Toe Clearance Research Articles

Impact of vertical vibrations on human rhythmic jumping

This paper investigates the human ability to perform rhythmic jumping on a vertically vibrating platform by analysing kinetics and kinematics. Ten test subjects participated, performing jumping on both non-vibrating and vibrating platforms. Vibration frequencies of 2.0, 2.4, and 2.8 Hz were used, with a vibration level of 2 m/s2. The frequency of jumping matched the vibration frequency, and for the first time, the jumps were timed relative to the platform's position in the vibration cycle. A metronome prompted landings at four target positions: (i)reference position and on the way down (mid-down), (ii)lowest position (trough), (iii)reference position and on the way up (mid-up), and (iv)highest position (peak), at each frequency. The study compared the achievement of the target frequency of jumping between non-vibrating and vibrating platform conditions for each frequency. Results showed the worst performance when the target frequency was 2.8 Hz on the non-vibrating platform, confirming the difficulty of faster jumping on non-vibrating surfaces. The discrete relative phase analysis revealed a preference for landing at the trough and mid-up positions on the vibrating platform, particularly at 2.8 Hz. The preferred timing of jumps corresponded to greater toe clearance and impact ratio, but shorter contact duration compared to the non-vibrating platform. These findings hold promise for improving human-structure interaction models for assembly structures used in sports and musical events.

Design, Control, and Validation of a Polycentric Hybrid Knee Prosthesis

This paper presents a novel polycentric hybrid knee prosthesis (PHKP) by enabling a multi-bar linkage to work for high-torque activities in active mode and for low-torque activities in passive mode. The mode transition is implemented by a servo-controlled telescopic slide rails. Distinguished from the single-axis hybrid knee prostheses, the PHKP Knee provides geometric stability in stance and notably increases toe clearance in swing by using an optimally designed instantaneous center of rotation (ICR) trajectory. In active mode, the PHKP Knee provides high transmission ratio and continuous peak torque offering sufficient support for torque-demanding activities. Impedance control was employed to regulate joint torque as a response to knee motion in the active mode. It was found that due to the inherent geometric stability of the polycentric mechanism in stance, the damping coefficient of the controller can be tuned much smoother than the single-axis knees leading to more compliant and comfortable interactions among the wearer, the prosthesis and the ground. The stair ascent tests showed that the joint angle and torque profiles of the PHKP Knee are similar to those of the able-bodied by demonstrating a step-over-step pattern with a peak angle of 73 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\deg$</tex-math></inline-formula> and a maximum torque of 0.92 Nm/Kg.

Gait Analysis, Metabolic Parameters and Adherence to the Mediterranean Diet in Patients with Type 2 Diabetes Mellitus Compared with Healthy Controls: A Pilot Study.

Patients with type 2 diabetes mellitus (T2DM) are prone to developing diabetic peripheral neuropathy (DPN) with an increased risk of injuries while walking, potentially leading to plantar ulcers. We aimed to assess the early gait changes in T2DM patients without clinical signs of DPN in comparison to age-matched healthy controls (HC). One hundred T2DM patients (78 women, mean age: 66.4 ± 11.5 years) and 50 age-matched HC (34 women, mean age 62.1 ± 7.9 years) were evaluated with the PODOSmart® gait analysis device. Anthropometric and biochemical data, as well as dietary habits were collected for all participants. T2DM patients also completed the Diabetes Distress (DS) self-report validated questionnaire. One patient was excluded from the study due to lack of recent biochemical data. Among the T2DM patients, 88.9% reported little or no DS and 11.1% moderate DS. The T2DM group had higher body mass index, waist circumference, systolic blood pressure, glycated hemoglobin A1c, sodium, white blood cell count, triglycerides and low-density lipoprotein cholesterol, but lower high-density lipoprotein cholesterol than HC (p < 0.05 for all comparisons). The MedDiet score was satisfactory in both groups (p > 0.05). Significant differences were found between the two study groups in gaitline heel off, propulsion speed, foot progression angle, time taligrade phase, stride length, walking speed, angle attack, oscillation speed, pronation-supination toe off and clearance. The T2DM patients without self-reported DS or clinical signs of DPN may exhibit significant differences in several gait parameters analyzed with PODOSmart®. Whether gait analysis can be used as an early diagnostic tool of T2DM complications should be further explored.

