scholarly journals Altered neuromechanical strategies of the paretic hip and knee joints during a step-up task

2020 ◽  
Author(s):  
Vatsala Goyal ◽  
Andrew Dragunas ◽  
Robert L. Askew ◽  
Theresa Sukal-Moulton ◽  
Roberto López-Rosado
Keyword(s):  
Lower Limb ◽  
Fixed Effects ◽  
Sagittal Plane ◽  
Knee Extension ◽  
Mixed Effects ◽  
Chronic Stroke ◽  
Knee Joints ◽  
Uneven Terrain ◽  
Hip Abduction ◽  
Hemiparetic Stroke

AbstractBackgroundStroke often leads to chronic, neural-derived motor impairments in the paretic lower limb, such as weakness, abnormal extensor torque coupling, and reduced ranges of motion. These impairments can constrain lower extremity movement and negatively impact the ability to navigate uneven terrain. Quantification of biomechanical strategies used by individuals with chronic stroke to step up would offer insight into the neural consequences of a stroke.Research QuestionWhat are the altered kinetic and kinematic strategies of the leading paretic hip and knee joints while swinging and pulling-up onto a step?MethodsA total of 10 participants were included in this mixed design study: 5 adults with hemiparetic stroke and 5 age-matched adults without stroke. Participants were instructed to step up onto a 4-inch platform, where joint kinetic and kinematics of the hip in the frontal plane and the hip and knee in the sagittal plane were quantified. A mixed effects linear regression model with two fixed effects of group (stroke and control) and lower limb (LL: dominant/non-paretic and non-dominant/paretic) was used to compare peak joint torques and angles. Another mixed effects model with two fixed effects of peak hip and knee extension torque was used to investigate whether these main effects could predict peak hip abduction torque.ResultsAltered biomechanical strategies of the paretic limb for step ascent included reduced sagittal plane flexion angles during swing, reduced hip abduction and knee extension torque combined with increased hip extension torque during pull-up stance, and abnormal torque coupling between the hip adductors and sagittal plane extensors.SignificanceThese differences can be linked to the neural consequences of a hemiparetic stroke, including corticospinal damage and upregulation of bulbospinal pathways as compensation. Overall, our findings can inform interventions for individuals with chronic stroke in navigating uneven terrain to maximize daily community activity.

scholarly journals Reliability of a New Portable Dynamometer for Assessing Hip and Lower Limb Strength

2021 ◽  
Vol 11 (8) ◽  
pp. 3391
Author(s):  
Jan Marušič ◽  
Goran Marković ◽  
Nejc Šarabon
Keyword(s):  
Lower Limb ◽  
External Rotation ◽  
Peak Torque ◽  
Knee Extension ◽  
Lower Limb Muscles ◽  
Lower Limb Strength ◽  
Flexion Extension ◽  
Strength Tests ◽  
Hip Abduction ◽  
Maximal Peak

The purpose of this study was to evaluate intra- and inter-session reliability of the new, portable, and externally fixated dynamometer called MuscleBoard® for assessing the strength of hip and lower limb muscles. Hip abduction, adduction, flexion, extension, internal and external rotation, knee extension, ankle plantarflexion, and Nordic hamstring exercise strength were measured in three sessions (three sets of three repetitions for each test) on 24 healthy and recreationally active participants. Average and maximal value of normalized peak torque (Nm/kg) from three repetitions in each set and agonist:antagonist ratios (%) were statistically analyzed; the coefficient of variation and intra-class correlation coefficient (ICC2,k) were calculated to assess absolute and relative reliability, respectively. Overall, the results display high to excellent intra- and inter-session reliability with low to acceptable within-individual variation for average and maximal peak torques in all bilateral strength tests, while the reliability of unilateral strength tests was moderate to good. Our findings indicate that using the MuscleBoard® dynamometer can be a reliable device for assessing and monitoring bilateral and certain unilateral hip and lower limb muscle strength, while some unilateral strength tests require some refinement and more extensive familiarization.

