Change search
Refine search result
1 - 20 of 20
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Bartonek, Asa
    et al.
    Karolinska Inst, Womens & Childrens Hlth, Motoriklab, Stockholm, Sweden..
    Lidbeck, Cecilia
    Karolinska Inst, Womens & Childrens Hlth, Stockholm, Sweden..
    Hellgren, Kerstin
    Karolinska Inst, Clin Neurosci, Stockholm, Sweden..
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. Karolinska Inst, Womens & Childrens Hlth, Stockholm, Sweden..
    Head and Trunk Movements During Turning Gait in Children with Cerebral Palsy2019In: Journal of motor behavior, ISSN 0022-2895, E-ISSN 1940-1027, Vol. 51, no 4, p. 362-370Article in journal (Refereed)
    Abstract [en]

    Thirty children with cerebral palsy (CP) and 22 typical developing (TD) were tested with 3D-gait analysis. At turning, trunk rotation was larger in CP2 (GMFCS II) than in TD and CP1 (GMFCS I), and head flexion was larger in CP3 (GMFCS III) than TD. Maximum head and trunk flexion values during the entire trial were larger in CP3 than in the other groups, and trunk flexion was larger in CP2 than in TD. Trial time increased with GMFCS-level. Less trunk rotation than TD and CP1 reflects spatial insecurity in CP2, which in CP3 is compensated by the walker. The flexed head and trunk in CP3 and trunk in CP2 may reflect deficits in proprioception and sensation requiring visual control of the lower limbs.

  • 2.
    Berg, Niclas
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Fuchs, Laszlo
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH Mech, Linne FLOW Ctr, BioMEx, SE-10044 Stockholm, Sweden..
    Blood Flow Simulations of the Renal Arteries - Effect of Segmentation and Stenosis Removal2019In: Flow Turbulence and Combustion, ISSN 1386-6184, E-ISSN 1573-1987, Vol. 102, no 1, p. 27-41Article in journal (Refereed)
    Abstract [en]

    Patient specific based simulation of blood flows in arteries has been proposed as a future approach for better diagnostics and treatment of arterial diseases. The outcome of theoretical simulations strongly depends on the accuracy in describing the problem (the geometry, material properties of the artery and of the blood, flow conditions and the boundary conditions). In this study, the uncertainties associated with the approach for a priori assessment of reconstructive surgery of stenoted arteries are investigated. It is shown that strong curvature in the reconstructed artery leads to large spatial- and temporal-peaks in the wall shear-stress. Such peaks can be removed by appropriate reconstruction that also handles the post-stenotic dilatation of the artery. Moreover, it is shown that the effects of the segmentation approach can be equally important as the effects of using advanced rheological models. This fact has not been recognized in the literature up to this point, making patient specific simulations potentially less reliable.

  • 3.
    Broman, Lars Mikael
    et al.
    Karolinska Univ Hosp, ECMO Ctr Karolinska, Dept Pediat Perioperat Med & Intens Care, Eugeniavagen 23, S-17176 Stockholm, Sweden.;Karolinska Inst, Dept Physiol & Pharmacol, Stockholm, Sweden.;EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England..
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Westlund, C. Jerker
    Karolinska Univ Hosp, ECMO Ctr Karolinska, Dept Pediat Perioperat Med & Intens Care, Eugeniavagen 23, S-17176 Stockholm, Sweden..
    Gilbers, Martijn
    Maastricht Univ, Dept Cardiothorac Surg, Heart & Vasc Ctr, Cardiovasc Res Inst Maastricht CARIM,Med Hosp, Maastricht, Netherlands.;Maastricht Univ, Dept Physiol, Maastricht, Netherlands..
    da Camara, Luisa Perry
    Hosp Curry Cabral, Ctr Hosp Lisboa Cent, Lisbon, Portugal..
    Swol, Justyna
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Paracelsus Med Univ, Dept Pulmonol, Intens Care Med, Nurnberg, Germany..
    Taccone, Fabio S.
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;ULB, Dept Intens Care, Hop Erasme, Brussels, Belgium..
    Malfertheiner, Maximilian V.
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Med Ctr Regensburg, Dept Internal Med Cardiol & Pneumol 2, Regensburg, Germany..
    Di Nardo, Matteo
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Childrens Hosp Bambino Gesu, IRCCS, Pediat Intens Care Unit, Rome, Italy..
    Vercaemst, Leen
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Hosp Gasthuisberg, Dept Perfus, Leuven, Belgium..
    Barrett, Nicholas A.
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Guys & St Thomas NHS Fdn Trust, Dept Crit Care, London, England.;Guys & St Thomas NHS Fdn Trust, Severe Resp Failure Serv, London, England..
    Pappalardo, Federico
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Vita Salute San Raffaele, Adv Heart Failure & Mech Circulatory Support Prog, Hosp San Raffaele, Milan, Italy..
    Belohlavek, Jan
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Charles Univ Prague, Gen Univ Hosp Prague, Dept Cardiovasc Med, Dept Med 2, Prague, Czech Republic.;Charles Univ Prague, Fac Med 1, Prague, Czech Republic..
    Mueller, Thomas
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Med Ctr Regensburg, Dept Internal Med Cardiol & Pneumol 2, Regensburg, Germany..
    Belliato, Mirko
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Fdn IRCCS Policlin San Matteo, UOC Anestesia & Rianimaz 1, Pavia, Italy..
    Lorusso, Roberto
    EuroElso, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Maastricht Univ, Dept Cardiothorac Surg, Heart & Vasc Ctr, Cardiovasc Res Inst Maastricht CARIM,Med Hosp, Maastricht, Netherlands..
    Pressure and flow properties of cannulae for extracorporeal membrane oxygenation I: return (arterial) cannulae2019In: Perfusion, ISSN 0267-6591, E-ISSN 1477-111X, Vol. 34, p. 58-64Article in journal (Refereed)
    Abstract [en]

