Changes in Foot Loading Following Plantar Fasciotomy: A Computer Modeling Study

Forward dynamic simulations of a toe-rise task were developed to explore the outcomes of plantar fasciotomy, a surgery commonly performed to relieve heel pain. The specific objectives of this study were to develop such a simulation, validate its predictions, and simulate rising on toes using a model from which the plantar fascia had been removed. Root-mean squared differences between the intact model and measurements of healthy subjects were found to be 0.009 body weights (BW) and 0.055 BW for the horizontal and vertical ground reaction forces and 7.1 mm, 11.3 mm, and 0.48 deg for the horizontal, vertical and rotational positions of the pelvis. Simulated plantar fasciotomy increased passive arch torques by 7.4%, increased metatarsal head contact forces by 18%, and resulted in greater toe flexor activity. These simulations may explain the mechanisms behind plantar fasciotomy complications when patients perform activities that require loading of the plantarflexors and the longitudinal arch.

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The biological limits to running speed are imposed from the ground up

Journal of Applied Physiology ◽

10.1152/japplphysiol.00947.2009 ◽

2010 ◽

Vol 108 (4) ◽

pp. 950-961 ◽

Cited By ~ 119

Author(s):

Peter G. Weyand ◽

Rosalind F. Sandell ◽

Danille N. L. Prime ◽

Matthew W. Bundle

Keyword(s):

High Speed ◽

Stance Phase ◽

Large Mass ◽

Running Speed ◽

Force Application ◽

Body Weights ◽

Reaction Forces ◽

Vertical Ground ◽

Ground Contact Time ◽

Vertical Ground Reaction Forces

Running speed is limited by a mechanical interaction between the stance and swing phases of the stride. Here, we tested whether stance phase limitations are imposed by ground force maximums or foot-ground contact time minimums. We selected one-legged hopping and backward running as experimental contrasts to forward running and had seven athletic subjects complete progressive discontinuous treadmill tests to failure to determine their top speeds in each of the three gaits. Vertical ground reaction forces [in body weights (Wb)] and periods of ground force application (Tc; s) were measured using a custom, high-speed force treadmill. At top speed, we found that both the stance-averaged (Favg) and peak (Fpeak) vertical forces applied to the treadmill surface during one-legged hopping exceeded those applied during forward running by more than one-half of the body's weight (Favg = 2.71 ± 0.15 vs. 2.08 ± 0.07 Wb; Fpeak = 4.20 ± 0.24 vs. 3.62 ± 0.24 Wb; means ± SE) and that hopping periods of force application were significantly longer (Tc = 0.160 ± 0.006 vs. 0.108 ± 0.004 s). Next, we found that the periods of ground force application at top backward and forward running speeds were nearly identical, agreeing to within an average of 0.006 s (Tc = 0.116 ± 0.004 vs. 0.110 ± 0.005 s). We conclude that the stance phase limit to running speed is imposed not by the maximum forces that the limbs can apply to the ground but rather by the minimum time needed to apply the large, mass-specific forces necessary.

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Use of an instrument sandwiched between the hoof and shoe to measure vertical ground reaction forces and three-dimensional acceleration at the walk, trot, and canter in horses

American Journal of Veterinary Research ◽

10.2460/ajvr.2000.61.979 ◽

2000 ◽

Vol 61 (8) ◽

pp. 979-985 ◽

Cited By ~ 29

Author(s):

Makoto Kai ◽

Osamu Aoki ◽

Atsushi Hiraga ◽

Hironori Oki ◽

Mikihiko Tokuriki

Keyword(s):

Three Dimensional ◽

Ground Reaction Forces ◽

Reaction Forces ◽

Vertical Ground ◽

Vertical Ground Reaction Forces

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Joint angle estimation with wavelet neural networks

Scientific Reports ◽

10.1038/s41598-021-89580-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Saaveethya Sivakumar ◽

Alpha Agape Gopalai ◽

King Hann Lim ◽

Darwin Gouwanda ◽

Sunita Chauhan

Keyword(s):

Gait Analysis ◽

Real Time ◽

Monitoring Applications ◽

Reaction Forces ◽

Multiple Sensor ◽

Vertical Ground ◽

Overall Performance ◽

Gait Monitoring ◽

Vertical Ground Reaction Forces ◽

And Control

AbstractThis paper presents a wavelet neural network (WNN) based method to reduce reliance on wearable kinematic sensors in gait analysis. Wearable kinematic sensors hinder real-time outdoor gait monitoring applications due to drawbacks caused by multiple sensor placements and sensor offset errors. The proposed WNN method uses vertical Ground Reaction Forces (vGRFs) measured from foot kinetic sensors as inputs to estimate ankle, knee, and hip joint angles. Salient vGRF inputs are extracted from primary gait event intervals. These selected gait inputs facilitate future integration with smart insoles for real-time outdoor gait studies. The proposed concept potentially reduces the number of body-mounted kinematics sensors used in gait analysis applications, hence leading to a simplified sensor placement and control circuitry without deteriorating the overall performance.