An Anthropometrically Parameterized Assistive Lower-limb Exoskeleton

2021 ◽  
Author(s):  
Curt Laubscher ◽  
Ryan Farris ◽  
Antonie van den Bogert ◽  
Jerzy T. Sawicki
Keyword(s):  
Lower Limb ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Mechanical Energy ◽  
Biceps Femoris ◽  
Knee Joints ◽  
Lower Limb Exoskeleton ◽  
Hip Abduction ◽  
The Subject ◽  
Muscle Activations

Abstract This paper presents a newly developed lower-limb exoskeleton tested for walking assistance. The novel exoskeleton design methodology uses additive manufacturing and a parametrized model based on user anthropometrics to give a person-specific custom fit. The process is applied to average children and a healthy adult, and a prototype device is fabricated for the adult to validate the feasibility of the approach. The developed prototype actuates the hip and knee joints without restricting hip abduction-adduction motion. To test usability of the device and evaluate walking assistance, user torque, mechanical energy generated, and muscle activation are analyzed in an assisted condition where the subject walks on a level treadmill with the exoskeleton powered. This is compared to an unassisted condition with the exoskeleton unpowered and a baseline condition with the subject not wearing the exoskeleton. Comparing assisted to baseline conditions, torque magnitudes increased at the hip and knee, mechanical energy generated increased at the hip but decreased at the knee, and muscle activations decreased in the Biceps Femoris and increased in the Vastus Lateralis. The presented preliminary results are inconclusive on whether the newly developed exoskeleton can assist in walking though show promise for basic usability of the device.

scholarly journals Runners Adapt Different Lower-Limb Movement Patterns With Respect to Different Speeds and Downhill Slopes

2021 ◽  
Vol 3 ◽  
Author(s):  
David Sundström ◽  
Markus Kurz ◽  
Glenn Björklund
Keyword(s):  
Lower Limb ◽  
Energy Cost ◽  
Degrees Of Freedom ◽  
Stance Phase ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Movement Pattern ◽  
Knee Extension ◽  
Generic Model ◽  
Energy Cost Of Running

The aim of this study was to investigate the influence of slope and speed on lower-limb kinematics and energy cost of running. Six well-trained runners (VO2max 72 ± 6 mL·kg−1·min−1) were recruited for the study and performed (1) VO2max and energy cost tests and (2) an experimental running protocol at two speeds, 12 km·h−1 and a speed corresponding to 80% of VO2max (V80, 15.8 ± 1.3 km·h−1) on three different slopes (0°, −5°, and −10°), totaling six 5-min workload conditions. The workload conditions were randomly ordered and performed continuously. The tests lasted 30 min in total. All testing was performed on a large treadmill (3 × 5 m) that offered control over both speed and slope. Three-dimensional kinematic data of the right lower limb were captured during the experimental running protocol using eight infrared cameras with a sampling frequency of 150 Hz. Running kinematics were calculated using a lower body model and inverse kinematics approach. The generic model contained three, one, and two degrees of freedom at the hip, knee, and ankle joints, respectively. Oxygen uptake was measured throughout the experimental protocol. Maximum hip extension and flexion during the stance phase increased due to higher speed (p < 0.01 and p < 0.01, respectively). Knee extension at the touchdown and maximal knee flexion in the stance phase both increased on steeper downhill slopes (both p < 0.05). Ground contact time (GCT) decreased as the speed increased (p < 0.01) but was unaffected by slope (p = 0.73). Runners modified their hip movement pattern in the sagittal plane in response to changes in speed, whereas they altered their knee movement pattern during the touchdown and stance phases in response to changes in slope. While energy cost of running was unaffected by speed alone (p = 0.379), a shift in energy cost was observed for different speeds as the downhill gradient increased (p < 0.001). Energy cost was lower at V80 than 12 km·h−1 on a −5° slope but worse on a −10° slope. This indicates that higher speeds are more efficient on moderate downhill slopes (−5°), while lower speeds are more efficient on steeper downhill slopes (−10°).

