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Purpose: The aim of this study was to determine outcomes of total hip replacement (THR) with the Lemania cemented femoral stem., Methods: A total of 78 THR patients were followed and compared to 17 "fit", healthy, elderly and 72 "frail" elderly subjects without THR, using clinical outcome measures and a portable, in-field gait analysis device at five and ten years follow-up., Results: Forty-one patients (53%), mean age 83.4 years, available at ten years follow-up, reported very good to excellent satisfaction. Mean Harris Hip and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were 81.2 and 10.5 points, respectively, with excellent radiological preservation of proximal femur bone stock. Spatial and temporal gait parameters were close to the fit group and better than the frail group., Conclusions: Lemania THR demonstrated very good, stable clinical and radiological results at ten years in an older patient group, comparable to other cemented systems for primary THR. Gait analysis confirmed good walking performance in a real-life environment.

In order to distinguish dysfunctional gait, clinicians require a measure of reference gait parameters for each population. This study provided normative values for widely used parameters in more than 1,400 able-bodied adults over the age of 65. We also measured the foot clearance parameters (i.e., height of the foot above ground during swing phase) that are crucial to understand the complex relationship between gait and falls as well as obstacle negotiation strategies. We used a shoe-worn inertial sensor on each foot and previously validated algorithms to extract the gait parameters during 20 m walking trials in a corridor at a self-selected pace. We investigated the difference of the gait parameters between male and female participants by considering the effect of age and height factors. Besides; we examined the inter-relation of the clearance parameters with the gait speed. The sample size and breadth of gait parameters provided in this study offer a unique reference resource for the researchers.

This study proposes a new robust classifier for sit-to-stand (SiSt) and stand-to-sit (StSt) detection in daily activity. The monitoring system consists of a single inertial sensor placed on the trunk. By using dynamic time warping, the trunk acceleration patterns of SiSt and StSi are classified based on their similarity with specific templates. The classification algorithm is validated with actual data obtained in a real-world environment (five healthy subjects and five chronic pain patients); the best accuracy is obtained through using a custom template defined for each subject ( > 95% for healthy subjects and 89% for chronic pain). Real-world examinations are found to be preferable because after validating results collected in both real-world and laboratory conditions, the controlled conditions' predictions are too optimistic. Finally, the potential of the new method in clinical evaluation is studied in both healthy and frail elderly subjects. Frail elderly participants show a significantly lower rate of postural transitions, longer SiSt duration, and lower SiSt trunk tilt and acceleration compared to healthy elderly subjects. We conclude that the proposed wearable system provides a simple method to detect and characterize postural transitions in healthy, chronic pain, and frail elderly subjects.

In this work we tackled the problem of accurate measurement of internal-external (IE) rotations in the prosthetic knee. We presented a magnetic measurement system to be implanted in the knee prostheses in order to measure IE without soft tissue artifacts. The measurement system consisted of a permanent magnet attached under the tibial plate of the prosthesis and a combination of magnetic sensors in the polyethylene insert. Two different sensor configurations were designed, and five different angle estimators for measurement of IE angles were defined and tested based on several static and dynamic measurements toward a stereophotogrammetry motion capture system. Also a noise analysis was done to see which estimators are less sensitive to measurement noise. One-sensor configuration provided lower power budget with dynamic RMS error of 0.49° and a noise range of ±0.53°. Two-sensor configuration doubles the power consumption but provided slightly lower dynamic RMS error (0.37°) and a noise range of ±0.42°, and offers the possibility of having redundancy in case of damaged sensor., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The purpose of this study was to validate a new interview-administered physical activity questionnaire (Assessment of Physical Activity in Frail Older People; APAFOP) in older people with and without cognitive impairment. The authors assessed feasibility, validity, and test-retest reliability in 168 people (n = 78 with, n = 88 without cognitive impairment). Concurrent validity was assessed against an inertia-based motion sensor and an established questionnaire. Sensitivity to change was tested in an ongoing study in patients with mild to moderate dementia (n = 81). Assessment of physical activity by the APAFOP and the motion sensor correlated well in the total sample (TS; p = .705), as well as in the subsamples with cognitive impairment (CI; p = .585) and without CI (p = .787). Excellent feasibility with an acceptance rate of 100%, test-retest reliability (intraclass correlation coefficients ranging from .973 (TS) to .975 (CI) to .966 (no CI), and sensitivity to change (effect sizes: 0.35-1.47) were found in both subsamples.