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Hindlimb muscular activity, kinetics and kinematics of cats jumping to their maximum achievable heights

Journal of Experimental Biology ◽

10.1242/jeb.91.1.73 ◽

1981 ◽

Vol 91 (1) ◽

pp. 73-86 ◽

Cited By ~ 1

Author(s):

F. E. Zajac ◽

M. R. Zomlefer ◽

W. S. Levine

Keyword(s):

Vertical Jump ◽

Muscular Activity ◽

Dynamic State ◽

Extensor Muscles ◽

Ankle Joints ◽

Flexor Muscles ◽

Reaction Forces ◽

Vertical Ground ◽

Vertical Ground Reaction Forces ◽

Propulsion Phase

Cats were trained to jump from a force platform to their maximum achievable heights. Vertical ground reaction forces developed by individual hindlimbs showed that the propulsion phase consists of two epochs. During the initial “preparatory phase' the cat can traverse many different paths. Irrespective of the path traversed, however, the cat always attains the same position, velocity and momentum at the end of this phase. Starting from this dynamic state the cat during the subsequent “launching phase' (about 150 ms long) generates significant propulsion as its hindlimbs develop force with identical, stereotypic profiles. Cinematographic data, electromyographic data, and computed torques about the hip, knee and ankle joints indicate that during the jump proximal extensor musculature is activated before distal musculature. During terminal experiments when the hindlimb was set at positions corresponding to those in the jump, isometric torques produced by tetanic stimulation of groups of extensor and flexor muscles were compared with computed torques developed by the same cat during previous jumps. These comparisons suggest that extensor muscles of the hindlimb are fully activated during the maximal vertical jump.

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Hip and Knee Kinematics and Kinetics During Landing Tasks After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-Analysis

Journal of Athletic Training ◽

10.4085/1062-6050-334-16 ◽

2018 ◽

Vol 53 (2) ◽

pp. 144-159 ◽

Cited By ~ 12

Author(s):

Adam S. Lepley ◽

Christopher M. Kuenze

Keyword(s):

Ligament Reconstruction ◽

Cruciate Ligament ◽

Meta Analysis ◽

Knee Extension ◽

Injured Limb ◽

Reaction Forces ◽

Vertical Ground ◽

Anterior Cruciate ◽

Vertical Ground Reaction Forces ◽

Kinematics And Kinetics

Objective: To evaluate the current evidence concerning kinematic and kinetic strategies adopted during dynamic landing tasks by patients with anterior cruciate ligament reconstruction (ACLR). Data Sources: PubMed, Web of Science. Study Selection: Original research articles that evaluated kinematics or kinetics (or both) during a landing task in those with a history of ACLR were included. Data Extraction: Methodologic quality was assessed using the modified Downs and Black checklist. Means and standard deviations for knee or hip (or both) kinematics and kinetics were used to calculate Cohen d effect sizes and corresponding 95% confidence intervals between the injured limb of ACLR participants and contralateral or healthy matched limbs. Data were further stratified by landing tasks, either double- or single-limb landing. A random-effects–model meta-analysis was used to calculate pooled effect sizes and 95% confidence intervals. Data Synthesis: The involved limbs of ACLR patients demonstrated clinically and significantly lower knee-extension moments during double-legged landing compared with healthy contralateral limbs and healthy control limbs (Cohen d range = −0.81 to −1.23) and decreased vertical ground reaction forces when compared with healthy controls, regardless of task (Cohen d range = −0.39 to −1.75). Conclusions: During single- and double-legged landing tasks, individuals with ACLR demonstrated meaningful reductions in injured-limb knee-extension moments and vertical ground reaction forces. These findings indicate potential unloading of the injured limb after ACLR, which may have significant implications for secondary ACL injury and long-term joint health.

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