| 1. |
- Alm, M., et al.
(författare)
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Clinical evaluation of seating in persons with complete thoracic spinal cord injury
- 2003
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Ingår i: Spinal Cord. - : Springer Science and Business Media LLC. - 1362-4393 .- 1476-5624. ; 41:10, s. 563-571
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Tidskriftsartikel (refereegranskat)abstract
- Study Design: Consecutive male patients studied with photographic measurement of a combination of clinical methods. Objectives: To describe seating in individuals with complete thoracic spinal cord injury (SCI) by using a combination of clinical methods. Setting: Spinalis SCI unit, Stockholm, Sweden. Methods: Wheelchair specifications were documented. Measurements of posture from photographs in 30 male subjects with complete thoracic SCI, sitting in a relaxed and an upright position on a standardized surface and in a wheelchair were calculated. A comparison was made between positions and seating surfaces. An examiner's classification of lower trunk position in wheelchair was compared to subjects' evaluations. SCI subjects reported sitting support, satisfaction, and wishes for improvement. Results: Most SCI subjects used similar wheelchair specifications. None of the backrests were custom designed. Relatively small differences were found between the relaxed and upright position in the wheelchair regarding measurements of posture and according to the examiner's classification of the lower trunk position. Only 13/30 SCI subjects were sitting with the lower trunk centered relative to the backrest in the upright position. The examiner's classification and the subjects' evaluation of asymmetric sitting were not always in agreement. Only 12/30 SCI subjects were satisfied with their way of sitting. Conclusion: Current wheelchair specifications and adjustments seem to inhibit a postural correction towards upright sitting and fail to provide sufficient lateral support. Findings indicate an inability for SCI subjects to vary their sitting position in a wheelchair to a large extent. Both an examiner's classification and subjects' evaluation of asymmetric sitting are necessary to obtain a sufficient knowledge base for subsequent adjustment. By using methods regarding different aspects of seating, a more comprehensive view of seating was achieved. The combination of clinical methods seems to be useful in order to describe seating in individuals with complete thoracic SCI.
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| 2. |
- Gutierrez-Farewik, Elena M., et al.
(författare)
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Measuring seating pressure, area, and asymmetry in persons with spinal cord injury
- 2004
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Ingår i: European spine journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 13:4, s. 374-379
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Tidskriftsartikel (refereegranskat)abstract
- The goal of this study was to measure characteristics of seat loading in manual wheelchair users with complete spinal cord injury (SCI). Pressure distribution on the seating area of 25 adult males with SCI and eight non-injured adult males was measured in a relaxed and an upright posture on a standardized hard surface. Subjects with SCI were also tested in their wheelchairs. Maximum pressure, contact area, area of the highest pressure, and three asymmetry indices were compared. Subjects with SCI have higher pressure distributed over a smaller area, have a much smaller contact area, and distribute the loading more asymmetrically than non-injured subjects. Upright posture only corrects for some loading problems, while the wheelchair corrects for more loading parameters. Routine clinical seat loading evaluation may lead to improved chair and cushion selection for patients with SCI and may even alert clinicians to patients at high risk for complications due to high or unbalanced loads.
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| 3. |
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| 4. |
- Naili, J. E., et al.
(författare)
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The centre of mass trajectory is a sensitive and responsive measure of functional compensations in individuals with knee osteoarthritis performing the five times sit-to-stand test
- 2018
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Ingår i: Gait & Posture. - : Elsevier. - 0966-6362 .- 1879-2219. ; 62, s. 140-145
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to evaluate whether the trajectory of the body's Centre of Mass (CoM) is a sensitive and responsive measure of functional compensations in individuals with knee osteoarthritis (OA) performing the Five Times Sit-to-Stand test (5STS). This prospective study included 21 individuals with OA and 21 age- and gender-matched controls. Motion analysis data was collected while participants performed the 5STS, one month prior and one year after total knee arthroplasty (TKA). Pain was evaluated using a visual analogue scale. Repeated measures ANOVAs were used to evaluate (1) differences in the area under the curve (AUC) of CoM trajectories, and (2) the effect of number of sit-to-stand cycles on the AUC. Preoperatively, individuals with OA displayed a larger contralateral shift (p = 0.009) and forward displacement of the CoM (p < 0.004) than controls. Postoperatively, CoM trajectories of OA individuals were not statistically different from controls. However, upon comparison of specific cycles, OA individuals displayed a larger forward displacement during the final cycle. Pain was significantly reduced postoperatively (p = 0.001). The CoM trajectory appears to be a sensitive and responsive measure of functional compensations. The increased contralateral shift of the CoM represents a strategy to reduce pain by unloading the affected knee. Postoperatively, when pain was substantially reduced, OA individuals were comparable to controls. The increased forward CoM displacement characterises a strategy to reduce muscular effort by reducing the required knee extension moment. Postoperatively, OA individuals were comparable to controls in all cycles but the last, possibly suggesting residual muscle weakness.
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| 5. |
- Örtqvist, M., et al.
(författare)
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Knee muscle strength-A challenge to measure
- 2014
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Ingår i: European Journal of Physiotherapy. - : Informa UK Limited. - 2167-9169 .- 2167-9177. ; 16:1, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- The aims were to assess the reliability of knee extensor and flexor muscle strength measurements using the Strength Measuring Chair (SMC) in children and adults, and to assess agreement between the SMC and an isokinetic dynamometer (ID). 20 healthy children (10/10 boys/girls, 5-13 years) and 23 adults (10/13 men/women, 23-60 years) were included. Muscle strength tests were performed in the SMC and in the ID. The intra-subject reliability was shown to be excellent in both instruments (ICC 0.93-0.99) and an excellent test-retest reliability of measurements in the SMC was found (ICC 0.87-0.93). Agreement between instruments was evaluated with ICC, paired t-test and Bland-Altman 95% limits of agreement plots. In both adults' and children's groups, disagreements were found between the two instruments, with more in the children's group. The SMC, which has previously shown to be valid and reliable for measuring plantarflexor muscle strength, reliably measured knee muscle strength in healthy children and adults. However, the large disagreement found between the instruments, especially in the children's group, warrants care in standardizing measuring positions for different body size and warrants caution in comparing one's muscle strength measured using different assessment methods.
