Reproducibility of gait parameters at different surface inclinations and speeds using an instrumented treadmill system

Impact of lateral meniscus injury detected by preoperative magnetic resonance imaging on midterm results after unicompartmental knee arthroplasty

BACKGROUND

The significance of lateral meniscus injury and its impact on success rates with medial unicompartmental knee arthroplasty (UKA) is still debated among scholars. This study aims to investigate whether preoperative magnetic resonance imaging (MRI) findings of lateral meniscus injury influence midterm outcomes following UKA.

METHODS

This study recruited 104 patients who underwent medial mobile-bearing UKA. Based on the extent of lateral meniscus injury indicated by the preoperative MRI and Stoller's classification system, patients were divided into two groups: the normal group (grade 0), and the lateral meniscus injury group (grade 3). Further, preoperative demographic and clinical outcome data (Hospital for Special Surgery score, lateral knee pain, squatting, and knee extension ability) were compared at least 2 years postoperatively.

RESULTS

No statistically significant difference in knee function or clinical outcome was found between the normal group (n = 59) and the lateral meniscus injury group (n = 45). During the 39.2 months (range: 24-64 months), no patient required any reoperation or revision procedures.

CONCLUSION

In summary, the presence of lateral meniscus injury as determined by preoperative MRI does not affect the midterm results after UKA. Without additional treatment for lateral meniscus injury, UKA can yield desired outcomes regardless of the presence of lateral meniscus injury on preoperative MRI.

Commercially available pressure sensors for sport and health applications: A comparative review

Pressure measurement systems have numerous applications in healthcare and sport. The purpose of this review is to: (a) describe the brief history of the development of pressure sensors for clinical and sport applications, (b) discuss the design requirements for pressure measurement systems for different applications, (c) critique the suitability, reliability, and validity of commercial pressure measurement systems, and (d) suggest future directions for the development of pressure measurements systems in this area. Commercial pressure measurement systems generally use capacitive or resistive sensors, and typically capacitive sensors have been reported to be more valid and reliable than resistive sensors for prolonged use. It is important to acknowledge, however, that the selection of sensors is contingent upon the specific application requirements. Recent improvements in sensor and wireless technology and computational power have resulted in systems that have higher sensor density and sampling frequency with improved usability - thinner, lighter platforms, some of which are wireless, and reduced the obtrusiveness of in-shoe systems due to wireless data transmission and smaller data-logger and control units. Future developments of pressure sensors should focus on the design of systems that can measure or accurately predict shear stresses in conjunction with pressure, as it is thought the combination of both contributes to the development of pressure ulcers and diabetic plantar ulcers. The focus for the development of in-shoe pressure measurement systems is to minimise any potential interference to the patient or athlete, and to reduce power consumption of the wireless systems to improve the battery life, so these systems can be used to monitor daily activity. A potential solution to reduce the obtrusiveness of in-shoe systems include thin flexible pressure sensors which can be incorporated into socks. Although some experimental systems are available further work is needed to improve their validity and reliability.

Neuromuscular response to the stimulation of plantar cutaneous during walking at different speeds

BACKGROUND

A lot of authors have been studied the consequence of postural control strategies through investigating the effects of foot-surface contact. In this context an important variable of textured surfaces or insoles could be related to material stiffness. We apply a particular textured insoles to evaluate neuromuscular response of plantar stimulation during walking.

RESEARCH QUESTION

Could textured insoles alter the human locomotion during walking at different speeds?

METHODS

Ten adults (age: 27 ± 5 years) completed three trials on the multifunction treadmill at 0.42 ms^-1, 0.89 ms^-1, and 1.5 ms^-1 walking speed. Temporal-spatial parameters, gait line, and kinetic parameters were analyzed. The Co-Contraction Index (CCI) and electromyography (EMG) of the right leg muscles were assessed during four phases of gait: first half stance (FHS), half stance (HS), second half stance (SHS), swing phase (SP). Textured insole and soft control insole were worn while walking.

RESULTS

Plantar stimulation improved cadence, stride time, stride length and gait line parameters with increasing speed. First force peaks and maximum force forefoot were always significant. The maximum force midfoot was significant at 0.42 and 0.89 ms^-1. The maximum force heel only was significant in lower velocity. The maximum pressure showed different significant values except for the heel. Significant differences in the CCI were always found in the FHS and SHS for the plantar muscles, and in the FHS and HS for the knee muscles. The differences in gait analysis in biomechanical and in electromyographic parameters were more significant in the higher speed tested.