Multiple motor function and strength assessment tools exist for the evaluation of neuromuscular diseases, but most do not directly assess functional ability in the patients' daily physical activity in their home environment. In this study our aim was to assess: 1) the feasibility and accuracy of physical activity monitoring during two days in a home environment of five DMD patients using a non-commercialized monitor containing a 3D accelerometer and a gyroscope, 2) if a difference in the physical activity parameters could be measured before and one month after starting prednisolone. We reliably quantified the time spend sitting, standing, lying, walking, the number of steps taken, the cadence, the number of walking episodes and their duration as well as how these were distributed over the day. Parameters possibly reflecting endurance, such as the duration of the walking episodes or the succession of two or three walking episodes lasting more than 30 s were the most improved after prednisolone treatment. This degree of detailed determination of physical activity in a home environment has not been previously reported in neuromuscular disorders to our knowledge and some of the reported parameters are potential new outcome measures in clinical trials., (© 2010 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Background and Aims: Falls efficacy has been shown to predict functional decline, but whether it is independently associated with frailty is still unclear. This study investigated the cross-sectional association between falls efficacy and the frailty phenotype in high-functioning older persons., Methods: Subjects (n=861) were a sub-sample of community-dwelling persons aged 65 to 70 years enrolled in the "Lc65+" cohort, who had gait assessment. Data included demographics, functional, cognitive, affective and health status, as well as measures of physical performance. Falls efficacy was measured with the Falls Efficacy Scale-International (FES-I) and frailty with Fried's criteria. Participants were categorized into robust (no frailty criterion) and vulnerable (1 or more criteria). Low falls efficacy was defined as a FES-I score in the lowest quartile., Results: Overall, 23.9% of participants were vulnerable. Compared with robust participants, they were more likely to report low falls efficacy (43.3% vs 19.1%, p<0.001) and had poorer health and functional and mental status. They had slower gait speed (1.07+/-0.18 vs 1.15+/-0.15 m/s, p<0.001) and increased gait speed variability (coefficient of variation 4.10+/-4.03 vs 3.33+/-1.45%, p<0.001), although only 6 participants (0.7%) fulfilled Fried's slow walking criterion. In multivariate analysis, low falls efficacy remained associated with being vulnerable (adjusted OR 1.80, 95% CI 1.19-2.74, p=0.006), independent of comorbidity, functional status, falls history and gait performance., Conclusion: In high-functioning older persons, low falls efficacy was associated with vulnerability, even after controlling for gait performance and falls history. Whether low falls efficacy is a potential target on the pathway leading to frailty should be further examined prospectively.

Timed Up and Go (TUG) test is a widely used clinical paradigm to evaluate balance and mobility. Although TUG includes several complex subcomponents, namely: sit-to-stand, gait, 180 degree turn, and turn-to-sit; the only outcome is the total time to perform the task. We have proposed an instrumented TUG, called iTUG, using portable inertial sensors to improve TUG in several ways: automatic detection and separation of subcomponents, detailed analysis of each one of them and a higher sensitivity than TUG. Twelve subjects in early stages of Parkinson's disease (PD) and 12 age matched control subjects were enrolled. Stopwatch measurements did not show a significant difference between the two groups. The iTUG, however, showed a significant difference in cadence between early PD and control subjects (111.1 +/- 6.2 versus 120.4 +/- 7.6 step/min, p < 0.006) as well as in angular velocity of arm-swing (123 +/- 32.0 versus 174.0+/-50.4 degrees/s, p < 0.005), turning duration (2.18 +/- 0.43 versus 1.79 +/- 0.27 s, p < 0.023), and time to perform turn-to-sits (2.96 +/- 0.68 versus 2.40 +/- 0.33 s, p < 0.023). By repeating the tests for a second time, the test-retest reliability of iTUG was also evaluated. Among the subcomponents of iTUG, gait, turning, and turn-to-sit were the most reliable and sit-to-stand was the least reliable.

