Validity Verification of Human Pose-Tracking Algorithms for Gait Analysis Capability.

Two-dimensional (2D) clinical gait analysis systems are more affordable and portable than contemporary three-dimensional (3D) clinical models. Using the Vicon 3D motion capture system as the standard, we evaluated the internal statistics of the Imasen and open-source OpenPose gait measurement systems, both designed for 2D input, to validate their output based on the similarity of results and the legitimacy of their inner statistical processes. We measured time factors, distance factors, and joint angles of the hip and knee joints in the sagittal plane while varying speeds and gaits during level walking in three in-person walking experiments under normal, maximum-speed, and tandem scenarios. The intraclass correlation coefficients of the 2D models were greater than 0.769 for all gait parameters compared with those of Vicon, except for some knee joint angles. The relative agreement was excellent for the time-distance gait parameter and moderate-to-excellent for each gait motion contraction range, except for hip joint angles. The time-distance gait parameter was high for Cronbach's alpha coefficients of 0.899-0.993 but low for 0.298-0.971. Correlation coefficients were greater than 0.571 for time-distance gait parameters but lower for joint angle parameters, particularly hip joint angles. Our study elucidates areas in which to improve 2D models for their widespread clinical application.

Reliability and validity of muscle activity analysis using wearable electromyographs.

[Purpose] The aim of this study was to develop a novel wearable surface electromyograph called NOK, and compare its reliability and validity to an existing electromyograph. [Participants and Methods] The study participants were 23 healthy university students (Seven males and 16 females; age 20.3 ± 1.1 years [mean ± standard deviation]; height 162.0 ± 6.7 cm; weight 58.4 ± 10.1 kg) who all gave informed written consent. The newly developed electromyograph (NOK) features a rubberized skin contact surface that requires no electrodes and allows the acquisition of up to 10 channels of muscle waveforms on a portable personal computer. After measuring maximal isometric elbow extension and flexion, we examined muscle waveforms during isometric contractions of elbow joint flexion and extension at approximately 50% of maximal voluntary contraction using both NOK and Delsys electromyographs and compared the results of the two devices. [Results] We found a significant moderate correlation between the measurements by the two devices for biceps and triceps. The measurements by the two devices also showed strong measure-retest reliability. Systematic errors were observed for elbow flexion and extension in the two measurements, indicating limited agreement between the two measurement methods. [Conclusion] Although the new device also has high repeatability and reliability, it is unsuitable for analyzing detailed muscle activity. However, since it can measure up to 10 channels of muscle activity, it is expected to be used in the rehabilitation and sports field in the future.

Factors influencing the prognosis of patients with acute cerebral infarction who received usual care: a multicenter prospective cohort study.

[Purpose] The prognostic factors for patients with acute stroke who received usual care (mobilization ≥48 h after admission) remain unclear. This study aimed to investigate the prognostic factors that predict functional outcomes using evaluations performed immediately after onset in patients with acute cerebral infarction who received usual care from admission until discharge. [Participants and Methods] Participants with acute cerebral infarction admitted to five acute care hospitals in Tokyo and Saitama, Japan and prescribed physical therapy were included. Participants information, functional evaluations, and progress were recorded during the first physical therapy session, mobilization, and discharge. Participants who received usual care were assigned to either the good- or poor-outcome group based on the Modified Rankin Scale at discharge. [Results] In total, 161 Participants receiving usual care (mobilization ≥48 h after admission) were included. Reinfarction and the First National Institutes of Health Stroke Scale score were identified as independent predictors of functional outcome at hospital discharge in participants who received usual care (median, 22.0 d). The cutoff NIHSS score was 4. [Conclusion] Our results provided evidence that the National Institutes of Health Stroke Scale score and reinfarction are useful predictors of functional outcomes in participants who received usual care.

Reliability and validity of impact absorption rate using accelerometers during single-leg drop-jump landings.

