Jasper Reenalda

Objective Evaluation of the Quality of Movement in Daily Life after Stroke

Background Stroke survivors are commonly left with disabilities that impair activities of daily living. The main objective of their rehabilitation program is to maximize the functional performance at home. However, the actual performance of patients in their home environment is unknown. Therefore, objective evaluation of daily life activities of stroke survivors in their physical interaction with the environment is essential for optimal guidance of rehabilitation therapy. Monitoring daily life movements could be very challenging, as it may result in large amounts of data, without any context. Therefore, suitable metrics are necessary to quantify relevant aspects of movement performance during daily life. The objective of this study is to develop data processing methods, which can be used to process movement data into relevant metrics for the evaluation of intra-patient differences in quality of movements in a daily life setting. Methods Based on an iterative requirement process, functional and technical requirements were formulated. These were prioritized resulting in a coherent set of metrics. An activity monitor was developed to give context to captured movement data at home. Finally, the metrics will be demonstrated in two stroke participants during and after their rehabilitation phases. Results By using the final set of metrics, quality of movement can be evaluated in a daily life setting. As example to demonstrate potential of presented methods, data of two stroke patients were successfully analyzed. Differences between in-clinic measurements and measurements during daily life are observed by applying the presented metrics and visualization methods. Heel height profiles show intra-patient differences in height, distance, stride profile, and variability between strides during a 10-m walk test in the clinic and walking at home. Differences in distance and stride profile between both feet were larger at home, than in clinic. For the upper extremities, the participant was able to reach further away from the pelvis and cover a larger area. Discussion Presented methods can be used for the objective evaluation of intra-patient differences in movement quality between in-clinic and daily life measurements. Any observed progression or deterioration of movement quality could be used to decide on continuing, stopping, or adjusting rehabilitation programs.

Analysis of healthy sitting behavior: Interface pressure distribution and subcutaneous tissue oxygenation

Pressure ulcers are a large problem in individuals who use a wheelchair for their mobility and have limited trunk stability and motor function. Because no relation between interface pressure and pressure ulcer development has been established and no clinical threshold for pressure ulcer development can be given, looking at the sitting behavior of nondisabled individuals is important. Nondisabled individuals do not develop pressure ulcers because they continuously shift posture. We analyzed the sitting behavior of 25 nondisabled male subjects by using a combination of interface pressure measurement and subcutaneous tissue oxygenation measurement by means of the Oxygen to See. These subjects shifted posture on average 7.8 +/- 5.2 times an hour. These posture shifts were merely a combination of posture shifts in the frontal and sagittal plane. Subcutaneous oxygen saturation increased on average 2.2% with each posture adjustment, indicating a positive effect of posture shifts on tissue viability. The results of this study can be used as a reference for seating interventions aimed at preventing pressure ulcers. Changing the sitting load at least every 8 minutes is recommended for wheelchair users.

Clinical Use of Interface Pressure to Predict Pressure Ulcer Development: A Systematic Review

ABSTRACT Pressure ulcers are a large problem in subjects who use a wheelchair for their mobility. These ulcers originate beneath the bony prominences of the pelvis and progress outward as a consequence of prolonged pressure. Interface pressure is used clinically to predict and prevent pressure ulcers. However, the relation between interface pressure and the development of pressure ulcers is not clear. A systematic review was performed to address the research question of whether interface pressure can be used to predict the development of pressure ulcers or to determine the prognosis of an ulcer once developed. Seven studies were identified that measured interface pressure and used the development or healing of pressure ulcers as an outcome measure. There appears to be a weak qualitative relation between interface pressure and the development of pressure ulcers. However, no conclusive clinical threshold for the interface pressure can be given. This, combined with the influence of individual characteristics, the low internal validity of interface pressure measurement for the prediction of pressure ulcers, and an incongruent relation between pressure magnitude and duration, results in the fact that no quantification of the predictive or prognostic value of interface pressure can be given.

