Mahyar Salavati

Reliability of center of pressure measures of postural stability in healthy older adults: Effects of postural task difficulty and cognitive load

Postural instability is a major risk factor of falling in the elderly. It is well documented that postural control may decline while performing a concurrent cognitive task and this effect increases with age. Despite the extensive use of dual tasking in balance assessment protocols, a lack of sufficient reliability information is evident. This study determines the reliability of the postural stability measures in older adults, assessed under single and dual-task conditions and different levels of postural difficulty. Sixteen older adults completed quiet stance postural measurements at three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed), with or without performing a concurrent backward counting task, in two sessions 1 week apart. Force plate data was used to calculate center of pressure (COP) parameters including mean velocity, phase plane portrait, area (95% confidence ellipse), standard deviation (SD) of amplitude, and SD of velocity. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), coefficient of variation (CV), and minimal metrically detectable change (MMDC) were calculated for each COP measure in all test conditions. Mean velocity, total phase plane, phase plane in ML direction, and SD of velocity in ML direction were the most reliable COP measures across all test conditions. ICC values were consistently higher in ML direction compared with AP direction. In general, velocity-related COP measures in ML direction showed to be highly reliable. Further research may explore the predictive and evaluative value of these COP parameters.

Validation of a Persian-version of Knee injury and Osteoarthritis Outcome Score (KOOS) in Iranians with knee injuries

OBJECTIVE To adapt culturally and validate Persian-version of the Knee injury and Osteoarthritis Outcome Score (KOOS) in a sample of Iranians with knee injuries. METHODS Cultural adaptation included providing of forward and backward translations, quality rating and pilot testing. A sample of 147 patients with anterior cruciate ligament (ACL), meniscus and combined (ACL and meniscus) injuries was asked to complete two questionnaires including the KOOS and Short-Form 36 Health Survey (SF-36). The KOOS was readministered to 54 patients 6-8 days after the first visit. Test-retest reliability and internal consistency were assessed, using Intraclass Correlation Coefficient (ICC) and Cronbachs alpha, respectively. Dimensionality was assessed, using item-scale correlation after correction for overlap and construct validity, using a priori hypothesized correlations with the SF-36. RESULTS All patients found the Persian-version of the KOOS to be clear and unambiguous in pilot testing. Minimum ICC level of 0.70 was exceeded by all subscales with the exception of Sport and Recreation (Sport/Rec) subscale. Minimum Cronbachs alpha level of 0.70 was exceeded by all subscales with the exception of Symptoms and Knee-related Quality of Life (QoL). Minimum Spearman correlation coefficient of 0.40 for each item-scale was exceeded by 34 items. All priori hypotheses were supported by the presence of higher correlations between similar constructs than between dissimilar constructs of the KOOS and SF-36. CONCLUSION The Persian-version of the KOOS is a culturally-adapted, reliable and valid outcome measure to be used in Iranian patients with knee injuries, with its psychometric properties in agreement with the original versions.

Knee injury and Osteoarthritis Outcome Score (KOOS); reliability and validity in competitive athletes after anterior cruciate ligament reconstruction.

OBJECTIVE To validate the Knee injury and Osteoarthritis Outcome Score (KOOS) for the assessment of competitive athletes with higher level sports activities after anterior cruciate ligament (ACL) reconstruction. METHODS AND MEASURES Fifty-seven athletes (39 males and 18 females; age, 25.6 ± 3.4 years; height, 179.6 ± 7.4 cm; weight, 77.6 ± 9.8 kg) after ACL reconstruction were asked to complete the Persian KOOS and Short Form-36 (SF-36) questionnaires in the test session. To evaluate test-retest reliability, all participants filled out the KOOS and SF-36, 6-8 days after the first visit. The properties of the KOOS in terms of reliability [Intraclass Correlation Coefficient (ICC)], internal consistency (Cronbachs alpha), dimensionality (item-scale correlation) and construct validity (Spearmans rank correlation) were evaluated. RESULTS No floor or ceiling effect was observed. The ICCs (S.E.M.s) of the KOOS subscales were: Pain 0.93 (2.2), Symptoms 0.85 (3.1), Activities of Daily Living 0.91 (2.9), Function in Sport and Recreation 0.75 (2.1) and Knee-related Quality of Life 0.89 (2.6). The Cronbachs alphas of the KOOS subscales were: Pain 0.91, Symptoms 0.75, Activities of Daily Living 0.96, Function in Sport and Recreation 0.86 and Knee-related Quality of Life 0.74. Spearmans rank correlations between the subscales of the KOOS and representative subscales of the SF-36 ranged from 0.40 to 0.79. CONCLUSION This study illustrates the validity and reliability of the KOOS in measuring the functional status and quality of life of athletes after ACL reconstruction. This study further validates the use of the KOOS in highly competitive athletes in research on knee injuries.