scholarly journals Lower limb symmetry index (LLSI) pre- and post-reconstruction of the ACL: a controlled study

2020 ◽  
pp. 1-6
Author(s):  
Luma Soares Lustosa ◽  
Nyck Douglas Claro Pereira ◽  
José Jamacy de Almeida Ferreira ◽  
Palloma Rodrigues de Andrade ◽  
Heleodório Honorato dos Santos
Keyword(s):  
Lower Limb ◽  
Knee Extension ◽  
Lower Limbs ◽  
Controlled Study ◽  
Knee Extensors ◽  
Emg Activity ◽  
Symmetry Index ◽  
Limb Symmetry Index ◽  
Treatment Comparison ◽  
Hip Abduction

Background: The anterior cruciate ligament (ACL) lesion causes a deficit in joint stability and mobility, trophism and muscular strength, generating asymmetries between the lower limbs. Objective: To verify the effect of a physiotherapeutic protocol on the Lower Limb Symmetry Index (LLSI) and the correlation between strength and EMGs, pre and post reconstruction of the ACL. Methods: Twenty subjects (10 ACLrg + 10 CONTg) were evaluated regarding isometric force and electrical activity of knee extensors, knee flexors and hip abductors. Results: A significant increase (P<0.01) in knee extension and flexion strength and hip abduction strength were observed both for the affected limb and non-affected limb. Regarding the LLSI, a significant increase was observed for knee extension and hip abduction movements in the pre- and post-treatment comparison, and between ACLrg X CONTg (P<0.01) for the knee extension movement in the pre-reconstruction phase of the ACL. A very strong correlation (r=0.945; P<0.01) was also observed between the LLSI strength X EMGs during knee extension, pre- and post-reconstruction surgery. Conclusions: Six months after reconstruction of the ACL, there was an increase in strength and EMG activity of the knee flexor, knee extensor and hip abductor muscles, leveling the LLSI between ACLrg and the CONTg, however, with a significant correlation between the two variables (strength X EMGs) for only one of the three movements (knee extension).

scholarly journals Different Lower-Limb Setup Positions Do Not Consistently Change Backstroke Start Time to 10 m

Sports ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 43
Author(s):  
Gordon E. Barkwell ◽  
James P. Dickey
Keyword(s):  
Lower Limb ◽  
Knee Flexion ◽  
High Speed ◽  
Sagittal Plane ◽  
Body Position ◽  
Knee Extension ◽  
Knee Extensors ◽  
Start Time ◽  
Performance Impact ◽  
Maximum Effort

Backstroke starts involve the athlete starting from a flexed position with their feet against the pool wall and then extending their ankles, knees, hips and back to push off; however, swimmers can start in different positions. The purpose of this study was to evaluate the performance impact of different knee extension angles in the setup position for a backstroke start. Ten backstroke swimmers completed maximum-effort starts in each of two setup positions: one with the knees maximally flexed, and one with the knees less flexed. The start handles and touchpad were instrumented with multi-axial force sensors. Activity of major hip and knee extensors was measured using surface electromyography. Body position in the sagittal plane was recorded using high-speed cameras. There was no overall difference in time to 10 m between the two conditions (p = 0.36, dz = 0.12), but some participants showed differences as large as 0.12 s in time to 10 m between start conditions. We observed that starts performed from a setup position with less knee flexion had an average 0.07 m greater head entry distance (p = 0.07, dz = 0.53), while starts from a setup position with maximal knee flexion had an average 0.2 m/s greater takeoff velocity (p = 0.02, dz = 0.78). Both head entry distance and takeoff velocity are related to start performance, suggesting each position may optimize different aspects of the backstroke start. Coaches should assess athletes individually to determine which position is optimal.

