Helena Grip - Academia.edu (original) (raw)

Papers by Helena Grip

Sensors, 2022

It is important to assess gait function in neurological disorders. A common outcome measure from ... more It is important to assess gait function in neurological disorders. A common outcome measure from clinical walking tests is average speed, which is reliable but does not capture important kinematical and temporal aspects of gait function. An extended gait analysis must be time efficient and reliable to be included in the clinical routine. The aim of this study was to add an inertial sensor system to a gait test battery and analyze the test-retest reliability of kinematic and temporal outcome measures. Measurements and analyses were performed in the hospital environment by physiotherapists using customized software. In total, 22 healthy persons performed comfortable gait, fast gait, and stair walking, with 12 inertial sensors attached to the feet, shank, thigh, pelvis, thorax, and arms. Each person participated in 2 test sessions, with about 3–6 days between the sessions. Kinematics were calculated based on a sensor fusion algorithm. Sagittal peak angles, sagittal range of motion, and...

Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke reh... more Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke rehabilitation research. The number of trials required to reach performance stability, as an important aspect of reliability, has not been investigated. Thus, the aims of this study were to determine the number of trials needed to reach within-session performance stability and to investigate trends in performance over a set of trials in non-disabled people and in a sample of individuals with chronic stroke. In addition, the between-sessions test-retest reliability in persons with stroke was established. MethodsThe drinking task was performed at least 10 times, following a standardized protocol, in 44 non-disabled and 8 post-stroke individuals. A marker-based motion capture system registered arm and trunk movements during 5 pre-defined phases of the drinking task. Intra class correlation statistics were used to determine the number of trials needed to reach performance stability as well as t...

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

This study present a new method for classification of subjects suffering from Whiplash Associated... more This study present a new method for classification of subjects suffering from Whiplash Associated Disorders (WAD) with a supervised resilient Back Propagation Neural Network (BPN). The only input needed, from each subject, is features extracted from 3dimensional motion data collected by a ProReflex system. The analysis with BPN results in a correct prediction for 84% of normal subjects and 89% percent of subjects with WAD.

Knee proprioception deficits and neuroplasticity have been indicated following injury to the ante... more Knee proprioception deficits and neuroplasticity have been indicated following injury to the anterior cruciate ligament (ACL). Evidence is however scarce regarding brain response to knee proprioception tasks and the impact of ACL injury. Twenty-one persons with unilateral ACL reconstruction (mean 23 months post-surgery) of either the right (n = 10) or left (n = 11) knee, as well as 19 controls (CTRL) matched for sex, age, height, weight and current activity level, performed a knee joint position sense (JPS) test during simultaneous functional magnetic resonance imaging (fMRI). Integrated motion capture recorded knee kinematics. Recruited brain regions included somatosensory cortices, prefrontal cortex and insula. Neither brain response nor JPS errors differed between groups, but across groups significant correlations revealed that greater errors were associated with greater ipsilateral response in the anterior cingulate (r = 0.476, P = 0.009), supramarginal gyrus (r = 0.395, P = 0.0...

Journal of NeuroEngineering and Rehabilitation, 2021

Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke reh... more Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke rehabilitation research. The number of trials required to reach performance stability, as an important aspect of reliability, has not been investigated for this task. Thus, the aims of this study were to determine the number of trials needed for the drinking task to reach within-session performance stability and to investigate trends in performance over a set of trials in non-disabled people and in a sample of individuals with chronic stroke. In addition, the between-sessions test–retest reliability in persons with stroke was established. Methods The drinking task was performed at least 10 times, following a standardized protocol, in 44 non-disabled and 8 post-stroke individuals. A marker-based motion capture system registered arm and trunk movements during 5 pre-defined phases of the drinking task. Intra class correlation statistics were used to determine the number of trials needed to rea...

