Stereovideographic evaluation of the postural geometry of healthy and scoliotic patients

Idiopathic scoliosis principally characterised by a deformation of the vertebral column can also be associated to postural abnormalities. The validity and reliability of current quantitative postural evaluations has not been thoroughly documented, frequently limited by a two dimensional view of the patient, and do not include the whole posture of the patient. The purpose of this study is to 1) quantify within and between-session reliability of a stereovideographic Postural Geometry (PG) evaluation and 2) to investigate the sensitivity of this technique for the postural evaluation of scoliosis patients. The PG of 14 control subjects and 9 untreated scoliosis patients were evaluated with 5 repeat trials, on two occasions. Postural geometry parameters that describe the position and orientation of the pelvis, trunk, scapular girdle and head were calculated based on the 3-dimensional co-ordinates of anatomical landmarks. The mean between and within-session variability across all parameters were 12.5 mm, 2.8 degrees and 5.4 mm and 1.4 degrees respectively. The patient group was heterogeneous with some noted pathological characteristics. This global stereovideographic postural geometry evaluation appears to demonstrate sufficient reliability and sensitivity to follow-up on the posture of scoliosis patients.     

Reliability and validity of the measurement of position sense in women with osteoarthritis of the knee

OBJECTIVE: We examined the test-retest reliability and the construct validity of the measurement of knee position sense for describing the functional weightbearing performance of women with osteoarthritis (OA) of the knee. METHODS: For the purpose of this study, position sense was defined as the error occurring when subjects attempted to reproduce a criterion angle in standing with visual cues eliminated. Five such tests were recorded photographically on 3 different occasions. On each occasion the 10 subjects also completed a self-paced walking test over a 13 m indoor walkway. RESULTS: The photographic measurements were reproducible (r = 0.90) and there was no change in positioning accuracy across sessions. There was a significant (p < 0.05) inverse correlation of 0.70 between the standard deviation of the mean individual measurements of position sense (precision of the test) and those of walking speed. CONCLUSION: Our study demonstrates good measurement reliability and a comparable mean angular error with repeated tests. It also suggests the amplitude of the variability of this error is a strong determinant of an individual OA patient's functional performance in walking.     

Postural coordination modes considered as emergent phenomena.

The coordination of multiple body segments (torso and legs) in the control of standing posture during a suprapostural task was studied. The analysis was motivated by dynamical theories of motor coordination. In 2 experiments it was found that multisegment postural coordination could be described by the relative phase of rotations around the hip and ankle joints. The effective length of the feet, the height of the center of mass, and the amplitude of head motions in a visual tracking task were varied. Across these variations, 2 modes of hip-ankle coordination were observed: in-phase and anti-phase. The emergence of these modes was influenced by constraints imposed by the suprapostural tracking task, supporting the idea that such tasks influence postural control in an adaptive manner. Results are interpreted in terms of a dynamical approach to coordination in which postural coordination modes can be viewed as emergent phenomena. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of stability of performance in patients with traumatic brain injury: Variability and consistency on reaction time tests.

The stability of performance of reaction times (RTs) on 3 visual discrimination tasks was assessed in patients with varying severity of traumatic brain injury (TBI) and in matched control Ss. Results were analyzed for group and individual variability and consistency of performance over time. There was significantly greater intersubject (group) variability in the TBI group. Individual patients (intrasubject) tended to be more variable in performance and less consistent over time than control Ss, but this occurred only with specific measures, which suggests that increased lack of stability in performance is not a general impairment after brain damage but requires specific analyses for identification of performance differences. This intrasubject variability was indepedent of test–retest and split-half test reliability. No obvious factors such as severity of brain injury were related to the variability and inconsistency of performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantitative evaluation of saccadic and smooth pursuit eye movements. Is it reliable?