[Purpose] To assess the reliability and validity of accelerometer-based impact absorption rate measurements during single-leg drop-jump landings. [Participants and Methods] Study participants were healthy adult males. The task involved a single-leg drop-jump from the platform with a forward landing onto a floor reaction force plate. Accelerometers were fastened to the trunk, while foot switches were attached to the forefoot plantar surfaces. The impact absorption rate was calculated as the peak composite acceleration during the single-leg drop-jump landing divided by the duration from foot contact to the attainment of peak value. The loading rate (LR) was calculated by dividing the peak vertical force by the duration from foot contact to the attainment of peak value, leveraging the data obtained from a floor reaction force plate. Intraclass correlation coefficients (ICC) were used for intra- and inter-rater reliability analyses of 18 and 12 participants, respectively. The validity was examined through the correlation between impact absorption rate and LR in the 18 participants. [Results] The intra- (ICC (1,1)) and inter-rater (ICC (2,1)) reliabilities for the impact absorption rates were 0.89 and 0.88, respectively. A significant positive correlation was observed between impact absorption rates and LR (r=0.71). [Conclusion] The impact absorption rate may be valuable in clinical practice.

Examination of Rehabilitation Intensity According to Severity of Acute Stroke: A Retrospective Study.

OBJECTIVES: To investigate the intensity and effectiveness of rehabilitation in acute stroke patients according to the severity of functional impairments in them. MATERIALS AND METHODS: This retrospective cohort study included 294 patients with acute hemispheric stroke admitted to three acute-care hospitals who subsequently underwent an inpatient rehabilitation program. Stroke severity was classified according to neurological deficits and trunk dysfunction. The following data were obtained from medical records: age, sex, stroke type, lesion side, hospitalization duration, initial functional status determined using the National Institutes of Health Stroke Scale, rehabilitation start date, first day out of bed after admission, total treatment duration, total number of treatment sessions, rehabilitation implementation rate between start of rehabilitation and discharge, trunk control test and Barthel Index score on the first day out of bed after admission and discharge, and post-discharge outcomes. Hierarchical cluster analysis was performed with clusters categorized using the National Institutes of Health Stroke Scale and trunk control test scores. Variables were compared using the Kruskal-Wallis test, and Dunn's nonparametric comparison test was performed for post-hoc analysis to determine differences between clusters. RESULTS: The National Institutes of Health Stroke Scale and trunk control test showed a significant correlation (r = -0.816, p < 0.01) using which cluster analysis identified three clusters. Rehabilitation showed a ceiling effect in patients with mild stroke and a floor effect in patients with severe stroke. CONCLUSION: These results may guide the determination of rehabilitation intensity with reference to the severity of neurological deficits and trunk dysfunction.

Characteristics of dynamic standing balance with and without an insole in patients with spastic diplegia cerebral palsy.

[Purpose] This study examined characteristics of dynamic standing balance, with an without an insole, in patients with spastic diplegia cerebral palsy (CP). [Participants and Methods] This cross-sectional study used a crossover design. Eleven patients with spastic diplegia CP and gross motor levels between I and III with spastic diplegia CP (according to the Gross Motor Function Classification System expanded and revised version) were randomly allocated to either the barefoot or insole groups. The Index of postural stability (IPS) was evaluated while each patient was barefoot and while wearing insoles. The Pediatric Evaluation of Disability Inventory (PEDI) was used to measure functional self-care and mobility domains. [Results] While wearing the insoles, the center movement distance between right and left positions was significantly higher. While barefoot, IPS and area of postural sway correlated with the PEDI subscales for mobility and self-care. [Conclusion] Insoles promote standing balance and dynamic balance to move the center of pressure within the base of support. Such improvements may enhance activities of daily living in patients with spastic diplegia CP.

The relationship between movement of the shank while running and foot alignment factors that lead to the onset of Achilles peritendinitis.

[Purpose] To clarify the relationship between movement of the shank relative to the global reference frame (shank angle) while running, and foot alignment factors that lead to the onset of Achilles peritendinitis. [Participants and Methods] This study included 54 healthy male participants. Running at a constant speed was measured by three-dimensional motion analysis. The shank angle at the time of the first peak of vertical ground reaction force and maximum ankle dorsiflexion were analyzed. The magnitude of ankle plantarflexion, inversion, and adduction angle in the propulsive phase as well as static foot alignment (navicular index, and range of ankle dorsiflexion angle) were measured. The relationships between shank angle features and these parameters were investigated. [Results] Outward inclination of the shank occurred at the time of the first peak of vertical ground reaction force and maximum ankle dorsiflexion, with this increase in movement correlating with parameters that increased the risk of Achilles peritendinitis. [Conclusion] These findings suggest that evaluation of the shank angle on the frontal plane while running may be used to estimate the onset of Achilles peritendinitis in clinical practice.