Developing a Mobile Lower Limb Robotic Exoskeleton for Gait Rehabilitation

2014 ◽  
Vol 8 (4) ◽  
Author(s):  
Zhao Guo ◽  
Haoyong Yu ◽  
Yue H. Yin
Keyword(s):  
Body Weight ◽  
Lower Limb ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Vertical Displacement ◽  
Knee Joints ◽  
Gait Rehabilitation ◽  
Neurologically Impaired ◽  
Robotic Exoskeleton ◽  
Weight Support

A new compact mobile lower limb robotic exoskeleton (MLLRE) has been developed for gait rehabilitation for neurologically impaired patients. This robotic exoskeleton is composed of two exoskeletal orthoses, an active body weight support (BWS) system attached to a motorized mobile base, allowing over-ground walking. The exoskeletal orthosis is optimized to implement the extension and flexion of human hip and knee joints in the sagittal plane. The motor-driven BWS system can actively unload human body weight and track the vertical displacement of the center of mass (COM). This system is compact and easy for therapist to help patient with different weight (up to 100 kg) and height (150–190 cm). Experiments were conducted to evaluate the performance of the robot with a healthy subject. The results show that MLLRE is a useful device for patient to achieve normal over-ground gait patterns.

Biomechanical Performance of Habitually Barefoot and Shod Runners during Barefoot Jogging and Running

2018 ◽  
Vol 38 ◽  
pp. 1-10 ◽  
Author(s):  
Suo Di Xu ◽  
Zhi Qiang Liang ◽  
Yu Wei Liu ◽  
Gusztáv Fekete
Keyword(s):  
Lower Limb ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Three Dimensional ◽  
Frontal Plane ◽  
Influential Factor ◽  
Hip Abduction ◽  
Foot Strike ◽  
Limb Kinematics

The purpose of this study was to evaluate the biomechanical performances, running stability of habitually barefoot (BR) and shod runners (SR) during barefoot jogging and running. Ten healthy male subjects, 5 habitually shod runners and 5 habitually barefoot runners, from two different ethnics participated in this study. Subjects performed jogging (2m/s) and running (4m/s) along a 10-m runway. Three-dimensional lower-limb kinematics, ground reaction force, center of pressure (COP) and contact time (CT), were collected during testing. During jogging and running, all participants adopted rear-foot strike pattern, SR had larger VALR. SR showed significantly larger lower-limb range of motion (ROM) in sagittal plane, significantly larger hip abduction and opposite knee ROM in frontal plane, as well as significantly larger ankle internal rotation in horizontal plane. All participants’ CT showed decreased trend with running speed up; and SR was significantly longer than BR; BR and SR in COP showed different trajectories, especially forefoot and rearfoot areas. Habitually barefoot and shod runner from different ethnics still exist significant differences in lower-extremity ROM; and different foot morphological of participants is an important influential factor for these variations.

scholarly journals Kinematic Analysis of Lower Limb Joint Asymmetry during Gait in People with Multiple Sclerosis

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 598
Author(s):  
Massimiliano Pau ◽  
Bruno Leban ◽  
Michela Deidda ◽  
Federica Putzolu ◽  
Micaela Porta ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Lower Limb ◽  
Sagittal Plane ◽  
Cross Sectional Study ◽  
Camera Motion ◽  
Cross Sectional ◽  
Temporal Parameters ◽  
Wide Range ◽  
Edss Score ◽  
Spatio Temporal