PURPOSE: The authors evaluated the reliability of the coefficients of the (1) amplitude/duration and (2) amplitude/peak velocity relationships of the mean precision values and the mean latency values (saccadic eye movements) and the coefficients of the target velocity/gain relationship (smooth pursuit eye movements). They computed test-retest maximum variability limits for these parameters. METHODS: After a 1-week interval, saccadic and smooth pursuit eye movements were recorded twice from 20 healthy subjects; 12 of these subjects underwent a third recording session. The estimate of the intraclass coefficient of reliability, R, was adopted to evaluate the reliability of eye movement quantitative analysis. RESULTS: The data demonstrated that the reliability was fairly good for the amplitude/peak velocity relationship, was good for the precision, and was excellent for the amplitude/duration, the target velocity/gain relationships, and the latency. CONCLUSIONS: Quantitative analysis of both saccadic and smooth pursuit eye movements is reliable. One statistic used to estimate reliability, ie, the within-subjects mean square value, also enables the determination of test-retest normal variability values for both the variances and the differences of measurements.     

Human recombinant apolipoprotein E-enriched liposomes can mimic low-density lipoproteins as carriers for the site-specific delivery of antitumor agents

This study investigated the effects of flooring on balance during quiet standing in healthy young and older participants. Seven flooring conditions were examined, including a hard tile floor and combinations of low-pile and high-pile carpet with urethane foam and rubber padding. The resulting floors provided a variety of compliant surfaces, ranging from very soft to hard. Participants stood during three separate visual conditions: eyes open, eyes closed, and looking at a moving visual surround. Three measures of postural sway were calculated using center of pressure recordings during the trails. The results showed that the amplitude of sway was higher in the older than in the younger participants, particularly in the moving visual surround condition. Flooring compliance was found to have an effect on sway during moving visual environments, with the largest effects found among the older participants. Softer floors increased the amount of sway in the older participants. These results suggest that floor compliance influences standing postural stability in older people, particularly in destabilizing visual environments.     

Position and velocity coupling of postural sway to somatosensory drive

Light touch contact of a fingertip to a stationary surface provides orientation information that enhances control of upright stance. Slight changes in contact force at the fingertip lead to sensory cues about the direction of body sway, allowing attenuation of sway. In the present study, the coupling of postural sway to a moving contact surface was investigated in detail. Head, center of mass, and center of pressure displacement were measured as the contact surface moved rhythmically at 0.1, 0.2, 0.4, 0.6, and 0.8 Hz. Stimulus amplitude decreased with frequency to maintain peak velocity constant across frequency. Head and body sway were highly coherent with contact surface motion at all frequencies except 0.8 Hz, where a drop-off in coherence was observed. Mean frequency of head and body sway matched the driving frequency 相似文献   

Validity and reliability of measurements taken by the Peak 5 motion analysis system

Many new measurement tools are becoming available for physiotherapists; however, there is often a lack of data to support their validity and reliability. This study attempts to address this issue with respect to the Peak 5 video analysis system. Five experiments were conducted. Experiment A investigated the validity of static angular measurements by filming a universal goniometer. A high level of agreement was recorded with a mean difference between the two instruments of 0.2 degree. Experiment B investigated the validity of angular joint velocity by filming a Biodex isokinetic dynamometer. A high level of agreement was recorded with a mean difference between the two instruments of 0.96 degree s-1. Experiment C investigated the reliability of reflective marker placements on the hip, knee and ankle on 17 healthy volunteers, in weight bearing on three separate days. Reliability was high with the 95% confidence interval (CI) for marker placement being 1.5 cm. Experiment D investigated the normal intrasubject variation of knee joint 'critical angle' and angular velocity measures over time, by filming 17 healthy volunteers performing an eccentric step test on three separate days. For 'critical angle' measures the standard deviation was 5.72 degrees and the 95% CI was +/- 11.44 degrees. For angular velocity measures the standard deviation was 8.51 degrees s-1 and the 95% CI was +/- 17.02 degrees s-1. Experiment E repeated analysis of the reflective marker placement (mean standard deviation 0.6 cm), the 'critical angle' (mean standard deviation 1.32 degrees) and the angular velocity (mean standard deviation 1.29 degrees s-1 showed high consistency, when analysing three pieces of film three times. Data generated in this study suggest that the Peak 5 provides valid angular and angular velocity data when compared to other measuring devices. Reliable data are produced when filming healthy volunteers performing an eccentric step test. These data will be used in the next stage of the project investigating Anterior Knee Pain Patients.     

