Leg Loading Research Articles

Increase in Leg Stiffness Reduces Joint Work During Backpack Carriage Running at Slow Velocities.

Optimal tuning of leg stiffness has been associated with better running economy. Running with a load is energetically expensive, which could have a significant impact on athletic performance where backpack carriage is involved. The purpose of this study was to investigate the impact of load magnitude and velocity on leg stiffness. We also explored the relationship between leg stiffness and running joint work. Thirty-one healthy participants ran overground at 3 velocities (3.0, 4.0, 5.0 m·s-1), whilst carrying 3 load magnitudes (0%, 10%, 20% weight). Leg stiffness was derived using the direct kinetic-kinematic method. Joint work data was previously reported in a separate study. Linear models were used to establish relationships between leg stiffness and load magnitude, velocity, and joint work. Our results found that leg stiffness did not increase with load magnitude. Increased leg stiffness was associated with reduced total joint work at 3.0 m·s-1, but not at faster velocities. The association between leg stiffness and joint work at slower velocities could be due to an optimal covariation between skeletal and muscular components of leg stiffness, and limb attack angle. When running at a relatively comfortable velocity, greater leg stiffness may reflect a more energy efficient running pattern.

Foundation punch-through in clay with sand: analytical modelling

Severe punch-through of jack-up rig foundations can occur due to the presence of a stronger sand layer in a bed of relatively soft clay. Analytical estimation of the bearing capacity and leg load–penetration response on such multi-layer stratigraphies is challenging. Accurate mechanism-based models need to be established in each of the layers involved and the effects of the mechanisms in each of the layers on the response in the other layers must be captured. Based on the recently developed failure stress-dependent punch-through models for sand–clay stratigraphies, an extended model is proposed for clay–sand–clay stratigraphies. Half-spudcan particle image velocimetry centrifuge tests and full-spudcan centrifuge tests are used in developing and validating the extended model. The centrifuge test results were discussed in a companion paper and this paper focuses on the analytical developments and prediction assessment. Both spudcan peak resistance (qpeak) and spudcan punch-through depth (dpunch) can be estimated using the model. The predictions by the extended model and by the current industry guidelines are compared against the centrifuge test data. The extended model proposed in this paper outperforms the approaches suggested in the guidelines. An advantage of the proposed approach is that it can be used for either sand–clay or clay–sand–clay scenarios and exhibits excellent performance compared to the model testing dataset considered in this work for both cases. The resulting penetration resistance model is a useful design tool for routine punch-through risk assessment.

The influence of the crutch setup on stability and weight-bearing parameters in post total hip replacement surgery patients during quiet standing

Purpose: The purpose of this study is to evaluate the influence of the crutch setup on standing, in post total hip replacement (THR) surgery patients. Materials and methods: Thirty patients after THR were randomly assigned to walking with the elbow flexed (EF) or elbow straight (ES) crutch setup. Subjects were asked to stand on a force platform in a comfortable position with the crutch positioned on the unaffected side, facing forward for 10 seconds. Centre of pressure total path and maximal excursion were evaluated in both medio-lateral and anterior–posterior planes. Difference in the asymmetry of left/right acromial height, measured with and without the crutch, was calculated (ACdiff). Percentage of body weight borne by the crutch (Fcr), symmetry (SIload) between operated and healthy limbs loading during the trial, together with shoulder forces and moments were measured. Results: No significant differences between the two groups (p > .05) were found for stability parameters. ACdiff, Fcr and shoulder load increased significantly (p < .05) in EF group compared to ES group. In addition leg loading symmetry was significantly reduced in the EF group. Conclusions: The present study showed that the ES setup reduced the force borne by the crutch, the load on the shoulder joint and it minimized postural and loading asymmetries when compared to EF setup. Conversely, postural stability was not influenced by the crutch setup. Implications for Rehabilitation Static posture and weight-bearing parameters are influenced by crutch setup during quiet standing. Crutch setup does not influence postural stability. Adjusting the crutch according to the elbow straight setup reduces the force borne by the crutch and the asymmetry in lower limbs loading. Forces and moments at the shoulder joint were reduced for the elbow straight setup group.

