Level Walking Research Articles

Effects of Unity Prosthetic Elevated Vacuum Suspension System on Minimum Swing Toe Clearance.

The risk of tripping in people with amputation is greater than that of able-bodied individuals due to reduced toe clearance during the swing phase. Appropriate prosthetic suspension may increase toe clearance by providing more secured attachment between the residual limb and prosthetic socket. Research is lacking on the Unity suspension system's effect on swing toe clearance. Twelve people with transtibial amputation were fitted with the Unity suspension system. After one month accommodation period, the person walked with active (ON) or inactive vacuum (OFF) in a CAREN-Extended virtual reality system, across multiple simulated real-world scenarios. Prosthetics minimum swing toe clearance, and kinematic data, while the vacuum was ON or OFF, were compared with the intact side and a group of 12 able-bodied individuals. Minimum swing toe clearance (MSTC) and knee flexion angle were larger on the prosthetic side (active and inactive vacuum) compared to both the intact side and the control group. However, hip flexion angle on the prosthetic side was approximately 17% smaller than the control group. Unlike the control group, MSTC with active and inactive vacuum suspension was not significantly different between level walking and other walking conditions. Finally, among all walking conditions, the lowest swing toe clearance for both control and the amputee groups was recorded when the limb was at the top of a side-slope. An effective suspension system could improve toe clearance; however, significant differences were not found between active and inactive vacuum conditions. The likelihood of inappropriate foot contact on side-slope ground might be greater than other walking conditions for both able-bodied and amputee groups, possibly leading to stumbling or falling.

Neuromuscular Age-Related Adjustment of Gait When Moving Upwards and Downwards.

Locomotor movements are accommodated to various surface conditions by means of specific locomotor adjustments. This study examined underlying age-related differences in neuromuscular control during level walking and on a positive or negative slope, and during stepping upstairs and downstairs. Ten elderly and eight young adults walked on a treadmill at two different speeds and at three different inclinations (0°, +6°, and −6°). They were also asked to ascend and descend stairs at self-selected speeds. Full body kinematics and surface electromyography of 12 lower-limb muscles were recorded. We compared the intersegmental coordination, muscle activity, and corresponding modifications of spinal motoneuronal output in young and older adults. Despite great similarity between the neuromuscular control of young and older adults, our findings highlight subtle age-related differences in all conditions, potentially reflecting systematic age-related adjustments of the neuromuscular control of locomotion across various support surfaces. The main distinctive feature of walking in older adults is a significantly wider and earlier activation of muscles innervated by the sacral segments. These changes in neuromuscular control are reflected in a reduction or lack of propulsion observed at the end of stance in older adults at different slopes, with the result of a delay in the timing of redirection of the centre-of-mass velocity and of an unanticipated step-to-step transition strategy.

Model Based Design of a Low Cost and Compliant Low Profile Prosthetic Foot.

This paper describes the design of a simple and low-cost compliant low-profile prosthetic foot based on a cantilevered beam of uniform strength. The prosthetic foot is developed such that the maximum stress experienced by the beam is distributed approximately evenly across the length of the beam. Due to this stress distribution, the prosthetic foot exhibits compliant behavior not achievable through standard design approaches (e.g., designs based on simple cantilevered beams). Additionally, due to its simplicity and use of flat structural members, the foot can be manufactured at low cost. An analytical model of the compliant behavior of the beam is developed that facilitates rapid design changes to vary foot size and stiffness. A characteristic prototype was designed and constructed to be used in both a benchtop quasi-static loading test as well as a dynamic walking test for validation. The model predicted the rotational stiffness of the prototype with 5% error. Furthermore, the prototype foot was tested alongside two commercially available prosthetic feet (a low profile foot and an energy storage and release foot) in level walking experiments with a single study participant. The prototype foot displayed the lowest stiffness of the three feet (6.0, 7.1, and 10.4 Nm/deg for the prototype foot, the commercial low profile foot, and the energy storage and release foot, respectively). This foot design approach and accompanying model may allow for compliant feet to be developed for individuals with long residual limbs.