SIGNIFICANCE

The perception of shape and texture through its linear response to skin deformation over a wide range of deformations could be the reason why the significant differences increase in the higher speed. In conclusion, sensory interventions fallowing appropriate insoles can influence significantly gait. Walking strategy positively adjusts locomotion with high efficiency.

Differences between Systems Using Optical and Capacitive Sensors in Treadmill-Based Spatiotemporal Analysis of Level and Sloping Gait

Modern technology has enabled researchers to analyze gait with great accuracy and in various conditions based on the needs of the trainees. The purpose of the study was to investigate the agreement between systems equipped with optical and capacitive sensors in the analysis of treadmill-based level and sloping gait. The spatiotemporal parameters of gait were measured in 30 healthy college-level students during barefoot walking on 0% (level), -10% and -20% (downhill) and +10% and +20% (uphill) slopes at hiking-related speeds using an optoelectric cell system and an instrumented treadmill. Inter-system agreement was assessed using the Intraclass Correlation Coefficients (ICCs) and the 95% limits of agreement. Our findings revealed excellent ICCs for the temporal and between moderate to excellent ICCs for the spatial parameters of gait. Walking downhill and on a 10% slope demonstrated better inter-system agreement compared to walking uphill and on a 20% slope. Inter-system agreement regarding the duration of gait phases was increased by increasing the number of LEDs used by the optoelectric cell system to detect the contact event. The present study suggests that systems equipped with optical and capacitive sensors can be used interchangeably in the treadmill-based spatiotemporal analysis of level and sloping gait.

Influence of Treadmill Design on Gait: Does Treadmill Size Affect Muscle Activation Amplitude? A Musculoskeletal Calculation With Individualized Input Parameters of Gait Analysis

With increasing age, gait changes often occur, leading to mobility problems and thus a higher risk of falling. Interest in training at home or at retirement homes has led to the development of “mobile treadmills.” A difference in treadmill surface length may influence walking parameters (i.e., step length) and therefore may affect muscle activation. This led to the question: Does the treadmill size affect the muscle activation, i.e., with the length of the walking surface. The study aimed to investigate the influence of treadmill size, i.e., length of the walking surface, on gait pattern and to determine differences in the amplitude of muscle activation using a participant-specific musculoskeletal model (AnyBody Technology A/S, Aalborg, Denmark). For a prospective, randomized study gait parameters were collected from 47 healthy participants (aged 50.19 ± 20.58 years) while walking on two different treadmills, a small mobile treadmill (walking surface length 100 cm) and a conventional treadmill (walking surface length 150 cm), at their preferred speed, 2 km/h, and 4 km/h. Muscle activation amplitude patterns were similar between treadmills (M. gastrocnemius medialis: rmean = 0.94, M. gastrocnemius lateralis: rmean = 0.92, M. gluteus medius rmean = 0.90, M. gluteus minimus rmean = 0.94). However, the gait analysis showed a decreased preferred velocity (p < 0.001, z = 4.54), reduced stride length (preferred velocity: p = 0.03, z = −2.17; 2 km/h: p = 0.36, z = 2.10; 4 km/h: p = 0.006, z = 2.76), shorter stride time (2 km/h: p < 0.001, z = 4.65; 4 km/h: p < 0.001, z = 4.15), and higher cadence (2 km/h: p < 0.001, z = −4.20; 4 km/h: p = 0.029, z = −2.18) on the mobile treadmill than on the conventional treadmill. Our observations suggest that the treadmill design (e.g., a 50 cm difference in walking surface length) may not influence muscle activity amplitude during walking. However, the design of the treadmill may influence gait characteristics (e.g., stride length, cadence) of walking.