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| 6. |
- Örtqvist, Maria, et al.
(författare)
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Reliability of a new instrument for measuring plantarflexor muscle strength
- 2007
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Ingår i: Archives of Physical Medicine and Rehabilitation. - : Elsevier BV. - 0003-9993 .- 1532-821X. ; 88:9, s. 1164-1170
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To test the reliability of a new muscle strength testing instrument (the Strength Measuring Chair [SMC]) designed to quantify isometric strength in the lower extremities, and to determine the agreement between the SMC and an isokinetic dynamometer (Biodex). Design: Isometric strength tests were performed in plantar-flexors with 2 different knee positions (60 degrees, 30 degrees). Measurements were taken at 3 different sessions. Setting: Strength testing laboratory. Participants: Twenty-three able-bodied adults and 15 able-bodied children. Interventions: Not applicable. Main Outcome Measure: Isometric plantarflexor strength. Results: The reliability of isometric strength measurements of plantarflexors taken in the SMC was excellent for both the adult and children groups (intraclass correlation coefficient range,.84-.87). A Bland-Altman 95% limit of agreement test showed no systematic variation in 3 of the 4 SMC test observations; systematic variation was only observed in the adult group at a knee position of 30 degrees. There was no systematic difference in the adult group between the SMC and the isokinetic dynamometer, but there was a systematic variation in the children's group. Conclusions: The SMC reliably measured isometric plantarflexor strength in the tested populations.
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| 7. |
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| 8. |
- Bartonek, Asa, et al.
(författare)
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A new carbon fibre spring orthosis for children with plantarflexor weakness
- 2007
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 25:4, s. 652-656
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Tidskriftsartikel (refereegranskat)abstract
- We tested a new orthosis with a carbon fiber spring constructed to enable energy storing during increasing dorsiflexion in mid-stance, and to use the energy at the end of stance phase to aid push-off. The orthosis was tested on children with plantarflexor weakness due to motor disorders. All subjects were tested with 3D gait analysis with both the new orthosis and with their regularly used orthosis. In this technical note, the results of three individuals are reported. The preliminary findings show increased dorsiflexion, altered knee kinematics and improved kinetic and temporo-spatial parameters. Although the carbon spring orthosis influenced the subjects' gait in different ways, we conclude that the tested subjects with plantarflexion weakness benefit from the carbon fiber spring orthoses during walking. The parents' and children's subjective impressions as acquired from a questionnaire were also positive.
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| 9. |
- Bartonek, Asa, et al.
(författare)
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Effects of carbon fibre spring orthoses on gait in ambulatory children with motor disorders and plantarflexor weakness
- 2007
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Ingår i: Developmental Medicine & Child Neurology. - : Wiley. - 0012-1622 .- 1469-8749. ; 49:8, s. 615-620
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Tidskriftsartikel (refereegranskat)abstract
- A consecutive series of 17 children (six males, 11 females; mean age 11y 11mo [SD 4y 5mo]; range 3y 11mo-17y 4mo) with plantarflexor weakness was assessed to compare gait differences between a carbon fibre spring orthosis (CFSO) and participants' regular orthoses. Twelve children had myelomeningocele, four children had arthrogryposis, and one child had neuropathy with peripheral muscle pareses. All participants underwent clinical examination and 3D gait analysis. Parents answered a questionnaire to assess subjective perceptions of the orthoses. Results from 3D gait analysis provided evidence that CFSOs enhance gait function in most participants by improving ankle plantarflexion moment (p < 0.001), ankle positive work (p < 0.001), and stride length (p < 0.001). The CFSO did not suit all participants, which emphasizes the importance of analyzing each patient's needs.
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| 10. |
- Bartonek, A., et al.
(författare)
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Influence of external visual focus on gait in children with bilateral cerebral palsy
- 2016
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Ingår i: Pediatric Physical Therapy. - 0898-5669 .- 1538-005X. ; 28:4, s. 393-399
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To explore whether focusing a target influenced gait in children with cerebral palsy (CP) and typical development (TD). Methods: Thirty children with bilateral CP (Gross Motor Function Classification System [GMFCS] I-III) and 22 with TD looked at a light at walkway end (Gaze Target) while walking and returned (No Target). Results: During Gaze versus No Target, children with TD reduced temporal-spatial parameters and movements in the sagittal (SPM) and transverse planes. In comparison, during Gaze Target, children in CP1 (GMFCS I) had larger trunk SPM, children in CP2 (GMFCS II) larger neck (SPM), and children in CP3 (GMFCS III) greater head and neck frontal plane movements, and reduced cadence and single support. Conclusions: Focusing a target altered gait in children with CP. Children in CP1 reduced movements similar to children with TD, children in CP2 behaved nearly unchanged, whereas children in CP3 reduced movements and temporalspatial parameters, potentially as a consequence of lack of sensory information from lower limbs.
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| 11. |
- Bartonek, Asa, et al.
(författare)
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Influence of heel lifts during standing in children with motor disorders
- 2011
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 34:3, s. 426-431
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Tidskriftsartikel (refereegranskat)abstract
- Heel wedges may influence standing posture but how and to what extent are unknown. Thirty-two children with motor disorders - 16 with arthrogryposis multiplex congenita (AMC) and 16 with cerebral palsy (CP) - and 19 control children underwent a three-dimensional motion analysis. Unassisted standing during 20s with shoes only and with heel lifts of 10,20 and 30 mm heights was recorded in a randomized order. The more weight-bearing limb or the right limb was chosen for analysis. In both the AMC and CP groups, significant changes were seen between various heel lifts in ankle, knee and pelvis, and in the control group in the ankle only. Between orthosis and non-orthosis users significant differences were seen between different heel lift conditions in ankle, knee and trunk in the AMC group and in the ankle in the CP group. Pelvis position changed toward less anterior tilt with increasing heel height, but led to increasing knee flexion in most of the children, except for the AMC Non-Ort group. Children with AMC and CP represent different motor disorders, but the heel wedges had a similar influence on pelvis, hip and knee positions in all children with CP and in the AMC orthosis users. A challenge is to apply heel heights adequate to each individual's orthopaedic and neurologic conditions to improve biomechanical alignment with respect to all body segments.