Differences in gait parameters when crossing real versus projected everyday life obstacles in healthy children and adolescents

Practicing complex everyday life walking activities is challenging in paediatric neurorehabilitation, although it would prepare patients more comprehensively for the requirements of daily life. Floor projections allow simulation and training of such situations in therapy. Twenty healthy youths aged 6–18 years stepped over a tree trunk and balanced over kerbstones in a real and projected condition. Spatiotemporal and kinematic parameters of the two conditions were compared by equivalence analysis, using the medians of the differences between the two conditions with their bootstrapped 95% confidence intervals. Velocity, step and stride length, step width, and single support time were generally equivalent between the two conditions. Knee and hip joint angles and toe clearance decreased substantially during the execution phase of the projected tree trunk condition. The largest differences were found at the end of the execution phase in both tasks for the ankle joints. As spatiotemporal parameters were equivalent between the conditions, floor projections seem suitable to train precise foot placement. However, differences in knee and hip joint kinematics and toe clearance revealed that floor projections are not applicable for obstacles with a vertical extension. Therefore, exercises aiming at knee and hip flexion improvement should favourably be trained with real objects.

Effects of diabetes mellitus on step length and minimum toe clearance adaptation

BackgroundAdaptive gait involves the ability to adjust the leading foot in response to the requirement of dynamic environments during walking. Accurate adjustments of the minimum toe clearance (MTC) height and step length can prevent older people from falling when walking and responding to hazards. Although older people with diabetes fall more frequently than healthy older adults, no previous studies have quantified their adaptive gait abilities. This study aimed to investigate the effects of diabetes mellitus on step length and MTC height adjustments using a non-immersive virtual-reality system.MethodsSixteen young adults (26 ± 5 years, 7 females), 16 healthy older adults (68 ± 5 years, 6 females), and 16 older adults with diabetes (70 ± 5 years, 6 females) completed adaptability tests while walking on a treadmill. A computer system visualised a continuous real-time signal of absolute step length and MTC on a monitor. Each person responded to four discrete participant-specific step length and MTC visual targets that were presented on the same signal. Tasks were to match the peaks of interest on each signal to presented targets. Targets were 10% longer or shorter than the mean baseline step length, and 2.5 cm, and 3.5 cm higher than the mean baseline MTC. When a target was displayed, it remained unchanged for 10 consecutive foot displacement adaptation attempts. Then, the target was removed and a new target or the same target was present after 10 consecutive steps and remained for 10 steps. Each target was randomly presented three times (3 × 10). Step length and MTC height adjustments in response to targets were measured and compared among groups.ResultsMean preferred walking speeds were not different among groups significantly when no targets were presented on the monitor in baseline walking. However, when participants walked on a treadmill while attempting to match step lengths or MTC heights to displayed targets on the monitor, the group with diabetes had reduced step length and MTC adjustments compared with other groups significantly. They showed greater errors (differences between their step lengths/MTC heights and presented targets) on the monitor.ConclusionsThis study quantified reduced abilities for older individuals with diabetes to adjust both step length and MTC in response to stimuli compared to healthy older counterparts. Reduced step length and MTC height adjustments can increase falls in at risk populations. The presented virtual-reality system has merits for assessing and training step and MTC adaptation.

