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  • 1. Aberg, A. C.
    et al.
    Thorstensson, A.
    Tarassova, O.
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH).
    Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: A reliability study2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 3, p. 352-357Article in journal (Refereed)
    Abstract [en]

    For older people balance control in standing is critical for performance of activities of daily living without falling. The aims were to investigate reliability of quantification of the usage of the two balance mechanisms M(1) 'moving the centre of pressure' and M(2) 'Segment acceleration' and also to compare calculation methods based on a combination of kinetic (K) and kinematic (Km) data, (K-Km), or Km data only concerning M(2). For this purpose nine physically fit persons aged 70-78 years were tested in narrow and single-leg standing. Data were collected by a 7-camera motion capture system and two force plates. Repeated measure ANOVA and Tukey's post hoc tests were used to detect differences between the standing tasks. Reliability was estimated by ICCs, standard error of measurement including its 95% Cl, and minimal detectable change, whereas Pearson's correlation coefficient was used to investigate agreement between the two calculation methods. The results indicated that for the tasks investigated, M(1) and M(2) can be measured with acceptable inter- and intrasession reliability, and that both Km and K-Km based calculations may be useful for M(2), although Km data may give slightly lower values. The proportional M(1) :M(2) usage was approximately 9:1, in both anterio-posterior (AP) and medio-lateral (ML) directions for narrow standing, and about 2:1 in the AP and of 1:2 in the ML direction in single-leg standing, respectively. In conclusion, the tested measurements and calculations appear to constitute a reliable way of quantifying one important aspect of balance capacity in fit older people.

  • 2. Bartonek, A.
    et al.
    Gutierrez-Farewik, Elena M.
    Haglund-Akerlind, Y.
    Saraste, H.
    The influence of spasticity in the lower limb muscles on gait pattern in children with sacral to mid-lumbar myelomeningocele: a gait analysis study2005In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 22, no 1, p. 10-25Article in journal (Refereed)
    Abstract [en]

    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.

  • 3. Bartonek, Asa
    et al.
    Eriksson, Marie
    Gutierrez-Farewik, Elena M.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    A new carbon fibre spring orthosis for children with plantarflexor weakness2007In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 25, no 4, p. 652-656Article in journal (Refereed)
    Abstract [en]

    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.

  • 4. Bartonek, Asa
    et al.
    Lidbeck, Cecilia M.
    Pettersson, Robert
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Weidenhielm, Eva Brostrom
    Eriksson, Marie
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Influence of heel lifts during standing in children with motor disorders2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 3, p. 426-431Article in journal (Refereed)
    Abstract [en]

    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.

  • 5.
    Bartonek, Åsa
    et al.
    Karolinska Institutet, Dept. of Women's and Child's Health.
    Wang, Ruoli
    KTH, School of Engineering Sciences (SCI), Mechanics, Biomechanics.
    Eriksson, Marie
    Karolinska Institutet, Dept. of Women's and Children's Health.
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics, Biomechanics. KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Comparison of two carbon fibre spring orthoses' effect on gait in children with myelomeningocele2012In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219Article in journal (Refereed)
  • 6. Frykberg, Gunilla E.
    et al.
    Thierfelder, Tomas
    Aberg, Anna Cristina
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Borg, Jorgen
    Hirschfeld, Helga
    Impact of stroke on anterior-posterior force generation prior to seat-off during sit-to-walk2012In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 35, no 1, p. 56-60Article in journal (Refereed)
    Abstract [en]