Effects of sagittal postural adjustments on seat reaction load

Wheelchair-dependent subjects often adopt a passive sitting posture and suffer from sitting acquired pressure ulcers (PU) that mainly occur when high buttock pressures sustain for a longer period of time. Body posture directly influences seating load and proper postural change is therefore essential. Many subjects cannot reposition themselves and seating systems that adjust sitting posture can regulate seating load and potentially diminish the risk to develop PU. We describe a mechanism for postural adjustments and investigated the influence of seat inclination (1), pelvis rotation (2) and chair recline (3) on buttock load. We developed an experimental simulator chair containing the concept to adjust body posture in the sagittal plane. Measurements involved quasi-static actuated chair movements in which chair configuration, buttock interface pressure and seating forces were simultaneously measured. Significant effects with high coefficients of determination (r(2)>0.8) were found for seating force, centre of pressure and sacral load. We conclude that a combination of independent pelvis rotation and seat inclination is effective to regulate the net buttock shear force and the sacral interface pressure in healthy subjects. Whether both techniques are also applicable in subjects without postural stability is still to be evaluated.

Continuous three dimensional analysis of running mechanics during a marathon by means of inertial magnetic measurement units to objectify changes in running mechanics

Recent developments in wearable and wireless sensor technology allow for a continuous three dimensional analysis of running mechanics in the sport specific setting. The present study is the first to demonstrate the possibility of analyzing three dimensional (3D) running mechanics continuously, by means of inertial magnetic measurement units, to objectify changes in mechanics over the course of a marathon. Three well trained male distance runners ran a marathon while equipped with inertial magnetic measurement units on trunk, pelvis, upper legs, lower legs and feet to obtain a 3D view of running mechanics and to asses changes in running mechanics over the course of a marathon. Data were continuously recorded during the entire 42.2km (26.2Miles) of the Marathon. Data from the individual sensors were transmitted wirelessly to a receiver, mounted on the handlebar of an accompanying cyclist. Anatomical calibration was performed using both static and dynamic procedures and sensor orientations were thus converted to body segment orientations by means of transformation matrices obtained from the segment calibration. Joint angle (hip, knee and ankle) trajectories as well as center of mass (COM) trajectory and acceleration were derived from the sensor data after segment calibration. Data were collected and repeated measures one way ANOVA׳s, with Tukey post-hoc test, were used to statistically analyze differences between the defined kinematic parameters (max hip angle, peak knee flexion at mid-stance and at mid-swing, ankle angle at initial contact and COM vertical displacement and acceleration), averaged over 100 strides, between the first and the last stages (8 and 40km) of the marathon. Significant changes in running mechanics were witnessed between the first and the last stage of the marathon. This study showed the possibility of performing a 3D kinematic analysis of the running technique, in the sport specific setting, by using inertial magnetic measurement units. For the three runners analyzed, significant changes were observed in running mechanics over the course of a marathon. The present measurement technique therefore allows for more in-depth study of running mechanics outside the laboratory setting.

Assessment of daily-life reaching performance after stroke

For an optimal guidance of the rehabilitation therapy of stroke patients in an in-home setting, objective, and patient-specific performance assessment of arm movements is needed. In this study, metrics of hand movement relative to the pelvis and the sternum were estimated in 13 stroke subjects using a full body ambulatory movement analysis system, including 17 inertial sensors integrated in a body-worn suit. Results were compared with the level of arm impairment evaluated with the upper extremity part of the Fugl-Meyer Assessment scale (uFMA). Metrics of arm movement performance of the affected side, including size of work area, maximum reaching distance and movement range in vertical direction, were evaluated during a simulated daily-life task. These metrics appeared to strongly correlate with uFMA scores. Using this body-worn sensor system, metrics of the performance of arm movements can easily be measured and evaluated while the subject is ambulating in a simulated daily-life setting. Suggested metrics can be used to objectively assess the performance of the arm movements over a longer period in a daily-life setting. Further development of the body-worn sensing system is needed before it can be unobtrusively used in a daily-life setting.