Vertical locomotion in the arboreal salamander Aneides vagrans

AbstractSalamanders are often used as a model of early tetrapod locomotion, due to their generalized tetrapod body plan. We imaged five individuals of wandering salamander, Aneides vagrans, during horizontal and vertical locomotion and compared kinematic and gait adjustments made to compensate for each condition. We used ImageJ to calculate duty factor, stride length, stride frequency, contralateral foot spread, heading of climbing, and forward velocity. Like other terrestrial salamanders, A. vagrans use a diagonal couplet, lateral sequence walk on horizontal surfaces. When walking vertically, however, they use a single‐foot gait, taking smaller steps and extending the duty factor compared with level walking. Salamanders adjusted their limbs to have a wider contralateral foot spread between fore‐ and hindfeet when walking downward as compared to walking upward or horizontally. These gait adjustments may minimize the risk of slipping or falling by increasing the number of contact points during the stride cycle, and by bringing their center of mass closer to the surface. We found that salamanders moved at a significantly faster velocity when traveling horizontally compared to vertically. Furthermore, we found no significant difference between upward and downward velocity, despite greater stride lengths in upward locomotion; this was explained by a higher stride frequency in downward locomotion. We estimate travel time up or down an old‐growth redwood tree to be on the scale of hours, a significant time investment that may encourage alternatives when available. These results suggest that, in an ecological context, while salamanders are capable of traveling straight down a redwood tree, they may simply tend to jump.

Recovery of gait and function during the first six months after tibial shaft fractures

BackgroundTibial shaft fractures require surgical stabilization preferably by intramedullary nailing. Recovery is often unsatisfactory due to limited knee function and pain, resulting in reduced quality of life. The extent of these functional limitations with respect to gait deficits has not been sufficiently recognized. Research questionAre there functional limitations during gait and squat performance during the first six months after surgically treated tibial shaft fractures? MethodsTwenty-three patients (BMI: 24 ± 3, Age:39 ± 15) with tibial shaft fractures and 23 healthy, matched controls (BMI: 24 ± 3, Age: 40 ± 14) were assessed using instrumented motion analysis two, three and six months after surgery. Kinematic and kinetic data of the lower extremities were collected during level walking and squat performance. Data were compared among follow-up time intervals and between groups. ResultsSignificant improvements were found for all spatiotemporal parameters and most kinetic parameters. Even six months after surgery functional deficits persisted when compared to healthy controls. There were only slight improvements in sagittal knee and ankle kinematics as well as knee moments and power within the follow-up period. A significant difference compared to the healthy controls can still be observed in these parameters. SignificanceAlthough patients with tibia fractures demonstrated functional improvements over the early course of healing, some residual deficits in lower extremity movement biomechanics were identified at six months post surgery. In particular knee kinematics in squatting as well as knee kinematics and kinetics during walking only recovered incompletely. This result can help explain the often-reported functional limitations.Clinical Trial Registration number: German register for clinical trials (DRKS00023790).

Lower limb joint angles and their variability during uphill walking.

