The influence of different force and pressure measuring transducers on lower extremity kinematics measured during walking

The examination of synchronous three dimensional (3-D) kinetics and kinematics of walking in laboratory based analyses typically requires participants/patients to make foot contact with a force or pressure measuring device. However it has been proposed that this may lead to targeting whereby participants modify their natural gait pattern in order to ensure contact with the device. This study aimed to determine the extent to which an embedded force plate (EFP) and two different pressure mats PMs affect natural gait kinematics. Male participants (n=12, age 24.23 SD 4.22 y, height 1.74m SD 0.10, mass 75.78 SD 6.90kg) walked at a velocity of 1.25 m.s-1 along a 22m walkway in four different conditions. 1. EFP, 2. FootScan (FS) PM, 3.Matscan (MS) PM, 4.No device (ND). 3-D angular kinematic parameters were collected using an eight camera motion analysis system.Differences in kinematics were examined using repeated measures ANOVAs. Significant differences were observed in hip abduction, knee flexion/extension and knee abduction between various conditions and may warrant consideration in future research. No significant differences were reported at the ankle joint in any conditions. Comparing the PMs no significant differences were observed, however significant differences between the MS and the EFP and ND conditions were identified. The research supports the efficacy of collecting gait kinematics at the ankle joint and in most variables measured at the knee and hip joints

Doctor of Philosophy

dissertationRailroad workers experience a unique exposure to walking on ballast and uneven ground walking is a possible risk factor for knee osteoarthritis. However, the effect of ballast on workers is still not clear, especially for mechanical joint loads. Published research on walking on ballast principally examines temporal gait parameters and joint kinematics. The aim of this research is to investigate the change of knee contact force (KCF) during walking on ballast as surface condition, surface configuration, and uphill or downhill limbs by using an new OpenSim model. There are two significant contributions of this research. First, a new OpenSim gait model with robust knee structures was developed, which included patella structures, a six degrees of freedom knee joint, and four main knee ligaments. Second, KCF was investigated when walking on ballast. Temporal gait parameters were found to be different between uphill and downhill limbs. A trend was observed that the second peak KCF decreased in ballast conditions compared with no ballast. The timing of the first peak KCF was different among no ballast, main ballast and walking ballast. Knee muscle cocontraction was higher in walking ballast compared with no ballast in both peak KCFs. Knee muscle cocontraction was also higher for the uphill limb than the downhill limb. Lateral collateral ligament force was larger and medial collateral ligament force was smaller for the downhill limb compared with the uphill limb in both peak KCFs. The effect of surface configuration was significant for some ligament bundles, including iv anterior cruciate ligament and medial collateral ligament in the first peak KCF, and lateral collateral ligament in the second peak KCF. There are two additional findings in this research. First, the ankle kinematics was found to be sensitive to toe marker placement error and muscle forces responded the residual variance of joint kinematics in various degrees based on the muscle function. Second, a method to combine ground reaction data from different trials was described, which can successfully simulate the gait cycle and obtain the results of joint moments and muscle forces in a certain acceptable range

The test-retest reliability of different ankle joint center location techniques

Accurate and reliable joint identification is imperative for the collection of meaningful kinetic and kinematic data. Of the lower kinetic chain both the hip and knee joints have received a considerable amount of attention in 3D modelling. However, the reliability of methods to define the ankle joint center have received very little attention. This study investigated the reliability of the two marker method (TMM) and the functional ankle method (FAM) on estimating the ankle joint center. Furthermore, the effects of the two-marker method reliability for defining the ankle joint center when the ankle was covered with a brace or protector was investigated. 3D kinematic data was collected from ten participants (8 female and 2 male) whilst walking. The ankle joint center was defined twice using each test condition; TMM (WITHOUT), FAM (FUNCTIONAL), TMM when the ankle was covered with a brace (BRACE), and TMM when the ankle was covered with a protector (PROTECTOR). Intraclass correlations (ICC) were utilised to compare test and retest waveforms and paired samples t-tests were used to compare angular parameters. Significant differences were found in the test-retest angular parameters in the transverse and sagittal planes for the WITHOUT, BRACE, and FUNCTIONAL conditions. The strongest test-retest ICC’s were observed in the WITHOUT and PROTECTOR conditions. The findings of the current investigation indicate that there are fewer errors using the TMM when the ankle is uncovered or when covered with soft foam that is easy to palpate through