Influence of peripheral magnetic stimulation of soleus muscle on H and M waves.

[Purpose] This study evaluated the effects of repetitive peripheral magnetic stimulation of the soleus muscle on spinal cord and peripheral motor nerve excitability. [Subjects and Methods] Twelve healthy adults (mean age 22 years) who provided written informed consent were administered repetitive peripheral magnetic stimulation for 10 min. Pre-and post-stimulation latencies and amplitudes of H- and M-waves of the soleus muscle were measured using electromyography and compared using paired t-tests. [Results] Pre- and post-stimulation latencies (28.3 ± 3.3 vs. 29.1 ± 1.3 ms, respectively) and amplitudes (35.8 ± 1.3 vs. 35.8 ± 1.1 mV, respectively) of H-waves were similar. Pre-stimulation latencies of M-waves were significantly higher than post-stimulation latencies (6.1 ± 2.2 vs. 5.0 ± 0.9 ms, respectively), although pre- and post-stimulation amplitudes were similar (12.2 ± 1.4 vs. 12.2 ± 1.3 mV, respectively). Motor neuron excitability, based on the excitability of motor nerves and peripheral nerve action, was increased by M-waves following magnetic stimulation. [Conclusion] The lack of effect of magnetic stimulation on the amplitude and latency of the H-reflex suggests that magnetic stimulation did not activate sensory nerve synapses of α motor neurons in the spinal cord. However, because motor nerves were stimulated together with sensory nerves, the increased H-wave amplitude may have reflected changes in peripheral rather than in α motor nerves.

Effects of an underwear-type hip abduction orthosis on sitting balance and sit-to-stand activities in children with spastic cerebral palsy.

[Purpose] Hip dislocation and subluxation are common in patients with cerebral palsy (CP). Hip abduction orthoses are used to prevent and treat these problems. This study investigated the effects of an underwear-type hip abduction orthosis on sitting balance and sit-to-stand (STS) activity in children with spastic CP. [Participants and Methods] This trial had a cross-over design. Eight children aged 6 to 18 years old with spastic CP and Gross Motor Function Classification level III and IV were randomly allocated to groups with or without use of the underwear-type hip orthosis. The trunk impairment scale (TIS) score was evaluated and the 5-times sit-to-stand test (FTSST) was conducted with and without the underwear. [Results] The dynamic sitting balance scores in the TIS and FTSST showed significant improvement with use of the orthotic underwear. [Conclusion] The dynamic sitting balance scores of the TIS and FTSST were higher, thus indicating better stability, when wearing the orthosis underwear. Thus, it was suggested that underwear-type hip abduction orthoses are effective for promoting sitting balance and STS activities in children with spastic CP.

Kinematics of judo breakfall for osoto-gari: Considerations for head injury prevention.

Previous studies suggest that increasing the skill level of judokas will decrease the number of head injuries sustained during judo. However, the kinematics are poorly understood, making it difficult to establish an effective breakfall teaching programme. Therefore, we studied the kinematic parameters of breakfall for osoto-gari to identify the risk of judo-related head injuries by comparing experienced and novice judokas. This information will provide insight into developing a better prevention plan for judo-related head injuries. A total of 10 experienced and 12 novice judokas volunteered to participate in this study. The kinematic data of the breakfall motion for osoto-gari were collected using a three-dimensional motion analysis technique (200 Hz). We observed a significantly higher peak neck extension momentum in the novice group than in the experienced group. This suggests that neck extension momentum during breakfall is associated with the risk of head injuries during judo. In addition, the novice judokas demonstrated a significantly greater flexed pattern in the trunk and hip movement than the experienced judokas (P < 0.05). The results suggest that the trunk and lower extremity motion are important kinematic parameters that determine the skill level in performing the breakfall for osoto-gari.

Easy assessment tool for motor imagery ability in elementary scool students.