Medical Engineering & Physics, 2021

Motion analysis using inertial measurement units (IMU) has emerged as an alternative to optical m... more Motion analysis using inertial measurement units (IMU) has emerged as an alternative to optical motion capture. However, the validity and reliability of upper limb measurements varies significantly between studies. The objective of this study was to determine how sensor placement affects kinematic output in the assessment of motion of the arm, shoulder, and scapula. IMUs were placed proximally/distally on arms, and medially/laterally on the scapula, in a group of eleven healthy participants, while performing nine different motion tasks. Linear regressions and mixed models analysed how these different sensor placements affected the estimated joint motion by establishing the linear relationship between sensors placed on the same body segment. The placement of sensors affected the measured kinematic output considerably, most prominent affect was seen for sensor placement on scapula during flexion and abduction, and on forearm during pronation/supination. The slope of the linear regression lines was 2.5 during flexion, 2.7 during abduction, and 1.8 for forearm pronation/supination. The results of this study suggest that the forearm sensor should be placed on the dorsal side of the forearm, at the distal end; the upper arm sensor should be placed laterally, on the distal part of the arm; and the sensor on the scapula should be placed cranially, along the spine of scapula.

The American Journal of Sports Medicine, 2020

Background: Atypical knee joint biomechanics after anterior cruciate ligament reconstruction (ACL... more Background: Atypical knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) are common. It is, however, unclear whether knee robustness (ability to tolerate perturbation and maintain joint configuration) and whole body movement strategies are compromised after ACLR. Purpose: To investigate landing control after ACLR with regard to dynamic knee robustness and whole body movement strategies during sports-mimicking side hops, and to evaluate functional performance of hop tests and knee strength. Study Design: Controlled laboratory study. Methods: An 8-camera motion capture system and 2 synchronized force plates were used to calculate joint angles and moments during standardized rebound side-hop landings performed by 32 individuals with an ACL-reconstructed knee (ACLR group; median, 16.0 months after reconstruction with hamstring tendon graft [interquartile range, 35.2 months]) and 32 matched asymptomatic controls (CTRL). Dynamic knee robustness was quantified us...

PLOS ONE, 2019

The purpose was to evaluate the dynamic knee control during a drop jump test following injury of ... more The purpose was to evaluate the dynamic knee control during a drop jump test following injury of the anterior cruciate ligament injury (ACL) using finite helical axes. Persons injured 17-28 years ago, treated with either physiotherapy (ACLPT, n = 23) or reconstruction and physiotherapy (ACLR, n = 28) and asymptomatic controls (CTRL, n = 22) performed a drop jump test, while kinematics were registered by motion capture. We analysed the Preparation phase (from maximal knee extension during flight until 50 ms post-touchdown) followed by an Action phase (until maximal knee flexion post-touchdown). Range of knee motion (RoM), and the length of each phase (Duration) were computed. The finite knee helical axis was analysed for momentary intervals of~15˚of knee motion by its intersection (ΔAP position) and inclination (ΔAP Inclination) with the knee's Anterior-Posterior (AP) axis. Static knee laxity (KT100) and self-reported knee function (Lysholm score) were also assessed. The results showed that both phases were shorter for the ACL groups compared to controls (CTRL-ACLR: Duration 35±8 ms, p = 0.000, CTRL-ACLPT: 33±9 ms, p = 0.000) and involved less knee flexion (CTRL-ACLR: RoM 6.6±1.9˚, p = 0.002, CTRL-ACLR: 7.5 ±2.0˚, p = 0.001). Low RoM and Duration correlated significantly with worse knee function according to Lysholm and higher knee laxity according to KT-1000. Three finite helical axes were analysed. The ΔAP position for the first axis was most anterior in ACLPT compared to ACLR (ΔAP position-1, ACLPT-ACLR: 13±3 mm, p = 0.004), with correlations to KT-1000 (rho 0.316, p = 0.008), while the ΔAP inclination for the third axis was smaller in the ACLPT group compared to controls (ΔAP inclination-3 ACLPT-CTRL:-13±5˚, p = 0.004) and showed a significant side difference in ACL injured groups during Action (Injured-Noninjured: 8±2.7˚, p = 0.006). Small ΔAP inclination-3 correlated with low Lysholm (rho 0.391, p = 0.002) and high KT-1000 (rho-0.450, p = 0.001).

