Frontal plane ankle stiffness increases with weight-bearing

NewsBot · Jul 24, 2021

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Frontal plane ankle stiffness increases with weight-bearing
MarieMatos et al
Journal of Biomechanics Volume 124, 19 July 2021, 110565

Ankle sprains are among the most common musculoskeletal injuries. They are not isolated innocuous injuries as 30–40% of people who sprain their ankles develop chronic ankle instability. Ankle instability is typically assessed under passive unloaded conditions, ignoring any potential contribution of joint loading or muscle activation to the maintenance of ankle stability. Thus, the relevance of unloaded ankle stability assessments to the evaluation of impairments in chronic ankle instability or the prediction of future ankle sprains is questionable. Ankle impedance, which quantifies the resistance to an imposed rotation, has often been used to quantify ankle stability. However, few studies have investigated impedance in the frontal plane where sprains occur, and none have systematically investigated the effect of weight-bearing on ankle impedance. The objective of this study was to determine whether weight-bearing affects frontal plane ankle impedance. We had subjects systematically alter the weight on the tested ankle, while imposed frontal plane rotations were applied to estimate the impedance. We found that ankle stiffness, the static component of impedance, increased proportionally with the weight on the ankle. This increase in stiffness was due to a combination of the increase loading on the joint and the increase in muscle activation that occurs during weight-bearing. Finally, we found that men had a greater stiffness than women over the majority of the weight-bearing range. These results highlight the importance of clinically assessing ankle stability during weight-bearing conditions to better determine the impairments in chronic ankle instability and identify those at risk for ankle sprains.
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NewsBot · Jun 16, 2022

Comparison of Existing Methods for Characterizing Bi-Linear Natural Ankle Quasi-Stiffness
Luke Nigro , Elisa Arch
J Biomech Eng. 2022 Jun 14

Natural ankle quasi-stiffness (NAS) is a mechanical property of the ankle joint during motion. NAS has been historically calculated as the average slope (linear regression) of the net ankle moment vs. ankle angle during discrete phases of stance. However, recent work has shown that NAS is nonlinear during stance. Specifically, during the loading phase (~10-60% of stance), plantarflexion moment increases at an accelerating rate compared to dorsiflexion angle. Updated models have been developed to better capture this inherent nonlinearity. One type of model is called bi-linear NAS (BL-NAS) divides the loading phase of stance into two sub-phases, called early loading (EL) and late loading (LL) NAS. Two papers, written by Crenna & Frigo in 2011 and Shamaei et al. in 2013, outline different BL-NAS models. Both models fit measured data better (lower RMSE) than standard single linear NAS (SL-NAS) models, but have not been widely adopted, possibly because of methodological discrepancies and lack of applicability to physical devices at the time. This paper compares these existing BL-NAS models and translate those findings to possible orthotic device designs. Results showed that both BL-NAS models had lower RMSE than SL-NAS, EL-NAS was not significantly different across walking speeds, and LL-NAS increased significantly at faster walking speeds. These improved NAS models better approximate natural human movement than commonly used SL-NAS models, and provide a basis to design ankle-foot devices with multiple stiffness properties to emulate and facilitate natural human motion.
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NewsBot · Nov 28, 2023

Reliability and minimal detectable change of stiffness and other mechanical properties of the ankle joint in standing and walking
Luis H. Cubillos et al
Gait & PostureVolume 108, February 2024, Pages 56-62

Background
Ankle joint stiffness and viscosity are fundamental mechanical descriptions that govern the movement of the body and impact an individual’s walking ability. Hence, these internal properties of a joint have been increasingly used to evaluate the effects of pathology (e.g., stroke) and in the design and control of robotic and prosthetic devices. However, the reliability of these measurements is currently unclear, which is important for translation to clinical use.

Research question
Can we reliably measure the mechanical impedance parameters of the ankle while standing and walking?

Methods
Eighteen able-bodied individuals volunteered to be tested on two different days separated by at least 24 h. Participants received several small random ankle dorsiflexion perturbations while standing and during the stance phase of walking using a custom-designed robotic platform. Three-dimensional motion capture cameras and a 6-component force plate were used to quantify ankle joint motions and torque responses during normal and perturbed conditions. Ankle mechanical impedance was quantified by computing participant-specific ensemble averages of changes in ankle angle and torque due to perturbation and fitting a second-order parametric model consisting of stiffness, viscosity, and inertia. The test-retest reliability of each parameter was assessed using intraclass correlation coefficients (ICCs). We also computed the minimal detectable change (MDC) for each impedance parameter to establish the smallest amount of change that falls outside the measurement error of the instrument.

Results
In standing, the reliability of stiffness, viscosity, and inertia was good to excellent (ICCs=0.67–0.91). During walking, the reliability of stiffness and viscosity was good to excellent (ICCs=0.74–0.84) while that of inertia was fair to good (ICCs=0.47–0.68). The MDC for a single subject ranged from 20%− 65% of the measurement mean but was higher (>100%) for inertia during walking.

Significance
Results indicate that dynamic measures of ankle joint impedance were generally reliable and could serve as an adjunct clinical tool for evaluating gait impairments.
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Frontal plane ankle stiffness increases with weight-bearing

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Frontal plane ankle stiffness increases with weight-bearing

NewsBot The Admin that posts the news.

NewsBot The Admin that posts the news.

NewsBot The Admin that posts the news.

Gravity Drive Pronation Linked to Cranial Frontal Plane Distortions

The influence of great toe valgus on pronation and frontal plane knee motion during running

Effect of frontal plane angulation of tibia on rearfoot motion

The Effect of a Prefabricated Foot Orthotic on Frontal Plane Joint Mechanics in Healthy Runners

Frontal plane change at rearfoot in orthoses (shod/unshod?)

Frontal plane compensation?

Frontal plane vs. transverse plane

Share This Page

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