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Cubillos LH, Rouse EJ, Augenstein TE, Joshi V, Claflin ES, Krishnan C. Reliability and minimal detectable change of stiffness and other mechanical properties of the ankle joint in standing and walking. Gait Posture 2024; 108:56-62. [PMID: 37988887 PMCID: PMC10854263 DOI: 10.1016/j.gaitpost.2023.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 11/09/2023] [Accepted: 11/13/2023] [Indexed: 11/23/2023]
Abstract
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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Affiliation(s)
- Luis H Cubillos
- Department of Physical Medicine and Rehabilitation, Michigan Medicine, Ann Arbor, MI, USA; Robotics Department, University of Michigan, Ann Arbor, MI, USA
| | - Elliott J Rouse
- Robotics Department, University of Michigan, Ann Arbor, MI, USA; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Thomas E Augenstein
- Department of Physical Medicine and Rehabilitation, Michigan Medicine, Ann Arbor, MI, USA; Robotics Department, University of Michigan, Ann Arbor, MI, USA
| | - Varun Joshi
- Department of Physical Medicine and Rehabilitation, Michigan Medicine, Ann Arbor, MI, USA; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA; School of Kinesiology, University of Michigan, Ann Arbor, MI, USA
| | - Edward S Claflin
- Department of Physical Medicine and Rehabilitation, Michigan Medicine, Ann Arbor, MI, USA
| | - Chandramouli Krishnan
- Department of Physical Medicine and Rehabilitation, Michigan Medicine, Ann Arbor, MI, USA; Robotics Department, University of Michigan, Ann Arbor, MI, USA; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA; School of Kinesiology, University of Michigan, Ann Arbor, MI, USA; Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Department of Physical Therapy, University of Michigan-Flint, Flint, MI, USA.
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Short MR, Ludvig D, Kucuktabak EB, Wen Y, Vianello L, Perreault EJ, Hargrove L, Lynch K, Pons JL. Haptic Human-Human Interaction During an Ankle Tracking Task: Effects of Virtual Connection Stiffness. IEEE Trans Neural Syst Rehabil Eng 2023; 31:3864-3873. [PMID: 37747854 DOI: 10.1109/tnsre.2023.3319291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
While treating sensorimotor impairments, a therapist may provide physical assistance by guiding their patient's limb to teach a desired movement. In this scenario, a key aspect is the compliance of the interaction, as the therapist can provide subtle cues or impose a movement as demonstration. One approach to studying these interactions involves haptically connecting two individuals through robotic interfaces. Upper-limb studies have shown that pairs of connected individuals estimate one another's goals during tracking tasks by exchanging haptic information, resulting in improved performance dependent on the ability of one's partner and the stiffness of the virtual connection. In this study, our goal was to investigate whether these findings generalize to the lower limb during an ankle tracking task. Pairs of healthy participants (i.e., dyads) independently tracked target trajectories with and without connections rendered between two ankle robots. We tested the effects of connection stiffness as well as visual noise to manipulate the correlation of tracking errors between partners. In our analysis, we compared changes in task performance across conditions while tracking with and without the connection. We found that tracking improvements while connected increased with connection stiffness, favoring the worse partner in the dyad during hard connections. We modeled the interaction as three springs in series, considering the stiffness of the connection and each partners' ankle, to show that improvements were likely due to a cancellation of random tracking errors between partners. These results suggest a simplified mechanism of improvements compared to what has been reported during upper-limb dyadic tracking.
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Jeong H, Haghighat P, Kantharaju P, Jacobson M, Jeong H, Kim M. Muscle coordination and recruitment during squat assistance using a robotic ankle-foot exoskeleton. Sci Rep 2023; 13:1363. [PMID: 36693935 PMCID: PMC9873637 DOI: 10.1038/s41598-023-28229-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 01/16/2023] [Indexed: 01/26/2023] Open
Abstract
Squatting is an intensive activity routinely performed in the workplace to lift and lower loads. The effort to perform a squat can decrease using an exoskeleton that considers individual worker's differences and assists them with a customized solution, namely, personalized assistance. Designing such an exoskeleton could be improved by understanding how the user's muscle activity changes when assistance is provided. This study investigated the change in the muscle recruitment and activation pattern when personalized assistance was provided. The personalized assistance was provided by an ankle-foot exoskeleton during squatting and we compared its effect with that of the no-device and unpowered exoskeleton conditions using previously collected data. We identified four main muscle recruitment strategies across ten participants. One of the strategies mainly used quadriceps muscles, and the activation level corresponding to the strategy was reduced under exoskeleton assistance compared to the no-device and unpowered conditions. These quadriceps dominant synergy and rectus femoris activations showed reasonable correlations (r = 0.65, 0.59) to the metabolic cost of squatting. These results indicate that the assistance helped reduce quadriceps activation, and thus, the metabolic cost of squatting. These outcomes suggest that the muscle recruitment and activation patterns could be used to design an exoskeleton and training methods.