Effect of Dual-Tasking on Postural Control in Subjects With Nonspecific Low Back Pain

Study Design. Three factors mixed-design with 1 between-subject and 2 within-subject factors. Objective. To compare the main effects and interactions of postural and cognitive difficulty on quiet stance between subjects with and without nonspecific low back pain (LBP). Summary of Background Data. The interference between postural control and cognitive tasks depends on factors such as sensorimotor/cognitive integrity. Changes in peripheral sensory and muscular systems as well as cognitive processes have been observed in LBP patients. It was hypothesized that the effect of cognitive task on postural performance might be different in subjects with nonspecific LBP as compared with healthy individuals. To the authors’ knowledge this has not been investigated before. Methods. Postural stability was measured by center of pressure parameters while nonspecific LBP (n = 22) and healthy (n = 22) subjects randomly performed quiet standing task with 3 levels of difficulty (rigid-surface eyes open, rigid-surface eyes-closed, and foam-surface eyes-closed) in isolation or concurrently with an easy or difficult digits backward cognitive task. Results. Subjects with nonspecific LBP had less postural sway than healthy subjects, while postural sway decreased with increase in the level of cognitive difficulty. Nonspecific LBP and healthy subjects had larger postural sway at more difficult sensory conditions such as rigid-surface eyes-closed and foam-surface eyes-closed. The response to dual-tasking was not significantly different between the 2 groups. Conclusion. The dual-tasking did not change the postural performance of nonspecific LBP subjects with low level of pain and disability differently compared to healthy subjects.

Effects of lifestyle and work-related physical activity on the degree of lumbar lordosis and chronic low back pain in a middle east population

The relationship between the degree of lumbar lordosis and chronic low back pain (LBP) has long been speculated. It is postulated that prolonged sitting and sedentary lifestyle might change the degree of lumbar lordosis and cause LBP. The purpose of this study was to determine the effects of lifestyle, exercise, work setting, work intensity, and other demographic factors such as age, height, weight, and gender on the degree of lumbar lordosis and occurrence of LBP. Eight hundred forty subjects between ages 20 and 65 years were equally categorized into four groups: normal male, normal female, males with LBP, and females with LBP. A questionnaire was used to obtain information about the subjects lifestyle, work setting, level of exercise, and work-related physical activity. A flexible ruler was used to measure lumbar lordosis in all subjects. The average degree of lumbar lordosis for all subjects was 37 degrees +/- 13 degrees. Females had greater lumbar lordosis (42 degrees +/- 15 degrees ) than males did (32 degrees +/- 10 degrees ). There was no significant difference in the degree of lumbar lordosis in subjects with different lifestyle (p = 0.97), level of physical activity (p = 0.36), work setting (p = 0.5), and with or without LBP (p = 0.28). The degree of lumbar lordosis was positively related with the number of pregnancies (p = 0.04, r = 0.25), age (p = 0.02, r = 0.1) and height (p = 0.0001, r = 0.31) and negatively related with weight (p = 0.04, r = 0.06) of the subjects. The likelihood of developing LBP was significantly higher in the subjects who had high work-related physical activity (p = 0.03) and those who exercised less often (p = 0.008). We found no significant relationship between LBP occurrence and the degree of lumbar lordosis (p = 0.68), work setting (p = 0.15), height (p = 0.08), weight (p =0.06), and age (p = 0.67) of the subjects. The degree of lumbar lordosis was not different between normal subjects and those with LBP. Lumbar lordosis was not affected by lifestyle, level of physical activity, or type of work setting. Although these factors have not been found to affect the degree of lumbar lordosis, some affected the occurrence of LBP. This finding indicates that the effect of these factors on LBP involves mechanisms other than changing the degree of lumbar lordosis.

Sensitivity, specificity and predictive value of the clinical trunk muscle endurance tests in low back pain

Objective: To describe the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of five clinical tests used to measure trunk muscle endurance in low back pain. Design: A cross-sectional non-experimental design. Setting: Orthopaedic and physical therapy departments of four hospitals and outpatient physical therapy clinics, Tehran, Iran. Subjects: Convenience sample of 200 subjects participated in this study. Subjects were categorized into four groups: men without low back pain (N = 50, mean (SD) age = 38 (12) years), women without low back pain (N = 50, mean (SD) age = 43 (11) years), men with low back pain (N = 50, mean (SD) age = 39 (12) years) and women with low back pain (N = 50, mean (SD) age = 43 (12) years). Main measures: Five clinical static endurance tests of trunk muscles such as: Sorensen test, prone isometric chest raise test, prone double straight-leg raise test, supine isometric chest raise test and supine double straight-leg raise test were measured in each group. Results: The result of receiver operating characteristics (ROC) curve analysis revealed that in a separate analysis of data for men and women, among all tests, the prone double straight-leg raise test had the highest sensitivity, specificity and predictive value in low back pain compared with other performed tests. Conclusions: It seems that the prone double straight-leg raise test has more sensitivity, specificity and predictive value in low back pain than other tests and could be used as a useful clinical method for testing the spinal muscle endurance to predict the probability of the occurrence of low back pain.