生物の神経構造と筋骨格を模した4脚動物モデルによる歩容遷移現象の創発

This study aims to understand the principles of gait (the order of the movement of four legs) transition phenomenon in quadrupedal animals. Each of a quadruped animal's gaits are considered to be generated by neural networks placed in the spinal cord. Furthermore, the gait is changed according to its speed. However, the mechanism of gait transition is still unrevealed. To reveal it, we built a simulated quadruped model which is equipped with a cat's musculoskeletal system and nervous system that consists of central pattern generators (CPGs) and sensory afferent feedbacks. The model safely locomoted with a trot gait at a variety of speeds. We aim to allow the model to walk with leg load feedbacks.

Influence of the structure of the support surface under the sole on vertical posture during standing with different body weight distributions between legs

The vertical posture was studied during standing with fееt on the support surfaces of different structures. The movements of the center of pressure (CP) of each leg and the common CP (CCP) were recorded while the subject stood with a support on a smooth floor and with the support of one foot on a spike mat (SM) with different load distributions between the legs. When the body weight was transferred to one leg during standing under ordinary conditions on a smooth floor, the CP of the loaded leg moved more than the CP of the unloaded leg; i.e., the posture sway was compensated mainly due to the activity of the loaded leg, which created a larger torque. When the subject stood with one foot on the SM, the CP movement of this leg did not depend on the leg load and was about 60% of the CP movement of the leg on the smooth floor. Apparently, the CP displacement of the unloaded leg on smooth support was larger than the CP displacement of the loaded leg creating the torque necessary for compensating the body sway. Thus, maintaining the vertical posture was carried out mainly by the leg standing on the smooth support. It is assumed that additional stimulation of different surface and deep receptors of the foot caused by foot support on the SM hampered the perception of its CP position, and the vertical posture was maintained mainly by the leg afferent signals from which more precisely reflected the CP position.

Single leg stance control in individuals with symptomatic gluteal tendinopathy

BackgroundLateral hip pain during single leg loading, and hip abductor muscle weakness, are associated with gluteal tendinopathy, but it has not been shown how or whether kinematics in single leg stance differ in those with gluteal tendinopathy. PurposeTo compare kinematics in preparation for, and during, single leg stance between individuals with and without gluteal tendinopathy, and the effect of hip abductor muscle strength on kinematics. MethodsTwenty individuals with gluteal tendinopathy and 20 age-matched pain-free controls underwent three-dimensional kinematic analysis of single leg stance and maximum isometric hip abductor strength testing. Maximum values of hip adduction, pelvic obliquity (contralateral pelvis rise/drop), lateral pelvic translation (ipsilateral/contralateral shift) and ipsilateral trunk lean during preparation for leg lift and average values in steady single leg stance, were compared between groups using an analysis of covariance, with and without anthropometric characteristics and strength as covariates. ResultsIndividuals with gluteal tendinopathy demonstrated greater hip adduction (standardized mean difference (SMD)=0.70, P=0.04) and ipsilateral pelvic shift (SMD=1.1, P=0.002) in preparation for leg lift, and greater hip adduction (SMD=1.2, P=0.002) and less contralateral pelvic rise (SMD=0.86, P=0.02) in steady single leg stance than controls. When including strength as a covariate, only between-group differences in lateral pelvic shift persisted (SMD=1.7, P=0.01). ConclusionIndividuals with gluteal tendinopathy use different frontal plane kinematics of the hip and pelvis during single leg stance than pain-free controls. This finding is not influenced by pelvic dimension or the potentially modifiable factor of body mass index, but is by hip abductor muscle weakness.