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Affiliation(s)
- Hyeongkeun Jeong
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Parian Haghighat
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Prakyath Kantharaju
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Michael Jacobson
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Heejin Jeong
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA.,Ira A. Fulton Schools of Engineering, Arizona State University, Arizona, Mesa, AZ, 85212, USA
| | - Myunghee Kim
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, 60607, USA.
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Krishnan C, Johnson AK, Palmieri-Smith RM. Mechanical Factors Contributing to Altered Knee Extension Moment during Gait after ACL Reconstruction: A Longitudinal Analysis. Med Sci Sports Exerc 2022; 54:2208-2215. [PMID: 35941516 PMCID: PMC9669176 DOI: 10.1249/mss.0000000000003014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study aimed to comprehensively examine the extent to which knee flexion angle at initial contact, peak knee flexion angle, and vertical ground reaction force (vGRF) contribute to knee extension moments during gait in individuals with anterior cruciate ligament (ACL) reconstruction. METHODS Overground gait biomechanics were evaluated in 26 participants with ACL reconstruction at three time points (about 2, 4, and 6 months after the surgery). Knee flexion angle at initial contact, peak knee flexion angle, peak vGRF, and peak knee extension moment were calculated for each limb during the early stance phase of gait for all three time points. A change score from baseline (time point 2 - time point 1 and time point 3 - time point 1) along with limb symmetry values (ACL - non-ACL limb values) was also calculated for these variables. Multiple linear regressions utilizing classical and Bayesian interference methods were used to determine the contribution of knee flexion angle and vGRF to knee extension moment during gait. RESULTS Peak knee flexion angle and peak vGRF positively contributed to knee extension moment during gait in both the reconstructed ( R2 = 0.767, P < 0.001) and nonreconstructed limbs ( R2 = 0.815, P < 0.001). Similar results were observed for the symmetry values ( R2 = 0.673, P < 0.001) and change scores ( R2 = 0.731-0.883; all P < 0.001), except that the changes in knee flexion angle at initial contact also contributed to the model using the change scores in the nonreconstructed limb (time point 2 - time point 1: R2 = 0.844, P < 0.001; time point 3 - time point 1: R2 = 0.883, P < 0.001). Bayesian regression evaluating the likelihood of these prediction models showed that there was decisive evidence favoring the alternative model over the null model (all Bayes factors >1000). Standardized β coefficients indicated that changes in knee flexion angle had a greater impact (>2×) on knee extension moments than vGRF at both time points in both limbs ( βvGRF = 0.204-0.309; βkneeflexion = 0.703-0.831). CONCLUSIONS The findings indicate that both knee flexion angle and peak vGRF positively contribute to altered knee extension moments during gait, but the contribution of knee flexion angle is much greater than vGRF. Therefore, treatment strategies targeting these variables may improve knee loading after ACL reconstruction.
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Affiliation(s)
- Chandramouli Krishnan
- Physical Medicine and Rehabilitation, Michigan Medicine, Ann Arbor, MI
- School of Kinesiology, University of Michigan, Ann Arbor, MI
- Robotics Institute, University of Michigan, Ann Arbor, MI
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI
- Physical Therapy Department, College of Health Sciences, University of Michigan-Flint, Flint, MI
| | | | - Riann M. Palmieri-Smith
- School of Kinesiology, University of Michigan, Ann Arbor, MI
- Department of Orthopedic Surgery, University of Michigan, Ann Arbor, MI
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Nalam V, Bliss C, Russell JB, Save O, Lee H. Understanding Modulation of Ankle Stiffness During Stance Phase of Walking on Different Ground Surfaces. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3191055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Varun Nalam
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Clayton Bliss
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Joshua B. Russell
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Omik Save
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Hyunglae Lee
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
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Foot contact forces can be used to personalize a wearable robot during human walking. Sci Rep 2022; 12:10947. [PMID: 35768457 PMCID: PMC9243054 DOI: 10.1038/s41598-022-14776-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/13/2022] [Indexed: 11/09/2022] Open
Abstract
Individuals with below-knee amputation (BKA) experience increased physical effort when walking, and the use of a robotic ankle-foot prosthesis (AFP) can reduce such effort. The walking effort could be further reduced if the robot is personalized to the wearer using human-in-the-loop (HIL) optimization of wearable robot parameters. The conventional physiological measurement, however, requires a long estimation time, hampering real-time optimization due to the limited experimental time budget. This study hypothesized that a function of foot contact force, the symmetric foot force-time integral (FFTI), could be used as a cost function for HIL optimization to rapidly estimate the physical effort of walking. We found that the new cost function presents a reasonable correlation with measured metabolic cost. When we employed the new cost function in HIL ankle-foot prosthesis stiffness parameter optimization, 8 individuals with simulated amputation reduced their metabolic cost of walking, greater than 15% (p < 0.02), compared to the weight-based and control-off conditions. The symmetry cost using the FFTI percentage was lower for the optimal condition, compared to all other conditions (p < 0.05). This study suggests that foot force-time integral symmetry using foot pressure sensors can be used as a cost function when optimizing a wearable robot parameter.
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