    Adequate extracorporeal membrane oxygenation support in the adult requires cannulae permitting blood flows up to 6-8 L/minute. In accordance with Poiseuille's law, flow is proportional to the fourth power of cannula inner diameter and inversely proportional to its length. Poiseuille's law can be applied to obtain the pressure drop of an incompressible, Newtonian fluid (such as water) flowing in a cylindrical tube. However, as blood is a pseudoplastic non-Newtonian fluid, the validity of Poiseuille's law is questionable for prediction of cannula properties in clinical practice. Pressure-flow charts with non-Newtonian fluids, such as blood, are typically not provided by the manufacturers. A standardized laboratory test of return (arterial) cannulae for extracorporeal membrane oxygenation was performed. The aim was to determine pressure-flow data with human whole blood in addition to manufacturers' water tests to facilitate an appropriate choice of cannula for the desired flow range. In total, 14 cannulae from three manufacturers were tested. Data concerning design, characteristics, and performance were graphically presented for each tested cannula. Measured blood flows were in most cases 3-21% lower than those provided by manufacturers. This was most pronounced in the narrow cannulae (15-17 Fr) where the reduction ranged from 27% to 40% at low flows and 5-15% in the upper flow range. These differences were less apparent with increasing cannula diameter. There was a marked disparity between manufacturers. Based on the measured results, testing of cannulae including whole blood flows in a standardized bench test would be recommended.

  • 4.
    Broman, Lars Mikael
    et al.
    Karolinska Univ Hosp, Dept Pediat Perioperat Med & Intens Care, ECMO Ctr Karolinska, S-17176 Stockholm, Sweden.;Karolinska Inst, Dept Physiol & Pharmacol, Stockholm, Sweden.;EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England..
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Westlund, C. Jerker
    Karolinska Univ Hosp, Dept Pediat Perioperat Med & Intens Care, ECMO Ctr Karolinska, S-17176 Stockholm, Sweden..
    Gilbers, Martijn
    Maastricht Univ, Hosp Med, Cardiovasc Res Inst Maastricht CARIM, Heart & Vasc Ctr,Dept Cardiothorac Surg, Maastricht, Netherlands.;Maastricht Univ, Dept Physiol, Maastricht, Netherlands..
    da Camara, Luisa Perry
    Hosp Curry Cabral, Ctr Hosp Lisboa Cent, Lisbon, Portugal..
    Westin, Jan
    Karolinska Univ Hosp, Dept Med Technol, Stockholm, Sweden..
    Taccone, Fabio Silvio
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;ULB, Dept Intens Care, Hop Erasme, Brussels, Belgium..
    Malfertheiner, Maximilian Valentin
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Med Ctr Regensburg, Dept Internal Med Cardiol & Pneumol 2, Regensburg, Germany..
    Di Nardo, Matteo
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Childrens Hosp Bambino Gesu, IRCCS, Pediat Intens Care Unit, Rome, Italy..
    Swol, Justyna
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Paracelsus Med Univ, Dept Pulmonol, Intens Care Med, Nurnberg, Germany..
    Vercaemst, Leen
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Hosp Gasthuisberg, Dept Perfus, Louven, Belgium..
    Barrett, Nicholas A.
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Guys & St Thomas NHS Fdn Trust, Dept Crit Care, London, England.;Guys & St Thomas NHS Fdn Trust, Severe Resp Failure Serv, London, England..
    Pappalardo, Federico
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Vita Salute San Raffaele, Hosp San Raffaele, Adv Heart Failure & Mech Circulatory Support Prog, Milan, Italy..
    Belohlavek, Jan
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Charles Univ Prague, Dept Med 2, Dept Cardiovasc Med, Gen Univ Hosp Prague, Prague, Czech Republic.;Charles Univ Prague, Fac Med 1, Prague, Czech Republic..
    Mueller, Thomas
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Univ Med Ctr Regensburg, Dept Internal Med Cardiol & Pneumol 2, Regensburg, Germany..
    Belliato, Mirko
    EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.;Fdn IRCCS Policlin San Matteo, UOC Anestesia & Rianimaz 1, Pavia, Italy..
    Lorusso, Roberto
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. EuroELSO, Working Grp Innovat & Technol, Newcastle Upon Tyne, Tyne & Wear, England.
    Pressure and flow properties of cannulae for extracorporeal membrane oxygenation II: drainage (venous) cannulae2019In: Perfusion, ISSN 0267-6591, E-ISSN 1477-111X, Vol. 34, p. 65-73Article in journal (Refereed)
    Abstract [en]

