Quantifying stair gait stability and plantar pressure in an aging community, with modifications to insoles and lighting

Introduction: Stair gait is an activity performed daily. Inherently falls during stair gait continue to be a concern especially for older adults 65 years +. Recently falls have become the most common cause of injury-related deaths in individuals over the age of 75 y.o. Stair descent falls account for 75% of stair falls and also present a greater injury severity. Poor shoes or insoles and lighting condition can contribute to an increased risk of falls during stair locomotion. Stability can be measured using the COM-BOS ‘stability margin’ relationship. Center of pressure (COP), another stability measure,can be calculated from a multi-axis force-plate system. As well, plantar pressure is an important indicator of gait pattern efficiency. Aim: To identify aspects of stair gait that increase the risk of falls. By measuring the COM-BOS ‘stability margin’, the COP and plantar pressure patterns of individuals during stair gait, while modifying insoles and lighting. Methods: Young and older adults will ascend and descend a 4 level staircase, with two imbedded AMTI-force platforms in varying lighting condition (low, normal). Participants will be fitted with standardized footwear with Medi-logic insoles placed under varying hardnesses of insoles. An Optotrak motion capture system will record 12 IRED markers placed on the individual to determine the COM trajectory and BOS of location. Hypothesis: Partipants should demonstrate a greater lateral displacement in the single support phase during dim lighting as opposed to normal lighting. The stability of older adults will be compromised with alteration to the insoles (soft and hard).

Listed In: Biomechanics, Gait, Other

Task-Invariant Learning of Continuous Joint Kinematics during Steady-State and Transient Ambulation Using Ultrasound Sensing

Natural control of limb motion is continuous and progressively adaptive to individual intent. While intuitive interfaces have the potential to rely on the neuromuscular input by the user for continuous adaptation, continuous volitional control of assistive devices that can generalize across various tasks has not been addressed. In this study, we propose a method to use spatiotemporal ultrasound features of the rectus femoris and vastus intermedius muscles of able-bodied individuals for task-invariant learning of continuous knee kinematics during steady-state and transient ambulation. The task-invariant learning paradigm was statistically evaluated against a task-specific paradigm for the steady-state (1) level-walk, (2) incline, (3) decline, (4) stair ascent, and (5) stair descent ambulation tasks. The transitions between steady-state stair ambulation and level-ground walking were also investigated. It was observed that the continuous knee kinematics can be learned using a task-invariant learning paradigm with statistically comparable accuracy to a task-specific paradigm. Statistical analysis further revealed that incorporating the temporal ultrasound features significantly improves the accuracy of continuous estimations (p < 0.05). The average root mean square errors (RMSEs) of knee angle and angular velocity estimation were 7.06° and 53.1°/sec, respectively, for the task-invariant learning compared to 6.00° and 51.8°/sec for the task-specific models. High accuracy of continuous task-invariant paradigms overcome the barrier of task-specific control schemes and motivate the implementation of direct volitional control of lower-limb assistive devices using ultrasound sensing, which may eventually enhance the intuitiveness and functionality of these devices towards a "free form" control approach.
Listed In: Biomechanical Engineering, Gait

Changes in Gait Biomechanics Between Level and Downhill Walking Do Not Differ Between Those With Anterior Cruciate Ligament Reconstruction and Controls

Conflicting evidence exists regarding the presence of aberrant gait biomechanics more than one-year following anterior cruciate ligament reconstruction (ACLR). Overground walking may not elucidate differences in those further removed from surgery due to the unexacting nature of the task. Quadriceps dysfunction is common post-ACLR and contributes to aberrant gait biomechanics, thus downhill walking may exacerbate differences as this task places greater demands on the quadriceps. Purpose: To compare gait biomechanics between individuals with ACLR and healthy controls during level and downhill walking conditions. Methods: 24 individuals more than 1-year removed from ACLR and 24 healthy controls completed both level and downhill (10 degree grade) gait biomechanics assessments on an instrumented split-belt treadmill at their preferred walking speed. Peak variables were evaluated over the first 50% of stance including the vertical ground reaction force, internal knee extension and abduction moments and knee flexion angle. Moments were normalized to %body weight*height (%BW*Ht) and vGRF was normalized to %body weight. Dependent variables were compared across groups and conditions via two-way repeated measures ANCOVAs controlling for gait speed. Results: There were no significant condition*group interaction effects nor group main effects for any outcomes. However, there were significant condition increases in knee extension moment (P=0.020) and knee flexion angle (P=0.018) from level to downhill. Conclusions: Downhill walking necessitates larger knee extension moments and knee flexion angle compared to level gait. Our results suggest that changes in gait biomechanics between level and downhill conditions do not differ between individuals with ACLR >1 year post-reconstruction and controls.
Listed In: Biomechanics, Gait, Orthopedic Research