Simultaneous oxygenation and perfusion imaging study of functional activity in primary visual cortex at different visual stimulation frequency: quantitative correlation between BOLD and CBF changes

A relationship between regional cerebral blood flow (CBF) and blood oxygenation level dependent (BOLD) changes in the primary visual cortex (V1) at varied visual stimulation frequency has been examined quantitatively using the multislice FAIR technique. A linear correlation in the common activation areas between functional BOLD and CBF maps was observed. This supports the hypothesis that the task-stimulated BOLD changes in microvasculature are correlated with the CBF changes that presumably reflect the degree of neuronal activity. The linear correlation coefficients for intrasubject comparisons are more significant than those for intersubject comparisons. This suggests that using intrasubject comparisons for quantitative studies of neuronal activity related to different task stimuli and task performances should be more reliable than using intersubject comparisons.     

Infants' sensitivity to optical flow for controlling posture.

Infants' sensitivity to optical flow for controlling sitting and standing was tested using a "moving room" in which all of the walls moved together, or only the side walls or front wall moved. Two questions motivated this research. (a) is the optical flow necessary for inducing postural compensations spatially distributed in the optic array? (b) Do visually induced compensations follow a developmental progression, or alternatively, emerge all at once? Experiment 1 was designed to test postural compensations by 14-month-old infants capable of standing in the moving room. Experiment 2 was designed to test postural compensations by 5- to 9-month-old infants who were passively supported while sitting in the moving room. The results revealed that partial flow is generally sufficient for inducing postural compensations, but that the amplitude and consistency of the response depend on the location of the flow in the optic array. In addition, there was evidence suggesting that compensatory responses become increasingly systematic during the second half of the first year. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of seven visual fatigue assessment techniques in three data-acquisition VDT tasks

We compared 7 methods of measuring visual fatigue--accommodation power, visual acuity, pupil diameter, critical fusion frequency (CFF), eye movement velocity, subjective rating of visual fatigue, and task performance--for their sensitivity to visual load. In the experiment, 10 participants performed a monitoring task at 2 viewing distances, read articles under 2 levels of screen contrast, and tracked visual targets at 2 different speeds. The same measurement techniques, excluding pupil diameter and eye movement velocity, were compared by extending the task time from 20 to 60 min with the same VDT tasks to test for possible improvement in sensitivity. The results indicated that sensitivities of accommodation power, visual acuity, and CFF were greatly improved by a longer task period, but these 3 measurement techniques did not distinguish among tasks. Pupil diameter, eye movement velocity, and subjective rating of visual fatigue were sensitive in differentiating tracking from reading and monitoring tasks. Eye movement velocity and subjective rating were sensitive to the changes in target velocity of the tracking task. Although task performance was not directly comparable to other measurement techniques, it helped to ensure that participants maintained the same performance level by devoting more resources to the high-load conditions. Actual or potential applications of this research include using some of these assessment techniques for the design of adaptive displays.     

Use of the repeated cross-over designs in assessing bioequivalence

We consider applications of the repeated 2 x 2 cross-over design to evaluating bioequivalence between the two formulations. The repeated 2 x 2 cross-over design allows us not only to assess bioequivalence on average bioavailability and to examine the subject-by-formulation interaction but also to obtain independent unbiased estimates of intrasubject variability. One consequence of unequal intrasubject variabilities is that the sum of squares of intersubject residuals and the sum of squares of subject-by-formulation residuals are not independent. We also discuss the relative merits of this design as compared to the standard 2 x 2 cross-over design without repeated measurements in terms of precision and sample size with respect to the ratio of the number of subjects to the repeated measurements per subject. We investigate other uses of the 2 x 2 cross-over in examining the bioequivalence between the two different dosing regimens. Possible applications of other repeated cross-over designs to bioequivalence for more than two formulations are explored. A numerical example illustrates the proposed procedure.     