Adaptation of the walking pattern to uphill walking demands immediate coordination between the lower limb segments. Nonetheless, knowledge about individual joints' responses and variability in response to the new slope angles are missing. This study investigated the impacts of uphill walking on the ankle, the knee and the hip joints angles and their variability. Twenty-three collegiate athletes (age: 22.04 ± 3.43years, body mass: 62.14 ± 9.26Kg, height: 168.29 ± 7.06 cm) walked on an inclined treadmill at 0 ° (level walking -LW), 5 ° (low-slope-walking -LSW), and 10 ° (high-slope-walking -HSW) slopes at their preferred walking speed (4.2 ± 0.51 km.h-1). The ankle, knee and hip joints angles and their variability (standard deviations) were calculated and analysed throughout the gait cycles in LW, LSW, and HSW. Repeated measure ANOVA portrayed significant differences between the ankle joint angles in sagittal (p < .001, ηp2>.14), frontal (p < .05, ηp2>.14), and transverse (p < .005, .14 < ηp2>.01) planes. In the knee joint, the sagittal (p < .001, ηp2>.14), frontal (p < .05, ηp2>.14), and transverse (p < .05, ηp2>.14) angles were significantly different (p < 0.05). Similarly, in the hip joint, the sagittal (p < .05, ηp2>.14), frontal (p < .05, ηp2>.14), and transverse (p < .05, ηp2>.14) angles were significantly different. Ankle angle variability was significantly different in sagittal (P < .001, ηp2>.14), frontal (p = .002, ηp2>.14) and horizontal (P < .001, ηp2>.14) planes, as well as knee joint angle variability in sagittal, frontal and horizontal planes p < 0.001, ηp2>.14. The hip joint variability was considerably different in sagittal (p = .031, ηp2>.14) and horizontal (p < .05, ηp2>.14) planes. Uphill walking involves further modifications in the ankle, knee and hip joints angle to adjust the whole-body movements to a new slope. This adjustment resulted in a firm base of support, provided by the ankle, to regulate the knee and hip joints modifications. Nevertheless, it caused less ankle movement variability and could end up with injuries over long-term uphill walking.

Tibial baseplate position and posterior cruciate ligament status impact patient-reported outcomes in conforming dual-pivot bearing total knee arthroplasty.

BackgroundIn an effort to optimize clinical outcomes and enhance stability, ultracongruent bearings have been increasingly used in primary total knee arthroplasty (TKA). The importance of the posterior cruciate ligament (PCL) and optimal sagittal tibial baseplate position in ultracongruent bearing TKA remains unknown. This study sought to determine whether these modifiable, surgical-technique-dependent variables meaningfully impact patient-reported outcome measures.MethodsA total of 759 primary TKAs of the same dual-pivot design performed using a consistent surgical technique between January 2016 and April 2019 were retrospectively reviewed. PCL status was recorded, and anteroposterior (AP) tibial baseplate position and posterior tibial slope were measured by two independent blinded raters. Patient-reported outcomes related to pain, function, satisfaction, and activity level were analyzed in relationship to PCL status, posterior tibial slope, and AP tibial baseplate position, in addition to other pertinent covariates.ResultsMedian age and body mass index of the cohort were 68.3 years and 33.4 kg/m2, respectively, with 73% being female. In multivariate analysis, partial or full release of the PCL was predictive of a knee “always” feeling normal (odds ratio 1.42, P = .041). Furthermore, tibial baseplate position closer to the middle of the tibia was associated with greater improvements in pain with level walking, pain while climbing stairs, and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement total scores (P ≤ .079).ConclusionIn congruent dual-pivot bearing TKA, partially or fully releasing the PCL and AP tibial baseplate position closer to the middle of the tibia may provide greater improvement in pain and function scores at minimum 1-year follow-up.

Balance control and lower limb joint work in children with bilateral genu valgum during level walking.

Genu valgum results in lower limb malalignment and altered joint mechanics. The study aimed to identify the effects of genu valgum on balance control and muscular work at the joints during gait in children. Would bilateral genu valgum affect balance control and muscular work at the joints during gait in children? Thirteen children with genu valgum and thirteen healthy peers walked at their preferred speed while the body's motions and ground reaction forces were measured to calculate the inclination angles (IA) and the rates of change of IA (RCIA) of the body's center of mass (COM) relative to the center of pressure (COP), as well as the muscular work done at the joints. An independent t-test was used to compare the variables between groups (α = 0.05). Compared to the controls, the patients showed significantly increased step width with altered frontal IA and RCIA variables (p < 0.05), including increased average IA over single-limb support and increased peak RCIA during double-limb support (p < 0.05). The patients significantly increased posterior RCIA at heel-strike but decreased anterior RCIA at toe-off (p < 0.05). The patients showed increased muscular work at both the hip and knee during single-limb support (p < 0.05). The children with genu valgum showed a specific balance control strategy during gait. In the frontal plane, greater hip and knee muscular work was needed to maintain balance under an increased IA, likely owing to increased step width associated with the valgus alignment. In the sagittal plane, less smooth and less stable COM-COP control with increased RCIA at the key gait events indicates faster weight transfer between double-limb and single-limb support. It is suggested that patients with genu valgum, especially in more severe cases, should be monitored for signs of decreased ability and/or muscular strength in maintaining balance during gait.