A Pressure-Pad-Embedded Treadmill Yields Time-Dependent Errors in Estimating Ground Reaction Force during Walking

Accurate and reliable vertical ground reaction force (VGRF) measurement is essential in various biomechanical and clinical studies. Recently, pressure-pad-embedded treadmills have been widely used for VGRF measurement as a relatively less expensive option than the force platform-mounted treadmills. Prior studies have shown that the popular Zebris treadmill is reliable when used to measure peak VGRF for short walking sessions. However, comprehensive evaluation of human walking requires information of gait parameters over sufficient gait cycles. In this study, we quantify the long-term temporal changes in VGRF values measured by the Zebris treadmill. Twenty participants walked on the treadmill for 10 min twice, with 10 min rest between trials. We found an evident decline in the measured VGRF and impulse over time for both trials. The Zebris system also consistently yielded the lower VGRF values during the second trials. These results indicate that the Zebris treadmill is unreliable in measuring VGRF during walking, and a 10 min break is not enough for the embedded sensors to recover their sensitivity. We provided a way to resolve these time-dependent errors; using the impulse-momentum theorem and collected kinematics of the participants, we formulated a curve-fitting model encapsulating the growing VGRF estimation error.

Multi-joint biomechanics during sloped walking in patients with developmental dysplasia of the hip

BACKGROUND

Developmental dysplasia of the hip is characterized by abnormal acetabular and femoral geometries that alter joint loading and increase the risk of hip osteoarthritis. Current understanding of biomechanics in this population remains isolated to the hip and largely focused on level-ground walking, which may not capture the variable loading conditions that contribute to symptoms and intra-articular damage.

METHODS

Thirty young adult females (15 with dysplasia) underwent gait analysis during level, 10° incline, and 10° decline walking while whole-body kinematics, ground reaction forces, and electromyography (EMG) were recorded. Low back, hip, and knee joint kinematics and internal joint moments were calculated using a 15-segment model and integrated EMG was calculated within the functional phases of gait. Dependent variables (peak joint kinematics, moments, and integrated EMG) were compared across groups with a one-way ANOVA with multiple comparisons controlled for using the Benjamini-Hochberg method (α = 0.05).

FINDINGS

During level and incline walking, patients with developmental dysplasia of the hip had significantly lower trunk flexion angles, lumbar and knee extensor moments, and erector spinae activity than controls. Patients with developmental dysplasia of the hip also demonstrated reduced rectus femoris activity during loading of level walking and increased gluteus maximus activity during mid-stance of decline walking.

INTERPRETATION

Patients with developmental dysplasia of the hip adopt compensations both proximal and distal to the hip, which vary depending on the slope of walking. Furthering the understanding of multi-joint biomechanical compensations is important for understanding the mechanism of osteoarthritis development as well as secondary conditions.

The impact of reducing the femoral stem length in total hip arthroplasty during gait

AIM

The length of the femoral stem in total hip arthroplasty (THA) is a practical consideration to prevent gait impairment. The aim of this study was to determine if reducing the femoral stem length in THA would lead to impaired gait biomechanics.

METHODS

Patients uniformly with the same brand implant of differing lengths (100 mm vs 140-166 mm) were taken retrospectively from a prospective trial introducing a new short stem. Twelve patients without any other disorder to alter gait besides contralateral differing length stem THA were tested at differing gradients and speed on a validated instrumented treadmill measuring ground reaction forces. An anthropometrically similar group of healthy controls were analysed to compare.

RESULTS

With the same posterior surgical approach, the offset and length of both hips were reconstructed within 5 mm of each other with an identical mean head size of 36 mm. The short stem was the last procedure for all the hips with gait analysis occurring at a mean of 31 and 79 months postoperatively for the short and long stem THA, respectively. Gait analysis between limbs of both stem lengths demonstrated no statistical difference during any walking condition. In the 90 gait assessments with three loading variables, the short stem was the favoured side 51% of the time compared 49% for the long stem.

CONCLUSION

By testing a range of practical walking activities, no lower limb loading differences can be observed by reducing the femoral stem length. A shorter stem demonstrates equivalence in preference during gait when compared to a reputable conventional stem in total hip arthroplasty.

[Analysis of gait and effectiveness after unicompartmental knee arthroplasty]

Objective

To explore the gait trajectory characteristics and effectiveness after unicompartmental knee arthroplasty (UKA).

Methods

Thirty patients (30 knees) with anterior medial compartment osteoarthritis who were treated with UKA between January 2017 and December 2018 were selected as subjects (UKA group). According to age, gender, and side, 30 patients (30 knees) with knee osteoarthritis treated with total knee arthroplasty (TKA) were selected as control (TKA group). In addition to the range of motion (ROM) before operation showing significant difference between the two groups ( t=4.25, P=0.00), there was no significant difference in gender, age, disease duration, sides, body mass index, and preoperative hip-knee-ankle angle (HKA), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score between the two groups ( P>0.05). The incision length, drainage volume within 24 hours after operation, and the changes of hemoglobin and albumin were recorded. The WOMAC score, ROM, and HKA before and after operation were compared between the two groups. At 1 year after operation, the gait trajectory characteristics of two groups were analyzed by Vicon three-dimensional gait capture system, and the absolute symmetry index (ASI) of the lower limbs of the two groups was calculated.

