Band 3, Heft 1

Abstract: Coping strategies of patients with obstetric brachial plexus palsy (OBPP) are highly individual. Up to now, individual movement performance is assessed by visual observations of physicians or therapists - a procedure, which is highly subjective and lacks objective data. However, objective data about the individual movement performance are the key to evidence-based and individualized treatment. In this paper, a new approach is presented, which provides objective information about the upper extremity movement performance of patients with OBPP. The approach is based on the use of accelerometers in combination with a classification procedure. The movement performance of 10 healthy volunteers and 41 patients with OBPP has been evaluated by experienced physiotherapists and has been assigned to one of 4 categories representing the Mallet Scale (MS) IV to I. Three triaxial-accelerometers were placed at chest, upper arm and wrist of the affected side of the patient. Acceleration signals have been recorded during repetitive movements with relevance regarding daily life. Here, especially the results from the “hand to mouth” task are presented. From the 9 recorded acceleration signals 13 relevant features were extracted. For each of the 13 features 4 thresholds have been determined distinguishing best between the 4 patient categories of the MS and the healthy subjects. With respect to the thresholds each feature value has been assigned to the discrete numbers 0, 1, 2, 3 or 4. Afterwards, each discrete number has been weighted by a factor regarding the correlation between the feature’s value and the MS score. The resulting weighted discrete numbers of all 13 features have been added resulting in a score, which quantifies the individual upper extremity movement performance. Based on this score the movement performance of each patient has been assigned to the classes “very good”, “good”, “regular” and “bad”. All movements of the 10 healthy volunteers were classified as “very good”. The movement performance of two patients MS IV were classified as “very good” as well and the movements of the other 16 patients as “good”. The movements of the entire group of MS III patients fell into the class “regular”. Just one MS II patient was assigned to the class “regular” while the others were classified as “bad”. It was not possible to classify the movements of MS I patients. This was mainly due to the fact that none of these patients MS I was able to complete the task successfully. The developed approach demonstrated its ability to quantify the movement performance of upper extremity movements based on accelerometers. This provides an easy to use tool to assess patient’s movement strategies during daily tasks for diagnosis and rehabilitation.

Abstract: This paper presents an analysis of two distinct human lifting movements regarding acceleration and angular velocity. For the first movement, the ergonomic one, the test persons produced the lifting power by squatting down, bending at the hips and knees only. Whereas performing the unergonomic one they bent forward lifting the box mainly with their backs. The measurements were taken by using a vest equipped with five Inertial Measurement Units (IMU) with 9 Dimensions of Freedom (DOF) each. In the following the IMU data captured for these two movements will be evaluated using statistics and visualized. It will also be discussed with respect to their suitability as features for further machine learning classifications. The reason for observing these movements is that occupational diseases of the musculoskeletal system lead to a reduction of the workers’ quality of life and extra costs for companies. Therefore, a vest, called CareJack, was designed to give the worker a real-time feedback about his ergonomic state while working. The CareJack is an approach to reduce the risk of spinal and back diseases. This paper will also present the idea behind it as well as its main components.

Abstract: Efficient dynamic balancing and movement coordination during walking are essential for stability. The objective of this preliminary study was to assess dynamic balancing responses in a selected post-stroke subject and to compare them with those assessed in neurologically intact individual. Balance Assessment Robot, a haptic robot that interfaces to a pelvis of a subject walking on an instrumented treadmill, was used to deliver perturbing pushes to the pelvis. We have assessed centre-of-pressure (CoP) and horizontal components of ground reaction forces (GRF) following outward pushes. The results have shown that depending on the amplitude of a perturbing push neurologically intact individual responded predominantly by “ankle” and “hip” strategies at lower amplitude of perturbation and “ankle” and “stepping” strategies at higher amplitude of perturbation. Post-stroke subject responded mainly by “ankle” and “hip” strategies when perturbed on the sound leg while the response when perturbed on the impaired leg was similar to the one observed in healthy subject. These preliminary results indicate that post-stroke subjects might be reluctant or not able to perform “cross step” with their impaired leg which is needed when counteracting outward perturbation.

Abstract: The amputee’s well-being and mobility are distinclty related to socket fit and resulting biomechanical interaction between residual limb and prosthetic socket. Understanding the dynamic interactions at the interface may lead to new socket standards. This paper introduces a physically-motivated reduced model of the interface, describing the dynamic interactions between residual limb and prosthetic socket. The model allows to investigate the sensitivity to changes of specific parameters in an isolated matter. A simulation study shows how stress distribution changes if friction coefficients are varied which might advance liner design.

Abstract: The assessment of hand posture and kinematics is increasingly important in various fields. This includes the rehabilitation of stroke survivors with restricted hand function. This paper presents a modular, ambulatory measurement system for the assement of the remaining hand function and for closed-loop controlled therapy. The device is based on inertial sensors and utilizes up to five interchangeable sensor strips to achieve modularity and to simplify the sensor attachment. We introduce the modular hardware design and describe algorithms used to calculate the joint angles. Measurements with two experimental setups demonstrate the feasibility and the potential of such a tracking device.

Abstract: Functional electrical stimulation (FES) therapies have shown effectiveness in restoring movement post-stroke, especially when applied functionally to assist participants’ voluntary intention during repeated, motivating tasks. Recent development in non-contact sensors allows feedback to advanced controllers that precisely adjust FES via an electrode array to assist functional reach and grasp tasks. This has given rise to significant reduction in impairment, as measured in clinical trials. This paper describes the recent developments of a compact system suitable for transference to patients’ homes, with the intention of reducing upper-limb impairment following chronic stroke.