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| 12. |
- Bartonek, A., et al.
(författare)
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The influence of spasticity in the lower limb muscles on gait pattern in children with sacral to mid-lumbar myelomeningocele : a gait analysis study
- 2005
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 22:1, s. 10-25
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Tidskriftsartikel (refereegranskat)abstract
- Gait analysis and recording of standing position were performed in 38 ambulatory children with myelomeningocele. Thirty-four were independent ambulators and four required a walking aid. All subjects were assigned one of four muscle function groups based on muscle strength. They were also divided into subgroups based on the distinction between flaccid and spastic paresis in the lower limb joints. A comparison was made between the gait pattern of the children with spasticity and that of the children with flaccid paresis in each muscle function group. Spasticity in only the ankle joint muscles influenced the subject's gait and standing position compared to the subgroups with a flaccid paresis. Even larger deviations in gait and standing position were observed when spasticity occurred in muscles at the knee and hip joints. When setting ambulatory goals the presence of additional neurological symptoms such as spasticity and inadequate balance should be taken into consideration.
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| 13. |
- Broström, Eva, et al.
(författare)
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Trunk and center of mass movements during gait in children with juvenile idiopathic arthritis
- 2007
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Ingår i: Human Movement Science. - : Elsevier BV. - 0167-9457 .- 1872-7646. ; 26:2, s. 296-305
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Tidskriftsartikel (refereegranskat)abstract
- Motion of the body center of mass (CoM) can often indicate the overall effect of the strategy of forward progression used. In the present study, focus is placed on trunk movements in the sagittal, coronal, and transverse/rotation plane, as well as placement of the CoM, during gait in children with juvenile idiopathic arthritis (JIA). Seventeen children with JIA, all with polyarticular lower extremity involvement were examined before and approximately two weeks after treatment with intra-articular cortico-steroid injections. Movement was recorded with a 6-camera 3D motion analysis system in both the children with JIA and in 21 healthy controls. Trunk and center of mass movements were compared between JIA and controls, and effects of intra-articular cortico-steroid treatment were evaluated. Children with JIA were more posteriorly tilted in the trunk, contrary to the common clinical impression, and had their CoM placed more posterior and off-centred, which may have been a result of pain. With such knowledge, it might be possible to better understand the effects of their pain and involvement, and ultimately to plan a treatment strategy for improving their gait patterns.
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| 14. |
- Dijkstra, Erik J., et al.
(författare)
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Computation of ground reaction force using Zero Moment Point
- 2015
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Ingår i: Journal of Biomechanics. - : Elsevier. - 0021-9290 .- 1873-2380. ; 48:14, s. 3776-3781
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Tidskriftsartikel (refereegranskat)abstract
- Motion analysis is a common clinical assessment and research tool that uses a camera system or motion sensors and force plates to collect kinematic and kinetic information of a subject performing an activity of interest. The use of force plates can be challenging and sometimes even impossible. Over the past decade, several computational methods have been developed that aim to preclude the use of force plates. Useful in particular for predictive simulations, where a new motion or change in control strategy inherently means different external contact loads. These methods, however, often depend on prior knowledge of common observed ground reaction force (GRF) patterns, are computationally expensive, or difficult to implement. In this study, we evaluated the use of the Zero Moment Point as a computationally inexpensive tool to obtain the GRFs for normal human gait. The method was applied on ten healthy subjects walking in a motion analysis laboratory and predicted GRFs are evaluated against the simultaneously measured force plate data. Apart from the antero-posterior forces, GRFs are well-predicted and errors fall within the error ranges from other published methods. Joint extension moments were underestimated at the ankle and hip but overestimated at the knee, attributable to the observed discrepancy in the predicted application points of the GRFs. The computationally inexpensive method evaluated in this study can reasonably well predict the GRFs for normal human gait without using prior knowledge of common gait kinetics.
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| 15. |
- Dijkstra, Erik J.
(författare)
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Constrained Optimization for Prediction of Posture
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ability to stand still in one place is important in a variety of activities of daily living. For persons with motion disorders, orthopaedic treatment, which changes geometric or biomechanical properties, can improve the individual'sposture and walking ability. Decisions on such treatment require insight in how posture and walking ability are aected, however, despite expectations based on experience, it is never a-priori known how a patient will react to a treatment. As this is very challenging to observe by the naked eye, engineering tools are increasingly employed to support clinical diagnostics and treatment planning. The development of predictive simulations allows for the evaluation of the eect of changed biomechanical parameters on the human biological system behavior and could become a valuable tool in future clinical decision making. In the first paper, we evaluated the use of the Zero Moment Point as a computationally inexpensive tool to obtain the ground reaction forces (GRFs) for normal human gait. The method was applied on ten healthy subjects walking in a motion analysis laboratory and predicted GRFs are evaluated against the simultaneously measured force plate data. Apart from the antero-posterior forces, GRFs are well-predicted and errors fall within the error ranges from other published methods. The computationally inexpensive method evaluated in this study can reasonably well predict the GRFs for normal human gait without using prior knowledge of common gait kinetics. The second manuscript addresses the complications in the creation and analysis of a posture prediction framework. The fmincon optimization function in MATLAB was used in conjunction with a musculoskeletal model in OpenSim. One clear local minimum was found in the form of a symmetric standing posture but perturbation analyses revealed the presence of many other postural congurations, each representing its own unique local minimum in the feasible parameter space. For human postural stance, this can translate to there being many different ways of standing without actually noticing a difference in the efforts required for these poses.