Results

The incisions of the two groups healed by first intention, with no complications. The incision length, drainage volume within 24 hours, and the changes of hemoglobin and albumin after operation in the UKA group were significantly smaller than those in the control group ( P<0.05). All patients were followed up completely, the follow-up time ranged from 13 to 20 months of UKA group (mean, 18 months) and 16 to 24 months of control group (mean, 20 months). The imaging review showed that the lower limb alignment of the two groups were restored to a neutral position, and the position of prosthesis was good. At 1 year after operation, the WOMAC score, HKA, and ROM of two groups were significantly improved when compared with those before operation ( P<0.05); the postoperative WOMAC score and ROM of the UKA group were significantly better than those of the control group ( P<0.05), and there was no significant difference in HKA between the two groups ( t=1.54， P=0.13). Gait analysis at 1 year after operation showed that the walking speed, stride length, knee extension at mid-stance, and flexion at swing in the UKA group were significantly better than those in the TKA group ( P<0.05); there was no significant difference in cadence, knee flexion at initial contact, and knee flexion at loading response between the two groups ( P>0.05). The ASI of bilateral knee flexion in the UKA group was significantly greater than that in the TKA group during the initial contact and loading response period ( P<0.05).

Conclusion

Compared with TKA, UKA has the advantages of small incision, less blood loss, and quicker functional recovery. The early gait after UKA is mainly manifested as the increase in walking speed, stride length, knee flexion at swing, and extension at mid-stance phase. From the analysis of gait symmetry, during the initial contact and loading response phase, the operation side after UKA undertakes more shock absorption and joint stabilization functions than the contralateral side.

A Narrative Review on the Tests Used in Biomechanical Functional Assessment of the Foot and Leg: Diagnostic Tests of Deformities and Compensations

BACKGROUND

To date, scientific literature has not as yet come up with any review showing the diagnostic tests used for functional assessment of the foot and leg.

METHODS

A literature review was conducted of electronic databases (MEDLINE, PEDro, DOAJ, BioMed Central, PLOS, and Centre for Reviews and Dissemination at the University of York) up to December 8, 2018. The biomechanical tests, which have adequate supportive literature, were divided into qualitative tests that provide a dichotomy/trichotomy-type answer to clinical diagnostic questions; semiquantitative tests that provide numerical data to clinical diagnostic questions; and quantitative tests that record continuous numerical data (in analogue or digital form).

RESULTS

These tests produce a useful functional evaluation model of the foot and leg for different purposes: evaluation of lower limb deficits or abnormalities in healthy patients and in athletes (in sports or other physical activities); assessment of tissue stress syndromes caused by pathomechanics; evaluation of lower limb deficits or abnormalities in rheumatic disease and diabetic foot patients; and to determine the appropriate functional or semifunctional foot orthotic therapy and therapeutic path used in gait rehabilitation.

CONCLUSIONS

Many of these tests have adequate diagnostic reliability and reproducibility and therefore can be considered diagnostic. Few of these are validated, and some have initiated the validation process by determining their sensitivity and specificity. The widespread use of these tools in clinical practice (diagnosis of function) lacks scientific evidence and in-depth analysis of their limitations.

The unicompartmental knee is the preferred side in individuals with both a unicompartmental and total knee arthroplasty

PURPOSE

To determine the preferred knee in patients with both one total and one unicompartmental knee arthroplasty.

METHOD

Patients simply with a unicompartmental (UKA) and total knee arthroplasty (TKA) on contralateral sides were retrospectively screened from three senior knee surgeon's logs over a 15 year period. Patients safe and free from other diseases to affect gait were approached. A total of 16 patients (mean age 70 ± 8) agreed to ground reaction force testing on an instrumented treadmill at a fair pace and incline. A gender-ratio identical group of 16 healthy control subjects (mean age 67 ± 10) and 16 patients with ipsilateral medial knee OA (mean age 66 ± 7) were analysed to compare.