    The use of extracorporeal life support devices such as extracorporeal membrane oxygenation in adults requires cannulation of the patient's vessels with comparatively large diameter cannulae to allow circulation of large volumes of blood (>5 L/min). The cannula diameter and length are the major determinants for extracorporeal membrane oxygenation flow. Manufacturing companies present pressure-flow charts for the cannulae; however, these tests are performed with water. Aims of this study were 1. to investigate the specified pressure-flow charts obtained when using human blood as the circulating medium and 2. to support extracorporeal membrane oxygenation providers with pressure-flow data for correct choice of the cannula to reach an optimal flow with optimal hydrodynamic performance. Eighteen extracorporeal membrane oxygenation drainage cannulae, donated by the manufacturers (n = 6), were studied in a centrifugal pump driven mock loop. Pressure-flow properties and cannula features were described. The results showed that when blood with a hematocrit of 27% was used, the drainage pressure was consistently higher for a given flow (range 10%-350%) than when water was used (data from each respective manufacturer's product information). It is concluded that the information provided by manufacturers in line with regulatory guidelines does not correspond to clinical performance and therefore may not provide the best guidance for clinicians.

  • 5.
    Fuchs, Alexander
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. Linköping Univ Hosp, Dept Radiol, SE-58185 Linköping, Sweden.
    Berg, Niclas
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Stenosis Indicators Applied to Patient-Specific Renal Arteries without and with Stenosis2019In: FLUIDS, ISSN 2311-5521, Vol. 4, no 1, article id 26Article in journal (Refereed)
    Abstract [en]

    Pulsatile flow in the abdominal aorta and the renal arteries of three patients was studied numerically. Two of the patients had renal artery stenosis. The aim of the study was to assess the use of four types of indicators for determining the risk of new stenosis after revascularization of the affected arteries. The four indicators considered include the time averaged wall shear stress (TAWSS), the oscillatory shear index (OSI), the relative reference time (RRT) and a power law model based in platelet activation modeling but applied to the endothelium, named endothelium activation indicator (EAI). The results show that the indicators can detect the existing stenosis but are less successful in the revascularized cases. The TAWSS and, more clearly, the EAI approach seem to be better in predicting the risk for stenosis relapse at the original location and close to the post-stenotic dilatation. The shortcomings of the respective indicators are discussed along with potential improvements to endothelial activation modeling and its use as an indicator for risks of restenosis.

  • 6.
    Fuchs, Gabriel
    et al.
    Karolinska Inst, Dept Physiol & Pharmacol, Stockholm, Sweden.;Sundsvall Reg Hosp, Dept Cardiol, Sundsvall, Sweden..
    Berg, Niclas
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Mechanics.
    Broman, L. Mikael
    Karolinska Inst, Dept Physiol & Pharmacol, Stockholm, Sweden.;Karolinska Univ Hosp, ECMO Ctr Karolinska, Pediat Perioperat Med & Intens Care, Stockholm, Sweden..
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Flow-induced platelet activation in components of the extracorporeal membrane oxygenation circuit2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 13985Article in journal (Refereed)
    Abstract [en]