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| 16. |
- Dijkstra, Erik J., et al.
(författare)
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Sensitivity in prediction of human posture by constrained optimization
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In a variety of activities of daily living, it is important to be able to stand still in one place. For persons with motion disorders, orthopaedic treatment, which changes geometric or biomechanical properties, can improve the individual's posture and walking ability. Such treatment requires insight into how posture and walking ability are affected. As this is very challenging to observe by the naked eye, engineering tools are increasingly employed to support clinical diagnostics and treatment planning. Because of their potential to help unravel the causal relation between treatment and its outcome, the number of predictive methods are increasing. This study addresses the complications in the creation and analysis of a posture prediction framework. The fmincon optimization function in MATLAB was used in conjunction with a musculoskeletal model in OpenSim. One clear local minimum was found in the form of a symmetric standing posture but perturbation analyses revealed the presence of many other postural congurations, each representing its own unique local minimum in the feasible parameter space. For human postural stance, this can translate to there being many different ways of standing without actually noticing a difference in the efforts required for these poses.
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| 17. |
- Eriksson, Marie, et al.
(författare)
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Gait dynamics in the wide spectrum of children with arthrogryposis : a descriptive study
- 2015
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Ingår i: BMC Musculoskeletal Disorders. - : BioMed Central. - 1471-2474. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: Arthrogryposis Multiplex Congenita (AMC) is a heterogeneous condition characterized by multiple joint contractures at birth. Greater movements in the trunk and pelvis during walking have been observed in children with AMC using orthoses compared to those wearing only shoes. This study investigated gait dynamics in children with AMC and identified compensatory mechanisms that accommodate walking. Methods: Twenty-six children with AMC who walked with orthoses or shoes and a control group consisting of 37 typically-developing children were evaluated in 3D gait analysis. Children with AMC were divided into subgroups based on which joints needed to be stabilized in the sagittal plane; AMC1 used knee-ankle-foot orthoses (KAFOs) with locked knee joints, AMC2 used KAFOs with open knee joints or ankle-foot orthoses, and AMC3 used shoes. Results: The Gait Deviation Index was lower in AMC groups than in the control group, with the lowest in AMC1. Excessive trunk movements in frontal and transverse planes were observed in AMC2 and especially in AMC1. Lower hip flexion moment was found in AMC1, while AMC2 and AMC3 showed similar hip flexion moments as the control group. Knee extension moments were similar between the groups. In the frontal plane there were only small differences between the groups in hip abduction moment. A joint work analysis indicated greater contribution from the hip muscles to overall positive work in AMC groups, particularly in AMC1, than in the control group. Conclusion: All AMC groups showed less hip extension than the control group, but hip flexion moment was significantly lower only in AMC1, which can be attributed to their gait strategy with bilateral locked KAFOs. AMC1, who had weak knee extensors, were helped by their locked KAFOs and therefore showed similar knee extension moment as the other groups. This finding, together with their gait patterns, demonstrates the children's high reliance on hip muscles and presumably trunk muscles to provide propulsion. Our study shows that with adequate orthotic support, children with AMC and even with severe weakness and contractures can achieve walking.
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| 18. |
- Gutierrez Farewik, Elena M, 1973-
(författare)
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A new model for diffuse brain injury by rotational acceleration: II. Effects on extracellular glutamate, intracranial pressure, and neuronal apoptosis
- 2001
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Ingår i: Journal of Neurotrauma. - 0897-7151 .- 1557-9042. ; 18:3, s. 259-73
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to monitor excitatory amino acids (EAAs) in the extracellular fluids of the brain and to characterize regional neuronaldamage in a new experimental model for brain injury, in which rabbits were exposed to 180-260 krad/s2 rotational head acceleration. This loading causes extensive subarachnoid hemorrhage, focal tissue bleeding, reactive astrocytosis, and axonal damage. Animals were monitored for intracranial pressure (ICP) and for amino acids in the extracellular fluids. Immunohistochemistry was used to study expression of the gene c-Jun and apoptosis with the terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) technique. Extracellular glutamate, glycine, and taurine increased significantly in the hippocampus within a few hours and remained high after 24 h. Neuronal nuclei in the granule layers of the hippocampus and cerebellum were positive for c-Jun after 24 h. Little immunoreactivity was detected in the cerebral cortex. c-Jun-positive neuronal perikarya and processes were found in granule and pyramidal CA4 layers of the hippocampus and among the Purkinje cells of the cerebellum. Also some microglial cells stained positively for c-Jun. TUNEL reactivity was most intense at 10 days after trauma and was extensive in neurons of the cerebral cortex, hippocampus, and cerebellum. The initial response of the brain after rotationalhead injury involves brain edema after 24 h and an excitotoxic neuronal microenvironment in the first hour, which leads to extensive delayed neuronal cell death by apoptosis necrosis in the cerebral cortex, hippocampus and cerebellum.
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| 19. |
- Gutierrez-Farewik, Elena M., et al.
(författare)
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Centre of mass motion during gait in persons with myelomeningocele
- 2003
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Ingår i: Gait & Posture. - 0966-6362 .- 1879-2219. ; 18:2, s. 37-46
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Tidskriftsartikel (refereegranskat)abstract
- The movement of the centre of mass in the vertical and lateral directions during gait in children with myelomeningocele was analyzed. The children were classified into five groups depending on the successive paresis of lower limb muscle groups and compared to a control group. In the groups with. dorsi- and plantarflexor weakness, the excursions increased and an anterior trend in the centre of mass was observed. In the groups with additional abductor paresis, the lateral excursion was highest and the vertical excursion low due to increased transverse and frontal motion and reduced sagittal motion. With further paresis of the hip extensors, the centre of mass was more posteriorly positioned due to compensatory trunk extension. Improved understanding of individual children's solutions to their muscle paresis can be obtained by visualizing the centre of mass relative to the pelvis. Centre of mass analyses in myelomeningocele offer an important complement to standard gait analysis.