Influence of joint interactional effects on the coordination of planar two-joint arm movements

We have examined EMG-movement relations in two-joint planar arm movements to determine the influence of interactional torques on movement coordination. Explicitly defined combinations of elbow movements (ranging from 20 to 70 degrees) and wrist movements (ranging from 20 to 40 degrees) were performed during a visual, step-tracking task in which subjects were specifically required to attend to the initial and final angles at each joint. In all conditions the wrist and elbow rotated in the same direction, that is, flexion-flexion or extension-extension. Elbow movement kinematics were only slightly influenced by motion about the wrist. In contrast, the trajectory of the wrist movement was significantly influenced by uncompensated reaction torques resulting from movement about the elbow joint. At any given wrist amplitude, wrist movement duration increased and peak velocity decreased as elbow amplitude increased. In addition, as elbow amplitude increased, wrist movement onset was progressively delayed relative to this elbow movement. Surprisingly, the changes between joint movement onsets were not accompanied by corresponding changes between agonist EMG onsets at the elbow and wrist joints. The mean difference in onset times between elbow and wrist agonists (22-30 ms) remained unchanged across conditions. In addition, a basic pattern of muscle activation that scaled with movement amplitude was observed at each joint. Phasic agonist activity at the wrist and elbow joints remained remarkably similar across conditions and thus the changes in joint movement onset could not be attributed to changes in the motor commands.(ABSTRACT TRUNCATED AT 250 WORDS)     

Measures of postural steadiness: differences between healthy young and elderly adults

Measures of postural steadiness are used to characterize the dynamics of the postural control system associated with maintaining balance during quiet standing. The objective of this study was to evaluate the relative sensitivity of center-of-pressure (COP)-based measures to changes in postural steadiness related to age. A variety of time and frequency domain measures of postural steadiness were compared between a group of twenty healthy young adults (21-35 years) and a group of twenty healthy elderly adults (66-70 years) under both eyes-open and eyes-closed conditions. The measures that identified differences between the eyes-open and eyes-closed conditions in the young adult group were different than those that identified differences between the eye conditions in the elderly adult group. Mean velocity of the COP was the only measure that identified age-related changes in both eye conditions, and differences between eye conditions in both groups. The results of this study will be useful to researchers and clinicians using COP-based measures to evaluate postural steadiness.     

Practical aspects of faculty practice. A model for excellence

The aim of the study was to determine the intrasubject variability of the pressure-transmission ratio (PTR) with various cough intensities in subjects with genuine stress incontinence. Thirty-six patients with genuine stress incontinence underwent multichannel urodynamics and had a series of pressure-transmission ratios (PTRs) determined with the urethral transducer placed at the point of the maximal closure pressure. Patients were asked to cough with increasing intensities and three to four different cough-induced PTRs were recorded for each subject. The data were analysed using regression analysis, repeated measures analysis of variance and comparison of variance. The PTRs showed a high degree of variability within subjects. The mean within subject standard deviation was 18.5%. The effect of parity, maximal urethral closure pressure and age were insignificant on the variability. Cough intensities of greater than 90 cmH2O have a lesser degree of variability. The mean PTR across all cough intensities was fairly constant in the 82%-87% range. It was concluded that the PTR in an individual has a high degree of variability independent of cough intensity, and cannot be relied upon as a diagnostic measure in subjects with genuine stress incontinence. However, the PTR for the population as a whole was consistent across all cough intensities.     

Postural control--a comparison between patients with chronic anterior cruciate ligament insufficiency and healthy individuals