Design and Evaluation of a Wearable Biofeedback Training System to Reduce Trip-Related Falls During Level Walking

Trip-related falls are a major concern especially for older adults and individuals with gait impairments as they can lead to serious injuries, hospitalizations and negatively impact the quality of life. A low Minimum Toe Clearance (MTC) can be a predictor of tripping risk and thus, increasing the MTC is a possible way to reduce trip-related falls. In this paper, a wearable system is proposed that can measure the MTC in real-time using two Time-of-Flight (ToF) sensors on the shoe and provide auditory biofeedback using a piezo buzzer. Ten healthy female adults were recruited to walk in four conditions: baseline, biofeedback, short retention (same day), and long retention (next day) to design and validate our gait training tool. Average MTC values were compared pre-feedback, post-feedback, and post-retention, and our analysis revealed significant differences between the feedback and retention sessions for the training system. Therefore, the proposed system has the potential to be used as a wearable training system to minimize tripping risks in older adults and gait-impaired populations.

Enhancement of awareness through feedback does not lead to interlimb transfer of obstacle crossing in virtual reality

Locomotor skill transfer is an essential feature of motor adaptation and represents the generalization of learned skills. We previously showed that gait adaptation after crossing virtual obstacles did not transfer to the untrained limb and suggested it may be due to missing feedback of performance. This study investigated whether providing feedback and an explicit goal during training would lead to transfer of adaptive skills to the untrained limb. Thirteen young adults crossed 50 virtual obstacles with one (trained) leg. Subsequently, they performed 50 trials with their other (transfer) leg upon notice about the side change. Visual feedback about crossing performance (toe clearance) was provided using a color scale. In addition, joint angles of the ankle, knee, and hip were calculated for the crossing legs. Toe clearance decreased with repeated obstacle crossing from 7.8 ± 2.7 cm to 4.6 ± 1.7 cm for the trained leg and from 6.8 ± 3.0 cm to 4.4 ± 2.0 cm (p < 0.05) for the transfer leg with similar adaptation rates between limbs. Toe clearance was significantly higher for the first trials of the transfer leg compared to the last trials of the training leg (p < 0.05). Furthermore, statistical parametric mapping revealed similar joint kinematics for trained and transfer legs in the initial training trials but differed in knee and hip joints when comparing the last trials of the trained leg with the first trials of the transfer leg. We concluded that locomotor skills acquired during a virtual obstacle crossing task are limb-specific and that enhanced awareness does not seem to improve interlimb transfer.

Validity of an inertial sensor-based system for the assessment of spatio-temporal parameters in people with multiple sclerosis.

Gait variability in people with multiple sclerosis (PwMS) reflects disease progression or may be used to evaluate treatment response. To date, marker-based camera systems are considered as gold standard to analyze gait impairment in PwMS. These systems might provide reliable data but are limited to a restricted laboratory setting and require knowledge, time, and cost to correctly interpret gait parameters. Inertial mobile sensors might be a user-friendly, environment- and examiner-independent alternative. The purpose of this study was to evaluate the validity of an inertial sensor-based gait analysis system in PwMS compared to a marker-based camera system. A sample N = 39 PwMS and N = 19 healthy participants were requested to repeatedly walk a defined distance at three different self-selected walking speeds (normal, fast, slow). To measure spatio-temporal gait parameters (i.e., walking speed, stride time, stride length, the duration of the stance and swing phase as well as max toe clearance), an inertial sensor system as well as a marker-based camera system were used simultaneously. All gait parameters highly correlated between both systems (r > 0.84) with low errors. No bias was detected for stride time. Stance time was marginally overestimated (bias = -0.02 ± 0.03 s) and gait speed (bias = 0.03 ± 0.05 m/s), swing time (bias = 0.02 ± 0.02 s), stride length (0.04 ± 0.06 m), and max toe clearance (bias = 1.88 ± 2.35 cm) were slightly underestimated by the inertial sensors. The inertial sensor-based system captured appropriately all examined gait parameters in comparison to a gold standard marker-based camera system. Stride time presented an excellent agreement. Furthermore, stride length and velocity presented also low errors. Whereas for stance and swing time, marginally worse results were observed.

Is foot clearance influenced by different types of dual task in once-only faller community-dwelling older adults?