An Inertial Sensor-Based Gait Analysis Pipeline for the Assessment of Real-World Stair Ambulation Parameters.

Climbing stairs is a fundamental part of daily life, adding additional demands on the postural control system compared to level walking. Although real-world gait analysis studies likely contain stair ambulation sequences, algorithms dedicated to the analysis of such activities are still missing. Therefore, we propose a new gait analysis pipeline for foot-worn inertial sensors, which can segment, parametrize, and classify strides from continuous gait sequences that include level walking, stair ascending, and stair descending. For segmentation, an existing approach based on the hidden Markov model and a feature-based gait event detection were extended, reaching an average segmentation F1 score of 98.5% and gait event timing errors below ±10 for all conditions. Stride types were classified with an accuracy of 98.2% using spatial features derived from a Kalman filter-based trajectory reconstruction. The evaluation was performed on a dataset of 20 healthy participants walking on three different staircases at different speeds. The entire pipeline was additionally validated end-to-end on an independent dataset of 13 Parkinson’s disease patients. The presented work aims to extend real-world gait analysis by including stair ambulation parameters in order to gain new insights into mobility impairments that can be linked to clinically relevant conditions such as a patient’s fall risk and disease state or progression.

Dynamic alignment changes during level walking in patients with dropped head syndrome: analyses using a three-dimensional motion analysis system

In patients with dropped head syndrome (DHS), cervical malalignment is one of the risk factors for impaired horizontal gaze and restrictions to ambulation. The characteristics of gait in patients with DHS have not been clarified biomechanically from the viewpoint of dynamic alignment and lower limb kinematics. This study aimed to clarify kinematic and kinetic differences during level walking in patients with DHS compared to the healthy elderly. Twelve patients with DHS and healthy elderly individuals performed level walking at a self-selected speed. Spatiotemporal, kinematic, and kinetic data were recorded using a three-dimensional motion analysis system. Statistical analysis was performed to compare these data between the two groups, respectively. Compared with the healthy elderly, stride length and peak hip-joint extension angle in patients with DHS were significantly shorter and smaller. The thorax was also significantly tilted backwards. Peak ankle-joint plantar-flexion moment was significantly smaller despite larger dorsiflexion angle compared with the healthy elderly. The walking of DHS patients demonstrated kinematic and kinetic characteristics of the lower limb joints and alignment of the thorax and pelvis corresponding to their short stride and walking speed.

Task dependent changes in mechanical and biomechanical measures result from manipulating stiffness settings in a prosthetic foot

BackgroundAdaptation of lower limb function to different gait tasks is inherently not as effective among individuals with lower limb amputation as compared to able-bodied individuals. Varying stiffness of a prosthetic foot may be a way of facilitating gait tasks that require larger ankle joint range of motion. MethodsThree stiffness settings of a novel prosthetic foot design were tested for level walking at three speeds as well as for 7,5° incline and decline walking. Outcome measures, describing ankle range of motion and ankle dynamic joint stiffness were contrasted across the three stiffness settings. Standardized mechanical tests were done for the hindfoot and forefoot. FindingsDorsiflexion angle was incrementally increased with a softer foot and a faster walking speed / higher degree of slope. The concurrent dynamic joint stiffness exhibited a less systematic change, especially during INCLINE and DECLINE walking. The small difference seen between the stiffness settings for hindfoot loading limits analysis for the effects of stiffness during weight acceptance, however, a stiffer foot significantly restricted plantarflexion during DECLINE. InterpretationsVarying stiffness settings within a prosthetic foot does have an effect on prosthetic foot dynamics, and differences are task dependent, specifically in parameters involving kinetic attributes. When considering the need for increased ankle range of motion while performing more demanding gait tasks, a foot that allows the users themselves to adjust stiffness according to the task at hand may be of benefit for active individuals, possibly enhancing the user's satisfaction and comfort during various daily activities.