Analysis of fatigue failure mode transition in load-carrying fillet-welded connections

In load-carrying fillet welded connections, two distinct fatigue failure modes are possible depending upon fillet weld leg size and loading conditions. One is weld toe cracking through base plate thickness and the other is through weld metal, often referred to as weld root cracking. Based on a recent comprehensive fatigue testing program in support of construction of lightweight ship structures, this paper examines a number of stress based fatigue parameters that can be used to formulate an effective criterion for determining failure mode transition from weld root to weld toe. A closed form solution has been developed for analytically determining the weld throat critical plane on which a traction stress based fatigue parameter attains its maximum and can be compared with that corresponding to weld toe cracking. It is found that both an effective weld throat stress based criterion by combining normal and shear traction stresses and an equivalent effective stress based criterion based on the master S-N curve formulation can be used for the determination of the minimum fillet weld leg size beyond which weld toe fatigue failure dominates. The proposed fillet weld sizing criteria are then validated using a large amount of fatigue test data on load-carrying cruciform fillet welded specimens.

A simple rule for quadrupedal gait generation determined by leg loading feedback: a modeling study.

We discovered a specific rule for generating typical quadrupedal gaits (the order of the movement of four legs) through a simulated quadrupedal locomotion, in which unprogrammed gaits (diagonal/lateral sequence walks, left/right-lead canters, and left/right-lead transverse gallops) spontaneously emerged because of leg loading feedbacks to the CPGs hard-wired to produce a default trot. Additionally, all gaits transitioned according to speed, as seen in animals. We have therefore hypothesized that various gaits derive from a trot because of posture control through leg loading feedback. The body tilt on the two support legs of each diagonal pair during trotting was classified into three types (level, tilted up, or tilted down) according to speed. The load difference between the two legs led to the phase difference between their CPGs via the loading feedbacks, resulting in nine gaits (32: three tilts to the power of two diagonal pairs) including the aforementioned.

Influence of the leg load and support mobility under leg on the anticipatory postural adjustments

Anticipatory postural adjustment is an essential part of equilibrium maintainance during standing in human. So changes in stance condition could affect both control of equilibrium and anticipatory adjustment. Anticipatory changes in the stabilogram of each leg were studied in standing subject during the early stage of quick right arm lifting while legs were on two separated supports. The center of pressure (CP) movement was analyzed in three variants of experiment: both legs on immovable support, with only right leg on the movable support and with only left leg on the moveable support. In each standing condition subject stood with symmetrical load on two legs or with the load voluntary transferred to one leg. The anticipatory CP shift depended on the mobility of the support under the leg and on loading of the leg. While standing on unmovable supports with symmetrical load on the legs before lifting of the right arm CP of right leg shifted backward and CP of left leg--forward. While standing with one leg on movable support the anticipatory CP shift of this leg was small and did not depend on the load on the leg. However the shift of CP of the leg that was placed on the unmovable support depended on the load in the same way as in the case when both legs were on unmovable supports. Results suggested that since on movable support the support and proprioceptive afferent flow from distal part of the leg that was did not supply unambiguous information about body position, the role of distal joints in posture control is reduced.