BackgroundTripping is one of the main causes of falls in older adults and has an important association with minimum toe clearance (MTC). MTC variability while performing alternating (ADT) or concurrent (CDT) dual-task activities may be a useful gait parameter to differentiate once-only fallers from non-faller older adults. Research questionIs the MTC variability influenced by ADT and CDT in once-only faller community-dwelling older adults? MethodsTwenty-two community-dwelling older adults with a self-report of up to one fall in the last 12 months were allocated to the fallers group and 38 to the non-fallers group. Gait data were collected by two foot-worn inertial sensors (Physilog® 5, GaitUp, Lausanne, Switzerland). MTC mean magnitude and variability, as well as the stride-to-stride variability, stride time and length, lower limb peak angular velocity, and foot forward linear speed at the MTC instant, were calculated across approximately 50 gait cycles for each participant and condition using the GaitUp Analyzer software (GaitUp, Lausanne, Switzerland). The statistical analyzes were performed in the Statistical Package for the Social Sciences (SPSS), v.22.0, using generalized mixed linear models, adopting an alpha of 5%. Results and SignificanceNo interaction effect was observed; however, faller participants reduced the MTC variability (standard deviation) [(mean difference, MD = −0.099 cm; confidence interval, 95%CI = −0.183 to −0.015)], regardless of the condition. CDT compared to a single task (only gait) reduced the mean magnitude of the foot forward linear speed (MD=−0.264 m/s; 95%CI=−0.462 to −0.067), peak angular velocity (MD = −25.205 degrees/s; 95%CI = −45.507 to −4.904), and gait speed (MD = −0.104 m/s; 95%CI = −0.179 to −0.029), regardless of the group. These results suggest that MTC variability, regardless of condition, may be a promising gait parameter to differentiate once-only faller community-dwelling older adults from non-fallers.

Effects of wearable visual cueing on gait pattern and stability in patients with Parkinson's disease.

The present study examined the effects of wearable visual cues, provided by a wearable laser device, on the gait pattern and stability in patients with Parkinson's disease (PD). In total, 18 patients with a clinical diagnosis of idiopathic PD (Hoehn and Yahr stage II-III) and 18 healthy controls were included. The main outcome measures included spatiotemporal parameters, sagittal plane kinematic parameters of joints in lower limbs, and dynamic center of pressure (COP) parameters. Significant intra-group improvement in gait parameters was observed in PD patients. Compared with that at baseline, the gait pattern improved in PD patients under the cued condition, with longer stride length and higher toe clearance, as well as shortening of double stance phase, especially the stride length, double stance phase and toe clearance were not significantly different between cued condition and healthy control groups. In kinematics, the ankle peak dorsiflexion in swing phase and the hip range of motion (ROM) in gait cycle was significantly improved in PD patients with visual cues and close to healthy controls. Decreased anteroposterior (AP) position of COP improved gait stability in patients with PD under the cued condition. Multiple linear regression analysis showed that the AP position has a negative correlation with ankle peak dorsiflexion in swing phase. Pearson's correlation coefficients showed that the minimum toe clearance (Mini TC) was positively correlated with the ankle peak dorsiflexion in swing phase. The immediate effect of wearable visual cues improved the gait pattern and stability in PD patients, suggesting that it may be effective when applied as an alternative technique in rehabilitation training for PD patients.

Accuracy and Precision of a Novel Photogate System to Measure Toe Clearance on Stairs

Background: Toe clearance on stairs is typically measured using optoelectronic systems, though these are often constrained to the laboratory, due to their complex setups. Here we measured stair toe clearance through a novel prototype photogate setup and compared this to optoelectronic measurements. Methods: Twelve participants (age 22 ± 3 years) completed 25 stair ascent trials, each on a seven-step staircase. Toe clearance over the fifth step edge was measured using Vicon and the photogates. Twenty-two photogates were created in rows through laser diodes and phototransistors. The height of the lowest photogate broken at step-edge crossing was used to determine photogate toe clearance. A limits of agreement analysis and Pearson's correlation coefficient compared the accuracy, precision and relationship between systems. Results: We found a mean difference of -1.5 mm (accuracy) between the two measurement systems, with upper and lower limits (precision) of 10.7 mm and -13.8 mm, respectively. A strong positive correlation was also found (r = 70, n = 12, p = 0.009) between the systems. Discussion: The results suggest that photogates could be an option for measuring real-world stair toe clearances, where optoelectronic systems are not routinely used. Improvements to the design and measurement factors may help to improve the precision of the photogates.