Objective: To investigate the association between fear of falling and gait performance in well-functioning older persons., Design: Survey., Setting: Community., Participants: Subjects (N=860, aged 65-70y) were a subsample of participants enrolled in a cohort study who underwent gait measurements., Interventions: Not applicable., Main Outcome Measures: Fear of falling and its severity were assessed by 2 questions about fear and related activity restriction. Gait performance, including gait variability, was measured using body-fixed sensors., Results: Overall, 29.6% (210/860) of the participants reported fear of falling, with 5.2% (45/860) reporting activity restriction. Fear of falling was associated with reduced gait performance, including increased gait variability. A gradient in gait performance was observed from participants without fear to those reporting fear without activity restriction and those reporting both fear and activity restriction. For instance, stride velocity decreased from 1.15+/-.15 to 1.11+/-.17 to 1.00+/-.19 m/s (P<.001) in participants without fear, with fear but no activity restriction and with fear and activity restriction, respectively. In multivariate analysis, fear of falling with activity restriction remained associated with reduced gait performance, independent of sex, comorbidity, functional status, falls history, and depressive symptoms., Conclusions: In these well-functioning older people, those reporting fear of falling with activity restriction had reduced gait performance and increased gait variability, independent of health and functional status. These relationships suggest that early interventions targeting fear of falling might potentially help to prevent its adverse consequences on mobility and function in similar populations., (Copyright 2010 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

The beneficial effect of physical exercise on bone mineral density (BMD) is at least partly explained by the forces exerted directly on the bones. Male runners present generally higher BMD than sedentary individuals. We postulated that the proximal tibia BMD is related to the running distance, as well as to the magnitude of the shocks (while running) in male runners. A prospective study (three yearly measurements) included 81 healthy male subjects: 16 sedentary lean subjects, and 3 groups of runners (5-30 km/wk, n = 19; 30-50 km/wk, n = 29; 50-100 km/wk, n = 17). Several measurements were performed at the proximal tibia level: volumetric BMD (vBMD) and cortical index (CI), i.e., an index of cortical bone thickness and peak accelerations (an index of shocks during heel strike) while running (measured by a three-dimensional accelerometer). A general linear model assessed the prediction of vBMD or CI by 1) simple effects (running distance, peak accelerations, time); and 2) interactions (for instance, if vBMD prediction by peak acceleration depends on running distance). CI and vBMD 1) increase with running distance to reach a plateau over 30 km/wk; and 2) are positively associated with peak accelerations over 30 km/wk. Running may be associated with high peak accelerations to have beneficial effects on BMD. More important strains are needed to be associated with the same increase in BMD during running sessions of short duration than those of long duration. CI and vBMD are associated with the magnitude of the shocks during heel strike in runners.

The purpose of the study was to investigate whether a 24-hr recording period is sufficient to describe physical activity (PA) of 1 week for intraindividual comparison in older adults. Furthermore, the authors analyzed whether physical performance can be used as a surrogate marker of PA. PA was captured on 7 consecutive days by a body-fixed sensor in 44 community-dwelling older adults (80.75 +/- 4.05 yr). Mean times of walking and of "time on feet" of the group were 10.2 hr (+/- 3.5) and 35.1 hr (+/- 9.43), respectively. Intraindividual variabilities of walking and of time on feet were 31.9% +/- 10.79% and 19.4% +/- 8.76%, respectively. Accumulated time of variables of PA showed no differences between weekdays, with variabilities of 3.8% and 1.8% for walking and time on feet, respectively. Association between Short Physical Performance Battery and PA was limited (walking r = .397, time on feet r = .41).