The effects of cognitive loading on balance control in patients with multiple sclerosis

The aim of this study was to compare the effects of concurrent cognitive task (silent backward counting) on balance performance between two groups of multiple sclerosis (MS) (n=23) and healthy (n=23) participates. Three levels of postural difficulty were studied on a force platform, i.e. rigid surface with eyes open, rigid surface with eyes closed, and foam surface with eyes closed. A mixed model analysis of variance showed that under difficult sensory condition of foam surface with eyes closed, execution of concurrent cognitive task caused a significant decrement in variability of sway velocity in anteroposterior direction for the patient group (P<0.01) while this was not the case for healthy participants (P=0.22). Also, the variability of sway velocity in mediolateral direction was significantly decreased during concurrent execution of cognitive task in patient group (P<0.01) and not in healthy participants (P=0.39). Furthermore, in contrast to single tasking, dual tasking had the ability to discriminate between the 2 groups in all conditions of postural difficulty. In conclusion, findings of variability in sway velocity seem to confirm the different response to cognitive loading between two groups of MS and healthy participants.

Reliability and validity of the Persian version of Foot and Ankle Ability Measure (FAAM) to measure functional limitations in patients with foot and ankle disorders

OBJECTIVE To translate the Foot and Ankle Ability Measure (FAAM) into Persian and to evaluate the psychometric properties of the Persian version of FAAM. METHODS 93 patients with a range of foot and ankle disorders, completed the Persian version of the FAAM and Short-Form 36 Health Survey (SF-36) in the test session. With an interval of 2-6 days, 60 patients filled out the FAAM in the retest session. The FAAM is composed of two subscales including activities of daily living (ADL) and SPORTS. Internal consistency was assessed using Cronbachs alpha, test-retest reliability using intraclass correlation coefficient (ICC) and standard error of measurement (s.e.m.), item internal consistency and discriminant validity using Spearmans correlation coefficient and construct validity using Spearmans correlation coefficient and Independent t-test. RESULTS Cronbachs alpha coefficient of 0.97 and 0.94 was obtained for ADL and SPORTS subscales, respectively. The ICC and s.e.m. were 0.98 and 3.13 for ADL and 0.98 and 3.53 for SPORTS subscale. Items were stronger measures of their hypothesized subscale than of other subscale. The ADL and SPORTS subscales had stronger correlation with SF-36 physical function (r=0.60, 0.53) and physical health summary measure (r=0.61, 0.48) than with SF-36 mental health (r=0.21, 0.10) and mental health summary measure (r=0.36, 0.27). A high correlation was found between FAAM scores and global scale of functional status for SPORTS (r=0.73) but not for ADL (r=0.42). FAAM scores were greater in individuals who rated their function as normal or nearly normal compared with those who rated as abnormal or severely abnormal for SPORTS (P=0.04) but not for ADL (P=0.15). CONCLUSION The Persian version of FAAM is a reliable and valid measure to quantify physical functioning in patients with foot and ankle disorders.

The effects of dual-tasking on postural control in people with unilateral anterior cruciate ligament injury

Several studies have investigated postural control in anterior cruciate ligament (ACL) deficient patients; yet the contribution of cognitive processing (attention) in the postural control of these patients is still unclear. A dual-task design was used to determine the effects of a concurrent digit span memory task on standing balance in a group of ACL patients (n=27) compared with a group of matched, healthy participants (n=27). In double limb stance, three levels of postural difficulty were studies on a force platform (rigid surface with eyes open, rigid surface with eyes closed, and foam surface with eyes closed). There were three cognitive conditions (no cognitive task, easy cognitive task and difficult cognitive task). For double limb stance, a mixed model analysis of variance showed that in the presence of a cognitive task, postural control was compromised yet there was no interaction between cognitive task difficulty and group (ACL or control). For single limb stance, the more difficult cognitive tasks were associated with lower standard deviations for velocity in the antero-posterior direction and the phase plane portraits. This cognitive task did not appear to compromise postural control in ACL injured patients to a greater extent than unimpaired people. Future studies should examine ACL patients with more severe disabilities and expose them to more demanding dynamic balance conditions to further explore dual-tasking effects.

Postural sway in low back pain: Effects of dual tasks

Recurrence quantification analysis (RQA), a nonlinear method of postural analysis, was used to explore the effects of dual-tasking on postural performance in people with nonspecific low back pain (LBP) compared with healthy participants. Postural performance was quantified by RQA % recurrence, % determinism, entropy and trend. People with nonspecific LBP (n=22) and unimpaired individuals (n=22) randomly performed quiet standing tasks with three levels of difficulty (rigid-surface eyes open, rigid-surface eyes closed and foam-surface eyes closed). These tasks were performed in isolation or concurrently with an easy or difficult cognitive task. Increasing postural difficulty was associated with higher % determinism, higher entropy and lower trend in anteroposterior (AP) and mediolateral (ML) directions in people with LBP and healthy participants. All RQA variables in the ML direction decreased as cognitive conditions became more difficult. Significant interactions between group and cognitive difficulty were shown for % recurrence, % determinism and trend in the AP direction. While healthy participants decreased % recurrence and trend by increasing the level of cognitive difficulty, the LBP patients did not. This preliminary study suggests that LBP may be one factor that modulates the posture-cognition interaction.