Musculoskeletal Modeling as a Tool for Biomechanical Analysis of Normal and Pathological Gait

In this work, a 3D lower limb musculoskeletal model and simulation of multiple sclerosis disease is presented. The Model was developed using the Musculoskeletal Modeling Software (MSMS), MSMS has the advantage that the model can be exported directly to Simulink allowing us to generate Functional Electrical Stimulation (FES) and evaluate different injuries. From the simulations, is possible to obtain the joint range of motion, joint torque, muscle-tendon length, force and moment arm, this is important not only to perform biomechanical analysis but also to design exoskeleton robots for rehabilitation and to generate reference trajectories for control purposes. In order to validate the results, a study case of a normal and pathological gait is presented, then, the results are compared with the literature and with real data obtained from a low cost, and a professional gait capture system.
Listed In: Biomechanical Engineering, Biomechanics, Gait

The Influence of Body Mass Index and Sex on Frontal and Sagittal Plane Joint Moments During Walking.

Obesity and female sex are considered independent risk factors for the development of knee osteoarthritis (KOA) which may be due to aberrant gait biomechanics. Few data exist on the interaction of obesity and female sex despite their independent influence on KOA risk. The purpose of this study was to examine the influence of sex and BMI on knee joint sagittal and frontal plane gait mechanics. Dependent variables included the knee flexion moment (KFM) and first peak knee adduction moment (KAM1). Gait biomechanics were assessed in 42 obese and 39 normal weight participants that were matched on age and sex. Kinematic and kinetic data were sampled using a 9-camera Qualisys system and 2 AMTI force-plates. Participants completed walking trials in laboratory standard neutral-cushion footwear at self-selected speed and the external KFM and KAM1 during the first 50% of stance was extracted and normalized to a product of bodyweight (N) and height (m). A 2 (BMI) by 2 (Sex) analysis of co-variance (α=0.05) was used to examine dependent variables with gait speed as a covariate. The BMI by sex interaction was not significant for KFM (p=0.073) or KAM1 (p=0.703). A main effect was observed for sex and females exhibited smaller KFM (p=0.05) and greater KAM1 (p=0.004) compared to males. No differences were found in normalized knee moments between BMI groups. Regardless of BMI, females exhibited aberrant gait mechanics that are indicative of KOA progression. Further studies are needed examining the influence of altered gait in young, healthy females on knee cartilage morphology.
Listed In: Biomechanics, Gait

Sudden Ankle Inversion Perturbation During Walking Alters Gait Kinematics in Chronic Ankle Instability Patients.

Context: Individuals with chronic ankle instability (CAI) have demonstrated altered lower-extremity joint kinematics during walking. The purpose of this study was to examine feedback control of gait kinematics following repeated sudden ankle inversion perturbation during walking in CAI patients relative to matched controls. Methods: Twenty-one CAI patients, 21 matched controls participated. Subjects performed five walking trials at a preferred speed both before and after 10 sudden ankle inversion perturbations during walking while 3D joint kinematic data were collected using high-speed video and in-ground force plate. Main outcome measures were ankle- (sagittal and frontal planes), knee- (sagittal plane), and hip-angles (sagittal and frontal planes) from heel-strike to toe-off. Spatial trajectories of 44 markers were smoothed using a digital filter. Functional analysis was used to detect mean differences. Results: CAI group demonstrated (i) less ankle dorsiflexion, (ii) more ankle eversion, (iii) less knee flexion, (iv) less hip flexion, and (v) more adduction during walking trails, compared to the control group. The 10 sudden ankle inversion perturbations resulted in more ankle dorsiflexion only in the CAI group. However, both the CAI and control groups demonstrated no differences in frontal ankle, sagittal knee and sagittal and frontal hip kinematics between pre- and post-intervention measurements. Conclusions: Sudden ankle inversion perturbations did not affect gait kinematics in both CAI and control groups except sagittal ankle kinematics in the CAI group. Increased ankle dorsiflexion after inversion perturbation in the CAI group may be the result of a change in motor control to avoid self-perceived vulnerable positions of the foot during walking.
Listed In: Biomechanics, Gait