    Extracorporeal membrane oxygenation (ECMO) is used for rescue in severe respiratory and/or circulatory failure. The patient's blood is pumped over artificial surfaces in the ECMO circuit. A platelet activation model was applied to study the potential thrombogenicity of ECMO circuit components: the centrifugal blood pump, cannulae, and tubing connectors. Based on the accumulated effect of the scalar form of the stress acting on the platelet over time, the activation model enables assessment of platelet activation and pinpoints regions of elevated activation risk in a component. Numerical simulations of the flow in different components of the ECMO circuit was carried out where the activation level is a function of the impact of local stress and its history along the path that the platelets follow. The results showed that the pump carried the largest risk for platelet activation followed by the reinfusion cannula and lastly the connectors. Pump thrombogenicity was mainly due to long residence time and high shear-rate while the connector showed a high level of non-stationary shear-rate that in turn may contribute to the formation of aggregates through direct platelet activation or through high shear-rate modulation of the vWF multimers.

  • 7.
    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.

  • 8.
    Leng, Yan
    et al.
    Sun Yat Sen Univ, Affiliated Hosp 1, Dept Rehabil Med, Guangzhou, Guangdong, Peoples R China..
    Wang, Zhu
    Sun Yat Sen Univ, Inst Diagnost & Intervent Ultrasound, Affiliated Hosp 1, Dept Med Ultrason, Guangzhou, Guangdong, Peoples R China..
    Bian, Ruihao
    Sun Yat Sen Univ, Affiliated Hosp 1, Dept Rehabil Med, Guangzhou, Guangdong, Peoples R China..
    Lo, Wai Leung Ambrose
    Sun Yat Sen Univ, Affiliated Hosp 1, Dept Rehabil Med, Guangzhou, Guangdong, Peoples R China..
    Xie, Xiaoyan
    Sun Yat Sen Univ, Inst Diagnost & Intervent Ultrasound, Affiliated Hosp 1, Dept Med Ultrason, Guangzhou, Guangdong, Peoples R China..
    Wang, Ruoli
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden.
    Huang, Dongfeng
    Sun Yat Sen Univ, Affiliated Hosp 1, Dept Rehabil Med, Guangzhou, Guangdong, Peoples R China.;Sun Yat Sen Univ, Affiliated Hosp 7, Dept Rehabil Med, Shenzhen, Peoples R China..
    Li, Le
    Sun Yat Sen Univ, Affiliated Hosp 1, Dept Rehabil Med, Guangzhou, Guangdong, Peoples R China..
    Alterations of Elastic Property of Spastic Muscle With Its Joint Resistance Evaluated From Shear Wave Elastography and Biomechanical Model2019In: Frontiers in Neurology, ISSN 1664-2295, E-ISSN 1664-2295, Vol. 10, article id 736Article in journal (Refereed)
    Abstract [en]

    This study aims to quantify passive muscle stiffness of spastic wrist flexors in stroke survivors using shear wave elastography (SWE) and to correlate with neural and non-neural contributors estimated from a biomechanical model to hyper-resistance measured during passive wrist extension. Fifteen hemiplegic individuals after stroke with Modified Ashworth Scale (MAS) score larger than one were recruited. SWE were used to measure Young's modulus of flexor carpi radialis muscle with joint from 0 degrees (at rest) to 50 degrees flexion (passive stretch condition), with 10 degrees interval. The neural (NC) and non-neural components i.e., elasticity component (EC) and viscosity component (VC) of the wrist joint were analyzed from a motorized mechanical device NeuroFlexor (R) (NF). Combining with a validated biomechanical model, the neural reflex and muscle stiffness contribution to the increased resistance can be estimated. MAS and Fugl-Meyer upper limb score were also measured to evaluate the spasticity and motor function of paretic upper limb. Young's modulus was significantly higher in the paretic side of flexor carpi radialis than that of the non-paretic side (p < 0.001) and it increased significantly from 0 degrees to 50 degrees of the paretic side (p < 0.001). NC, EC, and VC on the paretic side were higher than the non-paretic side (p < 0.05). There was moderate significant positive correlation between the Young's Modulus and EC (r = 0.565, p = 0.028) and VC (r = 0.645, p = 0.009) of the paretic forearm flexor muscle. Fugl-Meyer of the paretic forearm flexor has a moderate significant negative correlation with NC (r = -0.578, p = 0.024). No significant correlation between MAS and shear elastic modulus or NF components was observed. This study demonstrated the feasibility of combining SWE and NF as a non-invasive approach to assess spasticity of paretic muscle and joint in stroke clinics. The neural and non-neural components analysis as well as correlation findings of muscle stiffness of SWE might provide understanding of mechanism behind the neuromuscular alterations in stroke survivors and facilitate the design of suitable intervention for them.

