Judit Takacs

Validation of the Fitbit One activity monitor device during treadmill walking

OBJECTIVES In order to quantify the effects of physical activity such as walking on chronic disease, accurate measurement of physical activity is needed. The objective of this study was to determine the validity and reliability of a new activity monitor, the Fitbit One, in a population of healthy adults. DESIGN Cross-sectional study. METHODS Thirty healthy adults ambulated at 5 different speeds (0.90, 1.12, 1.33, 1.54, 1.78 m/s) on a treadmill while wearing three Fitbit One activity monitors (two on the hips and one in the pocket). The order of each speed condition was randomized. Fitbit One step count output was compared to observer counts and distance output was compared to the calibrated treadmill output. Two-way repeated measures ANOVA, concordance correlation coefficients, and Bland and Altman plots were used to assess validity and intra-class correlation coefficients (ICC) were used to assess reliability. RESULTS No significant differences were noted between Fitbit One step count outputs and observer counts, and concordance was substantial (0.97-1.00). Inter-device reliability of the step count was high for all walking speeds (ICC ≥ 0.95). Percent relative error was less than 1.3%. The distance output of the Fitbit One activity monitors was significantly different from the criterion values for each monitor at all speeds (P<0.001) and exhibited poor concordance (0.0-0.05). Inter-device reliability was excellent for all treadmill speeds (ICC ≥ 0.90). Percent relative error was high (up to 39.6%). CONCLUSIONS The Fitbit One activity monitors are valid and reliable devices for measuring step counts in healthy young adults. The distance output of the monitors is inaccurate and should be noted with caution.

The effect of contralateral pelvic drop and trunk lean on frontal plane knee biomechanics during single limb standing

Pelvic drop as a result of hip abductor weakness has been hypothesized as a potential modifier of frontal plane knee joint kinetics during gait in individuals with pathology such as knee osteoarthritis (OA). However, hip muscle strengthening interventions have failed to find significant reductions in frontal plane loading measures such as the external knee adduction moment (KAM) with altered hip strength. Since this could in part be due to a lack of change in pelvic kinematics between conditions or test sessions or due to alterations in lateral trunk lean angle, the relationship between pelvic drop and subsequent changes in centre of mass with knee joint loading remains unclear. The purpose of this study was to examine the effect of a consciously altered frontal plane centre of mass position (pelvic drop and trunk lean to the contralateral side) on the KAM during single limb standing. Twenty healthy individuals performed a series of single limb standing trials, where they were asked to balance on their dominant leg. KAM was assessed during single limb stance in two conditions: with pelvis and trunk maintained in a level position, and with contralateral pelvic drop. A third condition involving contralateral pelvic drop and trunk lean was assessed to examine exaggerated changes in centre of mass. The KAM increased significantly with contralateral pelvic drop (p=0.001) and with combined contralateral pelvic drop and trunk lean (p<0.001) compared to the level pelvis trials. These findings suggest that pelvic drop alone can significantly increase KAM magnitude, a risk factor for the progression of knee OA. Assessment of pelvic obliquity prior to treatment may allow those with marked pelvic drop to be targeted for hip muscle strengthening.

Effects of a 10-week toe-out gait modification intervention in people with medial knee osteoarthritis: a pilot, feasibility study

OBJECTIVE To examine the feasibility of a 10-week gait modification program in people with medial tibiofemoral knee osteoarthritis (OA), and to assess changes in clinical and biomechanical outcomes. DESIGN Fifteen people with medial knee OA completed 10 weeks of gait modification focusing on increasing toe-out angle during stance 10° compared to their self-selected angle measured at baseline. In addition to adherence and performance difficulty outcomes, knee joint symptoms (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale and total score, numerical rating scale (NRS) of pain), and knee joint loading during gait (late stance peak knee adduction moment (KAM)) were assessed. RESULTS Participants were able to perform the toe-out gait modification program with minimal to moderate difficulty, and exhibited significant increases in self-selected toe-out angle during walking (P < 0.001). Joint discomfort was reported by five participants (33%) in the hip or knee joints, though none lasted longer than 2 weeks. Participants reported statistically significant reductions in WOMAC pain (P = 0.02), NRS pain (P < 0.001), WOMAC total score (P = 0.02), and late stance KAM (P = 0.04). CONCLUSIONS These preliminary findings suggest that toe-out gait modification is feasible in people with medial compartment knee OA. Preliminary changes in clinical and biomechanical outcomes provide the impetus for conducting larger scale studies of gait modification in people with knee OA to confirm these findings.