Sensors, 2019

A hip prosthesis design with larger femoral head size may improve functional outcomes compared to... more A hip prosthesis design with larger femoral head size may improve functional outcomes compared to the conventional total hip arthroplasty (THA) design. Our aim was to compare the range of motion (RoM) in lower body joints during squats, gait and stair walking using a wearable movement analysis system based on inertial measurement units (IMUs) in three age-matched male groups: 6 males with a conventional THA (THAC), 9 with a large femoral head (LFH) design, and 8 hip- and knee-asymptomatic controls (CTRL). We hypothesized that the LFH design would allow a greater hip RoM, providing movement patterns more like CTRL, and a larger side difference in hip RoM in THAC when compared to LFH and controls. IMUs were attached to the pelvis, thighs and shanks during five trials of squats, gait, and stair ascending/descending performed at self-selected speed. THAC and LFH participants completed the Hip dysfunction and Osteoarthritis Outcome Score (HOOS). The results showed a larger hip RoM during...

Scandinavian Journal of Medicine & Science in Sports, 2019

Access to the published version may require subscription. N.B. When citing this work, cite the or... more Access to the published version may require subscription. N.B. When citing this work, cite the original published paper.

Sensors, 2019

Ordinal scales with low resolution are used to assess arm function in clinic. These scales may be... more Ordinal scales with low resolution are used to assess arm function in clinic. These scales may be improved by adding objective kinematic measures. The aim was to analyze within-subject, inter-rater and overall reliability (i.e., including within-subject and inter-rater reliability) and check the system’s validity of kinematic measures from inertial sensors for two such protocols on one person. Twenty healthy volunteers repeatedly performed two tasks, finger-to-nose and drinking, during two test sessions with two different raters. Five inertial sensors, on the forearms, upper arms and xiphoid process were used. Comparisons against an optical camera system evaluated the measurement validity. Cycle time, range of motion (ROM) in shoulder and elbow were calculated. Bland–Altman plots and linear mixed models including the generalizability (G) coefficient evaluated the reliability of the measures. Within-subject reliability was good to excellent in both tests (G = 0.80–0.97) and may serve...

Gait & Posture, 2015

A modified standardized nine hole peg test for valid and reliable kinematic assessment of dexteri... more A modified standardized nine hole peg test for valid and reliable kinematic assessment of dexterity post-stroke

Scandinavian journal of medicine & science in sports, Jan 28, 2015

Reduced dynamic knee stability, often evaluated with one-leg hops (OLHs), is reported after anter... more Reduced dynamic knee stability, often evaluated with one-leg hops (OLHs), is reported after anterior cruciate ligament (ACL) injury. This may lead to long-standing altered movement patterns, which are less investigated. 3D kinematics during OLH were explored in 70 persons 23 ± 2 years after ACL injury; 33 were treated with physiotherapy in combination with ACL reconstruction (ACLR ) and 37 with physiotherapy alone (ACLPT ). Comparisons were made to 33 matched controls. We analyzed (a) maximal knee joint angles and range of motion (flexion, abduction, rotation); (b) medio-lateral position of the center of mass (COM) in relation to knee and ankle joint centers, during take-off and landing phases. Unlike controls, ACL-injured displayed leg asymmetries: less knee flexion and less internal rotation at take-off and landing and more lateral COM related to knee and ankle joint of the injured leg at landing. Compared to controls, ACLR had larger external rotation of the injured leg at landin...

Aviation, space, and environmental medicine, 2003

Air is commonly trapped within the skull in patients who have been treated for trauma or intracra... more Air is commonly trapped within the skull in patients who have been treated for trauma or intracranial hemorrhage. In Sweden, when such a patient is transported by air ambulance it is standard procedure to maintain sea-level pressure in the cabin to prevent increased intracranial pressure (ICP). However, this type of flight operation is more difficult and expensive. Maintenance of sea-level cabin pressure is not common practice all over the world, and the criteria supporting the choice of pressurization during transport are inadequate and in need of evaluation. The purpose of this study was to develop and evaluate a model to simulate the influence of intracranial air on ICP during air transport. We identified an existing nonlinear model of the cerebral spinal fluid and intracranial pressure dynamics, then added intracranial air as a new component and evaluated the model through simulations. The model behaved as expected, and the simulations indicated that under normal flying conditio...