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| 20. |
- Gutierrez-Farewik, Elena M., et al.
(författare)
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Characteristic gait kinematics in persons with lumbosacral myelomeningocele
- 2003
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Ingår i: Gait & Posture. - 0966-6362 .- 1879-2219. ; 18:3, s. 170-177
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Tidskriftsartikel (refereegranskat)abstract
- Thirty self-ambulatory children with mid-lumbar to low-sacral myelomeningocele who walked without aids and 21 control children were evaluated by three-dimensional gait analysis. Characteristic kinematic patterns and parameters in the trunk, pelvis, hip, knee and ankle were analyzed with respect to groups with successive weakness of the ankle plantarflexor, ankle dorsiflexor, hip abductor, hip extensor and knee flexor muscles. Extensive weakness of the plantarflexors resulted in kinematic alterations in the trunk, pelvis, hip and knee and in all three planes seen as knee flexion, anterior pelvic tilt and trunk and pelvic rotation. Additional extensive weakness of the dorsiflexors made little difference in the walking strategy. Large kinematic alterations in all planes were observed where there was a large extent of additional weakness of the hip abductor but strength remaining in the hip extensors. In this group, gait was characterized by large lateral sway of the trunk, rotation of the trunk and pelvis, pelvic hike and increased extension of the knees. In the group with total poresis hip extensors but yet some knee flexion, gait was similar to the previous group but there was less sagittal plane movement greates and posterior trunk tilt. Gait analysis provides an understanding of the compensatory strategies employed in these patients. Clinical management can be directed towards stabilizing the lower extremities and accommodating large upper body motion to preserve this method of self-ambulation even in children who have considerable hip extensor and abductor weakness.
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| 21. |
- Gutierrez-Farewik, Elena M., et al.
(författare)
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Comparison and evaluation of two common methods to measure center of mass displacement in three dimensions during gait
- 2006
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Ingår i: Human Movement Science. - : Elsevier BV. - 0167-9457 .- 1872-7646. ; 25:2, s. 238-256
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Tidskriftsartikel (refereegranskat)abstract
- Center of mass displacement during gait has frequently been used as an indicator of gait efficiency or as a complement to standard gait analysis. With technological advances, measuring the center of mass as the centroid of a multi-segment system is practical and feasible, but must first be compared to the well-established Newtonian computation of double-integrating the ground reaction force. This study aims to verify that the kinematic centroid obtained from a commonly-used model (Vicon Peak (R) Plug-In-Gait) provides at least as reliable measurements of center of mass displacement as those obtained from the ground reaction forces. Gait data was collected for able-bodied children and children with myelomeningocele who use larger lateral center of mass excursions during gait. Reasonable agreement between methods was found in fore-aft and vertical directions, where the methods' excursions differed by an average of less than 10 mm in either direction, and the average RMS differences between methods' computed curves were 6 and 13 mm. Particularly good agreement was observed in the lateral direction, where the calculated excursions differed by an average of less than 2 mm and the RMS difference was 5 mm. Error analyses in computing the center of mass displacement from ground reaction forces were performed. A 5% deviation in mass estimation increased the computed vertical excursion twofold, and a 5% deviation in the integration constant of initial velocity increased the computed fore-aft excursions by 10%. The suitability of calculating center of mass displacement using ground reaction forces in a patient population is questioned. The kinematic centroid is susceptible to errors in segment parameters and marker placement, but results in plausible results that are at least within the range of doubt of the better-established ground reaction force integration, and are more useful when interpreting 3-D gait data.
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| 22. |
- Lidbeck, Cecilia M., et al.
(författare)
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Postural Orientation During Standing in Children With Bilateral Cerebral Palsy
- 2014
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Ingår i: Pediatric Physical Therapy. - 0898-5669 .- 1538-005X. ; 26:2, s. 223-229
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate postural orientation and maintenance of joint position during standing in children with bilateral spastic cerebral palsy (BSCP). Methods: Standing was examined with 3-D motion analysis in 26 children with BSCP, and 19 children typically developing (TD). Two groups of children with cerebral palsy (CP) were analyzed: 15 who were able to maintain standing without support and 11 who needed support. Results: Children with CP stood with more flexion than children TD. In the CP groups, children standing without support stood more asymmetrically with less hip and knee flexion and less movement than those who required support. Conclusion: Children with CP had varying abilities to stand and maintain standing posture with or without support. Both CP groups stood with more flexion than their potential passive joint angle, more obvious in children requiring support. Investigations on how muscle strength and spatial perception influence posture remains to be explored.
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| 23. |
- Lidbeck, Cecilia, et al.
(författare)
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The role of visual stimuli on standing posture in children with bilateral cerebral palsy
- 2016
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Ingår i: BMC Neurology. - : BioMed Central. - 1471-2377. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: In children with bilateral cerebral palsy (CP) maintaining a standing position can be difficult. The fundamental motor task of standing independently is achieved by an interaction between the visual, somatosensory, and vestibular systems. In CP, the motor disorders are commonly accompanied by sensory and perceptual disturbances. Our aims were to examine the influence of visual stimuli on standing posture in relation to standing ability. Methods: Three dimensional motion analysis with surface electromyography was recorded to describe body position, body movement, and muscle activity during three standing tasks: in a self-selected position, while blindfolded, and during an attention-demanding task. Participants were twenty-seven typically-developing (TD) children and 36 children with bilateral CP, of which 17 required support for standing (CP-SwS) and 19 stood without support (CP-SwoS). Results: All children with CP stood with a more flexed body position than the TD children, even more pronounced in the children in CP-SwS. While blindfolded, the CP-SwS group further flexed their hips and knees, and increased muscle activity in knee extensors. In contrast, the children in CP-SwoS maintained the same body position but increased calf muscle activity. During the attention-demanding task, the children in CP-SwoS stood with more still head and knee positions and with less muscle activity. Conclusions: Visual input was important for children with CP to maintain a standing position. Without visual input the children who required support dropped into a further crouched position. The somatosensory and vestibular systems alone could not provide enough information about the body position in space without visual cues as a reference frame. In the children who stood without support, an intensified visual stimulus enhanced the ability to maintain a quiet standing position. It may be that impairments in the sensory systems are major contributors to the difficulties to stand erect in children with CP.