[Purpose] The final purpose of the present study was to propose easy and quick mental rotation task. Since subjects can easily understand mental rotation task that they have to do, the task is considered to be available in particular children. However, existing mental rotation task using specific software asked subjects more than ten trials per one pictured stimulus, meaning that relatively long time is required to accurately measure. Thus, children have difficulty to keep their attention during the existing task and to demonstrate their ability accurately. To address the purpose of the present study, the performance of mental rotation task using paper was investigated whether the performance has similar characteristics to an existing mental rotation task using specific software, in order to verify the usability of the task using paper. [Subjects and Methods] Sixty-three elementary school participants were asked to determine whether a rotating hand picture was left or right as quickly as possible and indicate it by writing a diagonal line on the paper. The total time required judgment of 16 pictures and the number of judgment errors were counted. [Results] The number of judgment errors increased with an increasing stimulus rotation angle. Also, the mental rotation time improved with age. [Conclusion] These results suggest that the performance of mental rotation using paper has the same characteristics as the existing method using specific software. Therefore, the mental rotation using paper would be practical method for subjects having difficulty to keep attention relatively long time, such as elementary school children.

A newly developed floor chair placed on an office chair reduces lumbar muscle fatigue by cyclically changing its lumbar supporting shape.

[Purpose] This study investigated lumbar muscle fatigue before and after maintaining a seated position for one hour, lumbar and pelvic inclination angle change, in subjects with and without active lumber support. [Subjects and Methods] Fourteen healthy subjects randomized into two groups sat on a floor chair, placed on an office chair, that cyclically changed its lumbar supporting shape to provide active lumbar support (ALS) or no ALS for one hour. Before and after, we measured the frequency of muscle waveforms of the trunk extensor muscles when the subjects lifted an object weighing 10% of their body weight, using both hands while seated. In addition, ROMt (Range of motion test) of trunk rotation, degree of fatigue and muscle stiffness were analyzed. [Results] Muscle frequency while lifting the weight decreased significantly without ALS compared to with ALS. Mean muscle stiffness increased, ROMt decreased in desk work task significantly without ALS compared to with ALS. [Conclusion] These results suggest that the lumbar muscles became fatigued, because low frequencies, increased muscle stiffness, and decreased ROMt without ALS. We suggest lumbar muscle fatigue was maintained low for subjects seated in a chair with ALS.

Maximal respiratory pressure in healthy Japanese children.

[Purpose] Normal values for respiratory muscle pressures during development in Japanese children have not been reported. The purpose of this study was to investigate respiratory muscle pressures in Japanese children aged 3-12 years. [Subjects and Methods] We measured respiratory muscle pressure values using a manovacuometer without a nose clip, with subjects in a sitting position. Data were collected for ages 3-6 (Group I: 68 subjects), 7-9 (Group II: 86 subjects), and 10-12 (Group III: 64 subjects) years. [Results] The values for respiratory muscle pressures in children were significantly higher with age in both sexes, and were higher in boys than in girls. Correlation coefficients were significant at values of 0.279 to 0.471 for each gender relationship between maximal respiratory pressure and age, height, and weight, respectively. [Conclusion] In this study, we showed pediatric respiratory muscle pressure reference value for each age. In the present study, values for respiratory muscle pressures were lower than Brazilian studies. This suggests that differences in respiratory muscle pressures vary with ethnicity.

Reliability and validity of the Japanese version of the selective control assessment of the lower extremity tool among patients with spastic cerebral palsy.

[Purpose] The aim of this study was to translate the Selective Control Assessment of the Lower Extremity (SCALE) tool from English to Japanese and to assess the reliability and validity of the Japanese version of the SCALE (SCALE-J) tool in Japanese patients with spastic cerebral palsy. [Subjects and Methods] The SCALE tool was translated into Japanese in accordance with the published guidelines. In total, 55 patients with spastic cerebral palsy were enrolled in the present study. Reliability by internal consistency (Cronbach's α), intrarater reliability, inter-rater reliability, and convergent validity by comparing Gross Motor Function Classification System (GMFCS) scores were examined. [Results] The Cronbach's α value of the SCALE-J tool was 0.97-0.98, whereas that of the intrarater and inter-rater reliability ranged from 0.93 to 0.96. The Spearman correlation coefficient revealed a good relationship between the SCALE tool and the GMFCS. [Conclusion] The SCALE-J tool was found to be reliable and valid; therefore, the SCALE tool may be useful for evaluation in clinical practice.