The correlation between posterior tibial slope and dynamic anterior tibial translation and dynamic range of tibial rotation

PurposeThe amount of passive anterior tibial translation (ATT) is known to be correlated to the amount of posterior tibial slope (PTS) in both anterior cruciate ligament-deficient and reconstructed knees. Slope-altering osteotomies are advised when graft failure after anterior cruciate ligament (ACL) reconstruction occurs in the presence of high PTS. This recommendation is based on studies neglecting the influence of muscle activation. On the other hand, if dynamic range of tibial rotation (rTR) is related to the amount of PTS, a “simple” anterior closing-wedge osteotomy might not be sufficient to control for tibial rotation. The purpose of this study was to evaluate the correlation between the amount of PTS and dynamic ATT and tibial rotation during high demanding activities, both before and after ACL reconstruction. We hypothesized that both ATT and rTR are strongly correlated to the amount of PTS.MethodsTen subjects were studied both within three months after ACL injury and one year after ACL reconstruction. Dynamic ATT and dynamic rTR were measured using a motion-capture system during level walking, during a single-leg hop for distance and during a side jump. Both medial and lateral PTS were measured on MRI. A difference between medial and lateral PTS was calculated and referred to as Δ PTS. Spearman’s correlation coefficients were calculated for the correlation between medial PTS, lateral PTS and Δ PTS and ATT and between medial PTS, lateral PTS and Δ PTS and rTR.ResultsLittle (if any) to weak correlations were found between medial, lateral and Δ PTS and dynamic ATT both before and after ACL reconstruction. On the other hand, a moderate-to-strong correlation was found between medial PTS, lateral PTS and Δ PTS and dynamic rTR one year after ACL reconstruction.ConclusionDuring high-demand tasks, dynamic ATT is not correlated to PTS. A compensation mechanism may be responsible for the difference between passive and dynamic ATT in terms of the correlation to PTS. A moderate-to-strong correlation between amount of PTS and rTR indicates that such a compensation mechanism may fall short in correcting for rTR. These findings warrant prudence in the use of a pure anterior closing wedge osteotomy in ACL reconstruction.Trial registrationNetherlands Trial Register, Trial 7686. Registered 16 April 2016—Retrospectively registered.Level of evidenceLevel 2, prospective cohort study

The impact of transfemoral socket adduction on pelvic and trunk stabilization during level walking - A biomechanical study.

It is common practice to align transfemoral prosthetic sockets in adduction, due to the physiologic, adducted femoral alignment in unimpaired legs. An adducted femoral and socket alignment helps tightening hip abductors to stabilize the pelvis and reduce pelvic and trunk related compensatory movements. How do different socket adduction conditions (SAC) of transfemoral sockets affect pelvic and trunk stabilization during level ground walking in the frontal plane? Seven persons with transfemoral amputation with medium residual limb length participated in this study. The prosthetic alignment in the sagittal plane was performed according to established recommendations. SAC varied (0°, 3°, 6°, 9°). Kinematic and kinetic parameters were recorded in a gait laboratory with a 12-camera optoelectronic system and two piezoelectric force plates embedded in a 12-m walkway. The measurements were performed during level ground walking with self-selected comfortable gait speed. In the frontal plane, nearly all investigated kinematic and kinetic parameters showed a strong correlation with the SAC. The pelvis was raised on the contralateral side throughout the gait cycle with increasing SAC. During the prosthetic side stance phase, the mean shoulder obliquity and mean lateral trunk lean to the prosthetic side tended to be reduced with increased SAC. Prosthetic side hip abduction moment decreased with increasing SAC. The results confirm that transfemoral SAC contributes to pelvic stabilization and reduced compensatory movements of the pelvis and trunk. Transfemoral SAC of 6 ± 1° for bench alignment seems adequate for amputees with medium residual limb length. However, the optimum value for the individual patient may differ slightly.