  • 9. Naili, J. E.
    et al.
    Broström, E. W.
    Gutierrez-Farewik, Elena M.
    KTH, School of Engineering Sciences (SCI), Mechanics, Biomechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Schwartz, M. H.
    The Centre Of Mass Trajectory Is A Sensitive And Responsive Measure Of Compensations For Pain And Weakness Among Individuals With Knee Osteoarthritis Performing A Sit-To-Stand Test2017In: Osteoarthritis and Cartilage, ISSN 1063-4584, E-ISSN 1522-9653, Vol. 25, p. S125-S126Article in journal (Other academic)
  • 10. 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.

  • 11.
    Naili, J. E.
    et al.
    Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden..
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Stalman, A.
    Karolinska Inst, Dept Mol Med & Surg, Stockholm Sports Trauma Res Ctr, Stockholm, Sweden.;Sophiahemmet, Capio Artro Clin, Stockholm, Sweden..
    Valentin, A.
    Karolinska Inst, Dept Mol Med & Surg, Stockholm Sports Trauma Res Ctr, Stockholm, Sweden.;Elisabethsjukhuset, Uppsala, Sweden..
    Skorpil, M.
    Karolinska Inst, Dept Mol Med & Surg, Stockholm, Sweden..
    Weidenhielm, L.
    Karolinska Inst, Dept Mol Med & Surg, Stockholm, Sweden..
    Improving Diagnostics of Femoroacetabular Impingement - A Feasibility Study2018In: Osteoarthritis and Cartilage, ISSN 1063-4584, E-ISSN 1522-9653, Vol. 26, p. S461-S462Article in journal (Other academic)
  • 12.
    Rakesh, Krishnan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. Univ Gavle, Dept Elect Math & Nat Sci, Gavle, Sweden..
    Bjorsell, Niclas
    Univ Gavle, Dept Elect Math & Nat Sci, Gavle, Sweden..
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Smith, Christian
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    A survey of human shoulder functional kinematic representations2019In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 57, no 2, p. 339-367Article, review/survey (Refereed)
    Abstract [en]

    In this survey, we review the field of human shoulder functional kinematic representations. The central question of this review is to evaluate whether the current approaches in shoulder kinematics can meet the high-reliability computational challenge. This challenge is posed by applications such as robot-assisted rehabilitation. Currently, the role of kinematic representations in such applications has been mostly overlooked. Therefore, we have systematically searched and summarised the existing literature on shoulder kinematics. The shoulder is an important functional joint, and its large range of motion (ROM) poses several mathematical and practical challenges. Frequently, in kinematic analysis, the role of the shoulder articulation is approximated to a ball-and-socket joint. Following the high-reliability computational challenge, our review challenges this inappropriate use of reductionism. Therefore, we propose that this challenge could be met by kinematic representations, that are redundant, that use an active interpretation and that emphasise on functional understanding.

  • 13.
    Rakesh, Krishnan
    et al.
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Björsell, N.
    Smith, Christian
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Segmenting humeral submovements using invariant geometric signatures2017In: 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 6951-6958, article id 8206619Conference paper (Refereed)
    Abstract [en]

    Discrete submovements are the building blocks of any complex movement. When robots collaborate with humans, extraction of such submovements can be very helpful in applications such as robot-assisted rehabilitation. Our work aims to segment these submovements based on the invariant geometric information embedded in segment kinematics. Moreover, this segmentation is achieved without any explicit kinematic representation. Our work demonstrates the usefulness of this invariant framework in segmenting a variety of humeral movements, which are performed at different speeds across different subjects. Our results indicate that this invariant framework has high computational reliability despite the inherent variability in human motion.

  • 14.
    Sandamas, Paul
    et al.
    Swedish Sch Sport & Hlth Sci, GIH, Lidingovagen 1, S-11433 Stockholm, Sweden..
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. Karolinska Inst, Stockholm, Sweden..
    Arndt, Anton
    Swedish Sch Sport & Hlth Sci, GIH, Lidingovagen 1, S-11433 Stockholm, Sweden.;Karolinska Inst, Stockholm, Sweden..
    The effect of a reduced first step width on starting block and first stance power and impulses during an athletic sprint start2019In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 37, no 9, p. 1046-1054Article in journal (Refereed)
    Abstract [en]