Relation of selective voluntary motor control of the lower extremity and extensor strength of the knee joint in children with spastic diplegia.

[Purpose] The aim of this study was to investigate differences in selective voluntary motor control of the lower extremities by objective assessment and determine the relationship between selective voluntary motor control and knee extensor strength in children with spastic diplegia. [Subjects and Methods] Forty individuals who had spastic cerebral palsy, with Gross Motor Function Classification System levels ranging from I to III, were assessed using the Selective Control Assessment of the Lower Extremity and by testing the maximum knee extensor strength. The unaffected side was defined as the lower limb with the higher score, and the affected side was defined as the lower limb with the lower score. [Results] The Selective Control Assessment of the Lower Extremity score on the affected side had a lower average than that on the unaffected side. The scores showed a significant inverse correlation with the maximum knee extensor strength. [Conclusion] There was bilateral difference in the selective voluntary motor control of the lower extremities in children with spastic diplegia, and the selective voluntary motor control of the lower extremity was related to maximum knee extensor strength.

Motion analysis of wheelchair propulsion movements in hemiplegic patients: effect of a wheelchair cushion on suppressing posterior pelvic tilt.

[Purpose] This study sought to ascertain whether, in hemiplegic patients, the effect of a wheelchair cushion to suppress pelvic posterior tilt when initiating wheelchair propulsion would continue in subsequent propulsions. [Subjects] Eighteen hemiplegic patients who were able to propel a wheelchair in a seated position participated in this study. [Methods] An adjustable wheelchair was fitted with a cushion that had an anchoring function, and a thigh pad on the propulsion side was removed. Propulsion movements from the seated position without moving through three propulsion cycles were measured using a three-dimensional motion analysis system, and electromyography was used to determine the angle of pelvic posterior tilt, muscle activity of the biceps femoris long head, and propulsion speed. [Results] Pelvic posterior tilt could be suppressed through the three propulsion cycles, which served to increase propulsion speed. Muscle activity of the biceps femoris long head was highest when initiating propulsion and decreased thereafter. [Conclusion] The effect of the wheelchair cushion on suppressing pelvic posterior tilt continued through three propulsion cycles.

Verification of biomechanical factors of gait related to medial knee loading in patients 6 Months after total knee arthroplasty.

Background: The knee adduction moment (KAM) is considered an index for estimating the knee mechanical load, and increased KAM peak and KAM impulse are related to increased medial knee load and progression of knee joint degeneration. We aimed to verify the biomechanical factors of gait related to medial knee loading in patients 6 months after TKA. Methods: Thirty-nine women who underwent TKA were enrolled. A three-dimensional gait analysis was performed 6 months postoperatively to generate data on the lower limb joint angle, moment, and power at the backward component (braking phase) and forward component (propulsion phase) peaks of the ground reaction force. Medial knee loading was evaluated using the time-integrated value of KAM during the stance period (KAM impulse). The higher the value of the KAM impulse, the higher the medial knee joint load. The relationships between the KAM impulse and the data for biomechanical factors were evaluated using partial correlation analysis with gait speed as a control factor. Results: In the braking phase, the KAM impulse positively correlated with the knee adduction angle (r = 0.377) and negatively correlated with the toe-out angle (r = -0.355). The KAM impulse positively correlated with the knee adduction angle (r = 0.402), the hip flexion moment (r = 0.335), and the hip adduction moment (r = 0.565) and negatively correlated with the toe-out angle (r = -0.357) in the propulsive phase. Conclusion: The KAM impulse 6 months after TKA was related to the knee adduction angle, hip flexion moment, hip adduction moment, and toe-out angle. These findings may provide fundamental data for controlling variable medial knee joint load after TKA and implementing patient management strategies to ensure implant durability.

Factor analysis for construct validity of a trunk impairment scale in Parkinson's disease: a cross-sectional study.