    Force generation during sit-to-walk (STW) post-stroke is a poorly studied area, although STW is a common daily transfer giving rise to a risk of falling in persons with disability. The purpose of this study was to describe and compare strategies for anterior-posterior (AP) force generation prior to seat-off during the STW transfer in both subjects with stroke and in matched controls. During STW at self-selected speed, AP force data were collected by 4 force plates, beneath the buttocks and feet from eight subjects with stroke '(>6 months after onset) and 8 matched controls. Subjects with post-stroke hemiparesis and matched controls generated a similar magnitude of total AP force impulses (F-1.71 = 0.67; p = 0.42) beneath buttocks and feet prior to seat-off during STW. However, there were significant group differences in AP force impulse generation beneath the stance buttock (i.e. the non-paretic buttock in the stroke group), with longer duration (F-1.71 = 8.78; p <0.005), larger net AP impulse (F-1.71 = 6.76; p < 0.05) and larger braking impulse (F-1.71 = 7.24; p <0.05) in the stroke group. The total braking impulse beneath buttocks and feet was about 4.5 times larger in the stroke group than in the control group (F-1.71 = 8.84; p < 0.005). An intra-and inter-limb dys-coordination with substantial use of braking impulses was demonstrated in the stroke group. This motor strategy differed markedly from the smooth force interaction in the control group. These results might be important in the development of treatment models related to locomotion post-stroke.

  • 7. Gullstrand, Lennart
    et al.
    Halvorsen, Kjartan
    Tinmark, Fredrik
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical Engineering.
    Nilsson, Johnny
    Measurements of vertical displacement in running, a methodological comparison2009In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 30, no 1, p. 71-75Article in journal (Refereed)
    Abstract [en]

    The aim was (1) to evaluate measurements of vertical displacements (V-disp) of a single point on sacrum as an estimate of the whole body centre of mass (CoM) V-disp during treadmill running and (2) to compare three methods for measuring this single point. These methods were based on a position transducer(PT), accelerometers (AMs) and an optoelectronic motion capture system. Criterion method was V-disp of the whole body CoM measured with the motion capture system. Thirteen subjects ran at 10, 12, 14, 16. 18, 20 and 22 km h(-1) with synchronous recordings with the three methods. Four measurements of the (V-disp) were derived: (1) V-disp of CoM calculated from a segment model consisting of 13 segments tracked with 36 reflective markets, (2) V-disp of the sacrum recorded with the PT, (3) V-disp of the sacrum Calculated from the AM, and (4) V-disp of the sacrum calculated as the mid point of two reflective markets (sacrum marker, SM) attached at the level of the sacral bone. The systematic discrepancy between the Measurements of sacrum V-disp and CoM V-disp varied between 0 and 1.5 mm and decreased with increasing running velocity and decreasing step duration. PT and SM measurements showed strong correlation, whereas the AM showed a variability increasing with velocity. The random discrepancy within each Subject was 7 mm for all three methods. In conclusion single-point recordings of the sacrum V-disp may be used to monitor changes in V-disp of CoM during treadmill running.

  • 8.
    Gutierrez, Elena
    Karolinska Institutet.
    Kinetics of compensatory gait in persons with myelomeningocele2005In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 21, no 1, p. 12-23Article in journal (Refereed)
    Abstract [en]

    This study investigated the kinetic strategy and compensatory mechanisms during self-ambulatory gait in children with lumbo-sacral myelomeningocele. Thirty-one children with mid-lumbar to low-sacral myelomeningocele who walked without aids and 21 control children were evaluated by three-dimensional gait analysis. Joint moments in all planes at the hip and knee and sagittal moments at the ankle, as well as joint power and work done at all three joints, were analyzed. Joint moment capacity lost due to plantarflexor and dorsiflexor weakness was provided instead by orthotic support, but other joints were loaded more to compensate for the weakness at the ankles and restricted ankle motion. Subjects with total plantarflexor and dorsiflexor paresis and strength in the hip abductors had more knee extensor loading due to plantarflexor weakness and dorsiflexion angle of the orthotic ankle joint. The subjects with orthoses also generated more power at the hip to supplement the power generation lost to plantarflexor weakness and fixed ankles. The most determinant muscle whose paresis changes gait kinetics was the hip abductor. Hip abductor weakness resulted in a characteristic pattern where the hips displayed an eccentric adduction moment, mediating energy transfer into the lower limbs, and the hips replaced the knees as power absorbers in early stance. Joint moment, power and work analyses complement a kinematic analysis to provide a complete picture of how children who have muscle paresis recruit stronger muscle groups to compensate for weaker ones.

