Arm position during daily activity.
ABSTRACT A new method of evaluation for functional assessment of the shoulder during daily activity is presented. An ambulatory system using inertial sensors attached on the humerus was used to detect the ability to work at a specific position of the shoulder. Nine arm positions were defined based on humerus elevation. The method was tested on 31 healthy volunteer subjects. First, we estimated the ability of the system to detect the different elevation angles and arm positions of each subject. Following that, we evaluated their arm positions during approximately 8h of daily activities. Each arm position was recognized with a good sensitivity (range 80-100%) and specificity (range 96-99%). During daily activity, we estimated the frequency (number/h) that the humerus reached each arm position during the periods of 0-1s (period P1), 1-5s (period P2) and 5-30s (period P3). Our data showed that all subjects had 96% of their arm position reached under the 5th level (100-120 degrees ). No significant difference was observed between dominant and non-dominant sides for the frequency and duration of arm positions (p>0.3). Our evaluation was in accordance with the clinical questionnaire (the Constant score) for the P1 duration, but differed for longer periods P2 and P3. By quantifying the arm positions and their durations for both shoulders, we proposed a new score to evaluate the ability to work at a specific level based on the symmetry index of the arms activity. Using this score, we obtained, on average, good symmetry for healthy subjects. This score can be useful in evaluating the asymmetry in arm function in patients with a shoulder disease. The proposed technique could be used in a number of shoulder diseases where problems in performing daily activities should be expressed in terms of objective measure of arm position.
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Conference Paper: Self-adaptive games for rehabilitation at home[Show abstract] [Hide abstract]
ABSTRACT: Computer games are a promising tool to support rehabilitation at home. It is widely recognized that rehabilitation games should (i) be nicely integrated in general-purpose rehabilitation stations, (ii) adhere to the constraints posed by the clinical protocols, (iii) involve movements that are functional to reach the rehabilitation goal, and (iv) adapt to the patients' current status and progress. However, the vast majority of existing rehabilitation games are stand-alone applications (not integrated in a patient station), that rarely adapt to the patients' condition. In this paper, we present the first prototype of the patient rehabilitation station we developed that integrates video games for rehabilitation with methods of computational intelligence both for on-line monitoring the movements' execution during the games and for adapting the gameplay to the patients' status. The station employs a fuzzy system to monitor the exercises execution, on-line, according to the clinical constraints defined by the therapist at configuration time, and to provide direct feedback to the patients. At the same time, it applies real-time adaptation (using the Quest Bayesian adaptive approach) to modify the gameplay according both (i) to the patient current performance and progress and (ii) to the exercise plan specified by the therapist. Finally, we present one of the games available in our patient stations (designed in tight cooperation with therapists) that integrates monitoring functionalities with in-game self-adaptation to provide the best support possible to patients during their routine.Computational Intelligence and Games (CIG), 2012 IEEE Conference on; 01/2012
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ABSTRACT: For all segments and tests, a modified Kalman filter and a quasi-static sensor fusion algorithm were equally accurate (precision and accuracy ∼2–3◦) compared to normalized least mean squares filtering, recursive least-squares filtering and standard Kalman filtering. The aims were to: (1) compare adaptive filtering techniques used for sensor fusion and (2) evaluate the precision and accuracy for a chosen adaptive filter. Motion sensors (based on inertial measurement units) are limited by accumulative integration errors arising from sensor bias. This drift can partly be handled with adaptive filtering techniques. To advance the measurement technique in this area, a new modified Kalman filter is developed. Differences in accuracy were observed during different tests especially drift in the internal/external rotation angle. This drift can be minimized if the sensors include magnetometers.Measurement Science and Technology 08/2013; 24(8):085703. · 1.35 Impact Factor
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ABSTRACT: The estimation of muscle forces in musculoskeletal shoulder models is still controversial. Two different methods are widely used to solve the indeterminacy of the system: electromyography (EMG)-based methods and stress-based methods. The goal of this work was to evaluate the influence of these two methods on the prediction of muscle forces, glenohumeral load and joint stability after total shoulder arthroplasty. An EMG-based and a stress-based method were implemented into the same musculoskeletal shoulder model. The model replicated the glenohumeral joint after total shoulder arthroplasty. It contained the scapula, the humerus, the joint prosthesis, the rotator cuff muscles supraspinatus, subscapularis and infraspinatus and the middle, anterior and posterior deltoid muscles. A movement of abduction was simulated in the plane of the scapula. The EMG-based method replicated muscular activity of experimentally measured EMG. The stress-based method minimised a cost function based on muscle stresses. We compared muscle forces, joint reaction force, articular contact pressure and translation of the humeral head. The stress-based method predicted a lower force of the rotator cuff muscles. This was partly counter-balanced by a higher force of the middle part of the deltoid muscle. As a consequence, the stress-based method predicted a lower joint load (16% reduced) and a higher superior-inferior translation of the humeral head (increased by 1.2 mm). The EMG-based method has the advantage of replicating the observed cocontraction of stabilising muscles of the rotator cuff. This method is, however, limited to available EMG measurements. The stress-based method has thus an advantage of flexibility, but may overestimate glenohumeral subluxation.Computer Methods in Biomechanics and Biomedical Engineering 04/2014; · 1.79 Impact Factor