Objectives: To investigate the construct validity of the Trunk Impairment Scale (TIS), which was developed to assess trunk impairment in patients with stroke, in patients with Parkinson's disease (PD). Design: This retrospective, cross-sectional study enrolled consecutive PD inpatients. Correlation analysis was performed to clarify whether the TIS assessment was related to other balance functions, lower extremity muscle strength, or walking ability. Factor analysis was performed to see how the background factors of TIS differ from balance function, lower limb muscle strength, and walking ability. Results: Examining the data of 471 patients with PD, there were relationships between TIS and the Mini-Balance Evaluation Systems Test (r = 0.67), Barthel Index (r = 0.57), general lower limb extension torque (r = 0.51), two-minute walk test (r = 0.54), Hoehn and Yahr stage (r = -0.61), and Movement Disorder Society Unified Parkinson's Disease Rating Scale part III total points (r = -0.59). Factor analysis showed that TIS items were divided into three factors (an abdominal muscles and righting reflex component; a perception and verticality component; and a rotational component), differing from other scales that included clinical assessment items. Conclusion: The TIS can be useful for assessing the underlying trunk impairment as a basis for activities of daily living, gait function, and balance ability in patients with PD.

Separated center-of-pressure measurements reveal new characteristics of reduced anticipatory postural adjustments during gait initiation in patients with Parkinson's disease.

BACKGROUND AND OBJECTIVE: Accelerations, ground reaction force data, and other quantitative data obtained from kinematic analyses of gait initiation serve as measures of dyskinesia in patients with Parkinson's disease. The objective of this study was to determine whether a separate center of pressure information could reveal new characteristics of reduced anticipatory postural adjustments in patients with Parkinson's disease. METHODS: Ten healthy elderly subjects and 10 patients with Parkinson's disease participated in this study. Motions at gait initiation in response to a light signal to begin the task were analyzed. Anticipatory postural adjustments were characterized using trunk acceleration data and center of pressure displacement data. RESULTS: The separated center of pressure in patients with Parkinson's disease showed longer peak latency (p < .01) and larger peak magnitude (p < .01) in the stance leg than in the stepping leg. In patients with Parkinson's disease, the displacement peak latency of the stance leg center of pressure correlated negatively with the Timed Up and Go time (r = -0.46, p < .05), while displacement peak latency of the stepping leg center of pressure correlated negatively with Unified Parkinson's Disease Rating Scale (r=  -0.47, p < .05), and positively with Berg Balance Scale score (r = 0.50, p < .05). CONCLUSIONS: Patients with Parkinson's disease experience asymmetry between the stance leg and stepping leg at gait initiation. These findings may help clinicians understand the changes to motor function in patients with Parkinson's disease and suggest strategies for improved rehabilitation training.

Early postoperative relationship between patient-reported outcome measures and gait biomechanical factors after total hip arthroplasty.

BACKGROUND: Patient-reported outcome measures (PROMs) have recently been considered as indicating clinical outcomes after total hip arthroplasty (THA). Although various factors are reportedly associated with post-THA and PROMs, the relationship with gait parameters, which are objective assessment factors after THA, remains unclear. RESEARCH QUESTION: What is the relationship between PROMs and gait biomechanical factors four weeks after THA? METHODS: Forty-five patients (six men and 39 women) who underwent THA were included. Three-dimensional gait analysis was performed four weeks post-THA; joint angle, internal moment, and power of the lower extremity at the first and second peaks of the vertical component of the floor reaction force were assessed for the operated side. PROMs were evaluated using the Japanese Orthopedic Association Hip Disease Evaluation Questionnaire (JHEQ). The relationship between the JHEQ score and extracted gait parameters was analyzed using gender and gait speed as control factors. RESULTS: For the JHEQ sub-domain, movement was positively correlated with the internal knee extension moment values at the first peak (r = 0.347). There was no significant correlation between JHEQ and the internal hip abduction moment value at the first peak. Mental status was negatively correlated with the hip flexion angle value at the second peak (r = -0.373), and positively correlated with the hip flexion moment value (r = 0.348). Total JHEQ scores and mental status were negatively correlated with the power of hip flexion value at the second peaks, respectively (r = -0.316, -0.444). SIGNIFICANCE: The results of this study may provide recovery guidelines to be used as an index for gait assessment in the early post-THA period. Further studies are needed to verify whether gait parameters can improve PROMs in the early post-THA period.