  • 9.
    Gutierrez, Elena M
    et al.
    Karolinska Institutet, Dept. of Surgical Sciences, Orthopedics Section.
    Bartonek, Åsa
    Karolinska Institutet, Dept. of Women's and Child's Health.
    Haglund-Åkerlind, Yvonne
    Karolinska Institutet, Dept. of Women's and Children's Health.
    Saraste, Helena
    Karolinska Institutet, Dept. of Surgical Sciences, Orthopedics Section.
    Kinetics of compensatory gait in persons with myelomeningocele2005In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 21, no 1, p. 12-23Article in journal (Refereed)
    Abstract [en]

    This study investigated the kinetic strategy and compensatory mechanisms during self-ambulatory gait in children with lumbo-sacral myelomeningocele. Thirty-one children with mid-lumbar to low-sacral myelomeningocele who walked without aids and 21 control children were evaluated by three-dimensional gait analysis. Joint moments in all planes at the hip and knee and sagittal moments at the ankle, as well as joint power and work done at all three joints, were analyzed. Joint moment capacity lost due to plantarflexor and dorsiflexor weakness was provided instead by orthotic support, but other joints were loaded more to compensate for the weakness at the ankles and restricted ankle motion. Subjects with total plantarflexor and dorsiflexor paresis and strength in the hip abductors had more knee extensor loading due to plantarflexor weakness and dorsiflexion angle of the orthotic, ankle joint. The subjects with orthoses also generated more power at the hip to supplement the power generation lost to plantarflexor weakness and fixed ankles. The most determinant muscle whose paresis changes gait kinetics was the hip abductor. Hip abductor weakness resulted in a characteristic pattern where the hips displayed an eccentric adduction moment, mediating energy transfer into the lower limbs, and the hips replaced the knees as power absorbers in early stance. Joint moment, power and work analyses complement a kinematic analysis to provide a complete picture of how children who have muscle paresis recruit stronger muscle groups to compensate for weaker ones.

  • 10. Gutierrez-Farewik, Elena M.
    et al.
    Bartonek, A.
    Haglund-Akerlind, Y.
    Saraste, H.
    Centre of mass motion during gait in persons with myelomeningocele2003In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 18, no 2, p. 37-46Article in journal (Refereed)
    Abstract [en]

    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.

  • 11. Gutierrez-Farewik, Elena M.
    et al.
    Bartonek, A.
    Haglund-Akerlind, Y.
    Saraste, H.
    Characteristic gait kinematics in persons with lumbosacral myelomeningocele2003In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 18, no 3, p. 170-177Article in journal (Refereed)
    Abstract [en]

    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.

  • 12.
    Halvorsen, Kjartan
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical Engineering.
    Gullstrand, Lennart
    Tinmark, Fredrik
    Nilsson, Johnny
    Minimal marker set for center of mass estimation in running2009In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 30, no 4, p. 552-555Article in journal (Refereed)
    Abstract [en]

    The purpose was to study the validity of a recently proposed method [Forsell C, Halvorsen K. A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum. journal of Biomechanics 2009;42(3):361-5] for estimating the trajectory of the whole-body center of mass (CoM) in the case of running at: velocities ranging from 10 to 22 km h(-1). The method gives an approximation to the CoM using the position of fewer markers on the body than the standard method of tracking each segment of the body. Fourteen male athletes participated. A standard method for determining the CoM from a model of 13 segments and using the position of 36 markers was used as reference method. Leave-one-out cross-validation revealed errors that decreased with increasing number of markers used in the approximative method. Starting from four markers, the error in absolute position of the CoM decreased from 15 mm to 3 mm in each direction. For the velocity of the CoM the estimation bias was neglectable, and the random error decreased from 0.15 to 0.05 m s(-1). The inter-subject and intra-subject variability in the estimated model parameters increased with increasing number of markers. The method worked well also when applied to running at velocities outside the range of velocities in the data used to determine the model parameters. The results indicate that a model using 10 markers represents a good trade-off between simplicity and accuracy, but users must take into account requirements of their specific applications.