Push recovery with stepping strategy based on time-projection control

In this paper, we present a simple control framework for on-line push recovery with dynamic stepping properties. Due to relatively heavy legs in our robot, we need to take swing dynamics into account and thus use a linear model called 3LP which is composed of three pendulums to simulate swing and torso dynamics. Based on 3LP equations, we formulate discrete LQR controllers and use a particular time-projection method to adjust the next footstep location on-line during the motion continuously. This adjustment, which is found based on both pelvis and swing foot tracking errors, naturally takes the swing dynamics into account. Suggested adjustments are added to the Cartesian 3LP gaits and converted to joint-space trajectories through inverse kinematics. Fixed and adaptive foot lift strategies also ensure enough ground clearance in perturbed walking conditions. The proposed structure is robust, yet uses very simple state estimation and basic position tracking. We rely on the physical series elastic actuators to absorb impacts while introducing simple laws to compensate their tracking bias. Extensive experiments demonstrate the functionality of different control blocks and prove the effectiveness of time-projection in extreme push recovery scenarios. We also show self-produced and emergent walking gaits when the robot is subject to continuous dragging forces. These gaits feature dynamic walking robustness due to relatively soft springs in the ankles and avoiding any Zero Moment Point (ZMP) control in our proposed architecture.Comment: 20 pages journal pape

A biomechanical analysis of the farmers walk, and comparison with the deadlift and unloaded walk

This study compared the biomechanical characteristics of the farmers walk, deadlift and unloaded walk. Six experienced male strongman athletes performed farmers' walks and deadlifts at 70% of their 1RM deadlift. Significant differences (p < 0.05) were apparent at knees passing with the farmers lift demonstrating greater trunk extension, thigh angle, knee flexion and ankle dorsiflexion. Significantly greater mean vertical and anterior forces were observed in the farmers lift than deadlift. The farmers walk demonstrated significantly greater peak forces and stride rates and significantly shorter stride lengths, ground contact times, and swing times than unloaded walk. Significantly greater dorsiflexion, knee flexion, thigh angle, and significantly lesser trunk angle at foot strike were also observed in the farmers walk. The farmers lift may be an effective lifting alternative to the deadlift, to generating more anterior-propulsive and vertical force with less stress to the lumbar spine due to the more vertical trunk position

3-D kinematic comparison of treadmill and overground running.

Studies investigating the mechanics of human movement are often conducted using the treadmill. The treadmill is an attractive device for the analysis of human locomotion. Studies comparing overground and treadmill running have analyzed discrete variables, however differences in excursion from footstrike to peak angle and range of motion during stance have yet to be examined. This study aimed to examine the 3-D kinematics of the lower extremities during overground and treadmill locomotion to determine the extent to which the two modalities differ. Twelve participants ran at 4.0m/s in both treadmill and overground conditions. 3-D angular kinematic parameters during the stance phase were collected using an eight camera motion analysis system. Hip, knee and ankle joint kinematics were quantified in the sagittal, coronal and transverse planes, then compared using paired t-tests. Of the parameters analyzed hip flexion at footstrike 12° hip range of motion 17°, peak hip flexion 12.7°, hip transverse plane range of motion 8° peak knee flexion 5° and peak ankle excursion range 6.6°, coronal plane ankle angle at toe-off 6.5° and peak ankle eversion 6.3° were found to be significantly different. These results lead to the conclusion that the mechanics of treadmill locomotion cannot be generalized to overground

Effect of a rigid ankle-foot orthosis on hamstring length in children with hemiplagia

Eighteen children with hemiplegia, mean age 8 years 5 months, underwent gait analysis and musculoskeletal modelling using specially designed software. The maximum lengths of the hamstrings were determined for each child walking in and out of an ankle–foot orthosis (AFO). The muscles were deemed to be short if shorter than the normal average – 1SD. In bare feet 8 participants had short medial hamstrings with a higher proportion of these in the less involved individuals. All participants showed an increase in maximum hamstring length when wearing an AFO. In all but one child this was sufficient to restore hamstring length to within normal limits. These finding suggest that hamstring pathology in hemiplegic gait is usually secondary to more distal lower limb pathology

The effect of heel height on frontal plane joint moments, impact accelertion, and shock attenuation during walking

