Master of Science / Department of Industrial & Manufacturing Systems Engineering / Shing I. Chang / This research aims to quantify human walking patterns through depth cameras to (1) detect walking pattern changes of a person with and without a motion-restricting device or a walking aid, and to (2) identify distinct walking patterns from different persons of similar physical attributes. Microsoft Kinect™ devices, often used for video games, were used to provide and track coordinates of 25 different joints of people over time to form a human skeleton. Two main studies were conducted. The first study aims at deciding whether motion-restricted devices such as a knee brace, an ankle brace, or walking aids – walkers or canes affect a person’s walking pattern or not. This study collects gait data from ten healthy subjects consisting of five females and five males walking a 10-foot path multiple times with and without motion-restricting devices. Their walking patterns were recorded in a form of time series via two Microsoft Kinect™ devices through frontal and sagittal planes. Two types of statistics were generated for analytic purposes. The first type is gait parameters converted from Microsoft Kinect™ coordinates of six selected joints. Then Sample Entropy (SE) measures were computed from the gait parameter values over time. The second method, on the other hand, applies the SE computations directly on the raw data derived from Microsoft Kinect™ devices in terms of (X, Y, Z) coordinates of 15 selected joints over time. The SE values were then used to compare the changes in each joint with and without motion-restricting devices. The experimental results show that both types of statistics are capable of detecting differences in walking patterns with and without motion-restricting devices for all ten subjects. The second study focuses on distinguishing two healthy persons with similar physical conditions. SE values from three gait parameters were used to distinguish one person from another via their walking patterns. The experimental results show that the proposed method using a star glyph summarizing the shape produced by the gait parameters is capable of distinguishing these two persons. Then multiple machine learning (ML) models were applied to the SE datasets from ten college-age subjects - five males and five females. In particular, ML models were applied to classify subjects into two categories: normal walking and abnormal walking (i.e. with motion-restricting devices). The best ML model (K-nearest neighborhood) was able to predict 97.3% accuracy using 10-fold cross-validation. Finally, ML models were applied to classify five gait conditions: walking normally, walking while wearing the ankle brace, walking while wearing the ACL brace, walking while using a cane, and walking while using a walker. The best ML model was again the K-nearest neighborhood performing at 98.7% accuracy rate.

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第18353号 / 人博第666号 / 新制||人||160(附属図書館) / 25||人博||666(吉田南総合図書館) / 31211 / 京都大学大学院人間・環境学研究科共生人間学専攻 / (主査)准教授 神﨑 素樹, 教授 森谷 敏夫, 准教授 久代 恵介, 教授 小田 伸午 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

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Walking disorders are one of the most visible symptoms of multiple sclerosis (MS). Multiple sclerosis (MS) is a chronic autoimmune neurodegenerative disease of the central nervous system that is the most common cause of disability of young adults. Walking disorders are one of the most common motor problems that accompany this disease, which patients themselves perceive as the most limiting. Walking disorders can be caused by many symptoms of MS such as: muscle weakness, spasticity, sensory disturbances, visual disturbances, sphincter problems, cognitive dysfunction, fatigue and thermosensitivity. Measuring of various gait parameters (most often speed and endurance) also helps to monitor the effects of treatment and to evaluate the progression of the disease. Even in patients with minimal neurological symptoms it is possible to detect deterioration of gait parameters. Realized studies have shown that subjectively perceived improvement in gait after treatment with natalizumab can be objectified with the aid of assessment of walking parameteres. Similarly, a functional gait test can be used to assess the therapeutic response (and thus evaluate the cost effectiveness of treatment) to symptomatic treatment with fampridine. As a physiotherapist, I was also interested in the possibility of influencing...

