Neck Flexion Angle Estimation during Walking

Neck pain is recently known as the fourth leading cause of disability and the number of patients is apparently increasing. By analyzing the effect of gravitational force on inertial sensor attached to the neck, this study aims to investigate the head flexion posture during walking. The estimated angle is compared with the craniovertebral angle which is measured with an optical tracker. A total of twenty subjects with no history of neck pain or discomfort were examined by walking on the treadmill inside the working range of an optical tracker. In our laboratory settings, the neck flexion angle (NFA) may have a linear relationship with the craniovertebral angle (CVA) in both static case and constant speed walking case. Therefore, inertial sensor, which is lightweight, low cost, and especially free in movement, can be used instead of a camera system. Our proposed estimation method shows its flexibility and gives a result with the mean of absolute error of estimated neck angle varying from 0.48 to 0.58 degrees, which is small enough to use in applications

Biomechanics

Biomechanics is a vast discipline within the field of Biomedical Engineering. It explores the underlying mechanics of how biological and physiological systems move. It encompasses important clinical applications to address questions related to medicine using engineering mechanics principles. Biomechanics includes interdisciplinary concepts from engineers, physicians, therapists, biologists, physicists, and mathematicians. Through their collaborative efforts, biomechanics research is ever changing and expanding, explaining new mechanisms and principles for dynamic human systems. Biomechanics is used to describe how the human body moves, walks, and breathes, in addition to how it responds to injury and rehabilitation. Advanced biomechanical modeling methods, such as inverse dynamics, finite element analysis, and musculoskeletal modeling are used to simulate and investigate human situations in regard to movement and injury. Biomechanical technologies are progressing to answer contemporary medical questions. The future of biomechanics is dependent on interdisciplinary research efforts and the education of tomorrow’s scientists

Personalized hip joint kinetics during deep squatting in young, athletic adults

The goal of this study was to report deep squat hip kinetics in young, athletic adults using a personalized numerical model solution based on inverse dynamics. Thirty-five healthy subjects underwent deep squat motion capture acquisitions and MRI scans of the lower extremities. Musculoskeletal models were personalized using each subject's lower limb anatomy. The average peak hip joint reaction force was 274 percent bodyweight. Average peak hip and knee flexion angles were 107 degrees and 112 degrees respectively. These new findings show that deep squatting kinetics in the younger population differ substantially from the previously reported in vivo data in older subjects

Modelling gait abnormalities and bone deformities in children with cerebel palsy

Cerebral palsy (CP) is a neuromuscular disorder that affects the motor control of muscles. CP children exhibit abnormal walking patterns and frequently develop lower limb, long bone deformities. To improve functionality and guide orthopaedic treatments effectively, it is critical to elucidate the relationship existing between bone morphology and movement of the lower limbs CP children. The hypothesis of this study is that gait abnormalities result in bone deformities. The investigation of this complex relationship represents the core of this thesis. The examination of magnetic resonance images and gait analysis of healthy and CP children showed different development in femoral and tibial morphology and varied gait characteristics between them. Similarly, different correlations between bone morphology and gait characteristics resulted in healthy and CP children. Gait characteristics also varied between CP children. An objective and quantitative graphical classification method of CP gait patterns was developed. This classified the CP children in overlapping clusters according to their gait patterns, confirming the presence of multiple gait abnormalities on the same lower limb for CP children. With the intention to define the effect of the walking characteristics on the bone structure, femoral muscle and hip contact forces in healthy and CP children with different walking strategies were estimated by using inverse dynamic analysis. The different gait styles resulted in different loadings on the developing femur bone. These constituted the loading conditions for bone growth analysis. A three-dimensional finite element model for femoral growth was developed and mechanobiological theories applied in order to predict femur changes over time in healthy and CP children. The models predicted higher femoral anteversion and neck3 shaft angle formation in children with CP, emphasizing how different gait characteristics can influence bone morphology. This information has potential to explain and eventually prevent or treat the development of bone deformities in CP children

An exploration of movement and handling by physiotherapists in a rehabilitation setting: a motion analysis study.

Work-related musculoskeletal disorders (WRMSD) affect between 56-80% of physiotherapists, with patient handling often reported as a risk factor. Physiotherapists use therapeutic handling to aid patient rehabilitation. Therapeutic handling involves the physiotherapist "guiding, facilitating, manipulating or providing resistance" to the patient. Therapeutic handling can subject physiotherapists to high loading forces during patient handling. The aims of this doctoral thesis were to quantify physiotherapists' movement during therapeutic patient handling tasks, assess risk of injury against a frequently used ergonomic tool, and investigate whether there may be a relationship between patient handling and WRMSD. This research employed a descriptive cross-sectional study design and a positivistic approach to explore and quantitatively measure physiotherapist movement. A portable three-dimensional motion analysis system, Xsens MTw Awinda, was used to measure physiotherapist movement during patient treatments in a neurological setting. The physiotherapists' movement and posture were quantified, described and assessed using the Rapid Upper Limb Assessment (RULA) tool. The incidence and personal impact of WRMSD were investigated with the extended Nordic Musculoskeletal Questionnaire (NMQ-E) and potential patient tasks of risk were discussed. The physiotherapists used four main positions during patient handling tasks: 1) kneeling; 2) half-kneeling; 3) standing; and 4) sitting. Eight patient handling tasks were identified: 1) lie-to-sit; 2) sit-to-lie; 3) sit-to-stand; 4) upper limb; 5) lower limb; 6) trunk; 7) standing; and 8) walking facilitation. Kneeling or sitting positions were used by the physiotherapists most often during lie-to-sit, sit-to-lie, sit-to-stand, upper limb, trunk and standing facilitation tasks. Standing was the most common physiotherapist position during lower limb and walking tasks. Kneeling, half-kneeling and sitting positions demonstrated greater neck extension, which scored highly with the RULA and indicated potential risk of injury. Standing demonstrated more cervicothoracic flexion than kneeling and sitting, which demonstrated greater lumbosacral flexion than standing. The physiotherapists' hips and knees often maintained end-range flexion when kneeling or half-kneeling, which is discouraged in ergonomics literature. The low back was the most frequent anatomical area of WRMSD, with 60% of the physiotherapists having experienced discomfort there within their career. Physiotherapists were found to temporarily have changed jobs, sought professional help or taken medication for their shoulder, elbow or low back discomfort. However, none of the physiotherapists had taken sick leave in the last twelve months. This research found that tasks were more often performed in kneeling or sitting positions than in standing. Moving and handling guidance considers the handler in a standing position; guidance should therefore start to consider the handler in the variety of positions found in clinical practice. Ergonomic assessments, such as the RULA, consider the trunk as one joint. This research investigated three trunk joints, with different postures found at the cervicothoracic and lumbosacral junctions. Future research should appreciate how the position of the handler can impact trunk posture. More research needs to be conducted to qualitatively investigate physiotherapists' perceptions and experiences of patient handling. This research has provided a detailed exploration into therapeutic handling the neurological setting which can be used to guide future research