Running birds prioritise safety on uneven terrain

Anyone who does cross-country running knows how uneven the real world is, and moving animals have to constantly negotiate bumps and obstacles in their surroundings. But how does size affect the strategy that animals use when encountering objects that impede progress, and which selective pressures have driven the strategies that they use for negotiating these obstacles? Monica Daley from the Royal Veterinary College, UK, explains that an animal's posture could dramatically affect how it manoeuvres across uneven terrain. Small animals that stand with a crouched posture could use a completely different strategy from large upright animals, and Daley wondered which physical factors have driven differently sized animals to select the strategy that works best for them. Explaining that ground-dwelling birds span a mind-boggling range of sizes from heavy weight ostriches down to dainty crouched quail, Daley and her student Aleksandra Birn-Jeffrey decided to find out more about the strategies that birds ranging in size from 0.2 kg up to 117 kg use when running over a step (p. 3786).However, sourcing many of the animals in the UK, some of which are native to the USA, was trickier than Daley had anticipated. She also recalls that working with the ostriches was particularly challenging. ‘Ola [Birn-Jeffrey] hand-raised these ostriches for 2 years so that they were imprinted on humans so that they could be handled easily and weren't as dangerous’, she says.Birn-Jeffrey and Yvonne Blum then filmed the birds as they ran over steps that ranged in size from 0.1 to 0.5 times the length of their leg, and also measured the forces exerted by the birds to find out how their bodies moved as they crossed the obstacle. However, after 4 years of bird rearing, and data collection and analysis, Birn-Jeffrey discovered that all of the birds, no matter how large or whether their posture was crouched or upright, negotiated the obstacle using the same strategy. Daley admits that she was surprised. ‘I thought that we would find that the small animals would crouch and extend the leg to buffer terrain variations and maintain a relatively smooth body motion’, she says, adding that she had expected the larger birds to vault up on to the obstacle and down the other side. Instead, all of the birds appeared to launch themselves up on to the obstacle and crouch slightly on top of it before extending their legs as they descended back down. ‘It's a compromise strategy in a sense’, says Daley.Meanwhile, Daley was also investigating the physical factors – known as task-level priorities – that influence how birds negotiate uneven terrain in collaboration with Jonathan Hurst, Christian Hubicki and Daniel Renjewski from Oregon State University, USA. The engineers built a computer model to simulate the running birds, and Daley says, ‘We used the model to say, here are two alternative “task level priorities”, one of them being to prioritise stability – to try to return to a steady gait as quickly as possible – or alternatively to minimise energy cost’. Simulating heavy birds with long legs and lighter birds with shorter legs, the team found that instead of evolving to prioritise stability when running over an obstacle, the birds' movements were determined by the need to move economically and avoid injury. ‘What you find is that the model does something very similar to birds when you minimise energy cost and control the leg posture at the start of stance to avoid excessive leg loading’, says Daley, who hopes that she and Hurst can now begin to apply the lessons learned from running birds to build stable bipedal robots.

Task-dependent inhibition of slow-twitch soleus and excitation of fast-twitch gastrocnemius do not require high movement speed and velocity-dependent sensory feedback.

Although individual heads of triceps surae, soleus (SO) and medial gastrocnemius (MG) muscles, are often considered close functional synergists, previous studies have shown distinct activity patterns between them in some motor behaviors. The goal of this study was to test two hypotheses explaining inhibition of slow SO with respect to fast MG: (1) inhibition occurs at high movement velocities and mediated by velocity-dependent sensory feedback and (2) inhibition depends on the ankle-knee joint moment combination and does not require high movement velocities. The hypotheses were tested by comparing the SO EMG/MG EMG ratio during fast and slow motor behaviors (cat paw shake responses vs. back, straight leg load lifting in humans), which had the same ankle extension-knee flexion moment combination; and during fast and slow behaviors with the ankle extension-knee extension moment combination (human vertical jumping and stance phase of walking in cats and leg load lifting in humans). In addition, SO EMG/MG EMG ratio was determined during cat paw shake responses and walking before and after removal of stretch velocity-dependent sensory feedback by self-reinnervating SO and/or gastrocnemius. We found the ratio SO EMG/MG EMG below 1 (p < 0.05) during fast paw shake responses and slow back load lifting, requiring the ankle extension-knee flexion moment combination; whereas the ratio SO EMG/MG EMG was above 1 (p < 0.05) during fast vertical jumping and slow tasks of walking and leg load lifting, requiring ankle extension-knee extension moments. Removal of velocity-dependent sensory feedback did not affect the SO EMG/MG EMG ratio in cats. We concluded that the relative inhibition of SO does not require high muscle velocities, depends on ankle-knee moment combinations, and is mechanically advantageous for allowing a greater MG contribution to ankle extension and knee flexion moments.

Swing-leg trajectory of running guinea fowl suggests task-level priority of force regulation rather than disturbance rejection.