  • 13.
    Harringe, Marita
    et al.
    Karolinska Institute.
    Halvorsen, Kjartan
    Swedish School of Sports and Health Sciences.
    Renström, Per
    Karolinska Institute.
    Werner, Suzanne
    Karolinska Institute.
    Postural control measured as the center of pressure excursion in young female gymnasts with low back pain or lower extremity injury2008In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 28, p. 38-45Article in journal (Refereed)
  • 14.
    Heintz, Sofia
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Static optimization of muscle forces during gait in comparison to EMG-to-force processing approach2007In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 26, no 2, p. 279-288Article in journal (Refereed)
    Abstract [en]

    Individual muscle forces evaluated from experimental motion analysis may be useful in mathematical simulation, but require additional musculoskeletal and mathematical modelling. A numerical method of static optimization was used in this study to evaluate muscular forces during gait. The numerical algorithm used was built on the basis of traditional optimization techniques, i.e., constrained minimization technique using the Lagrange multiplier method to solve for constraints. Measuring exact muscle forces during gait analysis is not currently possible. The developed optimization method calculates optimal forces during gait, given a specific performance criterion, using kinematics and kinetics from gait analysis together with muscle architectural data. Experimental methods to validate mathematical methods to calculate forces are limited. Electromyography (EMG) is frequently used as a tool to determine muscle activation in experimental studies on human motion. A method of estimating force from the EMG signal, the EMG-to-force approach, was recently developed by Bogey et al. [Bogey RA, Perry J, Gitter AJ. An EMG-to-force processing approach for determining ankle muscle forcs during normal human gait. IEEE Trans Neural Syst Rehabil Eng 2005;13:302-10] and is based on normalization of activation during a maximum voluntary contraction to documented maximal muscle strength. This method was adapted in this study as a tool with which to compare static optimization during a gait cycle. Muscle forces from static optimization and from EMG-to-force muscle forces show reasonably good correlation in the plantarflexor and dorsiflexor muscles, but less correlation in the knee flexor and extensor muscles. Additional comparison of the mathematical muscle forces from static optimization to documented averaged EMG data reveals good overall correlation to patterns of evaluated muscular activation. This indicates that on an individual level, muscular force patterns from mathematical models can arguably be more accurate than from those obtained from surface EMG during gait, though magnitude must still be validated.

  • 15.
    Iversen, Maura D.
    et al.
    Karolinska Inst, Karolinska Univ Hosp, Dept Womens & Childrens Hlth, Stockholm, Sweden.;Harvard Med Sch, Sect Clin Sci, Div Rheumatol Immunol & Allergy, Brigham & Womens Hosp, Boston, MA USA.;Northeastern Univ, Dept Phys Therapy Movement & Rehabil Sci, Bouve Coll Hlth Sci, Boston, MA 02115 USA..
    Weidenhielm-Brostrom, Eva
    Karolinska Inst, Karolinska Univ Hosp, Dept Womens & Childrens Hlth, Stockholm, Sweden..
    Wang, Ruoli
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Mechanics. Karolinska Inst, Karolinska Univ Hosp, Dept Womens & Childrens Hlth, Stockholm, Sweden..
    Esbjörnsson, Anna-Clara
    Lund Univ, Skdne Univ Hosp, Dept Orthoped, Clin Sci, Lund, Sweden..
    Hagelberg, Stefan
    Karolinska Inst, Karolinska Univ Hosp, Dept Womens & Childrens Hlth, Stockholm, Sweden..
    Astrand, Per
    Karolinska Inst, Karolinska Univ Hosp, Dept Womens & Childrens Hlth, Stockholm, Sweden..
    Self-rated walking disability and dynamic ankle joint stiffness in children and adolescents with Juvenile Idiopathic Arthritis receiving intraarticular corticosteroid joint injections of the foot2019In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 67, p. 257-261Article in journal (Refereed)
    Abstract [en]