RESULTS

Radiographically the mode preoperative Kellgren-Lawrence knee grade for each side was 3. Postoperatively, the TKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 89° with a mean posterior slope of 5° in the sagittal plane. The UKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 86° with a mean posterior slope of 4° in the sagittal plane. In 7 patients, the TKA was the first procedure, while 6 for the UKA and 3 done simultaneously. Gait analysis demonstrated in both walking conditions the UKA limb was the preferred side through all phases of loading (p < 0.05) and nearer to normal than the TKA limb when compared to healthy controls and patients with knee OA. The greatest difference was observed between the transition of weight acceptance and midstance (p = 0.008), when 22% more load was taken by the UKA side.

CONCLUSION

By using a dynamic metric of an everyday activity, a distinct gait difference between differing arthroplasty types were established. A more natural loading pattern can be achieved with unicompartmentals as compared to total knees.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Augmenting propulsion demands during split-belt walking increases locomotor adaptation of asymmetric step lengths

Background

Promising studies have shown that the gait symmetry of individuals with hemiparesis due to brain lesions, such as stroke, can improve through motor adaptation protocols forcing patients to use their affected limb more. However, little is known about how to facilitate this process. Here we asked if increasing propulsion demands during split-belt walking (i.e., legs moving at different speeds) leads to more motor adaptation and more symmetric gait in survivors of a stroke, as we previously observed in subjects without neurological disorders.

Methods

We investigated the effect of propulsion forces on locomotor adaptation during and after split-belt walking in the asymmetric motor system post-stroke. To test this, 12 subjects in the chronic phase post-stroke experienced a split-belt protocol in a flat and incline session so as to contrast the effects of two different propulsion demands. Step length asymmetry and propulsion forces were used to compare the motor behavior between the two sessions because these are clinically relevant measures that are altered by split-belt walking.

Results

The incline session resulted in more symmetric step lengths during late split-belt walking and larger after-effects following split-belt walking. In both testing sessions, subjects who have had a stroke adapted to regain speed and slope-specific leg orientations similarly to young, intact adults. Importantly, leg orientations, which were set by kinetic demands, during baseline walking were predictive of those achieved during split-belt walking, which in turn predicted each individual’s post-adaptation behavior. These results are relevant because they provide evidence that survivors of a stroke can generate the leg-specific forces to walk more symmetrically, but also because we provide insight into factors underlying the therapeutic effect of split-belt walking.

Conclusions

Individuals post-stroke at a chronic stage can adapt more during split-belt walking and have greater after-effects when propulsion demands are augmented by inclining the treadmill surface. Our results are promising since they suggest that increasing propulsion demands during paradigms that force patients to use their paretic side more could correct gait asymmetries post-stroke more effectively.

Gait Recognition via Deep Learning of the Center-of-Pressure Trajectory

The fact that every human has a distinctive walking style has prompted a proposal to use gait recognition as an identification criterion. Using end-to-end learning, I investigated whether the center-of-pressure (COP) trajectory is sufficiently unique to identify a person with high certainty. Thirty-six adults walked for 30 min on a treadmill equipped with a force platform that continuously recorded the positions of the COP. The raw two-dimensional signals were sliced into segments of two gait cycles. A set of 20,250 segments from 30 subjects was used to configure and train convolutional neural networks (CNNs). The best CNN classified a separate set containing 2250 segments with an overall accuracy of 99.9%. A second set of 4500 segments from the six remaining subjects was then used for transfer learning. Several small subsamples of this set were selected randomly and used to fine tune the pretrained CNNs. Training with two segments per subject was sufficient to achieve 100% accuracy. The results suggest that every person produces a unique trajectory of underfoot pressures while walking and that CNNs can learn the distinctive features of these trajectories. By applying a pretrained CNN (transfer learning), a couple of strides seem enough to learn and identify new gaits. However, these promising results should be confirmed in a larger sample under realistic conditions.

Gait after Birmingham Hip Resurfacing: an age-matched controlled prospective study

Aims

The aim of this study was to assess the functional gain achieved following hip resurfacing arthroplasty (HRA).

Patients and Methods

A total of 28 patients (23 male, five female; mean age, 56 years (25 to 73)) awaiting Birmingham HRA volunteered for this prospective gait study, with an age-matched control group of 26 healthy adults (16 male, ten female; mean age, 56 years (33 to 84)). The Oxford Hip Score (OHS) and gait analysis using an instrumented treadmill were used preoperatively and more than two years postoperatively to measure the functional change attributable to the intervention.