2011 International Conference on Virtual Rehabilitation, 2011

3D motion analysis was applied to assess goal-directed arm movements in 15 children with cerebral... more 3D motion analysis was applied to assess goal-directed arm movements in 15 children with cerebral palsy (CP) before and after four weeks of home training with low-cost motion interactive video games. The results indicated that the children improved movement precision when playing the virtual games, improved movement smoothness when reaching for real targets, and reduced the involvement of the trunk especially when reaching with the non-dominant side.

Gait & Posture, 2014

The purpose of the study was to apply the Arm Posture Score (APS) to a stroke population, since c... more The purpose of the study was to apply the Arm Posture Score (APS) to a stroke population, since comprehensive measures to quantify arm swing in the affected and non-affected arms during gait are lacking. A further aim was to investigate how gait speed and upper limb function estimated by clinical measures are related to the APS in the stroke group. The APS is the summarized root mean square deviation (RMSD) from normal, based on kinematics. Four arm movements (sagittal and frontal planes) as well as six arm movements (incorporating transversal plane) were included in the calculation of APS, referred to as APS 4 and APS 6 , respectively. The study population consisted of 25 persons with stroke and 25 age-and gender-matched controls. The APS measures were significantly different between the affected and non-affected arms, as well as between the affected arm and the non-dominant arm of the controls (p 0.001). Spasticity significantly influenced both APS measures, while speed only had a significant effect on the APS 4. The APS measures correlated significantly to clinical measures of upper limb function. Both APS measures seem to be useful indices to quantify and discriminate between impaired and normal arm swing during gait after stroke. The variability of rotational arm movements needs to be studied further before considering the additional value of the APS 6 over the APS 4. When interpreting the APS, complementary kinematics should be taken into account, as the single value of the APS gives no information about the direction of the deviation.

umu.diva-portal.org

ub.umu.se. Publications. ...

Manual Therapy, 2011

Symptoms of dizziness, unsteadiness and visual disturbances are frequent complaints in persons wi... more Symptoms of dizziness, unsteadiness and visual disturbances are frequent complaints in persons with persistent whiplash associated disorders. This study investigated eye, head coordination and gaze stability in subjects with persistent whiplash (n ¼ 20) and asymptomatic controls (n ¼ 20). Wireless motion sensors and electro-oculography were used to measure: head rotation during unconstrained head movement, head rotation during gaze stability and sequential head and eye movements. Ten control subjects participated in a repeatability study (two occasions one week apart). Between-day repeatability was acceptable (ICC > 0.6) for most measures. The whiplash group had significantly less maximal eye angle to the left, range of head movement during the gaze stability task and decreased velocity of head movement in head eye coordination and gaze stability tasks compared to the control group (p < 0.01). There were significant correlations (r > 0.55) between both unrestrained neck movement and neck pain and head movement and velocity in the whiplash group. Deficits in gaze stability and head eye coordination may be related to disturbed reflex activity associated with decreased head range of motion and/or neck pain. Further research is required to explore the mechanisms behind these deficits, the nature of changes over time and the tests' ability to measure change in response to rehabilitation.

International Journal of Industrial Ergonomics, 2004

Work related neck and shoulder disorders are a great problem for string musicians. A playing tech... more Work related neck and shoulder disorders are a great problem for string musicians. A playing technique with more relaxed muscles and a greater variation in the muscle activity pattern, i.e., with shorter sequences at a varied number of amplitude levels as reflected by electromyography (EMG), might prevent pain. This study used EMG to study variations in the trapezius muscle activity pattern in 12 string musicians performing a piece of music at two playing sessions separated by a ten-week interval. Nine of the string musicians played violin, two viola and one cello. Exposure variation analysis and principal component analysis were used for analysis of the EMG. The trapezius muscle activity pattern was similar in the first and second playing sessions showing that each musician repeated his/her own muscular activity pattern. However, there was considerable variability in the muscle activity pattern between cello, violin and viola players and between individual violin players. Thus, this EMG method has the potential to identify variations and reproducibility of trapezius muscle activity in string musicians. This method may be used to analyse individual differences when performing a musical work task and to evaluate intervention studies. Relevance to industry Intervention studies on muscle activity pattern which try to change the work technique need to be evaluated.