Changes in lower-limb joint torques when using a passive back-support exoskeleton for level walking

Changes in lower-limb joint torques when using a passive back-support exoskeleton for level walking

Kinematic Alterations After Anterior Cruciate Ligament Reconstruction via Transtibial Techniques With Medial Meniscal Repair Versus Partial Medial Meniscectomy

Background: The treatment strategies for meniscal injuries during anterior cruciate ligament (ACL) reconstruction remain a topic of debate. Hypothesis: After ACL reconstruction, knee kinematics would be affected by different medial meniscal treatment (partial medial meniscectomy [PMM] and medial meniscal repair [MMR]). Study Design: Controlled laboratory study. Methods: A total of 161 patients underwent primary single-bundle ACL reconstruction and simultaneous medial meniscal treatment. Of these, 32 patients were eligible to participate in the kinematic assessment at 24.8 ± 1.7 months after surgery. Patients were divided into 2 groups: (1) those who underwent MMR (Group MMR; n = 18) and (2) those who underwent PMM (Group PMM; n = 14). Twenty healthy participants (Group Intact) were recruited who were comparable in age, body mass index, and sex. The kinematic parameters were collected using an optical tracking system during treadmill gait. Range of motion and kinematic parameters at key events during the gait cycle were compared between the 3 groups. The primary outcomes were the differences in adduction/abduction and internal/external rotation. Results: Patients in Group PMM walked with increased adduction as compared with those in Group Intact during the early stance phase (P = .003; η2 = 0.172) and midstance phase (P = .003; η2 = 0.167). In terms of internal/external rotation, patients in Group PMM walked with significantly larger tibial external rotation when compared with Group MMR by approximately 3.4° to 3.7° (loading response: P = .026, η2 = 0.090; midstance: P = .035, η2 = 0.093) and Group Intact (P = .028; η2 = 0.095) in the early stance phase. In addition, there was significantly increased anterior tibial translation in Groups MMR and PMM compared with Group Intact. Conclusion: ACL reconstruction (via transtibial technique) with concurrent PMM demonstrated larger adduction and external tibial rotation at 24 months of follow-up during level walking. Clinical Relevance: Patients undergoing different medial meniscal treatment strategies in the presence of ACL reconstruction showed distinct knee kinematics. These results suggest that MMR is strongly recommended during ACL reconstructive surgery to reduce the abnormal kinematics close to that of the ACL-intact condition.

Hip Joint Kinematic Covariation During Gait Before and 1-Year After Hip Arthroscopic Surgery for Femoroacetabular Impingement Syndrome.

The primary aim of this study was to determine if the three-dimensional (3D) hip joint motion coordination during gait changes after arthroscopic surgery for femoroacetabular impingement syndrome (FAIS). Three-dimensional hip joint kinematic data were collected with a 12-camera motion capture system. Five trials of level walking were collected preoperatively (PRE) and at 1-year postoperatively (POST) in 8 patients diagnosed with FAIS and at a single time point in 8 healthy controls. Planar covariation analysis was performed to quantify the 3D hip joint motion coordination strategy during gait. Independent sample's t-test were used to determine differences between the FAIS group at the preoperative time point (PRE) and healthy controls. Paired samples t-tests were used to determine differences between the PRE and POST time points within the FAIS group. The %VAF by PC 1 for the FAIS group at the PRE time point was significantly less than that of healthy controls (PRE: 77.2 ± 8.7% vs. Control: 96.1 ± 2.8%; p = 0.0001), and the % VAF of the second PC (PC2) was significantly greater [PRE: 22.8 (8.7)%; Control: 3.9 (2.8)%; p = 0.0001]. No differences in %VAF were found between the PRE and POST time points within the FAIS group for PC1 [PRE: 77.2 (8.7)% vs. POST: 79.3 (11.1)%; p = 0.472] or PC2 [PRE: 22.7 (8.7)%; POST: 20.7 (11.1)%; p = 0.472]. Significant differences in the plane specific contribution to the 3D motion coordination strategy were found between the FAIS patients at the PRE and POST time points for the sagittal plane [PRE: 5.6 (2.7) vs. POST: 0.91 (6.1); p = 0.012] and frontal plane [PRE: −10.4 (2.2) and −1.5 (6.3); p = 0.005]. Patients with FAIS demonstrated a more complex coordination strategy of 3D hip joint motion than controls and this strategy remains unchanged after hip arthroscopic surgery despite changes in the plane specific contribution to this strategy. These findings indicate that motor control impairments in FAIS patients do exist and seem to persist for at least 1 year after hip arthroscopic surgery.