To achieve robust and stable legged locomotion in uneven terrain, animals must effectively coordinate limb swing and stance phases, which involve distinct yet coupled dynamics. Recent theoretical studies have highlighted the critical influence of swing-leg trajectory on stability, disturbance rejection, leg loading and economy of walking and running. Yet, simulations suggest that not all these factors can be simultaneously optimized. A potential trade-off arises between the optimal swing-leg trajectory for disturbance rejection (to maintain steady gait) versus regulation of leg loading (for injury avoidance and economy). Here we investigate how running guinea fowl manage this potential trade-off by comparing experimental data to predictions of hypothesis-based simulations of running over a terrain drop perturbation. We use a simple model to predict swing-leg trajectory and running dynamics. In simulations, we generate optimized swing-leg trajectories based upon specific hypotheses for task-level control priorities. We optimized swing trajectories to achieve i) constant peak force, ii) constant axial impulse, or iii) perfect disturbance rejection (steady gait) in the stance following a terrain drop. We compare simulation predictions to experimental data on guinea fowl running over a visible step down. Swing and stance dynamics of running guinea fowl closely match simulations optimized to regulate leg loading (priorities i and ii), and do not match the simulations optimized for disturbance rejection (priority iii). The simulations reinforce previous findings that swing-leg trajectory targeting disturbance rejection demands large increases in stance leg force following a terrain drop. Guinea fowl negotiate a downward step using unsteady dynamics with forward acceleration, and recover to steady gait in subsequent steps. Our results suggest that guinea fowl use swing-leg trajectory consistent with priority for load regulation, and not for steadiness of gait. Swing-leg trajectory optimized for load regulation may facilitate economy and injury avoidance in uneven terrain.

Asymmetry of Achilles tendon mechanical and morphological properties between both legs.

Although symmetry of Achilles tendon (AT) properties between legs is commonly assumed in research and clinical settings, different loading profiles of both legs in daily life (i.e., foot dominance) may affect the tendon properties in a side-depended manner. Therefore, AT properties were examined with regard to symmetry between legs. Thirty-six male healthy adults (28 ± 4 years), who were physically active but not involved in sports featuring dissimilar leg load participated. Mechanical and morphological AT properties of the non-dominant and dominant leg were measured by means of ultrasound, magnetic resonance imaging and dynamometry. The AT of the dominant leg featured a significant higher Young's modulus and length (P < 0.05) but a tendency toward lower maximum strain (P = 0.068) compared with the non-dominant leg. The tendon cross-sectional area and stiffness were not significantly different between sides. The absolute asymmetry index of the investigated parameters ranged from 3% to 31% indicating poor AT side symmetry. These findings provide evidence of distinct differences of AT properties between both legs in a population without any sport-specific side-depended leg loading. The observed asymmetry may be a result of different loading profiles of both legs during daily activities (i.e., foot dominance) and challenges the general assumption of symmetrical AT properties between legs.

Analysis of a rotary task following total knee arthroplasty: Stair descent with a cross-over turn

Leg loading and knee angle differences have been reported in total knee replacement individuals during straight gait; however, little is known about the impact on the knee during turning. Rotary motions may be difficult following total knee replacement surgery; therefore, some individuals may develop strategies or utilize pre-surgical strategies in order to maintain function. The primary aim of this study was to identify differences in individuals with a total knee replacement as compared to their healthy counterparts during stair descent followed by a cross-over turn. Ground reaction force, knee angle and moments were recorded on 10 total knee replacement and 12 healthy individuals during stair descent followed by a turn and compared to walking straight. Variables were analyzed for the affected, unaffected and healthy knees during the gait cycle. On initial contact, the total knee replacement group had less ground reaction force on the affected leg compared to the unaffected leg (p = 0.021) and had delayed contact (p = 0.044) and a slower loading rate (p = 0.020) compared to healthy group. During mid-stance, the affected leg had less ground reaction force compared to the healthy leg (p = 0.049). The affected stance leg had less knee flexion during mid-stance in both the straight trial (p = 0.002) and turn (p = 0.010). Moment differed between straight and turn trials but not between groups. Stair descent with or without a turn was approached in a precautionary manner by individuals with a total knee replacement. Slow approach, reduced impact and weight-bearing with a more extended knee on the affected leg may suggest a protective strategy to avoid risk of fall.