Results

The mean OHS improved significantly from 27 to 46 points (p < 0.001) at a mean of 29 months (12 to 60) after HRA. The mean metal ion levels at a mean 32 months (13 to 60) postoperatively were 1.71 (0.77 to 4.83) µg/l (ppb) and 1.77 (0.68 to 4.16) µg/l (ppb) for cobalt and chromium, respectively. When compared with healthy controls, preoperative patients overloaded the contralateral good hip, limping significantly. After HRA, patients walked at high speeds, with symmetrical gait, statistically indistinguishable from healthy controls over almost all characteristics. The control group could only be distinguished by an increased push-off force at higher speeds, which may reflect the operative approach.

Conclusion

Patients undergoing HRA improved their preoperative gait pattern of a significant limp to a symmetrical gait at high speeds and on inclines, almost indistinguishable from normal controls. HRA with an approved device offers substantial functional gains, almost indistinguishable from healthy controls.

Cite this article: Bone Joint J 2019;101-B:1423–1430.

An improved technique for increasing the accuracy of joint-to-ground distance tracking in kinect v2 for foot-off and foot contact detection

The Kinect sensor has been widely used in different applications such as rehabilitation and gait analysis. Whilst Kinect v2 was released with several improvements over its predecessor, it still incorporates depth-map intrinsic inaccuracies. This results in inconsistencies in skeletal-data acquisition, especially in joint localisation and distance-to-ground tracking with respect to the Kinect's 3-D Cartesian coordinate reference point. This research proposes a correction technique based on the two-point linear equation derived from the information gathered from different subjects' skeletal data and data regression analysis to compensate the inaccuracies in joint-to-ground data collection. The research also proposes a new footsteps detection method based on skeletal data and plane detection techniques that calculates a footstep by using the ankle's Euclidean distance from the floor, regardless of the subject's distance from the camera. The results show that after the correction technique was applied, data acquisition proved to be consistent and more accurate within a distance range of 1.6-2.9 m from the Kinect camera, regardless of the subject's location to the camera's reference point. Moreover, the inconsistency of joint data read by the Kinect was reduced from 25.69% to 5.25% and the footsteps detection accuracy increased from 42.85% to 79.76% on average for both legs.

Force measurements during running on different instrumented treadmills

One method to determine the forces produced during running is to conduct extensive kinematic and kinetic analysis. These analyses can be performed by having an individual perform repeated over-ground running trials or simply run continuously on an instrumented treadmill. The forces produced during over-ground running may not be the same as the forces during treadmill running and these differences could be attributed to a number of factors, including the design of the instrumented treadmill. The purpose of this paper was to determine whether there are differences in force measurements on different instrumented treadmill setups in comparison to over-ground running and to correct for any of these differences using a theoretical model. 11 participants ran on three different treadmills and performed over-ground running at 2.7, 3.6, and 4.5 m/s. Ground reaction forces were measured via force plates and an instrumented pressure insole. We found that the magnitude of the vertical ground reaction force differed between the three treadmills and over-ground running. The difference in ground reaction forces estimated by the pressure insole and the treadmill-force-plate system or instrumented treadmill can be explained by a three degree of freedom mechanical model of a person running on a treadmill and this model could potentially be used to correct for errors in force measurement from instrumented treadmills. The model included a force plate, a treadmill, and a wobbling mass with varying natural frequencies and damping characteristics, and constant masses. These findings provide researchers a method to correct forces from an instrumented treadmill set-up to determine a close approximation of the actual forces experienced by a participant during treadmill running.