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| 24. |
- Löwing, K., et al.
(författare)
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Effects of Botulinum Toxin-A and Goal-Directed Physiotherapy in Children with Cerebral Palsy GMFCS Levels I & II
- 2017
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Ingår i: Physical & Occupational Therapy in Pediatrics. - : Taylor & Francis Group. - 0194-2638 .- 1541-3144. ; 37:3, s. 268-282
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To evaluate short and long-term effects of botulinum toxin-A combined with goal-directed physiotherapy in children with cerebral palsy (CP). Method: A consecutive selection of 40 children, ages 4–12 years, diagnosed with unilateral or bilateral CP, and classified in GMFCS levels I–II. During the 24 months, 9 children received one BoNT-A injection, 10 children two injections, 11 children three injections, and 10 children received four injections. 3D gait analysis, goal-attainment scaling, and body function assessments were performed before and at 3, 12, and 24 months after initial injections. Results: A significant but clinically small long-term improvement in gait was observed. Plantarflexor spasticity was reduced after three months and remained stable, while passive ankle dorsiflexion increased after 3 months but decreased slightly after 12 months. Goal-attainment gradually increased, reached the highest levels at 12 months, and levels were maintained at 24 months. Conclusion: The treatments’ positive effect on spasticity reduction was identified, but did not relate to improvement in gait or goal-attainment. No long-term positive change in passive ankle dorsiflexion was observed. Goal attainment was achieved in all except four children. The clinical significance of the improved gait is unclear. Further studies are recommended to identify predictors for positive treatment outcome.
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| 25. |
- Murans, Girts, et al.
(författare)
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Kinematic and kinetic analysis of static sitting of patients with neuropathic spine deformity
- 2011
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 34:4, s. 533-538
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Tidskriftsartikel (refereegranskat)abstract
- Wheelchair dependent children with neuropathic and neuromuscular diseases have up to 90% risk for progressive spine deformities. An unbalanced sitting can induce progression of spinal and pelvic deformities. Many current clinical assessment methods of sitting of such patients are semi-quantitative, or questionnaire-based. A 3D movement analysis offers quantitative and objective biomechanical analysis of sitting. The aim was to validate a method to describe quiet sitting and differences between patients and controls as well as to apply the methodology for pre- and post-operative comparison. The analysis was performed on 14 patients and 10 controls. Four patients were retested after spine surgery. Seat load asymmetry was up to 30% in the patient group comparing to maximum 7% in the control group. The asymmetric position of Ground Reaction Force vector between left and right sides was significant. Plumb line of cervical 7th vertebra over sacral 1st was different only in rotation. The location of Common Center of Pressure relative to inter-trochanteric midpoint was more anterior in controls than in patients. Pelvic inclination in patients was smaller, the obliquity and rotation was similar. There were no significant differences between patients and controls of the thorax position. Results with more changes in the seat-loading domain in comparison with posture indicate good postural control compensation of spinal deformity induced disequilibrium despite neuromuscular disease in the background. The comparison of the pelvic obliquity data from kinematics and X-ray showed good correlation. The four patients tested postoperatively improved after surgery.
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| 26. |
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| 27. |
- Nielsen, C., et al.
(författare)
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Seat load characteristics in children with neuromuscular and syndrome-related scoliosis : effects of pathology and treatment
- 2008
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Ingår i: Journal of pediatric orthopedics. Part B. - 1060-152X .- 1473-5865. ; 17:3, s. 139-144
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Tidskriftsartikel (refereegranskat)abstract
- The amount of correction from spine deformity surgery that is required to avoid asymmetric and unbalanced sifting is not known, and methods sensitive enough to document moderate changes in pressure distribution over time are few, as the commonly used methods are qualitative or semiquantitative. The aim was to analyse seating pressure distribution with a pressure sensor mat system in patients with nonidiopathic scoliosis and to compare the pressure distribution with that in able-bodied controls. The aim was also to apply the method in a surgically treated scoliosis group before and after the spine fusion. Peak pressure, contact area of the entire and the maximum pressure surface, and three measures of asymmetry were calculated. Patients had higher peak pressure and more asymmetric loading than controls. Significant difference was indicated in contact area. After the spine fusion, all asymmetry indices improved. The method fulfilled clinical needs to detect the differences from normal controls as well as the surgery-dependent changes.
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| 28. |
- Romanato, M., et al.
(författare)
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Influence of different calibration methods on surface electromyography-informed musculoskeletal models with few input signals
- 2023
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033 .- 1879-1271. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although model personalization is critical when assessing individuals with morphological or neurological abnormalities, or even non-disabled subjects, its translation into routine clinical settings is hampered by the cumbersomeness of experimental data acquisition and lack of resources, which are linked to high costs and long processing pipelines. Quantifying the impact of neglecting subject-specific information in simulations that aim to estimate muscle forces with surface electromyography informed modeling approaches, can address their potential in relevant clinical questions. The present study investigates how different methods to fine-tune subject-specific neuromuscular parameters, reducing the number of electromyography input data, could affect the estimation of the unmeasured excitations and the musculotendon forces. Methods: Three-dimensional motion analysis was performed on 8 non-disabled adult subjects and 13 electromyographic signals captured. Four neuromusculoskeletal models were created for 8 participants: a reference model driven by a large set of sEMG signals; two models informed by four electromyographic signals but calibrated in different fashions; a model based on static optimization. Findings: The electromyography-informed models better predicted experimental excitations, including the unmeasured ones. The model based on static optimization obtained less reliable predictions of the experimental data. When comparing the different reduced models, no major differences were observed, suggesting that the less complex model may suffice for predicting muscle forces with a small set of input in clinical gait analysis tasks. Interpretation: Quantitative model performance evaluation in different conditions provides an objective indication of which method yields the most accurate prediction when a small set of electromyographic recordings is available.