Changes in turning are one of the early motor deficiencies in Parkinson's Disease (PD). We have proposed a system based on wearable, inertial sensors and a novel automatic analysis algorithm that can assess 180 degrees turns. Twelve patients in early stages of PD and 14 age-matched healthy subjects were enrolled in this study. Inertial sensors were attached on shanks and sternum. Measurement protocol included walking on a straight pathway, turning 180 degrees and returning back. Subjects were measured 4 times, once every 6 months during an 18 months period. At the baseline, 9 subjects from each group repeated the test twice to assess test-retest reliability. Patients with mild PD had a very low Postural Instability Gait Difficulty (PIGD subscore of UPDRS III) score (average 0.67, min 0, max 3). The analysis showed that the patients had a significantly longer turning duration (2.18+/-0.43 vs. 1.79+/-0.27 seconds, p<0.02) and longer delay in their last step before initiating a turn (0.56+/-0.04 vs. 0.52+/-0.04 seconds, p<0.03). Estimated turning duration and other metrics had a high test-retest reliability (rho>0.85). Turning duration also showed a significant Group *Time interaction (p<0.03) during the longitudinal study highlighting early signs of the progression of the disease.

A major challenge for researchers and clinicians who address health issues in the ageing population is to monitor functioning, and to timely initiate interventions that aim to prevent loss of functional abilities and to improve the quality of life of older people. With the progress of technologies in the last decades, methods have become available that use body fixed sensors (BFS) to measure aspects of human performance under real-life conditions. These methods are based on the use of miniaturised and integrated sensors in combination with lightweight, small measuring devices that both can be carried on the body without interfering with normal behaviour. This paper addresses the potential relevance of new technology for monitoring motor function in older people, thereby specifically focusing on mobility assessment. After a short introduction with background information about BFS based technology, this paper identifies areas of particular relevance, and discusses the application of ambulatory techniques for long-term monitoring of daily physical activity, fall detectors, fall risk evaluation, and assessment of motor performance such as gait and balance control. Examples are given how these techniques can become clinically relevant, particularly in the context of fall interventions for older people.

Many studies have shown the efficacy of orientation and three-dimensional joint angle measurement for patient evaluation or rehabilitation purposes. But currently, the use of these systems for routine practice is questionable. The commercially available devices are generally too expensive and complicated-to-use. This study proposed the fusion between two affordable types of orientation measuring systems, which used separately couldn't satisfy the health professionals' needs. One was a portable magnetic tracker limited in accuracy, sampling frequency and possibly distorted. The other was triplets of gyroscopes limited by their bias, which generates orientation drift after integration. The fusion algorithm presented here relay on two cascaded complementary Kalman filters to estimate the bias of the gyroscopes and to provide accurate and high frequency orientation even during distortion periods. This system was assessed during treadmill walking and reported good performances.

The objective of this study was to objectively assess the physical activity of daily living in chronic pain patients treated with spinal cord stimulation (SCS). Changes in pain and spontaneous physical activity following SCS were evaluated under real life conditions. Five series of measurements were performed before the implant (baseline) and at one, three, six, and 12 months after the implantation of an SCS system. Compared to baseline values, physical activity increased consistently during the entire follow-up period. The time spent walking and standing was statistically increased after six months (p < 0.01) and the time spent lying decreased significantly (p < 0.001) at the same time. The average total walking distance increased up to 389% at 12 months, reaching statistical significance (p < 0.05) after three months. The stride length and the speed increased (p < 0.01) at all times. We conclude that the reduction in pain intensity due to SCS is associated with a progressive and sustained improvement in physical activity. j.