Specific rehabilitation is a key period for a lower-limb amputee patient. While learning how to walk with a prosthesis, the patient needs to avoid any gait compensations that may lead to future comorbidities. To reach a gait pattern close to the one of a healthy person, objective data may be of great help to complement the experience of the clinician team. By using 6 IMUs located on the feet, shanks and thighs accompanied by 3 accelerometers on the pelvis, sternum and head, data could be recorded during walking exercises of 7 rehabilitation sessions of a patient. To compute the absolute symmetry index of the stance phase duration and the stride duration all over the instrumented sessions, the gait events defining the transitions between gait phases were determined thanks to several algorithms. By first comparing the error obtained in the calculation of the stance phase duration with all tested algorithms as compared to the data from pressure insoles considered as a reference system, the algorithm developed by Trojaniello and collaborators [1] was found to be the most adapted to this situation. Using this algorithm on the data from all sessions highlighted the possibility to detect changes in the symmetry of stance phase duration and stride duration, that are relative to the gait quality. This means that IMUs seem to be able to monitor the progress of a patient during his rehabilitation. Hence, IMUs have proven themselves to be a system of great interest in the analysis of the gait pattern of a lower-limb amputee patient in rehabilitation, by allowing for an embedded measurement of much more parameters than the pressure insoles, whose calibration constituted a real limitation.

yes / Background: Minimum toe clearance is a critical gait event because it coincides with peak forward velocity of the swing foot, and thus, there is an increased risk of tripping and falling. Trans-tibial amputees have increased risk of tripping compared to able-bodied individuals. Assessment of toe clearance during gait is thus clinically relevant. In able-bodied gait, minimum toe clearance increases with faster walking speeds, and it is widely reported that there is synchronicity between when peak swing-foot velocity and minimum toe clearance occur. There are no such studies involving lower-limb amputees. Objectives: To determine the effects of walking speed on minimum toe clearance and on the temporal relationship between clearance and peak swing-foot velocity in unilateral trans-tibial amputees. Study design: Cross-sectional. Methods: A total of 10 trans-tibial participants walked at slow, customary and fast speeds. Minimum toe clearance and the timings of minimum toe clearance and peak swing-foot velocity were determined and compared between intact and prosthetic sides. Results: Minimum toe clearance was reduced on the prosthetic side and, unlike on the intact side, did not increase with walking speed increase. Peak swing-foot velocity consistently occurred (~0.014 s) after point of minimum toe clearance on both limbs across all walking speeds, but there was no significant difference in the toe–ground clearance between the two events. Conclusion: The absence of speed related increases in minimum toe clearance on the prosthetic side suggests that speed related modulation of toe clearance for an intact limb typically occurs at the swing-limb ankle. The temporal consistency between peak foot velocity and minimum toe clearance on each limb suggests that swing-phase inter-segmental coordination is unaffected by trans-tibial amputation. Clinical relevance The lack of increase in minimum toe clearance on the prosthetic side at higher walking speeds may potentially increase risk of tripping. Findings indicate that determining the instant of peak swing-foot velocity will also consistently identify when/where minimum toe clearance occurs.