The influence of changes in trunk and pelvic posture during single leg standing on hip and thigh muscle activation in a pain free population

BackgroundThigh muscle injuries commonly occur during single leg loading tasks and patterns of muscle activation are thought to contribute to these injuries. The influence trunk and pelvis posture has on hip and thigh muscle activation during single leg stance is unknown and was investigated in a pain free population to determine if changes in body posture result in consistent patterns of changes in muscle activation.MethodsHip and thigh muscle activation patterns were compared in 22 asymptomatic, male subjects (20–45 years old) in paired functionally relevant single leg standing test postures: Anterior vs. Posterior Trunk Sway; Anterior vs. Posterior Pelvic Rotation; Left vs. Right Trunk Shift; and Pelvic Drop vs. Raise. Surface EMG was collected from eight hip and thigh muscles calculating Root Mean Square. EMG was normalized to an “upright standing” reference posture. Repeated measures ANOVA was performed along with associated F tests to determine if there were significant differences in muscle activation between paired test postures.ResultsIn right leg stance, Anterior Trunk Sway (compared to Posterior Sway) increased activity in posterior sagittal plane muscles, with a concurrent deactivation of anterior sagittal plane muscles (p: 0.016 - <0.001). Lateral hip abductor muscles increased activation during Left Trunk Shift (compared to Right) (p :≤ 0.001). Lateral Pelvic Drop (compared to Raise) decreased activity in hip abductors and increased hamstring, adductor longus and vastus lateralis activity (p: 0.037 - <0.001).ConclusionChanges in both trunk and pelvic posture during single leg stance generally resulted in large, predictable changes in hip and thigh muscle activation in asymptomatic young males. Changes in trunk position in the sagittal plane and pelvis position in the frontal plane had the greatest effect on muscle activation. Investigation of these activation patterns in clinical populations such as hip and thigh muscle injuries may provide important insights into injury mechanisms and inform rehabilitation strategies.

Influence of Achilles tendon vibration on the vertical posture during standing with asymmetrical leg loading

The shift of center of pressure (CP) of body and CP of each leg was studied during Achilles tendon vibration of one or both legs while subject was standing with symmetrical load on the legs or with the load transferred on one leg. The CP shift of standing subject during unilateral Achilles tendon vibration depended both on the side of the tendon vibration and on the leg load. When standing with a load transferred on one leg the shift of common CP was larger than when the vibration was applied to the loaded leg. The CP shift of one leg was greater if the vibration, and the load was applied to it. Vibration of unloaded leg caused a CP shift in the contralateral loaded leg. In this case, the vibration of left unloaded leg caused no noticeable CP shift of left leg, while the vibration of the unloaded right leg caused CP shift of right foot. In the same conditions of load and vibration the CP displacement of right leg was larger than the CP shift of left foot. It can be assumed that the change in the load on the leg and unilateral vibration of leg muscles change of the internal representation of the vertical body axis, which affects the CP position of one leg during the muscles vibration.

Assessment of asymmetric leg loading before and after total hip arthroplasty using instrumented shoes

BackgroundTotal hip arthroplasty is a successful surgical treatment in patients with osteoarthritis of the hip. Different questionnaires are used by the clinicians to assess functional capacity and the patient's pain, despite these questionnaires are known to be subjective. Furthermore, many studies agree that kinematic and kinetic parameters are crucial to evaluate and to provide useful information about the patient’s evolution for clinicians and rehabilitation specialists. However, these quantities can currently only be obtained in a fully equipped gait laboratory. Instrumented shoes can quantify gait velocity, kinetic, kinematic and symmetry parameters. The aim of this study was to investigate whether the instrumented shoes is a sufficiently sensitive instrument to show differences in mobility performance before and after total hip arthroplasty.MethodsIn this study, patients undergoing total hip arthroplasty were measured before and 6–8 months after total hip arthroplasty. Both measurement sessions include 2 functional mobility tasks while the subject was wearing instrumented shoes. Before each measurement the Harris Hip Score and the Traditional Western Ontario and McMaster Universities osteoarthritis index were administered as well.ResultsThe stance time and the average vertical ground reaction force measured with the instrumented shoes during walking, and their symmetry index, showed significant differences before and after total hip arthroplasty. However, the data obtained with the sit to stand test did not reveal this improvement after surgery.ConclusionsOur results show that inter-limb asymmetry during a walking activity can be evaluated with the instrumented shoes before and after total hip arthroplasty in an outpatient clinical setting.