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| 29. |
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| 30. |
- Sandamas, Paul Nicolas
(författare)
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Athletic Sprint Start Biomechanics : Investigations into the relationships between three dimensional starting technique, first step width and performance
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The block and early acceleration phase plays a very important role in the overall outcome of athletic sprint events. During this part of the race it is commonly observed that sprinters use a lower-body technique that involves the swing leg crossing medially in front of the athlete followed by wide steps. These wide initial steps give the impression that the legs are flailing out to the side. Some coaches believe that this action could be inefficient and thus should be curtailed. However, there is limited knowledge about this movement pattern and its relation to performance.Therefore, the overall aim of this thesis was to help elucidate from a biomechanical perspective a) the fundamental underlying kinematic and mechanical basis to this technique and b) how both performance and muscular contributions to propulsion would be affected when step width was restricted.A cross sectional study design was used to examine specific kinematic and kinetic variables from 11 competitive sprinters (9 male, 2 female) performing maximum effort 15 m sprint starts. Three-dimensional kinematics, ground reaction force and electromyographical data were recorded from the block phase to the end of the 1st stance phase. Each athlete performed five trials with their natural technique and five trials inside a 0.3 m wide lane. A 15-segment, full-body model and a 37 degrees of freedom full-body musculoskeletal model were created and used to calculate relevant variables/parameters. Normalised average horizontal external power was used as the performance measure.A combination of pelvis list and rotation (but not hip adduction) was found to be coupled with the thigh of the swing leg moving medially during the single push phase. In the unrestricted width trials, pelvic list range of motion and medial impulses correlated positively with step width but step width was not found to be related to performance. When step width was restricted, a more forward pointing normalised average ground reaction force vector was seen but lower body muscular contributions to acceleration were reduced and no immediate improvement to performance was found.The primary kinematic reason behind the lower body posture the sprinters adopt during the block phase whereby the swing leg moves medially in front of the body is caused by a combination of three dimensional pelvis rotations rather than simply hip internal rotation/or adduction of the swing leg. Trying to reduce pelvic range of motion or minimising the flailing leg motion is unlikely to lead to an improvement in performance. Therefore, the notion that this technique is inefficient, was not supported by this study.
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| 31. |
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| 32. |
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| 33. |
- Su, Binbin
(författare)
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Human motion prediction using wearable sensors and machine Learning
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Accurately measuring and predicting human movement is important in many contexts, such as in rehabilitation and the design of assistive devices. Thanks to the development and availability of a wide variety of sensors, scientists study human movement in many settings and capture characteristic properties unique to individuals as well as to larger study populations. Inertial measurement units (IMU), which contain accelerometers and gyroscopes, measure segment accelerations and angular velocities, and electromyography (EMG) sensors measure muscle excitation. These types of wearable sensors can be donned at the same time and can record data at a high frequency, potentially resulting in a large amount of data. Machine learning (ML) is an effective tool to extract the prominent features and make statistical inferences from data and has the potential to enhance human motion analyses through data-driven prediction. The overall aim of this thesis was to predict human motion through data-driven approaches and musculoskeletal simulations using wearable sensors and ML. A deterministic machine learning approach using a convolutional neural network (CNN) was first proposed to segment gait cycles into five phases based on experimental IMU data in subjects at different walking speeds. The proposed CNN was able to capture kinematic characteristics in raw IMU data, such as linear acceleration, rotational velocity, and magnetic field, and distinguish different gait phases. In recognizing all gait phases, it achieved an overall accuracy of 97.5% on a well-trained model, with up to 99.6% accuracy in detecting the swing phase. Our results also showed walking speed did not have a major influence on the overall gait phase recognition accuracy for people with typical gait patterns. However, while the swing was most accurately recognized, the terminal stance was least accurately recognized, and even more so at lower walking speeds.We then developed a long short-term (LSTM) network to predict both gait phase (loading response, midstance, terminal stance, pre-swing, and swing) and gait trajectory (angular velocities of thigh, shank, and foot segments) in up to the subsequent 200ms, based on immediately prior data. The overall accuracy of gait phase prediction was up to 94%, with the swing phase the most accurately predicted (97%). Our results also showed a high correlation between predicted and true values of the angular velocity of the thigh, shank, and foot segments. People walk on different terrains daily, for instance, level-ground walking, ramp/stairs ascent/descent, and stepping over obstacles. Movements patterns change as people move from one terrain to another, i.e. transition from one locomotion mode to another. Locomotion modes are typically labeled between two gait events, foot contact (FC) and toe off (TO). Since there is no exact instance for discriminating the transition between two locomotion modes, we identified TO as the critical gait event. We integrated locomotion mode prediction and gait event identification into one machine learning framework comprising two multilayer perceptrons (MLP), using fused data from two types of wearable sensors, namely EMG sensors and IMUs. The first MLP successfully identified FC and TO; FC events were identified accurately, and a small number of misclassifications only occurred near TO events. A small time difference (2.5 and -5.3 ms for FC and TO respectively) was found between predicted and true gait events. The second MLP correctly identified walking, ramp ascent, and ramp descent transitions with the best aggregate accuracy of 96.3%, 90.1%, and 90.6%, respectively, with sufficient prediction time before the critical events, using EMG and IMU signals as input features.Data-driven approaches using wearable sensors are incapable of modeling the mechanism between neuromuscular control and wearable sensor outputs. Musculoskeletal simulation can, on the other hand, explain the interactions between muscular control, kinematics, and kinetics in human motion. Thus, we integrated a reinforcement learning algorithm, a reflex-based controller, and a musculoskeletal model including trunk, pelvis, and leg segments to simulate reasonably realistic human walking at different speeds. We further generated pathological gaits that may result from ankle plantarflexor weakness using the same approach. The simulated hip and knee angles correlate reasonably well with reported experimental data, though less so for ankle kinematics. The computed muscle excitations in major low limb muscles largely correspond to the expected on-off timing of these muscles during walking. In summary, the studies in this thesis describe and predict human movement with wearable sensors and machine learning algorithms. We detected and predicted gait phases and events, predicted segment movements and identified intended transitions between walking modes during the stance phase of the previous gait cycle on the same side, before the step into the new mode, all based on data from wearable sensors. This has important potential implications in continuous monitoring and analysis of a person's movements outside a lab environment. The musculoskeletal simulation provided insight into the relationship between neuromuscular control and sensory feedback, which could also be applied to better understand and predict likely changes in gait when changes occur in neuromuscular control. Our approaches combining wearable sensors and machine learning could be ultimately applied to facilitate the design of exoskeletons that can provide seamless assistance for people with motor disorders.