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Of all children in the US born with Cerebral Palsy (CP), 30-40% of them will be diagnosed with Hemiplegic CP (HCP), presenting with one side of the body weaker than the other. The resulting asymmetries impede the ability of children with HCP to distribute weight evenly between their lower limbs. This often contributes to poor postural control and 'favoring' of their uninvolved side for stability during balance and gait. Much is still unknown about the biomechanical characteristics of asymmetry in the lower limbs. There are a few previous research studies completed in biomechanics labs that highlight some gaps in knowledge regarding our understanding of posture and balance in this population of children, but the availability of clinical assessments that help inform the implementation and impact of treatment targets for posture and balance are sparse. This dissertation showcases two independent studies aimed at some of the gaps in knowledge for posture and balance in children with HCP. The first study in this dissertation presents and tests the reliability when a clinical measure, the Posture and Postural Ability Scale (PPAS) was modified for use in children with HCP going through a therapeutic process. The PPAS was originally developed and tested with adults in controlled settings, often with individuals being placed in postures for examination. For the study presented here, modifications focused on scoring postures when children with HCP naturally assumed various sitting and standing postures during treatment. Researchers and an experienced therapist video-coded the modified PPAS. Intrarater and interrater reliability was calculated via Cohen's kappa, percent agreement and Intraclass Correlation Coefficients. Although reliability amongst and between researchers were weak (kappas < 0.7), videos were successfully scored, demonstrating the tool is feasible. In addition, some high levels of intrarater reliability was obtained by a more experienced clinician. Suggestive that this modified PPAS could serve as a potential tool for qualified clinicians to collect meaningful posture and postural control data. The second study addressed a specific gap in knowledge about the characteristics of gait anticipation (GA, i.e., expectation of initiating a step) in children with HCP on balance. Balance and limb symmetry metrics were compared during standing in three children with HCP and typically developing (TD) peers that were matched by age and sex, alongside a third (independent) sample of 12 unmatched TD children. Motion capture analysis and force plate technology were utilized to record and follow how center of pressure (COP) and center of mass (COM) move during quiet standing (without anticipating gait) and standing with GA. This study applied a Symmetry Index (SI) to COP displacement and COP velocity allowing for quantification of asymmetries between the lower limbs during standing with and without the anticipation of gait. Children completed multiple standing trials where they were ask to stand for 35 seconds (5 seconds to obtain balance and 30 seconds of data collection). Standing trials, involved sets where children were instructed that they would not walk forward and GA trials where they were asked to stand knowing that a light would indicate they should walk forward. The light also indicated which limb (i.e. right or left) the child should step forward with first. Limb designation for stepping forward was randomly generated. Data was examined across and within (15 second blocks) 30 seconds of standing. We had the following hypotheses: 1) GA would increase COP displacement and COP velocity for children with HCP greater than TD peers who would have no change; 2) children with HCP would have different levels of symmetry between the lower limbs when expecting to walk than TD peers; and 3) children with HCP would have different reaction times based on the limb (i.e., involved versus uninvolved) they were asked to start walking with. The HCP group showed the largest increase in COP displacement when comparing standing with no expectation of walking where they had an average of 22.0 ± 10.0 mm over 30 seconds of standing to an average of 24.5 ±9.90mm during GA. The matched group average was 11.3 ±8.87mm with no expectation of walking and 4.6 ±12.6mm with GA. The TD group's COP displacement remained relatively similar with an average of 8.04 ±6.40mm during when not expecting to walk and an average of 8.29 ±6.70mm with GA. Similar increases were seen for COP velocity. Comparisons for symmetry between limbs showed that COP was displaced more underneath the uninvolved side (first 15s was 79.52%) for children with HCP, and that COP displacement asymmetry switched to become larger underneath the involved side over time (the latter 15s was -82.81%) when there was no expectation for walking. This was inverted during GA, where children with HCP initially had more COP displacement on the involved side (-72.68%) and transitioned to higher levels on the uninvolved side (99.66%) as they prepared for gait initiation. Children with HCP took 0.2 seconds longer to initiate gait with their uninvolved (not preferred) side and also took twice as long to initiate gait overall in comparison to TD peers. Our data suggests that our listed hypotheses may be correct. However, this study has limitations to sample size, demographics and biomechanical metrics. Future studies should replicate these findings and include larger, more diverse samples with further metrics such as load. If findings are confirmed, this data suggests that therapies should consider that children with HCP might change postural strategies during standing when they are anticipating walking forward in comparison to simply standing in place. This dissertation seeks to set a foundation for collaborations between biomechanists and therapists alike, potentially highlighting novel opportunities to develop more innovative treatment options for children with HCP. / Doctor of Philosophy / Children with hemiplegic cerebral palsy (HCP) show limitations in coordination and activation of muscles on one side of their body; additionally, clinicians report an asymmetrical distribution of weight in their legs during standing and walking based on observation. This lower limb asymmetry is often paired with poor coordination and is believed to negatively impact posture and balance. Children with HCP often have difficulty starting and stopping walking, altered balance during sitting and standing, and challenges completing everyday activities such as navigating around or across obstacles and climbing up steps. I have worked together with my committee members to complete two independent projects measuring posture and postural control. The first project is a reliability study where researchers tested the utility of a modified measurement tool that could be used to score postures and postural control of children assuming natural postures during therapy sessions. The modified tool was based on a previously developed tool called the Posture and Postural Ability Scale (PPAS). The study had multiple researchers and a therapist score previously recorded treatment videos. Outcomes suggest that our modified PPAS could be used to score postures from video recordings of therapy session, but that increased modifications in the tool and scoring protocol are needed to improve the reliability of the tool. The second project funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development involved children with HCP and typically developing (TD) peers. The goal of the project was to understand if children with HCP change characteristics of standing when they know they will begin to walk. We also wanted to better understand issues surrounding how symmetrical (or not) children with HCP were with the use of both their involved and uninvolved legs. We found that children with HCP do alter characteristics of standing when they anticipate walking much more that TD peers. We also found asymmetries between the two limbs during standing that differed based on children with HCP's anticipation of walking.