Decoupled pelvis rotation in sitting: A passive motion technique that regulates buttock load associated with pressure ulcer development

Wheelchair-users who cannot reposition themselves often suffer from pressure ulcers which are places of tissue breakdown in the buttock region under the sacrum and ischial tuberosities. Periodic pressure relief is needed to recover the buttock tissue from continuous deformation and impairment of tissue perfusion. Because pelvis alignment directly affects body posture and buttock load, a passive motion technique was developed that adjusts pelvis orientation independent from the trunk and seat support. This study investigates the effects of the so-called decoupled pelvis rotation (DPR) on the loads at the buttock-seat interface and evaluates whether this technique is applicable to regulate buttock load in sitting. Eighteen healthy male subjects participated in this study. Experiments were performed with a computer-aided adjustable simulator chair, instrumented with a concept of DPR. Measurements involved quasi-static actuated pelvis movements in the sagittal and frontal plane. Pelvis orientation, buttock interface pressures, seat reaction forces and centre of pressure were simultaneously measured. As a result of the induced passive pelvis movements, the pelvis rotated 19+/-2 degrees and 9+/-2 degrees in the sagittal and frontal plane, respectively. Significant relations were found between pelvis rotation and most quantities of buttock load. Findings suggest that DPR is an effective technique to regulate buttock load in able-bodied individuals. For clinical application, this technique is still to be evaluated on individuals who cannot functionally reposition themselves. Impairments to the neuromuscular function influence postural response from chair adjustments which makes clinical investigation necessary.

Daily-life monitoring of stroke survivors motor performance: The INTERACTION sensing system

The objective of the INTERACTION Eu project is to develop and validate an unobtrusive and modular system for monitoring daily life activities, physical interactions with the environment and for training upper and lower extremity motor function in stroke subjects. This paper describes the development and preliminary testing of the project sensing platform made of sensing shirt, trousers, gloves and shoes. Modular prototypes were designed and built considering the minimal set of inertial, force and textile sensors that may enable an efficient monitoring of stroke patients. The single sensing elements are described and the results of their preliminary lab-level testing are reported.

Body segments decoupling in sitting: Control of body posture from automatic chair adjustments

BACKGROUND Individuals who cannot functionally reposition themselves adopt a passive body posture and suffer from physical discomfort in long-term sitting. To regulate body load and to prevent sitting related mobility problems, proper posture control is important. The inability to reposition underlines the importance for seating interventions that control body posture from automatic chair adjustments. We developed an adjustable simulator chair that allows the alignment of the trunk, pelvis and thighs to be controlled independently. This study describes the system for decoupled body segments adjustment and develops a predictive model that computes angular chair configuration for desired body postures. METHODS Eighteen healthy male subjects participated in this study. The experiment involved a protocol of five trials, each investigating the effect of individual chair segment angle adjustment on body segments rotation. Quasi-static chair adjustments were performed, in which angular chair configuration and body segments orientation were measured using an infrared motion capturing system and an inertia sensor attached on the pelvis. RESULTS Linear best-fit equations together with the coefficients of determination were computed. Significant relations have been found between angular chair configuration and body segments orientation leading to an algorithm that predicts chair configuration for desired body posture. CONCLUSIONS The predictive algorithm seems applicable to compute angular chair configuration for desired body posture when the initial body-chair configuration is known. For clinical application, future experiments must be performed on impaired individuals to validate the algorithm in terms of accuracy.

Usability evaluations of a wearable inertial sensing system and quality of movement metrics for stroke survivors by care professionals

Background Inertial motion capture systems are used in many applications such as measuring the movement quality in stroke survivors. The absence of clinical effectiveness and usability evidence in these assistive technologies into rehabilitation has delayed the transition of research into clinical practice. Recently, a new inertial motion capture system was developed in a project, called INTERACTION, to objectively measure the quality of movement (QoM) in stroke survivors during daily-life activity. With INTERACTION, we are to be able to investigate into what happens with patients after discharge from the hospital. Resulting QoM metrics, where a metric is defined as a measure of some property, are subsequently presented to care professionals. