽  
Haiyan Hu
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Excitation Amplitude ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Stiffness Characteristic ◽  
Negative Stiffness Mechanism ◽  
Isolation Systems ◽  
Vibration Isolation Performance

The vibration isolation system using a pair of oblique springs or a spring-rod mechanism as a negative stiffness mechanism exhibits a high-static low-dynamic stiffness characteristic and a nonlinear jump phenomenon when the system damping is light and the excitation amplitude is large. It is possible to remove the jump via adjusting the end trajectories of the above springs or rods. To realize this idea, the article presents a vibration isolation system with a cam–roller–spring–rod mechanism and gives the detailed numerical and experimental studies on the effects of the above mechanism on the vibration isolation performance. The comparative studies demonstrate that the vibration isolation system proposed works well and outperforms some other vibration isolation systems.

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