    This study investigated how manipulating first step width affects 3D external force production, centre of mass (CoM) motion and performance in athletic sprinting. Eight male and 2 female competitive sprinters (100m PB: 11.03 +/- 0.36 s male and 11.6 +/- 0.45 s female) performed 10 maximal effort block starts. External force and three-dimensional kinematics were recorded in both the block and first stance phases. Five trials were performed with the athletes performing their preferred technique (Skating) and five trials with the athletes running inside a 0.3 m lane (Narrow). By reducing step width from a mean of 0.31 +/- 0.06 m (Skating) to 0.19 +/- 0.03 m (Narrow), reductions were found between the two styles in medial block and medial 1st stance impulses, 1st stance anterior toe-off velocity and mediolateral motion of the CoM. No differences were found in block time, step length, stance time, average net resultant force vector, net anteroposterior impulse nor normalised external power. Step width correlated positively with medial impulse but not with braking nor net anteroposterior impulse. Despite less medially directed forces and less mediolateral motion of the CoM in the Narrow trials, no immediate improvement to performance was found by restricting step width.

  • 15.
    Schickhofer, Lukas
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH Royal Institute of Technology.
    Dahlkild, Anders
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Aeroacoustics of an elastic element in unsteady flow of low Reynolds numbers2016In: AIAA Technical Paper 2016-2700, 22nd AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics, 2016, 2016Conference paper (Refereed)
    Abstract [en]

    Vibrations of elastic structures are a common occurrence in numerous fields of engineering such as aeronautics, aerodynamics, civil engineering, and biomechanics. Particular e ort is dedicated to aeroacoustics of elements that are excited to oscillatory behaviour due to fluid instabilities. The current study is concerned with the numerical investigation of the flow-induced vibrations of a flexible, beam-like element in crossflow at low Reynolds numbers of Re = 100 − 1000 by means of fluid-structure interaction simulations. The aeroa-coustics in the near field are assessed with direct computation of the compressible airflow. Additionally, an acoustic analogy is applied, characterising the acoustic sources and the corresponding sound propagation. At low Reynolds numbers and high elastic moduli the dipole source produces the highest pressure perturbation in the near field. At higher Reynolds numbers and low elastic moduli, however, the monopole source due to structural vibrations becomes the important sound generating mechanism.

  • 16.
    Wang, Ruoli
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Mechanics. Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.
    Gäverth, J.
    Herman, Pawel
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Changes in the neural and non-neural related properties of the spastic wrist flexors after treatment with botulinum toxin a in post-stroke subjects: An optimization study2018In: Frontiers in Bioengineering and Biotechnology, E-ISSN 2296-4185, Vol. 9, no June, article id 73Article in journal (Refereed)
    Abstract [en]

    Quantifying neural and non-neural contributions to the joint resistance in spasticity is essential for a better evaluation of different intervention strategies such as botulinum toxin A (BoTN-A). However, direct measurement of muscle mechanical properties and spasticity-related parameters in humans is extremely challenging. The aim of this study was to use a previously developed musculoskeletal model and optimization scheme to evaluate the changes of neural and non-neural related properties of the spastic wrist flexors during passive wrist extension after BoTN-A injection. Data of joint angle and resistant torque were collected from 21 chronic stroke patients before, and 4 and 12 weeks post BoTN-A injection using NeuroFlexor, which is a motorized force measurement device to passively stretch wrist flexors. The model was optimized by tuning the passive and stretch-related parameters to fit the measured torque in each participant. It was found that stroke survivors exhibited decreased neural components at 4 weeks post BoNT-A injection, which returned to baseline levels after 12 weeks. The decreased neural component was mainly due to the increased motoneuron pool threshold, which is interpreted as a net excitatory and inhibitory inputs to the motoneuron pool. Though the linear stiffness and viscosity properties of wrist flexors were similar before and after treatment, increased exponential stiffness was observed over time which may indicate a decreased range of motion of the wrist joint. Using a combination of modeling and experimental measurement, valuable insights into the treatment responses, i.e., transmission of motoneurons, are provided by investigating potential parameter changes along the stretch reflex pathway in persons with chronic stroke.

  • 17.
    Wang, Ruoli
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Biomechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. Karolinska Institutet, Sweden.
    Herman, Pawel
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Ekeberg, Örjan
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Gäverth, Johan
    Dept Women's and Children's Health, Karolinska Institutet.
    Fagergren, Anders
    AggeroMedTech AB, Stockholm.
    Forssberg, Hans
    Dept Women's and Children's Health, Karolinska Institutet.
    Neural and non-neural related properties in the spastic wrist flexors: An optimization study2017In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 47, p. 198-209Article in journal (Refereed)
    Abstract [en]