Gait as a Potential Marker of Cognitive Decrements in Type 2 Diabetes (T2DM): Early Results from the ENBIND Study

Background and Aim: Type 2 Diabetes (T2DM) in midlife represents a potent risk factor for the development of dementia in later life. Early indicators to highlight particular individuals with T2DM who are at risk of cognitive decline are lacking. Subtle abnormalities in gait (and particularly dual-task gait with a cognitive task) have emerged as a potential predictor of cognitive decline in older adults, but have not been investigated in patients with T2DM. The ENBIND Study (Exploring Novel Biomarkers of Brain health IN Diabetes) aims to assess patients with T2DM in midlife without cognitive impairment and follow participants over the course of several years to establish early predictors of cognitive decline in this poorly characterised yet high-risk group. Methods: Patients with midlife T2DM (40-65 yrs) were recruited at the time of their diabetic clinic appointment. Patients were excluded if they had a diagnosis of peripheral neuropathy, peripheral vascular disease, musculoskeletal disease, previous stroke, any form of diagnosed cognitive impairment or diabetic retinopathy/nephropathy. Patients underwent medical/diabetes assessment and examination by a physician. Cognition was screened using the Montreal Cognitive Assessment (MoCA) and assessed using a computerised cognitive battery designed for prodromal Alzheimer's Disease (CANTAB®). Gait was then assessed using both a raw clinical measure (stopwatch) and Shimmer® Inertial Measurement Units (IMUs) across four tasks: (i) 30 metre walk at a normal pace (turn at 15m), (ii) 30 metre fast walk (turn at 15m) (iii) dual cognitive-gait task (reciting alternate letters of the alphabet) and (iv) a long walk at a self-selected pace. Between group differences were assessed using t-tests and appropriate non-parametric equivalents Results: 20 participants with T2DM (52.05 yrs ± 2.13) and 10 matched healthy volunteers (mean age 52.2 yrs ± 2.74) were recruited. T2DM was associated with a significantly lower score on the MoCA (29.2 vs 27.6; p=0.0452). Participants with T2DM had slower but non-significant self-selected (0.87 ms-1 vs 0.8ms-1) and fast gait speed (0.66 ms-1 vs 0.59 ms-1). On the dual-cognitive task, participants with T2DM made more errors (1.1 vs 0.6), and had higher dual-task cost (9.17% vs 2.7%, p=0.014). Dual-task cost (the percentage decrement in walking speed due to introduction of the cognitive task) was significantly correlated with total MoCA score (R2 = 0.17, p =0.031). Discussion: Otherwise healthy participants with midlife T2DM display significantly poorer scores on MoCA. Performance on the dual-cognitive gait task was significantly correlated with MoCA score. Our study adds evidence to the presence of cognitive decrements in midlife T2DM, in-keeping with its role as a potent risk factor for the later development of dementia. We provide early data to support the utility of simple clinical gait analysis, particularly where a dual-cognitive paradigm is employed. Expansion of the sample size of patients in this study as well as longitudinal follow up should afford more detailed insight into using gait as a potential marker for cognition in this high risk cohort
Listed In: Biomechanical Engineering, Biomechanics, Gait, Neuroscience