Postural control in the sagittal plane was evaluated in 22 patients with chronic anterior cruciate ligament (ACL) deficiency and the result was compared to that of a control group of 20 uninjured subjects. Measurement of the body sway was done on a fixed and sway-referenced force plate in both single-limb and two-limb stance, with the eyes open and closed, respectively. Further, an analysis of the postural reactions to perturbations backwards and forwards, respectively, was made in single-limb stance. The results demonstrated statistically significant deficits of the postural control in the patient group compared to the control group, but also within the patient group. There was a significantly higher body sway within the patient group when standing on a stable support surface on the injured limb than standing on the uninjured limb with the eyes open, but no difference with the eyes closed. When standing on a stable support surface, there was a significantly higher body sway in the patient group standing on the injured leg than in the control group, both with eyes open and closed. The patient group also showed a significantly impaired postural control compared to the control group when standing on the uninjured leg with the eyes closed. There was no difference between the groups in the two-limb stance. When standing on the sway-referenced support surface, the patient group had a significantly larger body sway than the control group when the eyes were open, but there was no significant difference between the groups with the eyes closed. The measurement of the postural corrective responses to perturbations backwards and forwards showed that the reaction time measured from the initiation of the force plate translation, and the amplitude of the body sway was significantly greater in the patient group than in the control group. We conclude that patients with a continuing chronic ACL insufficiency several years after injury have an impaired postural control in the antero-posterior direction in single-limb stance on their injured leg. They also show a greater body sway and a prolonged reaction time when subjected to antero-posterior perturbations when standing on their injured leg.     

The IPCS Collaborative Study on Neurobehavioral Screening Methods: V. Results of chemical testing. Steering Group

The goal of the International Programme on Chemical Safety (IPCS) Collaborative Study on Neurobehavioral Screening Methods was to determine the intra- and inter-laboratory reliability of a functional observational battery (FOB) and an automated assessment of motor activity in eight laboratories worldwide. The control data were crucial to the outcome of the studies in terms of sensitivity and reliability of the test measures, which in turn impact on the between-laboratory comparisons of chemical effects. In addition, analyses of control data can aid in determining endpoints that may require modification to improve their sensitivity and reliability. The control data from the eight laboratories were examined in terms of the following parameters: 1) control variability within studies for each laboratory; 2) within-laboratory replicability of control values across studies; 3) within-laboratory stability of control values over the course of testing for a given study; and 4) between-laboratory comparisons of parameters (1), (2), and (3). The analyses indicated considerable differences across endpoints, wherein some measures showed high variability and little replicability, while others were extremely reproducible. Generally, there were similar ranges of variability and replicability of control data across laboratories, although in some cases one or two laboratories were markedly different from the others. The physiological (weight, body temperature) and neuromuscular (grip strength, landing foot splay) endpoints exhibited the least variability, whereas the subjective assessments of reactivity varied the most. These data indicate a reasonable degree of comparability in the data generated in the participating laboratories.     

Emotional states alter force control during a feedback occluded motor task.

The aim of the current experiment was to determine the extent to which pleasant and unpleasant emotional states altered the ability of men and women to control force production on a feedback occluded motor task that was not direction specific. Participants produced a precision pinch grip with visual feedback. After 5 s, feedback was occluded and replaced with a pleasant, unpleasant, or neutral image. The amplitude, variability, and structure of force production were calculated. As expected, the removal of visual feedback led to progressive force decay. More important, relative to neutral conditions, pleasant and unpleasant emotional states led to greater force production, resulting in attenuated force decay. The variability and structure of force production were not altered by affective state. In addition, men and women performed similarly across all conditions for all measures. We conclude that when sustained force production is not directed toward or away from the body, pleasant and unpleasant emotional states similarly excite the motor system. Neurobiological mechanisms are proposed to account for these findings. Implications and future research directions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postural stabilization of looking.

The authors studied relations between postural sway, optical flow, and constraints on posture imposed by a suprapostural looking task. Optical flow resulted from unperturbed sway and was not imposed by the experimenters. Participants fixated a distant target or a nearby target. In the key condition, participants looked past (i.e., ignored) a nearby target to fixate the distant target. The authors recorded the variability of head position as a measure of the amplitude of postural sway. In 5 of 7 experiments, sway variability was influenced by the location of the fixated target not by the distance of the nearest visible surface (the unfixated nearby target). Postural sway was modulated to facilitate the performance of suprapostural tasks and was not driven by optical flow in an autonomous (task-dependent) manner. The authors concluded that posture can be understood only in the context of explicit manipulations of suprapostural tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)