Abstract: Motor functions can be hindered in consequence to a stroke or a spinal cord injury. This often results in partial paralyses of the upper limb. The effectiveness of rehabilitation therapy can be improved by the use of rehabilitation robotics and Functional Electrical Stimulation (FES). We consider a hybrid arm weight support combining both. In order to compensate the effect of FES-induced muscle fatigue, we introduce a method to substitute the decreasing level of FES support by cable-driven robotics. We evaluated the approach in a trial with one healthy subject performing repetitive arm lifting. The controller automatically adapted the support and thus no increase in user generated volitional effort was observed when FES induced muscle fatigue occured.

Abstract: Introduction: The lack of knowledge of mechanical loads in orthotic joints can lead to oversized or breaking components. Previous studies suffer from small sample size and technical limitations. The goal of this study was to develop and validate a method that allows the direct measurement of moments in sagittal, frontal and transverse planes in knee and ankle joints of existing custom made orthoses. Methods: We developed a modular measurement system based on standard joint components, which were instrumented with strain gauges. To ensure sufficient signals and reduce cross talk an iterative approach based on FEM simulation was utilized. The system also contains inertial sensors for mobile gait analysis. Results: Instrumented joints show good results regarding linearity, hysteresis and cross talk. First pilot trials with post-polio and ICP patients demonstrated that joint loads depend on several factors and not solely on body weight. If combined with conventional gait analysis, measurement results can characterize the individual muscle situation of the patient. Conclusion: A novel method for obtaining data on loads in orthotic components was developed and validated. It provides the basis to develop safety testing standards and clinical guidelines, as well as allowing individual optimization of orthotic devices.

Abstract: Robotic therapy devices have been an important part of clinical neurological rehabilitation for several years. Until now such devices are only available for patients receiving therapy inside rehabilitation hospitals. Since patients should continue rehabilitation training after hospital discharge at home, intelligent robotic rehab devices could help to achieve this goal. This paper presents therapeutic requirements and early phases of the user-centered design process of the patient’s work station as part of a novel robot-based system for motor telerehabilitation.

Abstract: Background and purpose: In patients with pathology of one limb, mirror therapy (MT) uses the mirror reflection of the unaffected side to improve function of the affected limb [1]. There is some evidence that Virtual Reality (VR) can substitute the real mirror [2]. To create a standardised VR based mirror therapy as a self-training, several steps of conceptual considerations are essential. The purpose of this project was to understand the therapeutic action of standardised MT and thus to pave the way for a partially automated VR based MT to be executed as a self-training. Methods: A principle of motor learning, called Shaping, is anchored in two existing standardised MT protocols (BeST & BeSTEP) [3], [4] . To understand the shaping process within MT, shaping items and criteria were extracted from the protocols. Additionally, a questionnaire and participatory observation during MT sessions were performed and standardisation rules by means of documentation sheets of MT units were analysed. Results and conclusion: The knowledge about the shaping process during conventional MT, especially in the BeST phase is currently not sufficient to derive machine learning and therefore to create an automated system at this time. Further conceptual investigations to gather this information are necessary and projected.

Abstract: This paper presents a method to adjust the instantaneous reference speed of the mobile platform or treadmill of robotic gait rehabilitation systems during compliant, synchronized therapy. This method is particularly useful when the robot-patient synchronization algorithms generate compensations that fluctuate significantly throughout the gait cycle, making it unsuitable to apply these compensations directly to the reference speed values. The method was tested with a synchronization algorithm that generates continues temporal-compensations based on a phase controller. The tests comprised simulation of different scenarios and a practical test with a healthy subject using an over-ground gait rehabilitation system.

Abstract: Using eye-tracking to assess visual attention in head-mounted devices (HMD) opens up many possibilities for virtual reality (VR)-based therapy. Existing therapy concepts where attention plays a major role can be transferred to VR. Furthermore, they can be expanded to a precise real-time attention assessment, which can serve as a foundation for new therapy approaches. Utilizing HMDs and eye-tracking in a clinical environment is challenging because of hygiene issues and requirements of patients with heterogeneous cognitive and motor impairments. In this paper, we provide an overview of those challenges, discuss possible solutions and present preliminary results of a study with patients.

Abstract: Robot based therapy is one of the prevalent therapeutic approaches in motor stroke rehabilitation. It is often used in hospitals in combination with conventional therapy. In order to optimize human-robot interaction, we aim to investigate how a therapist physically supports patients during motor training of the upper extremities. This paper presents the design of a flexible textile sensor matrix, which measures the pressure exerted between therapist and patient during direct haptic interaction as well as the hand position and orientation in space. The matrix contains 144 sensors which enables measuring pressure intensity and localization of areas where the pressure is applied. The measurement matrix was evaluated with four healthy participants.

Abstract: The usability of flexible electrodes in moving environment is limited due to different mechanical characteristics of their metallic and polymeric components. To achieve structure compatible electrodes, all used materials need to have similar Young’s moduli as the surrounding tissue. This paper describes the characterization of macroscopic as well as miniaturized electrodes entirely made out of modified silicone (PDMS). Electrochemical, mechanical, biological, optical, and applicative methods were used. It could be shown, that PDMS electrodes are capable to be used for recording electrocardiograms with similar form and amplitude as with standard electrodes.

Abstract: New technologies can be implemented in clinical rehabilitation processes or to close the gap in health care provision by transferring them to the patients’ home. Successful use can only be achieved under the assumption that the technology is accepted by its users. The involvement of users in iterative development processes is to be shown to increase the quality of health care systems and to prevent refusal. In this review potentials of user acceptance and satisfaction surveys in the development of stroke rehabilitation systems are discussed. The surveys are conducted as a method for improving the ongoing design process of innovative technical systems developed in the BMBF funded project “BeMobil”.