The majority of people with Multiple Sclerosis (pwMS), report lower limb motor dysfunctions, which may relevantly affect postural control, gait and a wide range of activities of daily living. While it is quite common to observe a different impact of the disease on the two limbs (i.e., one of them is more affected), less clear are the effects of such asymmetry on gait performance. The present retrospective cross-sectional study aimed to characterize the magnitude of interlimb asymmetry in pwMS, particularly as regards the joint kinematics, using parameters derived from angle-angle diagrams. To this end, we analyzed gait patterns of 101 pwMS (55 women, 46 men, mean age 46.3, average Expanded Disability Status Scale (EDSS) score 3.5, range 1–6.5) and 81 unaffected individuals age- and sex-matched who underwent 3D computerized gait analysis carried out using an eight-camera motion capture system. Spatio-temporal parameters and kinematics in the sagittal plane at hip, knee and ankle joints were considered for the analysis. The angular trends of left and right sides were processed to build synchronized angle–angle diagrams (cyclograms) for each joint, and symmetry was assessed by computing several geometrical features such as area, orientation and Trend Symmetry. Based on cyclogram orientation and Trend Symmetry, the results show that pwMS exhibit significantly greater asymmetry in all three joints with respect to unaffected individuals. In particular, orientation values were as follows: 5.1 of pwMS vs. 1.6 of unaffected individuals at hip joint, 7.0 vs. 1.5 at knee and 6.4 vs. 3.0 at ankle (p < 0.001 in all cases), while for Trend Symmetry we obtained at hip 1.7 of pwMS vs. 0.3 of unaffected individuals, 4.2 vs. 0.5 at knee and 8.5 vs. 1.5 at ankle (p < 0.001 in all cases). Moreover, the same parameters were sensitive enough to discriminate individuals of different disability levels. With few exceptions, all the calculated symmetry parameters were found significantly correlated with the main spatio-temporal parameters of gait and the EDSS score. In particular, large correlations were detected between Trend Symmetry and gait speed (with rho values in the range of –0.58 to –0.63 depending on the considered joint, p < 0.001) and between Trend Symmetry and EDSS score (rho = 0.62 to 0.69, p < 0.001). Such results suggest not only that MS is associated with significantly marked interlimb asymmetry during gait but also that such asymmetry worsens as the disease progresses and that it has a relevant impact on gait performances.

Association of infrapopliteal medial arterial calcification with lower-limb amputations in high-risk patients: A systematic review and meta-analysis

2020 ◽  
pp. 1358863X2097973
Author(s):  
Fabrizio Losurdo ◽  
Roberto Ferraresi ◽  
Alessandro Ucci ◽  
Anna Zanetti ◽  
Giacomo Clerici ◽  
...  
Keyword(s):  
Risk Factor ◽  
High Risk ◽  
Lower Limb ◽  
Fixed Effects ◽  
Meta Analysis ◽  
Arterial Calcification ◽  
High Risk Patients ◽  
Patients With Diabetes ◽  
Risk Patients ◽  
Medial Arterial Calcification

Medial arterial calcification (MAC) is a known risk factor for cardiovascular morbidity. The association between vascular calcifications and poor outcome in several vascular districts suggest that infrapopliteal MAC could be a risk factor for lower-limb amputation (LLA). This study’s objective is to review the available literature focusing on the association between infrapopliteal MAC and LLA in high-risk patients. The PubMed and Embase databases were systematically searched. We selected original studies reporting the association between infrapopliteal MAC and LLAs in patients with diabetes and/or peripheral artery disease (PAD). Estimates were pooled using either a fixed-effects or a random-effects model meta-analysis. Heterogeneity was evaluated using the Q and I2 statistics. Publication bias was investigated with a funnel plot and Egger test. The trim-and-fill method was designed to estimate the possibly missing studies. Influence analysis was conducted to search studies influencing the final result. Test of moderators was used to compare estimates in good versus non-good-quality studies. Fifteen articles satisfied the selection criteria ( n = 6489; median follow-up: 36 months). MAC was significantly associated with LLAs (pooled adjusted risk ratio (RR): 2.27; 95% CI: 1.89–2.74; I2 = 25.3%, Q-test: p = 0.17). This association was kept in the subgroup of patients with diabetes (RR: 2.37; 95% CI: 1.76–3.20) and patients with PAD (RR: 2.48; 95% CI: 1.72–3.58). The association was maintained if considering as outcome only major amputations (RR: 2.11; 95% CI: 1.46–3.06). Our results show that infrapopliteal MAC is associated with LLAs, thus suggesting MAC as a possible new marker of the at-risk limb.

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