Validity and Reliability of the Community Balance and Mobility Scale in Individuals With Knee Osteoarthritis

Background There is a high incidence of falls in older adults with knee osteoarthritis (OA). Adequate dynamic balance and mobility reduce the risk of falls; however, there are currently no validated, advanced tests of dynamic balance and mobility for individuals with knee OA. Objective The purpose of this study was to determine the convergent validity, known-groups validity, and test-retest reliability of a dynamic test of balance and mobility, the Community Balance and Mobility Scale (CB&M), in a knee OA population. Design A cross-sectional design was used. Methods Twenty-five individuals aged 50 years and older with medial knee OA and an equal number of healthy controls completed the CB&M and other tests of balance and mobility, including the Berg Balance Scale, the Timed “Up & Go” Test, a test of maximal single-leg stance time, and the 10-Meter Walk Test (self-selected and fast walking speed). Convergent validity of balance tests with the CB&M was assessed using Pearson product moment correlation coefficients, and known-groups validity was assessed using independent t tests. Test-retest reliability of the CB&M was assessed using intraclass correlation coefficients (ICCs) and standard error of measurement (SEM). Results Scores on the CB&M were significantly correlated with all measures of balance and mobility for those with knee OA. There were significant differences in CB&M scores between groups. Scores on the CB&M were highly reliable in people with knee OA (ICC=.95, 95% confidence interval [95% CI]=0.70 to 0.99; SEM=3, 95% CI=2.68 to 4.67). Limitations Few participants had severe knee OA. Conclusions The CB&M displayed moderate convergent validity, excellent known-groups validity, and high test-retest reliability. The CB&M can be used as a valid and reliable tool to assess dynamic balance and mobility deficits in people with knee OA.

Knee and ankle biomechanics with lateral wedges with and without a custom arch support in those with medial knee osteoarthritis and flat feet

This study compared immediate changes in knee and ankle/subtalar biomechanics with lateral wedge orthotics with and without custom arch support in people with knee osteoarthritis and flat feet. Twenty‐six participants with radiographic evidence of medial knee osteoarthritis (22 females; age 64.0 years [SD 8.0 years], BMI 27.2 kg/m2 [4.2]) and flat feet (median foot posture index = + 5) underwent three‐dimensional gait analysis for three conditions: Control (no orthotic), lateral wedge, and lateral wedge plus arch support. Condition order was randomized. Outcomes included frontal plane knee and ankle/subtalar biomechanics, and comfort. Compared to the control, lateral wedge and lateral wedge with arch support reduced the knee adduction moment impulse by 8% and 6%, respectively (p < 0.05). However, the lateral wedge resulted in a more everted foot position (4.3 degrees) than lateral wedge plus arch support (3.2 degrees) (p < 0.05). In contrast, lateral wedge plus arch support reduced foot frontal plane excursion compared to other conditions (p < 0.05). Participants self‐reported significantly more immediate comfort with lateral wedge plus arch support compared to the control, whereas there was no difference in self‐reported comfort between lateral wedge and control. No immediate changes in knee pain were observed in any condition. Clinical significance: Rather than prescribing lateral wedges to all patients with knee osteoarthritis, those who have medial knee osteoarthritis and flat feet may prefer to use the combined orthotic to reduce loads across the knee, and to minimize the risk of foot and ankle symptoms as a consequence of orthotic treatment.

Comparison of Mirror, Raw Video, and Real-Time Visual Biofeedback for Training Toe-Out Gait in Individuals With Knee Osteoarthritis

OBJECTIVE To compare performance error and perceived difficulty during toe-out gait modification in people with knee osteoarthritis (OA) across 3 different types of visual feedback: mirror, raw video, and real-time biofeedback of toe-out angle. DESIGN Repeated-measures, within-subject trial. SETTING University motion analysis laboratory. PARTICIPANTS Individuals with knee OA (N=20; 11 women; mean age, 65.4±9.8y) participated in this study. Seven participants had mild knee OA, 9 had moderate knee OA, and 4 had severe knee OA. INTERVENTIONS Participants were trained to walk on a treadmill while matching a target indicating a 10° increase in stance phase toe-out compared with toe-out angle measured during self-selected walking. The target was provided visually via the 3 types of feedback listed above and were presented in a random order. MAIN OUTCOME MEASURES Kinematic data were collected and used to calculate the difference between the target angle and the actual performed angle for each condition (toe-out performance error). Difficulty was assessed using a numerical rating scale (0-10) provided verbally by participants. RESULTS Toe-out performance error was significantly less when using the real-time biofeedback method than when using the other 2 methods (P=.025; mean difference vs mirror=2.05°; mean difference vs raw video=1.51°). Perceived difficulty was not statistically different between the groups (P=.51). CONCLUSIONS Although statistically significant, the 2° difference in toe-out gait performance error may not necessitate the large economic and personnel costs of real-time biofeedback as a means to modify movement in clinical or research settings.

Lateral trunk lean gait modification increases the energy cost of treadmill walking in those with knee osteoarthritis.

OBJECTIVE To compare the energy expenditure of increased lateral trunk lean walking - a suggested method of reducing medial compartment knee joint load - compared to normal walking in a population of older adults with medial knee osteoarthritis (OA). METHOD Participants completed two randomly-presented treadmill walking conditions: 15 min of normal walking or walking with ten degrees of peak lateral trunk lean. Lateral trunk lean angle was displayed in front of the participant in real-time during treadmill conditions. Energy expenditure (VO2 and METs), heart rate (HR), peak lateral trunk lean angle, knee pain and perceived exertion were measured and differences between conditions were compared using paired t-tests. RESULTS Twelve participants (five males, mean (standard deviation (SD)) age 64.1 (9.4) years, body mass index (BMI) 28.3 (4.9) kg/m²) participated. All measures were significantly elevated in the lateral trunk lean condition (P < 0.008), except for knee pain (P = 0.22). Oxygen consumption (VO2) was, on average 9.5% (95% CI 4.2-14.7%) higher, and HR was on average 5.3 beats per minute (95% CI 1.7-9.0 bpm) higher during increased lateral trunk lean walking. CONCLUSION Increased lateral trunk lean walking on a treadmill resulted in significantly higher levels of steady-state energy expenditure, HR, and perceived exertion, but no difference in knee pain. While increased lateral trunk lean has been shown to reduce biomechanical measures of joint loading relevant to OA progression, it should be prescribed with caution given the potential increase in energy expenditure experienced when it is employed.