Large Propulsion Demands Increase Locomotor Adaptation at the Expense of Step Length Symmetry

There is an interest to identify factors facilitating locomotor adaptation induced by split-belt walking (i.e., legs moving at different speeds) because of its clinical potential. We hypothesized that augmenting braking forces, rather than propulsion forces, experienced at the feet would increase locomotor adaptation during and after split-belt walking. To test this, forces were modulated during split-belt walking with distinct slopes: incline (larger propulsion than braking), decline (larger braking than propulsion), and flat (similar propulsion and braking). Step length asymmetry was compared between groups because it is a clinically relevant measure robustly adapted on split-belt treadmills. Unexpectedly, the group with larger propulsion demands (i.e., the incline group) changed their gait the most during adaptation, reached their final adapted state more quickly, and had larger after-effects when the split-belt perturbation was removed. We also found that subjects who experienced larger disruptions of propulsion forces in early adaptation exhibited greater after-effects, which further highlights the catalytic role of propulsion forces on locomotor adaptation. The relevance of mechanical demands on shaping our movements was also indicated by the steady state split-belt behavior, during which each group recovered their baseline leg orientation to meet leg-specific force demands at the expense of step length symmetry. Notably, the flat group was nearly symmetric, whereas the incline and decline group overshot and undershot step length symmetry, respectively. Taken together, our results indicate that forces propelling the body facilitate gait changes during and after split-belt walking. Therefore, the particular propulsion demands to walk on a split-belt treadmill might explain the gait symmetry improvements in hemiparetic gait following split-belt training.

Repeatability of spatiotemporal, plantar pressure and force parameters during treadmill walking and running

BACKGROUND

Instrumented treadmills with integrated pressure mats measure spatiotemporal, pressure and force parameters and are often used to investigate changes in gait patterns due to injury or rehabilitation.

RESEARCH QUESTION

What is the within- and between-day repeatability of such an instrumented treadmill for spatiotemporal parameters, peak pressures and forces during walking and running?

METHODS

Treadmill gait and running analysis were performed at 5.0, 6.5, and 9.0 km/h in 33 healthy adults (age: 31.6 ± 7.4 years; body mass index: 23.8 ± 3.2 kg/m²) once on day 1 and twice on day 7. For all three speeds, intraclass correlation coefficents (ICC) and smallest detectable differences (SDC) corresponding to 95% limits of agreement were calculated for spatiotemporal parameters and peak pressures and forces in the heel, midfoot, and forefoot regions.

RESULTS

All spatiotemporal parameters and peak forces in the heel, midfoot, and forefoot regions showed a good within- and between-day repeatability (ICCs > 0.878) for all gait speeds with within-day repeatability being generally higher. For peak pressures, only the heel and forefoot regions but not the midfoot region, showed good repeatability (ICC > 0.9) at all gait speeds. SDCs ranged from 1.5 to 2.5° for foot rotation, 4.4 to 6.6 cm for stride length, 0.7 to 2.5% for length of stance phases, and 2.8 to 9.2 N/cm² for peak pressures in all foot regions. For walking, SDCs of peak forces in the heel, midfoot and forefoot regions were below 60 N, and for running below 135 N.

SIGNIFICANCE

Except for peak pressures in the midfoot, spatiotemporal and kinetic gait parameters during walking and running showed a good within- and between-day repeatability. Hence, the investigated treadmill is suitable to analyze gait patterns and changes in gait patterns due to interventions.

The effect of uphill and downhill walking on gait parameters: A self-paced treadmill study

It has been shown that gait parameters vary systematically with the slope of the surface when walking uphill (UH) or downhill (DH) (Andriacchi et al., 1977; Crowe et al., 1996; Kawamura et al., 1991; Kirtley et al., 1985; McIntosh et al., 2006; Sun et al., 1996). However, gait trials performed on inclined surfaces have been subject to certain technical limitations including using fixed speed treadmills (TMs) or, alternatively, sampling only a few gait cycles on inclined ramps. Further, prior work has not analyzed upper body kinematics. This study aims to investigate effects of slope on gait parameters using a self-paced TM (SPTM) which facilitates more natural walking, including measuring upper body kinematics and gait coordination parameters. Gait of 11 young healthy participants was sampled during walking in steady state speed. Measurements were made at slopes of +10°, 0° and -10°. Force plates and a motion capture system were used to reconstruct twenty spatiotemporal gait parameters. For validation, previously described parameters were compared with the literature, and novel parameters measuring upper body kinematics and bilateral gait coordination were also analyzed. Results showed that most lower and upper body gait parameters were affected by walking slope angle. Specifically, UH walking had a higher impact on gait kinematics than DH walking. However, gait coordination parameters were not affected by walking slope, suggesting that gait asymmetry, left-right coordination and gait variability are robust characteristics of walking. The findings of the study are discussed in reference to a potential combined effect of slope and gait speed. Follow-up studies are needed to explore the relative effects of each of these factors.