Identification of characteristics of foot position and angle during swing phase in fallers using principal component analysis.

Identifying the characteristics of fallers is important for preventing falls because such events may reduce quality of life. It has been reported that several variables related to foot positions and angles during gait (e.g., sagittal foot angle and minimum toe clearance) differ between fallers and non-fallers. However, examining such representative discrete variables may not be sufficient to detect crucial information, which may be contained in the large portions of unanalyzed data. Therefore, we aimed to identify the comprehensive characteristics of foot position and angle during the swing phase of gait in non-fallers and fallers using principal component analysis (PCA). Thirty non-fallers and 30 fallers were recruited for this study. We performed PCA to reduce the dimensions of foot positions and angles during the swing phase and obtained principal component scores (PCSs) for each principal component vector (PCV), which were then compared between groups. The results revealed that the PCS of PCV3 in fallers was significantly larger than that in non-fallers (p = 0.003, Cohen's d = 0.80). We reconstructed waveforms of foot positions and angles during the swing phase using PCV3 and our main findings can be summarized as follows. Compared to non-fallers, fallers have a 1) low average foot position in the z-axis (i.e., height) during the initial swing phase 2) small average foot angle in the x-axis (i.e., rotation in the sagittal plane), during the initial swing phase, and 3) large variability in foot position in the y-axis (i.e., anterior/posterior position) during the initial swing phase. We can conclude that these are characteristics of gait related to fallers. Therefore, our findings may be beneficial for evaluating fall risk during gait using a device such as a shoe- or insole-embedded inertial measurement unit.

The effect of tibialis anterior weakness on foot drop and toe clearance in patients with facioscapulohumeral dystrophy

BackgroundFacioscapulohumeral dystrophy is a genetic disease characterized by progressive muscle weakness leading to a complex combination of postural instability, foot drop during swing and compensatory strategies during gait that have been related to an increased risk of falling. The aim is to assess the effect of tibialis anterior muscle weakness on foot drop and minimum toe clearance of patients with facioscapulohumeral dystrophy during gait. MethodsEight patients allocated to a subgroup depending on the severity of tibialis anterior muscle weakness, assessed by manual muscle testing (i.e., severe and mild weakness), and eight matched control participants underwent gait analysis at self-selected walking speeds. FindingsWalking speed, for all facioscapulohumeral dystrophy patients, and step length, for patients with severe weakness only, were significantly decreased compared to control participants. Minimum toe clearance was similar across all groups, but its variability was increased only for patients with severe weakness. A greater foot drop was systematically observed for patients with severe weakness during swing and only in late swing for patients with mild weakness. Individual strategies to compensate for foot drop remain unclear and may depend on other muscle impairment variability. InterpretationAlthough all patients were able to control the average height of their foot trajectory during swing, patients with severe tibialis anterior muscle weakness exhibited increased foot drop and minimum toe clearance variability. Manual muscle testing is a simple, cheap and effective method to assess tibialis anterior muscle weakness and seems promising to identify facioscapulohumeral dystrophy patients with an increased risk of tripping.

Effect of visual information from binocular vision on the motor control of step over obstacles in walking with 90° turn.