Hip Mechanics of Unilateral Drop Landings

Increased hip forces are a proposed factor for osteoarthritis and femoroacetabular impingement. These forces can be estimated through musculoskeletal modeling using measured kinematics and kinetics. An understanding of hip joint loading during landing in a asymptomatic population will begin to elucidate what, if any, sex differences exist and how changes in landing condition alter hip mechanics. The overall purpose of this dissertation was to explore how sex and landing condition effect landing mechanics. Landing mechanics were quantified using ground reaction forces (GRF), hip joint forces (HJF), and lower extremity kinematics during unilateral drop landings from 30-cm, 40-cm, and 50-cm, as well as, a 40-cm land-and-cut task. The relationships between sex and limb side, sex and landing task, and sex and landing height on landing mechanics were assessed using three sub-studies. Eighty-three, recreationally active, adult volunteers completed landing tasks (40 participants completed the land-and-cut task). For sex-limb side, bilateral differences (right versus left) were examined at 40-cm. No bilateral differences were identified. For sex-landing task, 40-cm drop landings were compared to land-and-cuts. Higher peak GRF (pGRF) and pGRF loading rates were identified for landing-only. Landing-only tasks were performed with less ankle dorsiflexion range of motion for landing (ROML) and impact (ROMI) phases. Landing-only tasks demonstrated more hip adduction ROML and more hip flexion ROMI. For sex-landing height, landings were compared between 30-cm and 50-cm. Increasing landing height resulted in increased pGRF, pHJF, pGRF loading rate, and pHJF loading rate. With increased height, larger 3-D hip and knee flexion ROMI and ROML were identified, as well as increased ankle dorsiflexion ROML. There were no interaction effects between sex and landing condition. Sex differences across sub-studies demonstrated consistent trends. In all studies, females incurred larger pGRF compared to males, yet only the landing height analysis demonstrated increased pHJF. Females exhibited larger hip adduction and reduced hip rotation ROML. Females exhibited larger hip flexion, hip adduction, and knee flexion ROMI. The landing task analysis identified increased female ankle dorsiflexion ROMI. Sex differences were identified between landing conditions, yet the lack of sex-landing condition interaction indicates both sexes may utilize similar modifications in response to changing landing conditions

Low-Cost Sensors and Biological Signals

Many sensors are currently available at prices lower than USD 100 and cover a wide range of biological signals: motion, muscle activity, heart rate, etc. Such low-cost sensors have metrological features allowing them to be used in everyday life and clinical applications, where gold-standard material is both too expensive and time-consuming to be used. The selected papers present current applications of low-cost sensors in domains such as physiotherapy, rehabilitation, and affective technologies. The results cover various aspects of low-cost sensor technology from hardware design to software optimization

Doctor of Philosophy

dissertationGeometric abnormalities of the human hip joint, as found in femoroacetabular impingement (FAI) and acetabular dysplasia, alter hip biomechanics and may be the primary causes of osteoarthritis in young adults. However, empirical evidence of direct correlations between abnormal geometry, altered biomechanics, and osteoarthritis is scarce. Also, clinical measures used to diagnose FAI and dysplasia still have substantial limitations, including questions about their reliability, assumptions about hip joint geometry and their ability to definitively distinguish pathologic from normal hips. The goals of this dissertation are twofold. First, a set of tools are presented and applied to quantify three-dimensional (3D) anatomical differences between hips with FAI and control subjects. The 3D tools were developed, validated and applied to patients with a subtype of FAI, called cam FAI, to improve basic understanding of the spectrum of FAI deformities, and to provide meaningful new metrics of morphology that are relatable to current diagnostic methods and translate easily for clinical use. The second goal of this dissertation is to improve our understanding of intra-articular hip contact mechanics as well as hip joint kinematics and muscle forces. To do so, a finite element study of intraarticular cartilage contact mechanics was completed with a cohort of live human subjects, using a validated modeling protocol. Finally, musculoskeletal modeling was used with gait data from healthy subjects and acetabular dysplasia patients to provide preliminary estimates of hip joint kinematics, kinetics, and muscle forces and compare differences between the groups. The translational methods of this dissertation utilized techniques from orthopaedics, computer science, physical therapy, mechanics, and medical imaging. Results from this dissertation offer new insight into the complex pathomechanics and pathomorphology of FAI and acetabular dysplasia. Application and extension of the work of this dissertation has the potential to help establish links between FAI and dysplasia with osteoarthritis and to improve patient care