    Background: Children and adolescents with Juvenile Idiopathic Arthritis (JIA) exhibit deviations in ankle dynamic joint stiffness (DJS, or moment-angle relationship) compared to healthy peers, but the relationship between ankle DJS and self-reported walking impairments has not been studied. This secondary analysis aimed to investigate the relationship between ankle DJS and self-reported walking disability in juveniles with JIA, and to determine whether intraarticular corticosteroid foot injections (IACI) were associated with long term changes in ankle DJS. Research questions: Is ankle DJS altered in children with JIA reporting walking difficulties compared to children with JIA reporting no walking difficulties? Are IACIs associated with persistent alterations in ankle DJS? Methods: Gait dynamics (DJS), foot pain, and foot-related disability were assessed in 33 children with JIA before intraarticular corticoid foot injection (IACI), and three months after IACI. Using self-reported walking capacity scores, children were classified as either having no walking difficulties (ND) or having walking difficulties (WD). Inferential statistics were used to compare demographics, pain, impairment scores, and ankle DJS between the groups. Results: Before treatment, in the WD group, ankle DJS was significantly decreased both in the early rising phase (ERP = 0.03 +/- 0.02 vs. 0.05 +/- 0.02 Nm(kg*deg)(-1)) and late rising phase (LRP = 0.11 +0.06 vs. 0.24+0.22 Nm (kg*deg)(-1)) compared to the ND group. At three months, the ERP was still significantly decreased in the WD group (ERP = 0.03 +/- 0.01 vs. 0.05+0.03 Nm(kg*deg)(-1)). Significance: Among children and adolescents with JIA who reported walking difficulties prior to IACIs, alterations in DJS in early stance phase (decreased ERP) remained three months after IACI suggesting persistent gait adaptations, possibly related to pain. Pre-treatment gait analysis may aid in identifying children who will not have long term benefit from IACIs in terms of improved gait, and therefore, may be informed and have the choice to be spared the risk of side effects associated with this treatment.

  • 16. Murans, Girts
    et al.
    Gutierrez-Farewik, Elena M.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Saraste, Helena
    Kinematic and kinetic analysis of static sitting of patients with neuropathic spine deformity2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 4, p. 533-538Article in journal (Refereed)
    Abstract [en]

    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.

  • 17. Naili, J. E.
    et al.
    Broström, E. W.
    Gutierrez-Farewik, Elena M.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Schwartz, M. H.
    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 test2018In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 62, p. 140-145Article in journal (Refereed)
    Abstract [en]

    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.

  • 18.
    Seidel, David
    et al.
    Engineering Design Centre, University of Cambridge.
    Hjalmarson, Jenny
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Freitag, Sonja
    Institution for Statutory Accident Insurance and Prevention in the Health&Welfare Services, Germany.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Brayne, Carol
    Institute of Public Health, University of Cambridge.
    Clarkson, P.John
    Engineering Design Centre, University of Cambridge.
    Measurement of stressful postures during daily activities: An observational study with older people2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 3, p. 397-401Article in journal (Refereed)
    Abstract [en]

    This study measured the postures of older people during cooking and laundry. A sample of men and women aged 75+ years (n=27) was recruited and observed in a home-like environment. Postures were recorded with a measurement system in an objective and detailed manner. The participants were videotaped to be able to see where 'critical' postures occurred, as defined by a trunk inclination of ≥60°. Analysis of data was facilitated by specially developed software. Critical postures accounted for 3% of cooking and 10% of laundry, occurring primarily during retrieving from and putting in lower cabinets, the refrigerator, laundry basket or washing machine as well as disposing into the waste bin. These tasks involve a great variation in postural changes and pose a particular risk to older people. The results suggest that the use of stressful postures may decrease efficiency and increase fatigue, eventually leading to difficulties with daily activities. The specific tasks identified during which critical postures occurred should be targeted by designers in order to improve the activities. A few examples are given of how better design can reduce or eliminate some of the postural constraints.