[Purpose] This study aimed to clarify the relationship between one-eye visual deprivation; thus, interfering with stereoscopic perception, and movement and obtain insights on the influence of visual perception on movement to step over obstacles. [Participants and Methods] Participants were 25 healthy individuals. There were two conditions of visual perception (stationary and approaching conditions) and two additional conditions of binocular and monocular visions. Under the four conditions, participants were asked to step over an obstacle immediately after a 90° turn while walking. Distance between the foot and obstacle, foot pressure distribution, and stance phase time were measured. [Results] Toe clearance was lower in the approaching condition than that in the binocular stationary condition. The trajectory length ratio was greater in the approaching condition than that in the stationary condition, and heel-ground contact, metatarsal-ground contact, and stance times were all shorter in the binocular condition. Additionally, heel contact, midfoot contact, metatarsal contact, and stance times were shorter in the approaching condition than that in the stationary condition. [Conclusion] In walking with a 90° turn, the binocular approaching condition provided more visual information and positively affected motor control of movements to step over an obstacle.

Taping-induced cutaneous stimulation to the ankle tendons reduces minimum toe clearance variability

Large variability of minimum toe clearance (MTC) leads to a higher risk of tripping. Visual feedback-based gait training systems have been used to regulate MTC distribution, but these systems are expensive and bulky. Furthermore, the effect of such training lasts only for a short period of time. Considering the efficacy of elastic adhesive tape-induced cutaneous stimulation to the ankle tendons in improving proprioception and movement detection, we hypothesize that application of tapes to the ankle tendons as a practical method for modifying MTC distribution. To test this hypothesis, we recruited 13 young and healthy adults and instructed them to walk on a treadmill under four conditions: no taping, taping the tibialis anterior tendon, taping the Achilles tendon, and taping both tendons. We measured MTC distribution, lower limb joint angles and muscle activations of the tibialis anterior and gastrocnemius medialis, and compared these outcomes under the four conditions. The application of elastic adhesive tape to the ankle tendons had no significant effect on the average MTC height, but tapes applied to the Achilles tendon and both tendons significantly reduced MTC variability. Taping decreased the variability of some lower limb joint angles, but taping did not induce significant changes in the activation levels of the shank muscles. These results demonstrate that elastic adhesive tape applied to the shank can reduce MTC variability with minimal resistance, inertia and cumbersomeness.

The effects of swing assistance in a microprocessor-controlled transfemoral prosthesis on walking at varying speeds and grades.

This article proposes, describes, and tests a swing-assist walking controller for a stance-controlled, swing-assisted knee prosthesis that aims to combine benefits of passive swing mechanics (e.g., quiet operation, biomimetic function, and low power requirements) with benefits of powered swing assistance (e.g., increased robustness of swing-phase motion and specifically increased toe clearance). A three-participant, multislope, multispeed treadmill walking study was performed using the swing-assist prosthesis and controller, as well as using the participants' prescribed microprocessor knee devices. The swing-assist device and approach were found to improve user minimum foot clearance during walking at slopes and speeds, and also to improve symmetry of knee motion. Hip power inputs from stance knee release to heel strike indicated that, on average, less hip power was required when using the swing-assist prosthesis, indicating that the observed benefits were likely the result of the knee device and its control methodology, rather than a result of increased hip joint effort.

Fatigue Effect on Minimal Toe Clearance and Toe Activity during Walking

This study investigates the effects of fatigue on the process of walking in young adults using the developed clog-integrated sensor system. The developed sensor can simultaneously measure the forefoot activity (FA) and minimum toe clearance (MTC). The FA was evaluated through the change in the contact area captured by a camera using a method based on a light conductive plate. The MTC was derived from the distance between the bottom surface of the clog and ground obtained using a time of flight (TOF) sensor, and the clog posture was obtained using an acceleration sensor. The induced fatigue was achieved by walking on a treadmill at the fastest walking speed. We evaluated the FA and MTC before and after fatigue in both feet for 14 participants. The effects of fatigue manifested in either the FA or MTC of either foot when the results were evaluated by considering the participants individually, although individual variances in the effects of fatigue were observed. In the dominant foot, a significant increase in either the FA or MTC was observed in 13 of the 14 participants. The mean MTC in the dominant foot increased significantly (p = 0.038) when the results were evaluated by considering the participants as a group.