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| 34. |
- Wang, Ruoli, et al.
(författare)
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Compensatory strategies during walking in response to excessive muscle co-contraction at the ankle joint
- 2014
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Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 39:3, s. 926-932
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Tidskriftsartikel (refereegranskat)abstract
- Excessive co-contraction causes inefficient or abnormal movement in several neuromuscular pathologies. How synergistic muscles spanning the ankle, knee and hip adapt to co-contraction of ankle muscles is not well understood. This study aimed to identify the compensation strategies required to retain normal walking with excessive antagonistic ankle muscle co-contraction. Muscle-actuated simulations of normal walking were performed to quantify compensatory mechanisms of ankle and knee muscles during stance in the presence of normal, medium and high levels of co-contraction of antagonistic pairs gastrocnemius + tibialis anterior and soleus + tibialis anterior. The study showed that if co-contraction increases, the synergistic ankle muscles can compensate; with gastrocmemius + tibialis anterior co-contraction, the soleus will increase its contribution to ankle plantarflexion acceleration. At the knee, however, almost all muscles spanning the knee and hip are involved in compensation. We also found that ankle and knee muscles alone can provide sufficient compensation at the ankle joint, but hip muscles must be involved to generate sufficient knee moment. Our findings imply that subjects with a rather high level of dorsiflexor + plantarflexor co-contraction can still perform normal walking. This also suggests that capacity of other lower limb muscles to compensate is important to retain normal walking in co-contracted persons. The compensatory mechanisms can be useful in clinical interpretation of motion analyses, when secondary muscle co-contraction or other deficits may present simultaneously in subjects with motion disorders.
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| 35. |
- Wang, Ruoli, et al.
(författare)
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One year follow-up after operative ankle fractures : A prospective gait analysis study with a multi-segment foot model
- 2010
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Ingår i: Gait & Posture. - Calre, Ireland : Elsevier BV. - 0966-6362 .- 1879-2219. ; 31:2, s. 234-240
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Tidskriftsartikel (refereegranskat)abstract
- Ankle fractures are one of the most common lower limb traumas. Several studies reported short- and long-term post-operative results, mainly determined by radiographic and subjective functional evaluations. Three-dimensional gait analysis with a multi-segment foot model was used in the current study to quantify the inter-segment foot motions in 18 patients 1 year after surgically treated ankle fractures. Data were compared to that from gender- and age-matched healthy controls. The correlations between Olerud/Molander ankle score and kinematics were also evaluated. Patients with ankle fractures showed less plantarflexion and smaller range of motion in the injured talocrural joint, which were believed to be a sign of residual joint stiffness after surgery and immobilization. Moreover, the forefoot segment had smaller sagittal and transverse ranges of motion, less plantarflexion and the hallux segment had less dorsiflexion and smaller sagittal range of motion. The deviations found in the forefoot segment may contribute to the compensation mechanisms of the injured ankle joint. Findings of our study show that gait analysis with a multi-segment foot model provides a quantitative and objective way to perform the dynamic assessment of post-operative ankle fractures, and makes it possible to better understand not only how the injured joint is affected, but also the surrounding joints.
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| 36. |
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| 37. |
- Yadav, Priti, et al.
(författare)
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Effect of growth plate geometry and growth direction on prediction of proximal femoral morphology
- 2016
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Ingår i: Journal of Biomechanics. - : Elsevier. - 0021-9290 .- 1873-2380. ; 49:9, s. 1613-1619
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical stimuli play a significant role in the process of endochondral growth. Thus far, approaches to understand the endochondral mechanical growth rate have been limited to the use of approximated location and geometry of the growth plate. Furthermore, growth has been simulated based on the average deflection of the growth plate or of the femoral neck. It has also been reported in the literature that the growth plate lies parallel to one of the principal stresses acting on it, to reduce the shear between epiphysis and diaphysis. Hence the current study objectives were (1) to evaluate the significance of a subject-specific finite element model of the femur and growth plate compared to a simplified growth plate model and (2) to explore the different growth direction models to better understand proximal femoral growth mechanisms. A subject-specific finite element model of an able-bodied 7-year old child was developed. The muscle forces and hip contact force were computed for one gait cycle and applied to a finite element model to determine the specific growth rate. Proximal femoral growth was simulated for two different growth direction models: femoral neck deflection direction and principal stress direction. The principal stress direction model captured the expected tendency for decreasing the neck shaft angle and femoral anteversion for both growth plate models. The results of this study suggest that the subject-specific geometry and consideration of the principal stress direction as growth direction may be a more realistic approach for correct prediction of proximal femoral growth morphology.
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| 38. |
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| 39. |
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| 40. |
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| 41. |
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