  • 19.
    Wang, Ruoli
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Gutierrez Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    The effect of subtalar inversion/eversion on the dynamic function of the tibialis anterior, soleus, and gastrocnemius during the stance phase of gait2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to determine how gait deviation in one plane (i.e. excessive subtalar inversion/eversion) can affect the dynamic function of the tibialis anterior, gastrocnemius, and soleus to accelerate the subtalar, ankle, knee and hip joints, as well as the body center of mass. Induced acceleration analysis was performed based on a subject-specific three-dimensional linkage model configured by stance phase gait data and driven by one unit of muscle force. Eight healthy adult subjects were examined in gait analysis. The subtalar inversion/eversion was modeled by offsetting up to 20 from the normal subtalar angle while other configurations remained unaltered. This study showed that the gastrocnemius, soleus and tibialis anterior generally functioned as their anatomical definition in normal gait, but counterintuitive function was occasionally found in the bi-articular gastrocnemius. The plantarflexors play important roles in the body support and forward progression. Excessive subtalar eversion was found to enlarge the plantarflexors and tibialis anterior's function. Induced acceleration analysis demonstrated its ability to isolate the contributions of individual muscle to a given factor, and as a means of studying effect of pathological gait on the dynamic muscle functions.

  • 20.
    Wang, Ruoli
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Gutierrez-Farewik, Elena M.
    KTH, School of Engineering Sciences (SCI), Mechanics, Biomechanics.
    Compensatory strategies during walking in response to excessive muscle co-contraction at the ankle joint2014In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 39, no 3, p. 926-932Article in journal (Refereed)
    Abstract [en]

    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.

  • 21.
    Wang, Ruoli
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Thur, Charlotte K.
    Gutierrez-Farewik, Elena M.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Wretenberg, Per
    Broström, Eva
    One year follow-up after operative ankle fractures: A prospective gait analysis study with a multi-segment foot model2010In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 31, no 2, p. 234-240Article in journal (Refereed)
    Abstract [en]

    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.

  • 22.
    Yan, S.
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. Sichuan University, Key Laboratory of Leather Chemistry and Engineering Ministry of Education, Chengdu, China.
    Schlippe, M.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Tarassova, O.
    Pennati, G. V.
    Arndt, A.
    Yang, L.
    Shi, B.
    Wang, R.
    KTH, School of Engineering Sciences (SCI), Mechanics. Karolinska Institutet, Department of Women’s and Children’s Health, Stockholm, Sweden.
    P 158 - A method to estimate passive mechanical properties of the soleus and gastrocnemius aspects of Achilles tendon2018In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 65, p. 501-502Article in journal (Refereed)
  • 23.
    Åberg, Anna Cristina
    et al.
    Swedish School of Sports and Health Sciences.
    Frykberg, Gunilla
    Uppsala University.
    Halvorsen, Kjartan
    The Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Medio-lateral stability of sit-to-walk performance in older individuals with and without fear of falling2010In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 31, no 4, p. 438-443Article in journal (Refereed)
    Abstract [en]

    Most falls in older people are due to loss of balance during everyday locomotion, e.g., when initiating walking from sitting; sit-to-walk (STW). It has been considered that the broader stride width in walking that is seen in many people with fear of falling (FoF) does not increase stability, but could be predictive of future falls because of increased medio-lateral (ML) velocity of the body centre of mass (CoM). This study was aimed to examine step-, velocity- and stability-related parameters, focusing on ML stability, in STW performance of people with and without FoF. Ten subjects with FoF and 10 matched controls, aged >= 70 years, were included. Kinematic and kinetic data were collected in a laboratory. Stability parameters were calculated from a formula implying that the vertical projection of the CoM extrapolated by adding its velocity times a factor root l/g (height of inverted pendulum divided by gravity) should fall within the base of support (BoS). A related spatial margin of stability (SMoS), defined as the minimum distance from the extrapolated CoM (XCoM) to the boundaries of the BoS, was also calculated. In the phase 'seat-off-second-toe-off, the FoF group had significantly (p < 0.05) shorter and broader steps, lower forward but similar ML CoM velocity, and broader CoM and XCoM widths. The FoF group therefore exhibited a disproportionately large sideways velocity compared to the controls. This indicates that STW may be a hazardous transfer for older people with FoF, which should be relevant in assessment and training aimed at preventing falls.

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