A new method of physical activity monitoring is presented, which is able to detect body postures (sitting, standing, and lying) and periods of walking in elderly persons using only one kinematic sensor attached to the chest. The wavelet transform, in conjunction with a simple kinematics model, was used to detect different postural transitions (PTs) and walking periods during daily physical activity. To evaluate the system, three studies were performed. The method was first tested on 11 community-dwelling elderly subjects in a gait laboratory where an optical motion system (Vicon) was used as a reference system. In the second study, the system was tested for classifying PTs (i.e., lying-to-sitting, sitting-to-lying, and turning the body in bed) in 24 hospitalized elderly persons. Finally, in a third study monitoring was performed on nine elderly persons for 45-60 min during their daily physical activity. Moreover, the possibility-to-perform long-term monitoring over 12 h has been shown. The first study revealed a close concordance between the ambulatory and reference systems. Overall, subjects performed 349 PTs during this study. Compared with the reference system, the ambulatory system had an overall sensitivity of 99% for detection of the different PTs. Sensitivities and specificities were 93% and 82% in sit-to-stand, and 82% and 94% in stand-to-sit, respectively. In both first and second studies, the ambulatory system also showed a very high accuracy (> 99%) in identifying the 62 transfers or rolling out of bed, as well as 144 different posture changes to the back, ventral, right and left sides. Relatively high sensitivity (> 90%) was obtained for the classification of usual physical activities in the third study in comparison with visual observation. Sensitivities and specificities were, respectively, 90.2% and 93.4% in sitting, 92.2% and 92.1% in "standing + walking," and, finally, 98.4% and 99.7% in lying. Overall detection errors (as percent of range) were 3.9% for "standing + walking," 4.1% for sitting, and 0.3% for lying. Finally, overall symmetric mean average errors were 12% for "standing + walking," 8.2% for sitting, and 1.3% for lying.

A new method of evaluating the characteristics of postural transition (PT) and their correlation with falling risk in elderly people is described. The time of sit-to-stand and stand-to-sit transitions and their duration were measured using a miniature gyroscope attached to the chest and a portable recorder placed on the waist. Based on a simple model and the discrete wavelet transform, three parameters related to the PT were measured, namely, the average and standard deviation of transition duration and the occurrence of abnormal successive transitions (number of attempts to have a successful transition). The comparison between two groups of elderly subjects (with high and low fall-risk) showed that the computed parameters were significantly correlated with the falling risk as determined by the record of falls during the previous year, balance and gait disorders (Tinetti score), visual disorders, and cognitive and depressive disorders (p < 0.01). In this study, the wavelet transform has provided a powerful technique for enhancing the pattern of PT, which was mainly concentrated into the frequency range of 0.04-0.68 Hz. The system is especially adapted for long-term ambulatory monitoring of elderly people.

In this study we describe an ambulatory system for estimation of spatio-temporal parameters during long periods of walking. This original method based on wavelet analysis is proposed to compute the values of temporal gait parameters from the angular velocity of lower limbs. Based on a mechanical model, the medio-lateral rotation of the lower limbs during stance and swing, the stride length and velocity are estimated by integration of the angular velocity. Measurement's accuracy was assessed using as a criterion standard the information provided by foot pressure sensors. To assess the accuracy of the method on a broad range of performance for each gait parameter, we gathered data from young and elderly subjects. No significant error was observed for toe-off detection, while a slight systematic delay (10 ms on average) existed between heelstrike obtained from gyroscopes and footswitch. There was no significant difference between actual spatial parameters (stride length and velocity) and their estimated values. Errors for velocity and stride length estimations were 0.06 m/s and 0.07 m, respectively. This system is light, portable, inexpensive and does not provoke any discomfort to subjects. It can be carried for long periods of time, thus providing new longitudinal information such as stride-to-stride variability of gait. Several clinical applications can be proposed such as outcome evaluation after total knee or hip replacement, external prosthesis adjustment for amputees, monitoring of rehabilitation progress, gait analysis in neurological diseases, and fall risk estimation in elderly.