Test re-test reliability of centre of pressure measures during standing balance in individuals with knee osteoarthritis

Assessment of changes in standing balance following an intervention requires accurate measurement of balance parameters. The reliability of centre of pressure measures of balance during single-leg standing has not been reported in individuals with knee osteoarthritis. The purpose of this study was to assess the test re-test reliability of force platform centre of pressure measures during single-leg standing in older adults with knee osteoarthritis. Twenty-five adults with radiographic evidence of knee osteoarthritis performed single-leg standing balance trials on a laboratory-grade force platform on two occasions, no more than 14 days apart. Participants were asked to stand on their more symptomatic limb for three, ten second trials. Centre of pressure measures collected included: standard deviation in the mediolateral and anteroposterior directions, mean path length, velocity, and area. The mean of the three trials was calculated. Intraclass correlation coefficients, standard error of measurement, Bland and Altman plots and the minimum detectable change were calculated. Intraclass correlation coefficients ranged from 0.54 to 0.87, suggesting mixed reliability of measures. Reliability was lowest for the centre of pressure area (intraclass correlation coefficient=0.54), and highest for centre of pressure velocity and path length (intraclass correlation coefficient=0.87 for both). Standard error of measurement values were low for standard deviation in the mediolateral direction and high for centre of pressure area. These results suggest that centre of pressure values, in particular path length and velocity, are appropriate for assessment of standing balance in people with medial knee osteoarthritis.

Factors Associated With Dynamic Balance in People With Knee Osteoarthritis

OBJECTIVE To identify potential neuromuscular factors associated with dynamic balance in individuals with knee osteoarthritis (OA). DESIGN Cross-sectional observational study; backward stepwise multiple linear regression was used to identify factors associated with dynamic balance in 2 statistical models. SETTING University clinical research laboratory. PARTICIPANTS Individuals aged ≥50 years (N=52) with osteoarthritic changes on radiograph participated. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Dynamic balance was assessed using the Community Balance and Mobility Scale (CB&M). Potentially modifiable neuromuscular factors associated with dynamic balance were measured, including the sum of concentric and eccentric lower-extremity muscle strength, 2 quadriceps-hamstrings muscle strength ratios, knee joint proprioception (joint position sense), anticipatory postural control velocity, and knee joint range of motion. RESULTS The first model for explaining variance in CB&M scores consisted of eccentric lower-extremity muscle strength and knee joint range of motion as factors. The model containing these 2 variables explained 50% of the variance in CB&M scores. The second model adjusted for descriptive variables, including age, body mass index, and knee pain, contained only the neuromuscular variables eccentric lower-extremity muscle strength, and explained 68% of the variance in CB&M scores. CONCLUSIONS These results suggest that muscle strength and, to a lesser extent, knee joint range of motion are important factors associated with dynamic balance as measured by the CB&M and should be considered in dynamic balance interventions.

Dynamic Balance Training Improves Physical Function in Individuals With Knee Osteoarthritis: A Pilot Randomized Controlled Trial

OBJECTIVE To examine the effect of a targeted balance training program on dynamic balance and self-reported physical function in people with medial tibiofemoral osteoarthritis (OA). DESIGN Single-blind randomized controlled trial. SETTING Exercise gymnasium and community dwellings. PARTICIPANTS Individuals with medial compartment knee OA (N=40). INTERVENTIONS Ten weeks of partially supervised exercises targeting dynamic balance and strength performed 4 times per week or no intervention (nonintervention group). MAIN OUTCOME MEASURES Dynamic balance was measured using the Community Balance and Mobility Scale (CB&M), and self-reported physical function was measured using the Western Ontario and McMaster Universities Arthritis Index physical function subscale. Secondary outcomes included knee pain, fear of movement, knee joint proprioception, and muscle strength. RESULTS Forty individuals underwent baseline testing, with 36 participants completing follow-up testing. Adherence to exercise in the training group was high, with 82.2% of all home-based exercise sessions completed. No significant changes were observed in any outcome in the nonintervention group at follow-up. Significant improvements in self-reported pain, physical function, and fear of movement were observed in the training group when compared with the nonintervention group. No other within- or between-group differences were observed. CONCLUSIONS A 10-week dynamic balance training program for people with knee OA significantly improved self-reported knee pain, physical function, and fear of movement; however, there was no change in dynamic balance as quantified by the CB&M. Further research is needed to investigate how exercise may result in improvement on objective measures of dynamic balance.