Sensors, 2022

It is important to assess gait function in neurological disorders. A common outcome measure from ... more It is important to assess gait function in neurological disorders. A common outcome measure from clinical walking tests is average speed, which is reliable but does not capture important kinematical and temporal aspects of gait function. An extended gait analysis must be time efficient and reliable to be included in the clinical routine. The aim of this study was to add an inertial sensor system to a gait test battery and analyze the test-retest reliability of kinematic and temporal outcome measures. Measurements and analyses were performed in the hospital environment by physiotherapists using customized software. In total, 22 healthy persons performed comfortable gait, fast gait, and stair walking, with 12 inertial sensors attached to the feet, shank, thigh, pelvis, thorax, and arms. Each person participated in 2 test sessions, with about 3–6 days between the sessions. Kinematics were calculated based on a sensor fusion algorithm. Sagittal peak angles, sagittal range of motion, and...

Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke reh... more Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke rehabilitation research. The number of trials required to reach performance stability, as an important aspect of reliability, has not been investigated. Thus, the aims of this study were to determine the number of trials needed to reach within-session performance stability and to investigate trends in performance over a set of trials in non-disabled people and in a sample of individuals with chronic stroke. In addition, the between-sessions test-retest reliability in persons with stroke was established. MethodsThe drinking task was performed at least 10 times, following a standardized protocol, in 44 non-disabled and 8 post-stroke individuals. A marker-based motion capture system registered arm and trunk movements during 5 pre-defined phases of the drinking task. Intra class correlation statistics were used to determine the number of trials needed to reach performance stability as well as t...

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

This study present a new method for classification of subjects suffering from Whiplash Associated... more This study present a new method for classification of subjects suffering from Whiplash Associated Disorders (WAD) with a supervised resilient Back Propagation Neural Network (BPN). The only input needed, from each subject, is features extracted from 3dimensional motion data collected by a ProReflex system. The analysis with BPN results in a correct prediction for 84% of normal subjects and 89% percent of subjects with WAD.

Knee proprioception deficits and neuroplasticity have been indicated following injury to the ante... more Knee proprioception deficits and neuroplasticity have been indicated following injury to the anterior cruciate ligament (ACL). Evidence is however scarce regarding brain response to knee proprioception tasks and the impact of ACL injury. Twenty-one persons with unilateral ACL reconstruction (mean 23 months post-surgery) of either the right (n = 10) or left (n = 11) knee, as well as 19 controls (CTRL) matched for sex, age, height, weight and current activity level, performed a knee joint position sense (JPS) test during simultaneous functional magnetic resonance imaging (fMRI). Integrated motion capture recorded knee kinematics. Recruited brain regions included somatosensory cortices, prefrontal cortex and insula. Neither brain response nor JPS errors differed between groups, but across groups significant correlations revealed that greater errors were associated with greater ipsilateral response in the anterior cingulate (r = 0.476, P = 0.009), supramarginal gyrus (r = 0.395, P = 0.0...

Journal of NeuroEngineering and Rehabilitation, 2021

Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke reh... more Background Kinematic analysis of the 3D reach-to-grasp drinking task is recommended in stroke rehabilitation research. The number of trials required to reach performance stability, as an important aspect of reliability, has not been investigated for this task. Thus, the aims of this study were to determine the number of trials needed for the drinking task to reach within-session performance stability and to investigate trends in performance over a set of trials in non-disabled people and in a sample of individuals with chronic stroke. In addition, the between-sessions test–retest reliability in persons with stroke was established. Methods The drinking task was performed at least 10 times, following a standardized protocol, in 44 non-disabled and 8 post-stroke individuals. A marker-based motion capture system registered arm and trunk movements during 5 pre-defined phases of the drinking task. Intra class correlation statistics were used to determine the number of trials needed to rea...