    Quantifying neural and non-neural contributions to increased joint resistance in spasticity is essential for a better understanding of its pathophysiological mechanisms and evaluating different intervention strategies. However, direct measurement of spasticity-related manifestations, e.g., motoneuron and biophysical properties in humans, is extremely challenging. In this vein, we developed a forward neuromusculoskeletal model that accounts for dynamics of muscle spindles, motoneuron pools, muscle activation and musculotendon of wrist flexors and relies on the joint angle and resistant torque as the only input measurement variables. By modeling the stretch reflex pathway, neural and non-neural related properties of the spastic wrist flexors were estimated during the wrist extension test. Joint angle and resistant torque were collected from 17 persons with chronic stroke and healthy controls using NeuroFlexor, a motorized force measurement device during the passive wrist extension test. The model was optimized by tuning the passive and stretch reflex-related parameters to fit the measured torque in each participant. We found that persons with moderate and severe spasticity had significantly higher stiffness than controls. Among subgroups of stroke survivors, the increased neural component was mainly due to a lower muscle spindle rate at 50% of the motoneuron recruitment. The motoneuron pool threshold was highly correlated to the motoneuron pool gain in all subgroups. The model can describe the overall resistant behavior of the wrist joint during the test. Compared to controls, increased resistance was predominantly due to higher elasticity and neural components. We concluded that in combination with the NeuroFlexor measurement, the proposed neuromusculoskeletal model and optimization scheme served as suitable tools for investigating potential parameter changes along the stretch-reflex pathway in persons with spasticity.

  • 18.
    Yadav, Priti
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Multiscale Modelling of Proximal Femur Growth: Importance of Geometry and Influence of Load2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Longitudinal growth of long bone occurs at growth plates by a process called endochondral ossification. Endochondral ossification is affected by both biological and mechanical factors. This thesis focuses on the mechanical modulation of femoral bone growth occurring at the proximal growth plate, using mechanobiological theories reported in the literature. Finite element analysis was used to simulate bone growth.

    The first study analyzed the effect of subject-specific growth plate geometry over simplified growth plate geometry in numerical prediction of bone growth tendency. Subject-specific femur finite element model was constructed from magnetic resonance images of one able- bodied child. Gait kinematics and kinetics were acquired from motion analysis and analyzed further in musculoskeletal modelling to determine muscle and joint contact forces. These were used to determine loading on the femur in finite element analysis. The growth rate was computed based on a mechanobiological theory proposed by Carter and Wong, and a growth model in the principal stress direction was introduced. Our findings support the use of subject- specific geometry and of the principal stress growth direction in prediction of bone growth.

    The second study aimed to illustrate how different muscle groups’ activation during gait affects proximal femoral growth tendency in able-bodied children. Subject-specific femur models were used. Gait kinematics and kinetics were acquired for 3 able-bodied children, and muscle and joint contact forces were determined, similar to the first study. The contribution of different muscle groups to hip contact force was also determined. Finite element analysis was performed to compute the specific growth rate and growth direction due to individual muscle groups. The simulated growth model indicated that gait loading tends to reduce neck shaft angle and femoral anteversion during growth. The muscle groups that contributes most and least to growth rate were hip abductors and hip adductors, respectively. All muscle groups’ activation tended to reduce the neck shaft and femoral anteversion angles, except hip extensors and adductors which showed a tendency to increase the femoral anteversion.

    The third study’s aim was to understand the influence of different physical activities on proximal femoral growth tendency. Hip contact force orientation was varied to represent reported forces from a number of physical activities. The findings of this study showed that all studied physical activities tend to reduce the neck shaft angle and anteversion, which corresponds to the femur’s natural course during normal growth.

    The aim of the fourth study was to study the hypothesis that loading in the absence of physical activity, i.e. static loading, can have an adverse effect on bone growth. A subject-specific model was used and growth plate was modeled as a poroelastic material in finite element analysis. Prendergast’s indicators for bone growth was used to analyse the bone growth behavior. The results showed that tendency of bone growth rate decreases over a long duration of static loading. The study also showed that static sitting is less detrimental than static standing for predicted cartilage-to-bone differentiation likelihood, due to the lower magnitude of hip contact force.

    The prediction of growth using finite element analysis on experimental gait data and person- specific femur geometry, based on mechanobiological theories of bone growth, offers a biomechanical foundation for better understanding and prediction of bone growth-related deformity problems in growing children. It can ultimately help in treatment planning or physical activity guidelines in children at risk at developing a femur or hip deformity. 