A preliminary investigation to establish the criterion validity of a qualitative scoring system of limb alignment during single leg squat and landing

Objective: The present study aimed to investigate the criterion validity of a novel qualitative assessment scheme to assess limb alignment during single leg loading activities. Design and setting: Observational laboratory study Main outcome measures: Performance of 5 participant’s single leg squat and hop landing was assessed using 3-D motion capture and the findings of this compared to the qualitative scoring scheme. Results: The range of percentage of agreement between the qualitative and 3-D score was for all subjects across both tasks 95.6100%. The kappa measure of agreement was k = 0.9 for hop landing and k = 0.97 for single leg squat. Conclusion: The scores generated by the qualitative scoring scheme used showed excellent association with the corresponding data from 3-D motion capture, implying the measurement tool shows criterion validity.

Effects of Gait Training with Added Load on Children with Hemiparetic Cerebral Palsy

The study aimed to evaluate the immediate effects of treadmill training with leg load on kinematic parameters of gait in children with spastic hemiparetic cerebral palsy (SHCP). Quasi-experimental study. Laboratory of Intervention and Movement Analysis on Federal University of Rio Grande do Norte (UFRN). 20 children with SHCP clinical diagnosis (mean age was 8.8 years ± 2.39), and independent walk (GMFCS I-II). Children walked with added load on ankles in a single treadmill training session during 5 minutes. Kinematic parameters were evaluated using the Qualisys Motion Capture System in three phases: before training (FBT); immediately after training (FPT); and 5 minutes after the end of training (FET). Significant increase in range of motion on knee (F=8.654; P =.001) and hip joint (F=6.053; P=.005), maximum flexion in swing phase of knee (F=16.252; P<.001) and hip joint (F=7.876; P=.001) and the maximum height of the paretic leg during the swing phase (F=12.309; P<.001) were observed when comparing FBT versusFPT versus FET. The Bonferroni test identified that difference occurred when comparing phases FBTversus FPT and FPTversus FET. Gait training with leg load seems modifies the locomotor strategy for children with SHCP, suggesting that this therapy may benefit the gait of these children.

Preoperative Ambulatory Measurement of Asymmetric Leg Loading During Sit-to-Stand in Hip Arthroplasty Patients

Total hip arthroplasty (TGA) is a successful surgical procedure to treat patients with hip osteoarthritis. Clinicians use different questionnaires to evaluate these patients. Gait velocity and these questionnaires; usually show significant improvement after TGA . This clinical evaluation does, however, not provide objective, quantifiable information about the movement patterns underlying the functional capacity, which is clinically important and can currently only be obtained in a gait laboratory. There is a need to improve patient instructions and to quantify the rehabilitation process. The sit-to-stand (STS) movement is an objective performance-based task, whose assessment is related with the evaluation of functional recovery. Twenty two patients with hip osteoarthritis participated in this study. For each patient, validated questionnaires were administered and gait velocity was measured. Time, ground reaction forces, and lower limb asymmetry parameters were calculated using the instrumented force shoes (IFS) during STS movement with and without armrest. Significant inter-limb asymmetry was observed. No correlation was found between any parameter and gait velocity and questionnaires outcomes. Significant differences in time and force parameters between with/without armrest were found. Concluding, inter-limb asymmetry can be evaluated with the IFS supplying important additional information not represented by gait velocity and questionnaires usually used.