Medical Engineering & Physics, 2021

Motion analysis using inertial measurement units (IMU) has emerged as an alternative to optical m... more Motion analysis using inertial measurement units (IMU) has emerged as an alternative to optical motion capture. However, the validity and reliability of upper limb measurements varies significantly between studies. The objective of this study was to determine how sensor placement affects kinematic output in the assessment of motion of the arm, shoulder, and scapula. IMUs were placed proximally/distally on arms, and medially/laterally on the scapula, in a group of eleven healthy participants, while performing nine different motion tasks. Linear regressions and mixed models analysed how these different sensor placements affected the estimated joint motion by establishing the linear relationship between sensors placed on the same body segment. The placement of sensors affected the measured kinematic output considerably, most prominent affect was seen for sensor placement on scapula during flexion and abduction, and on forearm during pronation/supination. The slope of the linear regression lines was 2.5 during flexion, 2.7 during abduction, and 1.8 for forearm pronation/supination. The results of this study suggest that the forearm sensor should be placed on the dorsal side of the forearm, at the distal end; the upper arm sensor should be placed laterally, on the distal part of the arm; and the sensor on the scapula should be placed cranially, along the spine of scapula.

The American Journal of Sports Medicine, 2020

Background: Atypical knee joint biomechanics after anterior cruciate ligament reconstruction (ACL... more Background: Atypical knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) are common. It is, however, unclear whether knee robustness (ability to tolerate perturbation and maintain joint configuration) and whole body movement strategies are compromised after ACLR. Purpose: To investigate landing control after ACLR with regard to dynamic knee robustness and whole body movement strategies during sports-mimicking side hops, and to evaluate functional performance of hop tests and knee strength. Study Design: Controlled laboratory study. Methods: An 8-camera motion capture system and 2 synchronized force plates were used to calculate joint angles and moments during standardized rebound side-hop landings performed by 32 individuals with an ACL-reconstructed knee (ACLR group; median, 16.0 months after reconstruction with hamstring tendon graft [interquartile range, 35.2 months]) and 32 matched asymptomatic controls (CTRL). Dynamic knee robustness was quantified us...

PLOS ONE, 2019

The purpose was to evaluate the dynamic knee control during a drop jump test following injury of ... more The purpose was to evaluate the dynamic knee control during a drop jump test following injury of the anterior cruciate ligament injury (ACL) using finite helical axes. Persons injured 17-28 years ago, treated with either physiotherapy (ACLPT, n = 23) or reconstruction and physiotherapy (ACLR, n = 28) and asymptomatic controls (CTRL, n = 22) performed a drop jump test, while kinematics were registered by motion capture. We analysed the Preparation phase (from maximal knee extension during flight until 50 ms post-touchdown) followed by an Action phase (until maximal knee flexion post-touchdown). Range of knee motion (RoM), and the length of each phase (Duration) were computed. The finite knee helical axis was analysed for momentary intervals of~15˚of knee motion by its intersection (ΔAP position) and inclination (ΔAP Inclination) with the knee's Anterior-Posterior (AP) axis. Static knee laxity (KT100) and self-reported knee function (Lysholm score) were also assessed. The results showed that both phases were shorter for the ACL groups compared to controls (CTRL-ACLR: Duration 35±8 ms, p = 0.000, CTRL-ACLPT: 33±9 ms, p = 0.000) and involved less knee flexion (CTRL-ACLR: RoM 6.6±1.9˚, p = 0.002, CTRL-ACLR: 7.5 ±2.0˚, p = 0.001). Low RoM and Duration correlated significantly with worse knee function according to Lysholm and higher knee laxity according to KT-1000. Three finite helical axes were analysed. The ΔAP position for the first axis was most anterior in ACLPT compared to ACLR (ΔAP position-1, ACLPT-ACLR: 13±3 mm, p = 0.004), with correlations to KT-1000 (rho 0.316, p = 0.008), while the ΔAP inclination for the third axis was smaller in the ACLPT group compared to controls (ΔAP inclination-3 ACLPT-CTRL:-13±5˚, p = 0.004) and showed a significant side difference in ACL injured groups during Action (Injured-Noninjured: 8±2.7˚, p = 0.006). Small ΔAP inclination-3 correlated with low Lysholm (rho 0.391, p = 0.002) and high KT-1000 (rho-0.450, p = 0.001).

Sensors, 2019

A hip prosthesis design with larger femoral head size may improve functional outcomes compared to... more A hip prosthesis design with larger femoral head size may improve functional outcomes compared to the conventional total hip arthroplasty (THA) design. Our aim was to compare the range of motion (RoM) in lower body joints during squats, gait and stair walking using a wearable movement analysis system based on inertial measurement units (IMUs) in three age-matched male groups: 6 males with a conventional THA (THAC), 9 with a large femoral head (LFH) design, and 8 hip- and knee-asymptomatic controls (CTRL). We hypothesized that the LFH design would allow a greater hip RoM, providing movement patterns more like CTRL, and a larger side difference in hip RoM in THAC when compared to LFH and controls. IMUs were attached to the pelvis, thighs and shanks during five trials of squats, gait, and stair ascending/descending performed at self-selected speed. THAC and LFH participants completed the Hip dysfunction and Osteoarthritis Outcome Score (HOOS). The results showed a larger hip RoM during...

Scandinavian Journal of Medicine & Science in Sports, 2019

Access to the published version may require subscription. N.B. When citing this work, cite the or... more Access to the published version may require subscription. N.B. When citing this work, cite the original published paper.

Sensors, 2019

Ordinal scales with low resolution are used to assess arm function in clinic. These scales may be... more Ordinal scales with low resolution are used to assess arm function in clinic. These scales may be improved by adding objective kinematic measures. The aim was to analyze within-subject, inter-rater and overall reliability (i.e., including within-subject and inter-rater reliability) and check the system’s validity of kinematic measures from inertial sensors for two such protocols on one person. Twenty healthy volunteers repeatedly performed two tasks, finger-to-nose and drinking, during two test sessions with two different raters. Five inertial sensors, on the forearms, upper arms and xiphoid process were used. Comparisons against an optical camera system evaluated the measurement validity. Cycle time, range of motion (ROM) in shoulder and elbow were calculated. Bland–Altman plots and linear mixed models including the generalizability (G) coefficient evaluated the reliability of the measures. Within-subject reliability was good to excellent in both tests (G = 0.80–0.97) and may serve...

Gait & Posture, 2015

A modified standardized nine hole peg test for valid and reliable kinematic assessment of dexteri... more A modified standardized nine hole peg test for valid and reliable kinematic assessment of dexterity post-stroke

Scandinavian journal of medicine & science in sports, Jan 28, 2015

Reduced dynamic knee stability, often evaluated with one-leg hops (OLHs), is reported after anter... more Reduced dynamic knee stability, often evaluated with one-leg hops (OLHs), is reported after anterior cruciate ligament (ACL) injury. This may lead to long-standing altered movement patterns, which are less investigated. 3D kinematics during OLH were explored in 70 persons 23 ± 2 years after ACL injury; 33 were treated with physiotherapy in combination with ACL reconstruction (ACLR ) and 37 with physiotherapy alone (ACLPT ). Comparisons were made to 33 matched controls. We analyzed (a) maximal knee joint angles and range of motion (flexion, abduction, rotation); (b) medio-lateral position of the center of mass (COM) in relation to knee and ankle joint centers, during take-off and landing phases. Unlike controls, ACL-injured displayed leg asymmetries: less knee flexion and less internal rotation at take-off and landing and more lateral COM related to knee and ankle joint of the injured leg at landing. Compared to controls, ACLR had larger external rotation of the injured leg at landin...

Aviation, space, and environmental medicine, 2003

Air is commonly trapped within the skull in patients who have been treated for trauma or intracra... more Air is commonly trapped within the skull in patients who have been treated for trauma or intracranial hemorrhage. In Sweden, when such a patient is transported by air ambulance it is standard procedure to maintain sea-level pressure in the cabin to prevent increased intracranial pressure (ICP). However, this type of flight operation is more difficult and expensive. Maintenance of sea-level cabin pressure is not common practice all over the world, and the criteria supporting the choice of pressurization during transport are inadequate and in need of evaluation. The purpose of this study was to develop and evaluate a model to simulate the influence of intracranial air on ICP during air transport. We identified an existing nonlinear model of the cerebral spinal fluid and intracranial pressure dynamics, then added intracranial air as a new component and evaluated the model through simulations. The model behaved as expected, and the simulations indicated that under normal flying conditio...