Gait Kinematic and Kinetic Characteristics of Older Adults With Mild Cognitive Impairment and Subjective Cognitive Decline: A Cross-Sectional Study.

BackgroundOlder adults with mild cognitive impairment (MCI) have slower gait speed and poor gait performance under dual-task conditions. However, gait kinematic and kinetic characteristics in older adults with MCI or subjective cognitive decline (SCD) remain unknown. This study was designed to explore the difference in gait kinematics and kinetics during level walking among older people with MCI, SCD, and normal cognition (NC).MethodsThis cross-sectional study recruited 181 participants from July to December 2019; only 82 met the inclusion criteria and consented to participate and only 79 completed gait analysis. Kinematic and kinetic data were obtained using three-dimensional motion capture system during level walking, and joint movements of the lower limbs in the sagittal plane were analyzed by Visual 3D software. Differences in gait kinematics and kinetics among the groups were analyzed using multivariate analysis of covariance (MANCOVA) with Bonferroni post-hoc analysis. After adjusting for multiple comparisons, the significance level was p < 0.002 for MANCOVA and p < 0.0008 for post-hoc analysis.ResultsTwenty-two participants were MCI [mean ± standard deviation (SD) age, 71.23 ± 6.65 years], 33 were SCD (age, 72.73 ± 5.25 years), and 24 were NC (age, 71.96 ± 5.30 years). MANCOVA adjusted for age, gender, body mass index (BMI), gait speed, years of education, diabetes mellitus, and Geriatric Depression Scale (GDS) revealed a significant multivariate effect of group in knee peak extension angle (F = 8.77, p < 0.0001) and knee heel strike angle (F = 8.07, p = 0.001) on the right side. Post-hoc comparisons with Bonferroni correction showed a significant increase of 5.91° in knee peak extension angle (p < 0.0001) and a noticeable decrease of 6.21°in knee heel strike angle (p = 0.001) in MCI compared with NC on the right side. However, no significant intergroup difference was found in gait kinetics, including dorsiflexion, plantar flexion, knee flexion, knee extension, hip flexion, and hip extension(p > 0.002).ConclusionAn increase of right knee peak extension angle and a decrease of right knee heel strike angle during level walking were found among older adults with MCI compared to those with NC.

Effects Of Clbp On Physical Stability Of The Elderly When Crossing Obstacles Of Different Heights

In the context of global aging, low back pain, as one of the chronic pain diseases with high incidence in the elderly, seriously affects their daily life. Previous studies mainly focused on level walking strategy. However, there is a paucity of research investigating how the elderly patients with chronic low back pain (CLBP) negotiate obstacles, which may better reflect the complexity of the real environment. PURPOSE: To explore the changes in the physical stability of the elderly patients with CLBP when crossing obstacles of different heights. METHODS: Sixteen elderly patients with CLBP (67.9 ± 5.4 yrs) were included as CLBP group, and nineteen healthy older adults (69.1 ± 5.8 yrs) were included as control (CONT) group. All the participants were invited to cross obstacles of different heights (level walking, crossing obstacles of 20% and 30% of leg length) in this study. A motion analysis system and two force plates were used to collect experimental data synchronously. Two-way (group by heights) ANOVA with repeated measures was used to evaluate the intervention effects on each variable. RESULTS: CLBP group had lower stride length (1.18 ± 0.08 vs. 1.26 ± 0.13 m, p < 0.05) and walking speed(1.08 ± 0.12 vs. 1.17 ± 0.13 m/s, p < 0.05) compared with CONT group during level walking. CLBP group had a higher support time(98.59 ± 10.31 vs. 91.82 ± 7.83 s, p < 0.05) during 30% of leg length obstacle-crossing. There were no significant differences in hip/knee/ankle joint moments and joint angles between two groups under three different crossing heights (p > 0.05) conditions. CONCLUSIONS: The elderly patients with CLBP adopt a conservative walking strategy when walking on level ground, which leads to the decline of physical stability. However, there were no significant differences in physical stability between the healthy older adult participants and CLBP participants when crossing obstacles of different heights.Fig 1