Variability and symmetry of gait kinematics under dual-task performance of older patients with depression

BackgroundDepression in old age is associated with an increased fall risk. Especially in cognitively challenging situations, fall-promoting gait deviations could appear due to depression- and age-related cognitive deficits.AimThis study investigates (i) whether there are differences in gait performance between depressed older patients and healthy controls and (ii) if gait patterns aggravate when performing a cognitive task whilst walking.Methods16 depressed older patients (mean age: 73.1 ± 5.8 years) and 19 healthy controls (mean age: 73.3 ± 6.1 years) were included in the study. Spatiotemporal gait parameters (speed, stride length, swing time) and minimum toe clearance were recorded using a three-dimensional motion-capture system under a single- and a dual-task condition (counting backwards).ResultsAfter Bonferroni correction, depressed older patients showed significantly slower walking speed, shorter strides and smaller minimum toe clearance, as well as greater variability in stride length than healthy controls. Under the dual-task, gait performance deteriorated compared with single-task, with slower gait speed, shorter strides, and longer swing time.DiscussionSlower walking speed and shorter steps of depressed patients may be a strategy to counteract their fall risk. Increased variability suggests a less stable gait pattern in patients, which could be a reason for their increased fall risk.ConclusionsDepression in old age has a strong effect on gait performance. Possible interventions that might prevent falls in this vulnerable group are discussed. The study was registered at Open Science Framework on May 18, 2021 (publicly accessible May 30, 2023).

Limited transfer and retention of locomotor adaptations from virtual reality obstacle avoidance to the physical world

Locomotor training based in virtual reality (VR) is promising for motor skill learning, with transfer of VR skills in turn required to benefit daily life locomotion. This study aimed to assess whether VR-adapted obstacle avoidance can be transferred to a physical obstacle and whether such transfer is retained after 1 week. Thirty-two young adults were randomly divided between two groups. A control group (CG) merely walked on a treadmill and an intervention group (IG) trained crossing 50 suddenly-appearing virtual obstacles. Both groups crossed three physical obstacles (transfer task) immediately after training (T1) and 1 week later (T2, transfer retention). Repeated practice in VR led to a decrease in toe clearance along with greater ankle plantarflexion and knee extension. IG participants crossed physical obstacles with a lower toe clearance compared to CG but revealed significantly higher values compared to the VR condition. VR adaptation was fully retained over 1 week. For physical obstacle avoidance there were differences between toe clearance of the third obstacle at T1 and the first obstacle at T2, indicating only partial transfer retention. We suggest that perception–action coupling, and thus sensorimotor coordination, may differ between VR and the physical world, potentially limiting retained transfer between conditions.

Obstacle Crossing in Older Adults with Total Knee Arthroplasty at the Initial Swing Phase

After undergoing a total knee arthroplasty (TKA) procedure, patients are at a high risk of falling because they present with ineffective mobility within a complex environment, especially during obstacle crossing. Toe clearance (TC) is an important factor to quantify the risks of trip-related falls. The study aimed to investigate TC height and toe trajectory and joint kinematic changes occurring in the lower limb following TKA during obstacle crossing at the initial swing phase. Twenty TKA patients, including those in preoperative and postoperative stages (three and six months), performed obstacle-crossing tasks to compare their performance with 20 healthy controls. Participants walked at self-pace along an 8 m walkway with 2.5, 5, and 10 cm obstacles positioned along the center of the path. For each participant, body segment motions were traced using reflective markers and the kinematics of lower extremity, toe clearance, and gait parameters were analyzed using a 3D-motion analysis system. TKA patients had lower TC height and toe trajectory at six months, slower toe elevation than controls when swing toe crossed 5 and 10 cm obstacles (p &lt; 0.05), and decreased hip and knee flexion (p &lt; 0.05). These altered gait patterns with decreased TC height and toe trajectory were identified as tripping factors as the toe trajectory was close to the ground surface. TKA patients had acquired different lower limb kinematics to maintain adequate TC. At long-term follow-up, there was an increasing trend for patients to trip after surgery. Therefore, more focus is needed on the exercise prescription for rehabilitation programs to improve muscle strength and stepping control.