  • 19.
    Yadav, Priti
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx.
    Shefelbine, Sandra J.
    Ponten, Eva
    Gutierrez-Farewik, Elena
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, BioMEx. Department of Women’s and Children’s Health, Pediatric Orthopaedic Surgery Karolinska Institutet Stockholm Sweden.
    Influence of muscle groups' activation on proximal femoral growth tendency2017In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940, Vol. 16, no 6, p. 1869-1883Article in journal (Refereed)
    Abstract [en]

    Muscle and joint contact force influence stresses at the proximal growth plate of the femur and thus bone growth, affecting the neck shaft angle (NSA) and femoral anteversion (FA). This study aims to illustrate how different muscle groups' activation during gait affects NSA and FA development in able-bodied children. Subject-specific femur models were developed for three able-bodied children (ages 6, 7, and 11 years) using magnetic resonance images. Contributions of different muscle groups-hip flexors, hip extensors, hip adductors, hip abductors, and knee extensors-to overall hip contact force were computed. Specific growth rate for the growth plate was computed, and the growth was simulated in the principal stress direction at each element in the growth front. The predicted growth indicated decreased NSA and FA (of about over a four-month period) for able-bodied children. Hip abductors contributed the most, and hip adductors, the least, to growth rate. All muscles groups contributed to a decrease in predicted NSA (similar to 0.01 degrees-0.04 degrees and FA (similar to 0.004 degrees-0.2 degrees), except hip extensors and hip adductors, which showed a tendency to increase the FA (similar to 0.004 degrees-0.2 degrees). Understanding influences of different muscle groups on long bone growth tendency can help in treatment planning for growing children with affected gait.

  • 20.
    Zhou, Guang-Quan
    et al.
    Southeast Univ, Sch Biol Sci & Med Engn, Nanjing, Jiangsu, Peoples R China.;Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, Nanjing, Jiangsu, Peoples R China..
    Zhang, Yi
    Southeast Univ, Sch Biol Sci & Med Engn, Nanjing, Jiangsu, Peoples R China.;Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, Nanjing, Jiangsu, Peoples R China..
    Wang, Ruo-Li
    KTH, School of Engineering Sciences (SCI), Centres, BioMEx. KTH, School of Engineering Sciences (SCI), Mechanics. Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden..
    Zhou, Ping
    Southeast Univ, Sch Biol Sci & Med Engn, Nanjing, Jiangsu, Peoples R China.;Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, Nanjing, Jiangsu, Peoples R China..
    Zheng, Yong-Ping
    Hong Kong Polytech Univ, Dept Biomed Engn, Hong Kong, Hong Kong, Peoples R China..
    Tarassova, Olga
    Swedish Sch Sport & Hlth Sci, Stockholm, Sweden..
    Arndt, Anton
    Swedish Sch Sport & Hlth Sci, Stockholm, Sweden.;Karolinska Inst, Dept Clin Intervent & Technol, Stockholm, Sweden..
    Chen, Qiang
    Southeast Univ, Sch Biol Sci & Med Engn, Nanjing, Jiangsu, Peoples R China.;Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, Nanjing, Jiangsu, Peoples R China..
    Automatic Myotendinous Junction Tracking in Ultrasound Images with Phase-Based Segmentation2018In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, article id 3697835Article in journal (Refereed)
    Abstract [en]

    Displacement of the myotendinous junction (MTJ) obtained by ultrasound imaging is crucial to quantify the interactive length changes of muscles and tendons for understanding the mechanics and pathological conditions of the muscle-tendon unit during motion. However, the lack of a reliable automatic measurement method restricts its application in human motion analysis. This paper presents an automated measurement of MTJ displacement using prior knowledge on tendinous tissues and MTJ, precluding the influence of nontendinous components on the estimation of MTJ displacement. It is based on the perception of tendinous features from musculoskeletal ultrasound images using Radon transform and thresholding methods, with information about the symmetric measures obtained from phase congruency. The displacement of MTJ is achieved by tracking manually marked points on tendinous tissues with the Lucas-Kanade optical flow algorithm applied over the segmented MTJ region. The performance of this method was evaluated on ultrasound images of the gastrocnemius obtained from 10 healthy subjects (26.0 +/- 2.9 years of age). Waveform similarity between the manual and automatic measurements was assessed by calculating the overall similarity with the coefficient ofmultiple correlation (CMC). In vivo experiments demonstrated that MTJ tracking with the proposedmethod (CMC = 0.97 +/- 0.02) was more consistent with the manual measurements than existing optical flow tracking methods (CMC = 0.79 +/- 0.11). This study demonstrated that the proposed method was robust to the interference of nontendinous components, resulting in a more reliable measurement of MTJ displacement, whichmay facilitate further research and applications related to the architectural change of muscles and tendons.

1 - 20 of 20
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf