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IntroductionTo assess activity limitations in people with haemophilia (PwH), the self-reported Haemophilia Activity List (HAL) is widely employed, despite several methodological limitations impacting the interpretation of categorical scores. Modern psychometric approaches avoid these limitations by using a probabilistic model, such as the Rasch model. The ACTIVLIM is a Rasch-built measurement of activity limitations previously validated in several clinical conditions like neuromuscular disorders. AimsThis study sought to develop the ACTIVLIM-Hemo, meaning an ACTIVLIM scale version specifically adapted to assess daily activity limitations in adult PwH. MethodsDaily activities were assessed as "impossible," "difficult" or "easy" by 114 PwH (median age of 44 years) with 63 of them reassessed after 12 days. The Rasch Rating Scale model was used to identify activities delineating a unidimensional and linear scale unbiased by demographic and clinical status. Concurrent validity was determined through correlation with the HAL sub-scores and sum score. ResultsThe ACTIVLIM-Hemo included 22 pertinent activities, with difficulties independent of demographic and clinical conditions, allowing a reliable measure of activity limitations (PSI = .92) expressed on a linear and unidimensional scale in PwH (7%-100 % range, ceiling effect of 1/114) with excellent test-retest reliability (ICC = .978). Spearman rank correlations between ACTIVLIM-Hemo and HAL sub-scores ranged between .623 and .869. ConclusionsThe ACTIVLIM-Hemo is an easy-to-administer, valid and reliable alternative to HAL in assessing activity limitations in PwH. Its invariant scale can be used across conditions and time to compare the functional status of PwH over a wide measurement range.

Background Dynamic analyses of walking rely on the 3D ground reaction forces (GRF) under each foot, while only the resultant force of both limbs may be recorded on a single-belt instrumented treadmill or when both feet touch the same force platform. Research question This study aims to develop a robust decomposition of the shear GRF to complete the most accurate decomposition of the vertical GRF [ 8 ]. Methods A retrospective study of 374 healthy adults records (age: 22.8 ± 2.6 years, speed: 1.34 ± 0.28 m/s) and of 434 patient records (age: 21.3 ± 17.8 years, speed: 0.64 ± 0.19 m/s) were used in a machine learning process to develop a robust predictive model to decompose the fore-aft GRF. The lateral GRF was decomposed by resolving the equilibrium of transverse moments around the center of pressure. Results A predictive linear model of the fore-aft GRF under the back foot every 5% of the double contact phase was obtained from 2 predictors: the total fore-aft GRF and the vertical GRF under the back foot. Each predictor uses a time series of 31 samples before and during the double contact. The model performs accurately in healthy (median[IQR] error of 3.0[2.2–4.1]%) and in clinical gaits (7.7[4.7–13.4]%). The error in lateral GRF decomposition is of 5.7[3.9–10.2]% in healthy gaits and of 12.0[7.2–19.2]% in patients under the back foot and about half of that under the front foot. Significance The decomposition of shear GRFs achieved in this study supports the mechanics of walking. It provides outstanding accuracy in healthy gait and also applies to neurologic and orthopedic disorders. Together with the vertical GRF decomposition [ 8 ], this approach for the shear components paves the way for robust single limb GRF determination on a single-belt instrumented treadmill or when both feet touch the same force platform in normal and clinical gait analysis.

The ability to monitor activities of daily living in the natural environments of patients could become a valuable tool for various clinical applications. In this paper, we show that a simple algorithm is capable of classifying manual activities of daily living (ADL) into categories using data from wrist- and finger-worn sensors. Six participants without pathology of the upper limb performed 14 ADL. Gyroscope signals were used to analyze the angular velocity pattern for each activity. The elaboration of the algorithm was based on the examination of the activity at the different levels (hand, fingers and wrist) and the relationship between them for the duration of the activity. A leave-one-out cross-validation was used to validate our algorithm. The algorithm allowed the classification of manual activities into five different categories through three consecutive steps, based on hands ratio (i.e., activity of one or both hands) and fingers-to-wrist ratio (i.e., finger movement independently of the wrist). On average, the algorithm made the correct classification in 87.4% of cases. The proposed algorithm has a high overall accuracy, yet its computational complexity is very low as it involves only averages and ratios.

Background Patients treated in hand surgery (HS) belong to different demographic groups and have varying impairments related to different pathologies. HS outcomes are measured to assess treatment results, complication risks and intervention reliability. A one-dimensional and linear measure would allow for unbiased comparisons of manual ability between patients and different treatment effects. Objective To adapt the ABILHAND questionnaire through Rasch analysis for specific use in HS patients and to examine its validity. Methods A preliminary 90-item questionnaire was presented to 216 patients representing the diagnoses most frequently encountered in HS, including distal radius fracture (n = 74), basal thumb arthritis (n = 66), carpal tunnel syndrome (n = 53), and heavy wrist surgery (n = 23). Patients were assessed during the early recovery and in the late follow-up period (0–3 months, 3–6 months and >6 months), leading to a total of 305 assessments. They rated their perceived difficulty with queried activities as impossible, difficult, or easy. Responses were analyzed using the RUMM2030 software. Items were refined based on item-patient targeting, fit statistics, differential item functioning, local independence and item redundancy. Patients also completed the QuickDASH, 12-item Short Form Survey (SF-12) and a numerical pain scale. Results The rating scale Rasch model was used to select 23 mostly bimanual items on a 3-level scale, which constitute a unidimensional, linear measure of manual ability with good reliability across all included diagnostic groups (Person-Separation Index = 0.90). The resulting scale was found to be invariant across demographic and clinical subgroups and over time. ABILHAND-HS patient measures correlated significantly (p Conclusion ABILHAND-HS is a robust person-centered measure of manual ability in HS patients.

Inertial measurement unit (IMU) records of human movement can be converted into joint angles using a sensor-to-segment calibration, also called functional calibration. This study aims to compare the accuracy and reproducibility of four functional calibration procedures for the 3D tracking of the lower limb joint angles of young healthy individuals in gait. Three methods based on segment rotations and one on segment accelerations were used to compare IMU records with an optical system for their accuracy and reproducibility. The squat functional calibration movement, offering a low range of motion of the shank, provided the least accurate measurements. A comparable accuracy was obtained in other methods with a root mean square error below 3.6&deg, and an absolute difference in amplitude below 3.4&deg, The reproducibility was excellent in the sagittal plane (intra-class correlation coefficient (ICC) &gt, 0.91, standard error of measurement (SEM) &lt, 1.1&deg, ), good to excellent in the transverse plane (ICC &gt, 0.87, SEM &lt, ), and good in the frontal plane (ICC &gt, 0.63, SEM &lt, 1.2&deg, ). The better accuracy for proximal joints in calibration movements using segment rotations was traded to distal joints in calibration movements using segment accelerations. These results encourage further applications of IMU systems in unconstrained rehabilitative contexts.

Objective To build a model of prediction of social participation of community-dwelling stroke survivors in Benin at 1 month, 3 months, and 6 months. Design An observational study with evaluations at 1 month, 3 months, and 6 months poststroke. Correlational analyses and multivariate linear regressions were performed. Setting Outpatient rehabilitation centers in Benin. Participants A volunteer sample of 91 stroke patients was enrolled at baseline; 64 (70%) patients completed all the study (N=64): 70% male and 52% right hemiparesis. Intervention Not applicable. Main Outcome Measures Participants were evaluated with the Participation Measurement Scale, ACTIVLIM-Stroke (activities of daily living [ADL]), Stroke Impairment Assessment Set, 6-minute walk test, Hospital Anxiety and Depression Scale, and the modified Rankin Scale. Results The significant predictors of social participation after controlling the confounders were the following: at 1 month ADL (0.4 [0.3, 0.6]) and depression (‒0.6 [‒0.8, ‒0.2]) with total model R2=0.44; at 3 months ADL (0.58 [0.4, 0.7]) and depression (‒0.58 [‒0.5, ‒0.7]) with total model R2=0.65; and at 6 months ADL (0.31 [0.2, 0.5]), impairments (‒0.82 [‒0.5, ‒0.7]), and depression (‒0.94 [‒0.8, ‒0.2]) with total model R2=0.78. Conclusions Using socioculturally tailored tools, the present study identified ADL performance (ACTIVLIM-Stroke), depression (Hospital Anxiety Depression Scale), and overall impairments (Stroke Impairment Assessment Set) as the significant determinants of social participation (Participation Measurement Scale) poststroke in Benin. These findings will be a valuable resource for rehabilitation stakeholders in evaluating interventions, programs, and policies designed to encourage social participation for stroke patients.

International audience; Objective: To develop a valid stroke-specific tool, named the Participation Measurement Scale (PM-Scale), for the measurement of participation after stroke. Design: Observational study and questionnaire development. Setting: Outpatient rehabilitation centers. Participants: Patients with stroke (N=276; mean age, 58.5±11.1y; 57% men). Interventions: Not applicable. Main outcome measures: Participants completed a 100-item experimental questionnaire of the PM-Scale. Items were scored as "not at all," "weakly," or "strongly." The Hospital Anxiety and Depression Scale was used to evaluate depression, and the modified Rankin Scale was used to categorize the severity of disability on the basis of observation. Results: After successive Rasch analyses using unrestricted partial credit parameterization, a valid, unidimensional, and linear 22-item scale for the measurement of participation was constructed. All 22 items fulfilled the measurement requirements of overall and individual item and person fits, category discrimination, invariance, and local response independence. The PM-Scale showed good internal consistency (person separation index, .93). The test-retest reliability of item difficulty hierarchy (r=.96; P

Neuromuscular disorders (NMDs) can lead to specific manual disabilities due to hand muscle weakness and atrophy, myotonia, or loss of sensory function. The aim of this study was to adapt and validate the ABILHAND questionnaire in children and adults with NMDs using the Rasch model. This questionnaire contained specific manual activities for children and for adults, as well as common manual activities. One hundred and twenty-four adult patients and the parents of 124 paediatric patients were asked to provide their perceived difficulty in performing each manual activity on a three-level scale: impossible (0), difficult (1) or easy (2). Items were selected from well-established psychometric criteria (ordered categories, equal item discrimination, adequate fit to the Rasch model, lack of redundancy) using the Rasch Unidimensional Measurement Models (RUMM2020((c))) computer programme. The 22 selected items contain 4 children specific items, 4 adult specific items and 14 items commonly applicable to both children and adults. They define a unidimensional and linear measure of manual ability and demonstrate continuous progression in their difficulty. The item hierarchy of difficulty was invariant across six patient-related factors. The scale exhibited good precision (r=0.95) and the 22 items were well targeted to the patients' locations. The ABILHAND measures were strongly related to the ACTIVLIM measures (r=0.76), and poorly related to grip strength (r=0.36 for the right hand and r=0.40 for the left hand). Moreover, the resulting scale can be used for adults and children, allowing manual ability to be assessed from childhood to adulthood.

Objective: To analyse cross-cultural validity of the Functional Independence Measure (FIM) in patients with stroke using the Rasch model. Settings: Thirty-one rehabilitation facilities within 6 different countries in Europe. Participants: A total of 2546 in-patients at admission, median age 63 years. Methods: Data from the FIM were evaluated with the Rasch model, using the Rasch analysis package RUMM2020. A detailed analysis of scoring functions of the 7 categories of the FIM items was undertaken prior to testing fit to the model. Categories were re-scored where necessary. Analysis of Differential Item Functioning was undertaken in pooled data for each of the FIM motor and social-cognitive scales, respectively. Results: Disordered thresholds were found on most items when using 7 categories. Fit to the Rasch model varied between countries. Differential Item Functioning was found by country for most items. Adequate fit to the Rasch model was achieved when items were treated as unique for each country and after a few country-specific items were removed. Conclusion: Clinical collected data from FIM for patients with stroke cannot be pooled in its raw form, or compared across countries. Comparisons can be made after adjusting for country-specific Differential Item Functioning, though the adjustments for Differential Item Functioning and rating scales may not generalize to other samples.

ObjectiveTactile explorations with the fingertips provide information regarding the physical properties of surfaces and their relative pleasantness. Previously, we performed an investigation in the active touch domain and linked several surface properties (i.e. frictional force fluctuations and net friction) with their pleasantness levels. The aim of the present study was to investigate physical factors being important for pleasantness perception during passive fingertip stimulation. Specifically we were interested to see whether factors, such as surfaces' topographies or their frictional characteristics could influence pleasantness. Furthermore, we ascertained how the stimulus pleasantness level was impacted by (i) the normal force of stimulus application (FN) and (ii) the stimulus temperature (TS).Methods and resultsThe right index fingertips of 22 blindfolded participants were stimulated using 27 different stimuli, which varied in average roughness (Ra) and TS. A 4-axis robot moved the stimuli horizontally under participants' fingertips with three levels of FN. The robot was equipped with force sensors, which recorded the FN and friction force (FT) during stimulation. Participants rated each stimulus according to a three-level pleasantness scale, as very pleasant (scored 0), pleasant (scored 1), or unpleasant (scored 2). These ordinal pleasantness ratings were logarithmically transformed into linear and unidimensional pleasantness measures with the Rasch model. Statistical analyses were conducted to investigate a possible link between the stimulus properties (i.e. Ra, FN, FT, and TS) and their respective pleasantness levels. Only the mean Ra and FT values were negatively correlated with pleasantness. No significant correlation was detected between FN or TS and pleasantness.ConclusionPleasantness perception, resulting from passive fingertip stimulation, seems to be influenced by the surfaces' average roughness levels and average FT occurring during fingertip stimulation.

OBJECTIVES: The present study investigated whether the impairment of tactile sensitivity after exposure to vibration disturbs the motor control of precision handling and, if so, whether it can result in an increased risk of injury during or after tasks involving the use of vibrating tools. METHODS: Twelve men were manually exposed to vibration from an electric sander for 30 min. Cutaneous sensitivity was quantified to measuring the pressure perception threshold and vibration perception threshold (125 Hz) on the pulp of the second finger. Manipulative skill was evaluated by grip-lift movements and the Purdue pegboard test. RESULTS: The vibration perception threshold increased very significantly from 94.0 dB (0.06 m/s2) before the vibration exposure to 127.5 dB (3.2 m/s2) immediately after the exposure. The pressure perception threshold tended to increase after vibration exposure, although not significantly, but manipulative skill was not altered. CONCLUSIONS: Change in vibration perception threshold was not associated with a significant increase in the pressure perception threshold or a perturbation of manual skill. Therefore, in conditions similar to those of our experiment, the safety of a precision task does not appear to be reduced after such vibration exposure.

Objectives Several ABILHAND Rasch-built manual ability scales were previously developed for chronic stroke (CS), cerebral palsy (CP), rheumatoid arthritis (RA), systemic sclerosis (SSc) and neuromuscular disorders (NMD). The present study aimed to explore the applicability of a generic manual ability scale unbiased by diagnosis and to study the nature of manual ability across diagnoses. Design Cross-sectional study. Setting Outpatient clinic homes (CS, CP, RA), specialised centres (CP), reference centres (CP, NMD) and university hospitals (SSc). Participants 762 patients from six diagnostic groups: 103 CS adults, 113 CP children, 112 RA adults, 156 SSc adults, 124 NMD children and 124 NMD adults. Primary and secondary outcome measures Manual ability as measured by the ABILHAND disease-specific questionnaires, diagnosis and nature (ie, uni-manual or bi-manual involvement and proximal or distal joints involvement) of the ABILHAND manual activities. Results The difficulties of most manual activities were diagnosis dependent. A principal component analysis highlighted that 57% of the variance in the item difficulty between diagnoses was explained by the symmetric or asymmetric nature of the disorders. A generic scale was constructed, from a metric point of view, with 11 items sharing a common difficulty among diagnoses and 41 items displaying a category-specific location (asymmetric: CS, CP; and symmetric: RA, SSc, NMD). This generic scale showed that CP and NMD children had significantly less manual ability than RA patients, who had significantly less manual ability than CS, SSc and NMD adults. However, the generic scale was less discriminative and responsive to small deficits than disease-specific instruments. Conclusions Our finding that most of the manual item difficulties were disease-dependent emphasises the danger of using generic scales without prior investigation of item invariance across diagnostic groups. Nevertheless, a generic manual ability scale could be developed by adjusting and accounting for activities perceived differently in various disorders.

BACKGROUND: Growing evidence exists that the somatic sensation has a modality for pleasant touch. OBJECTIVE: Investigate pleasant touch at fingertip level (i.e. glabrous skin site) through the elaboration of a linear unidimensional scale locating (i) various materials according to their pleasantness level they elicit through active fingertip explorations and (ii) subjects according to their pleasantness leniency levels.SUBJECTS: 198 healthy subjects without any neurological disease participated in this study. METHODS: Blindfolded subjects actively explored 48 materials with their index fingertip and reported, for each material, their perceived pleasantness of touch on a 4-level scale. The subjects’ fingertip moisture levels were measured before the experimental session. The data has been analysed by using the Rasch model.RESULTS: An unidimensional linear scale has been elaborated. This scale locates 37 materials according to the pleasantness of touch they elicit through active touch explorations. Furthermore, the pleasantness level of 21 materials was differently perceived depending on the subjects’ fingertip moisture levels. Each of these 21 materials defines a low- and a high- moisture item.CONCLUSION: A Pleasant Touch Scale has been elaborated. The investigations indicate that the fingertip moisture level appears to be a major factor of the (un)pleasant feeling during active explorations.

ACTIVLIM is a Rasch-built measure of activity limitations in children and adults with neuromuscular disorders. This study aims to investigate its psychometric properties as used in clinical practice in the Belgian NeuroMuscular Disease Registry (BNMDR). A sample of 2986 consecutive patients (56 % male, 92 % adult over 16 years, and 85 % Dutch speakers) was assessed at least once in the BNMDR over years 2011 and 2012 in 6 reference centers across the three main regions in Belgium, leading to 4146 records. The dataset was analyzed with the Rasch rating scale model in order to determine the difficulty of each item (i.e. the calibration) and their targeting to the ability of the patients on a unidimensional and linear scale, to investigate item and person fit and item invariance across demographic and clinical sub-groups, to determine the reliability in this dataset, to compare the BNMDR item difficulty hierarchy with the original scale calibration and to measure the patients change in activity (t-score) over on year (n = 1128). The BNMDR ACTIVLIM data showed excellent fit to a unidimensional scale. The reliability index was 0.95 in the BNMDR and the items were well targeted for 87 % of the patients. Invariant item difficulties were observed across age, gender, language, regions, centers, chronicity, item presentation orders and over time. Slight clinically meaningful variations in item difficulty hierarchy were observed across diagnoses. The item calibration was similar to the original publication but with a 3-fold accuracy. A slight but significant deterioration in activity (t = 0.39 ± 1.70; p 0.1). The ACTIVLIM records in the BNMDR demonstrated very good psychometric properties.

Fine prehension is ubiquitous in everyday skilled hand manipulations. The anticipatory nature of the control of normal grip forces exerted against tangential loads has been extensively used to provide insights into the working of neural control of movements. We designed a new versatile device to measure the three dimensional forces and torques during a broad panel of precision grip tasks. The instrument measures constraints exerted independently on two grip surfaces by the thumb and the opposing fingers. In addition, the device can be loaded to increase the weight and/or induce torques and can be easily integrated in a variety of experimental contexts. Its compactness improves its stability during movement and allows an ergonomic manipulation for impaired persons or children.

OBJECTIVE: Hand and upper limb involvement is common in patients with rheumatoid arthritis (RA). However, its impact on manual activities of daily life has not been fully evaluated. A measure of manual ability was developed, through the Rasch measurement model, by adapting and validating the ABILHAND questionnaire, which measures the patient's perceived difficulty in performing everyday manual activities. METHODS: 112 patients with RA were evaluated. The following tests were performed: the ABILHAND questionnaire, the Health Assessment Questionnaire (HAQ), the Jamar grip and key pinch strength tests, the Box and Block dexterity test and the Purdue pegboard dexterity test. In total, 35 patients were reassessed to determine the test-retest reliability of the ABILHAND, and 6 patients were studied before and after therapy with tumour necrosis factor (TNF) blockers to address sensitivity to change. RESULTS: The Rasch refinement of the ABILHAND led to a selection of 27 items rated on a 3-point scale. The resulting ability scale was targeted to the ability of the patients. The item-difficulty hierarchy was stable across demographic and clinical subgroups and over time. Grip and key pinch strength and manual and digital dexterity on both hands were significantly, though moderately, correlated with the ABILHAND measures. Manual ability was also significantly related to the number of affected hands, disease duration, tender and swollen joint counts on upper limbs, disease activity and the HAQ. Sensitivity to change was demonstrated in patients treated with TNF blockers, commensurate with their clinical improvement. CONCLUSION: The ABILHAND questionnaire is a clinically valid person-centred measure of manual ability that could be useful in longitudinal RA studies.

To analyse cross-culture validity of the Functional Independence Measure (FIM) in patients with a spinal cord injury using a modern psychometric approach.A total of 19 rehabilitation facilities from four countries in Europe.A total of 647 patients at admission, median age 46 years, 69% male.Data from the FIM, collected on inpatient admission, was fitted to the Rasch model. A detailed analysis of scoring functions of the seven categories of the FIM items was undertaken before to testing fit to the model. Categories were rescored where necessary. Fit to the model was assessed initially within country, and then in the pooled data. Analysis of differential item functioning (DIF) was undertaken in the pooled data for each of the FIM motor and social cognitive scales, respectively. Final fit to the model was tested for breach of local independence by principle components analysis (PCA).The present scoring system for the FIM motor and cognitive scales, that is a seven category scale, was found to be invalid, necessitating extensive rescoring. Following this, DIF was found in a number of items within the motor scale, requiring a complex solution of splitting items by country to allow for the valid pooling of data. Five country-specific items could not be retained within this solution. The FIM cognitive scale fitted the Rasch model after rescoring, but there was a substantial ceiling effect.Data from the FIM motor scale for patients with spinal cord injury should not be pooled in its raw form, or compared from country to country. Only after fit to the Rasch model and necessary adjustments could such a comparison be made, but with a loss of clinical important items. The FIM cognitive scale works well following rescoring, and data may be pooled, but many patients were at the maximum score.

Les questionnaires d'evaluation sont les instruments les plus utilises aujourd'hui dans le domaine de la medecine et des sciences humaines pour evaluer des variables telles que l'incapacite physique, l'altruisme ou la douleur. Pourtant les praticiens connaissent souvent mal ces instruments. Que mesurent-ils vraiment ? Comment les resultats doivent-ils etre interpretes ? Le present ouvrage s'efforce de repondre a ces questions. Il ne s'agit pas d'un simple mode d'emploi des questionnaires d'evaluation. Son objectif principal est de fournir a tous, chercheurs et praticiens, les bases methodologiques necessaires pour developper un tel instrument et pour en interpreter les resultats. Apres avoir expose les fondements d'une mesure objective formules par le modele de Rasch, les auteurs adressent une serie de questions frequemment posees dans leur contexte d'application. Quels sont les criteres d'une mesure objective ? Les resultats peuvent-ils etre interpretes de maniere quantitative ? Comment valider un tel instrument de mesure ? Peut-on comparer les reponses observees chez differents groupes de sujets ? Six chapitres, agrementes de nombreux exemples pratiques et d'exercices resolus, exposent les bases methodologiques de l'evaluation quantitative a l'aide du modele de Rasch. Le septieme chapitre decrit, pas a pas, les etapes du developpement et de la validation d'une echelle de mesure de l'habilete manuelle.

Objective:To develop a clinical tool for measuring manual ability (ABILHAND-Kids) in children with cerebral palsy (CP) using the Rasch measurement model.Methods:The authors developed a 74-item questionnaire based on existing scales and experts’ advice. The questionnaire was submitted to 113 children with CP (59% boys; mean age, 10 years) without major intellectual deficits (IQ > 60) and to their parents, and resubmitted to both groups after 1 month. The children’s and parents’ responses were analyzed separately with the WINSTEPS Rasch software to select items presenting an ordered rating scale, sharing the same discrimination, and fitting a unidimensional scale.Results:The final ABILHAND-Kids scale consisted of 21 mostly bimanual items rated by the parents. The parents reported a finer perception of their children’s ability than the children themselves, leading to a wider range of measurement, a higher reliability (R = 0.94), and a good reproducibility over time (R = 0.91). The item difficulty hierarchy was consistent between the parents and the experts. The ABILHAND-kids measures are significantly related to school education, type of CP, and gross motor function.Conclusions:ABILHAND-Kids is a functional scale specifically developed to measure manual ability in children with CP providing guidelines for goal setting in treatment planning. Its range and measurement precision are appropriate for clinical practice.

Investigating cyclic vertical arm movements with an instrumented hand-held load in an airplane undergoing parabolic flight profiles allowed us to determine how humans modulate their grip force when the gravitational and the inertial components of the load force are varied independently. Eight subjects participated in this study; four had already experienced parabolic flights and four had not. The subjects were asked to move the load up and down continuously at three different gravitational conditions (1 g, 1.8 g, and 0 g). At 1 g, the grip force precisely anticipated the fluctuations in the load force, which was maximum at the bottom of the object trajectory and minimum at the top. When gravity changed, the temporal coupling between grip force and load force persisted for all subjects from the first parabola. At 0 g, the grip force was accurately adjusted to the two load force peaks occurring at the two opposite extremes of the trajectory due to the absence of weight. While the experienced subjects exerted a grip force appropriate to a new combination of weight and inertia since their first trial, the inexperienced subjects dramatically increased their grip when faced with either high or low force levels for the first time. Then they progressively released their grip until a continuous grip-load force relationship with regard to 1 g was established after the fifth parabola. We suggest that a central representation of the new gravitational field was rapidly acquired through the incoming vestibular and somatic sensory information.

IN many areas of the world that lack a transportation infrastructure, people routinely carry extraordinary loads supported by their heads, for example the Sherpa of the Himalayas and the women of East Africa, It has previously been shown that African women from the Kikuyu and Luo tribes can carry loads substantially more cheaply than army recruits(1); however, the mechanism for their economy has remained unknown, Here we investigate, using a force platform, the mechanics of carrying head-supported loads by Kikuyu and Luo women, The weight-specific mechanical work, required to maintain the motion of the common centre of mass of the body and load, decreases with load in the African women, whereas it increases in control subjects, The decrease in work by the African women is a result of a greater conservation of mechanical energy resulting from an improved pendulum-like transfer of energy during each step, back and forth between gravitational potential energy and kinetic energy of the centre of mass.

This article is a brief review of the outcome evaluation of the hand and wrist according to the International Classification of Functioning, Disability, and Health. Several tools currently exist to quantify outcome in hand surgery at the impairment level (eg, mobility, hand strength, cutaneous sensation, dexterity). According to the World Health Organization's paradigm, however, activity limitations and participation restrictions are also clinically relevant. The authors have recently built a measure of an upper limb-impaired individual's ability to manage manual activities in daily life. Participation and quality of life are difficult outcomes to measure because they are multidimensional and depend on such factors as functional abilities, general physical health, financial security, and stability of the social and familial environment.

This preliminary study presents the development and testing of an instrumented treadmill device measuring the ground reaction forces (GRFs) and the feasibility of using this force measuring treadmill (FMT) in clinical gait analysis. A commercially available treadmill was modified and fitted out with three-dimensional strain-gauge force transducers. Tests of linearity, centre of pressure position (CoP), cross talk, natural frequency, background noises, and belt speed were undertaken in order to assess the performance of the FMT. In addition, the GRFs and segmental kinematics were recorded while healthy subjects and patients walked on the FMT, in order to compute the net ankle joint moments and the body centre of mass (CMb) kinematics and mechanics. The preliminary results of technical tests were satisfactory with an error less than 10% and dynamic tests in healthy subjects corresponded to the literature. The results of patients were clearly disturbed, demonstrating the ability of the FMT to discriminate pathological gaits from normal ones. We concluded that the GRFs measurements obtained from the FMT seem valid and the clinical assessment of net joint moments and CMb kinematics and mechanics seem feasible. The FMT could be useful device for clinical research and routine gait analysis since it allows gaining some extra room and quickly collecting the GRFs during a large number of successive gait cycles and over a wide range of steady-state gait speeds. However, more work is needed in this area in order to confirm the present results, collect reference data and validate the methodology across pathologies.

Background and Purpose —Chronic hemiparetic patients often retain the ability to manage activities requiring both hands, either through the use of the affected arm or compensation with the unaffected limb. A measure of this overall ability was developed by adapting and validating the ABILHAND questionnaire through the Rasch measurement model. ABILHAND measures the patient’s perceived difficulty in performing everyday manual activities. Methods —One hundred three chronic (>6 months) stroke outpatients (62% men; mean age, 63 years) were assessed (74 in Belgium, 29 in Italy). They lived at home and walked independently and were screened for the absence of major cognitive deficits (dementia, aphasia, hemineglect). The patients were administered the ABILHAND questionnaire, the Brunnström upper limb motricity test, the box-and-block manual dexterity test, the Semmes-Weinstein tactile sensation test, and the Geriatric Depression Scale. The brain lesion type and site were recorded. ABILHAND results were analyzed with the use of Winsteps Rasch software. Results —The Rasch refinement of ABILHAND led to a change from the original unimanual and bimanual 56-item, 4-level scale to a bimanual 23-item, 3-level scale. The resulting ability scale had sufficient sensitivity to be clinically useful. Rasch reliability was 0.90, and the item-difficulty hierarchy was stable across demographic and clinical subgroups. Grip strength, motricity, dexterity, and depression were significantly correlated with the ABILHAND measures. Conclusions —The ABILHAND questionnaire results in a valid person-centered measure of manual ability in everyday activities. The stability of the item-difficulty hierarchy across different patient classes further supports the clinical application of the scale.

Typically, ground reaction forces (GRFs) are recorded using floor-mounted force platforms in order to compute net joint torques. The assessment of these data during several cycles is time consuming...

INTRODUCTION: In Europe it is common for outcome measures to be translated for use in other languages. This adaptation may be complicated by culturally specific approaches to certain tasks; for example, bathing. In this context the issue of cross-cultural validity becomes paramount. OBJECTIVE: To facilitate the pooling of data in international studies, a project set out to evaluate the cross-cultural validity of impairment and activity limitation measures used in rehabilitation from the perspective of the Rasch measurement model. METHODS: Cross-cultural validity is assessed through an analysis of Differential Item Functioning (DIF) within the context of additive conjoint measurement expressed through the Rasch model. Data from patients undergoing rehabilitation for stroke was provided from 62 centers across Europe. Two commonly used outcome measures, the Mini-Mental State Examination (MMSE) and the Functional Independence Measure (FIM) motor scale are used to illustrate the approach. RESULTS: Pooled data from 3 countries for the MMSE were shown to fit the Rasch model with only 1 item displaying DIF by country. In contrast, many items from the FIM expressed DIF and misfit to the model. Consequently they were allowed to be unique across countries, so resolving the lack of fit to the model. CONCLUSIONS: Where data are to be pooled for international studies, analysis of DIF by culture is essential. Where DIF is observed, adjustments can be made to allow for cultural differences in outcome measurement.