2011 International Conference on Virtual Rehabilitation, 2011

3D motion analysis was applied to assess goal-directed arm movements in 15 children with cerebral... more 3D motion analysis was applied to assess goal-directed arm movements in 15 children with cerebral palsy (CP) before and after four weeks of home training with low-cost motion interactive video games. The results indicated that the children improved movement precision when playing the virtual games, improved movement smoothness when reaching for real targets, and reduced the involvement of the trunk especially when reaching with the non-dominant side.

Gait & Posture, 2014

The purpose of the study was to apply the Arm Posture Score (APS) to a stroke population, since c... more The purpose of the study was to apply the Arm Posture Score (APS) to a stroke population, since comprehensive measures to quantify arm swing in the affected and non-affected arms during gait are lacking. A further aim was to investigate how gait speed and upper limb function estimated by clinical measures are related to the APS in the stroke group. The APS is the summarized root mean square deviation (RMSD) from normal, based on kinematics. Four arm movements (sagittal and frontal planes) as well as six arm movements (incorporating transversal plane) were included in the calculation of APS, referred to as APS 4 and APS 6 , respectively. The study population consisted of 25 persons with stroke and 25 age-and gender-matched controls. The APS measures were significantly different between the affected and non-affected arms, as well as between the affected arm and the non-dominant arm of the controls (p 0.001). Spasticity significantly influenced both APS measures, while speed only had a significant effect on the APS 4. The APS measures correlated significantly to clinical measures of upper limb function. Both APS measures seem to be useful indices to quantify and discriminate between impaired and normal arm swing during gait after stroke. The variability of rotational arm movements needs to be studied further before considering the additional value of the APS 6 over the APS 4. When interpreting the APS, complementary kinematics should be taken into account, as the single value of the APS gives no information about the direction of the deviation.

umu.diva-portal.org

ub.umu.se. Publications. ...

Manual Therapy, 2011

Symptoms of dizziness, unsteadiness and visual disturbances are frequent complaints in persons wi... more Symptoms of dizziness, unsteadiness and visual disturbances are frequent complaints in persons with persistent whiplash associated disorders. This study investigated eye, head coordination and gaze stability in subjects with persistent whiplash (n ¼ 20) and asymptomatic controls (n ¼ 20). Wireless motion sensors and electro-oculography were used to measure: head rotation during unconstrained head movement, head rotation during gaze stability and sequential head and eye movements. Ten control subjects participated in a repeatability study (two occasions one week apart). Between-day repeatability was acceptable (ICC > 0.6) for most measures. The whiplash group had significantly less maximal eye angle to the left, range of head movement during the gaze stability task and decreased velocity of head movement in head eye coordination and gaze stability tasks compared to the control group (p < 0.01). There were significant correlations (r > 0.55) between both unrestrained neck movement and neck pain and head movement and velocity in the whiplash group. Deficits in gaze stability and head eye coordination may be related to disturbed reflex activity associated with decreased head range of motion and/or neck pain. Further research is required to explore the mechanisms behind these deficits, the nature of changes over time and the tests' ability to measure change in response to rehabilitation.

International Journal of Industrial Ergonomics, 2004

Work related neck and shoulder disorders are a great problem for string musicians. A playing tech... more Work related neck and shoulder disorders are a great problem for string musicians. A playing technique with more relaxed muscles and a greater variation in the muscle activity pattern, i.e., with shorter sequences at a varied number of amplitude levels as reflected by electromyography (EMG), might prevent pain. This study used EMG to study variations in the trapezius muscle activity pattern in 12 string musicians performing a piece of music at two playing sessions separated by a ten-week interval. Nine of the string musicians played violin, two viola and one cello. Exposure variation analysis and principal component analysis were used for analysis of the EMG. The trapezius muscle activity pattern was similar in the first and second playing sessions showing that each musician repeated his/her own muscular activity pattern. However, there was considerable variability in the muscle activity pattern between cello, violin and viola players and between individual violin players. Thus, this EMG method has the potential to identify variations and reproducibility of trapezius muscle activity in string musicians. This method may be used to analyse individual differences when performing a musical work task and to evaluate intervention studies. Relevance to industry Intervention studies on muscle activity pattern which try to change the work technique need to be evaluated.