Walking Biomechanics of Persons with Diabetes - A 3D Gait Analysis approach

Gait is influenced by peripheral circulation and neuro musculoskeletal system which can be affected by diabetes. Gait variations play an important role in increasing the peak plantar pressure in persons with diabetes. Biomechanical alterations in diabetic neuropathy could facilitate foot injuries, thus contributing to foot ulceration [1]. Understanding the gait characteristics in different category of diabetic population during walking can reveal the biomechanical factors which may collectively lead to foot pathology. 3-Dimensional (3D) Gait analysis was performed on 28 subjects with similar age, height, weight and Body Mass Index (BMI) (p > 0.05) with diabetes and without neuropathy (D), persons with diabetic neuropathy (DN) and persons who had a history of foot ulcer (DHU). Spatial and Temporal gait parameters along with kinematics and kinetics were compared between the three groups. The lower extremity gait data shows that DHU subjects show increased hip flexion throughout the gait cycle with delay in peak extension and DN subjects showing a slight delay in achieving peak hip extension. DHU show a significant deviation in hip, knee and ankle mechanics when compared to other two groups. There is a slight increase in dorsiflexion among diabetic subjects during the mid - stance phase. The ground reaction force (GRF) graphs shows that the breaking force and propelling force is less in magnitude for all the three groups when compared to normal. The vertical GRF data reveals there is no significant difference among the three groups but the graph shows delayed heel rocker during the gait. The compensation gait observed in DHU group may be due to the muscle weakness acquired in the past when there was active foot ulcer. This altered compensatory gait observed in DHU participants need to be addressed using proper corrective footwear and gait training sessions for preventing recurrence of ulcer. References [1] Katoulis EC, Ebdon-Parry M, Lanshammar H, Vileikyte L, Kulkarni J, Boulton AJM. Gait Abnormalities in Diabetic Neuropathy. Diabetes Care. 1997 Dec; 20(12): 1904-1907. Acknowledgements 1. M. V. Hospital for Diabetes, Royapuram, Chennai 2. CSIR – Central Leather Research Institute and Department of Science and Technology, India
Listed In: Gait

Kinetics and kinematics of the lower extremity during performance of two typical Tai Chi movements by the elders

Tai Chi (TC) has the rehabilitative potential to prevent falls in the elderly, however it is unclear how TC training improves postural control capacity. Fifteen male participants with more than 4 years of TC experience were asked to perform two TC movements, the “Repulse Monkey (RM)” and “Wave-hands in clouds (WHIC).” Three-dimensional (3-D) temporospatial, kinematic and kinetic data was collected using VICON motion analysis system with 10 infrared cameras and 4 force plates. Stride width, step length, step width, single- and double-support times, center of mass (COM) displacement, peak joint angles, range of motion, peak joint moments, time to peak moment, and ground reaction force (GRF) were analyzed. The differences in the measurements of the two TC movements were compared with walking using two-way ANOVA analysis. Compared with walking kinematics, both TC movements spent less time in single-support; RM and WHIC had larger mediolateral and vertical displacement of the COM. Compared with walking kinetics, both TC movements generated significantly smaller peak ground reaction forces in all directions, except the anterior; larger hip extension, adduction and internal rotational moments, knee adduction/abduction and internal rotation moments and eversion/inversion and external/internal moments of ankle–foot; and longer peak moment generation time for hip extension, adduction and internal rotation, knee extension and ankle dorsiflexion and inversion. The slow, gentle stepping-action and loading patterns that are consistent with the mechanical behavior of biological tissues. These two TC movements would be suitable training to help strengthen the lower extremities and prevent falls in the elderly.
Listed In: Biomechanics, Gait, Sports Science

Gait variability in patients with COPD during a self-paced 6-minute walk test

Patients with chronic obstructive pulmonary disease (COPD) have an increased fall risk [1] and demonstrate gait deficits [2,3]. Gait variability has been associated with increased fall risk in the aging population [4]. However, studies reporting gait variability in COPD are scarce. Therefore, we aim to assess gait variability in patients with COPD during the 6-minute walk test (6MWT). Eighty patients with COPD (62±7yrs; FEV1:56±19%pred.) and 39 healthy subjects (62±6yrs; FEV1:119±17%pred.) performed two self-paced 6MWTs while kinematic parameters were recorded (100Hz, Vicon). The amount (coefficient of variation; CoV) and structure (sample entropy; SE) of variability of stride time, stride length and step width, and local divergence exponent (LDE) of the centre of mass velocity (CoMv) in three directions were computed. The sub-analysis accounted for gait speed influences on gait variability between groups. Stride time was longer (MD:0.13s, p<0.001) and stride length was smaller (MD:-0.30 m, p<0.001) in COPD. CoV for stride length was increased (MD:1.8%, p<0.001) and stride length SE was lower in COPD (MD:0.21, p<0.001). LDE for CoMv differed in vertical (MD: -0.12, p=0.001) and anteroposterior direction (MD: 0.10, p=0.017). The CoV for stride length remained higher in COPD (MD:1.0%, p=0.003) and stride length SE remained lower in COPD (MD:-0.12, p=0.011), after the sub-analysis of 14 patients with COPD and 14 healthy subjects with comparable walking speeds (MD:-0.02m/s, p=0.588). Patients with COPD demonstrate alterations in the amount and structure of variability in stride length, indicating alterations in the control of stride length variability patterns.
Listed In: Biomechanics, Gait