Wearing high heels alters walking kinematics and kinetics and can create potentially adverse effects on the body. Our purpose was to determine how heel height affects frontal plane joint moments at the hip, knee, and ankle, with a specific focus on the external knee moment due to its importance in medial loading and knee osteoarthritis. In addition, this study examined the effect of heel height on impact acceleration of tibia and head and shock attenuation of the body. Fifteen women completed overground walking trials in three different heel height conditions (1, 5, and 9 cm) for a fixed walking speed (1.3 m/s) and a preferred walking speed while kinematic and force platform data were collected concurrently. Accelerometers were attached to the tibia and forehead in order to measure peak tibial and head acceleration and shock attenuation of the body. For both fixed and preferred speeds, peak external knee adduction moment increased systematically with an increase in heel height. Peak internal ankle eversion moment increased systematically with an increase in heel height, and though little change was evident at the hip, peak hip abduction moment was slightly higher for the 9 cm heel height compared to the 1 and 5 cm conditions. For both fixed and preferred speeds, peak tibial acceleration (PTA) was significantly higher for the 5 cm heel height condition compared to the 1 and 9 cm conditions, which was similar in PTA amplitude. Peak head acceleration (PHA) followed a similar but more subtle trend as PTA for both speed conditions. Substantial shock attenuation (70 to 75%) was responsible for the muted PHA responses in both speed conditions. Although not specifically identified, the unexpected PTA response is likely due to a combination of kinematic gait alterations that result in a lower PTA for the 9 cm heel height. This may have important implications on how heel height affects repetitive impulsive loading during walking. The higher peak external knee adduction moment with increasing heel height suggests greater medial loading at the knee, which can contribute to joint degeneration and the development of knee osteoarthritis. The kinetic changes observed at the ankle with increasing heel height may contribute to larger medial loads at the knee. Overall, wearing high heels, particularly those with higher heel heights, may put individuals at greater risk for joint degeneration and developing knee OA

Identifying Trippers and Non-Trippers Based on Knee Kinematics During Obstacle-Free Walking

Trips are a major cause of falls. Sagittal-plane kinematics affect clearance between the foot and obstacles, however, it is unclear which kinematic measures during obstacle-free walking are associated with avoiding a trip when encountering an obstacle. The purpose of this study was to determine kinematic factors during obstacle-free walking that are related to obstacle avoidance ability. It was expected that successful obstacle avoidance would be associated with greater peak flexion/dorsiflexion and range of motion (ROM), and differences in timing of peak flexion/dorsiflexion during swing of obstacle-free walking for the hip, knee and ankle. Three-dimensional kinematics were recorded as 35 participants (young adults age 18–45 (N = 10), older adults age 65+ without a history of falls (N = 10), older adults age 65+ who had fallen in the last six months (N = 10), and individuals who had experienced a stroke more than six months earlier (N = 5)) walked on a treadmill, under obstacle-free walking conditions with kinematic features calculated for each stride. A separate obstacle avoidance task identified trippers (multiple obstacle contact) and non-trippers. Linear discriminant analysis with sequential feature selection classified trippers and non-trippers based on kinematics during obstacle-free walking. Differences in classification performance and selected features (knee ROM and timing of peak knee flexion during swing) were evaluated between trippers and non-trippers. Non-trippers had greater knee ROM (P = .001). There was no significant difference in classification performance (P = .193). Individuals with reduced knee ROM during obstacle-free walking may have greater difficulty avoiding obstacles

Effects of additional anterior body mass on gait

BACKGROUND: Gradual increases in mass such as during pregnancy are associated with changes in gait at natural velocities. The purpose of this study was to examine how added mass at natural and imposed slow walking velocities would affect gait parameters. METHODS: Eighteen adult females walked at two velocities (natural and 25 % slower than their natural pace) under four mass conditions (initial harness only (1 kg), 4.535 kg added anteriorly, 9.07 kg added anteriorly, and final harness only (1 kg)). We collected gait kinematics (100 Hz) using a motion capture system. RESULTS: Added anterior mass decreased cycle time and stride length. Stride width decreased once the mass was removed (p < .01). Added mass resulted in smaller peak hip extension angles (p < .01). The imposed slow walking velocity increased cycle time, double limb support time and decreased stride length, peak hip extension angles, and peak plantarflexion angles (p < .01). With added anterior mass and an imposed slow walking velocity, participants decreased cycle time when mass was added and increased cycle time once the mass was removed (p < .01). CONCLUSIONS: Gait adaptations may be commensurate with the magnitude of additional mass when walking at imposed slow versus natural velocities. This study presents a method for understanding how increased mass and imposed speed might affect gait independent of other effects related to pregnancy. Examining how added body mass and speed influence gait is one step in better understanding how women adapt to walking under different conditions.K12 HD055931 - NICHD NIH HHS; K23 AR063235 - NIAMS NIH HH