A Novel Application of Flexible Inertial Sensors for Ambulatory Measurement of Gait Kinematics

Ambulatory motion sensors can generate a mobile system for human kinematics measurement as an alternative to the more constrained optical motion capture systems. Flexible inertial sensors are emerging as a potential solution to overcome the drawback of the conventional inertial measurement sensors with a soft, flexible design that allows for direct body-conforming adhesion to the skin. Thus, this study aims to establish the viability of the flexible inertial sensors for the ambulatory measurement of human knee flexion-extension (F/E) during level walking. The accuracy of flexible inertial sensors with our proposed algorithm is investigated by comparing the derived kinematics with those measured using a conventional motion capture system. Three volunteers (two males and one female, aged 24-27) served as subjects. Three flexible inertial sensors were placed on the subjects' right legs, two on the thigh (lateral thigh and distal anterolateral thigh), and one on the lateral shank, and subjects performed level walking with varied walking cadence (80, 100, and 120 steps/min). The overall root-mean-square-error across all participants is 7.8° for distal anterolateral thigh sensor (using the data of distal anterolateral thigh sensor and shank sensor to estimate knee F/E) and 4.5° for lateral thigh sensor (using the data of lateral thigh sensor and shank sensor to estimate knee F/E). The results illustrate that our proposed method can generate comparable results with motion capture systems and is insensitive to different walking cadence. A significant effect of sensor placement is observed, and a more proximal lateral thigh strategy is suggested. The advantages of the flexible inertial sensors in human motion analysis over the existing inertial measurement units are also highlighted.

Research on Kinematic Parameters of Multiple Gait Pattern Transitions

Gait recognition technology is the key technology in the field of exoskeletons. In the current research of gait recognition technology, there is less focus on the recognition of the transition between gait patterns. This study aims to determine which kinematic parameters have significant differences in the transitions (between level and stair walking and between level and ramp walking) of different gait patterns, to determine whether these parameters change differently in different gait pattern transitions, and the order the significant differences occur through a comparative analysis of various kinematic parameters between the transition stride and the before stride in the former pattern. We analyzed 18 parameters concerning both lower limbs and trunk. We compared each time point of the transition strides to the corresponding time points of the before stride using a series of two-sample t-tests, and we then evaluated the difference between the transition stride and the before stride based upon the number of time points within the gait cycle that were statistically different. We found that the sagittal plane angular velocity and the angular acceleration of all joints and the resultant velocity of the thigh and shank of the leading limb had significant differences in the process of transition; the sagittal plane angular velocity of all joints of the trailing limb and the velocity of the trunk in the coronary axis direction also showed a significant difference. The angular acceleration of all joints, the sagittal plane angular velocity of the ankle joint of the leading limb, and the acceleration of the trunk in the coronal axis direction showed a difference in the early stage of the transition. In general, the leading limb had a significant difference earlier than the trailing limb, and the acceleration parameters changed earlier than the velocity parameters. These parameters showed different combinations of changes in the transition of different gait patterns, and the changes in these parameters reflected different gait pattern transitions. Therefore, we believe that the results of this study can provide a reference for the gait pattern transition recognition of wearable exoskeletons.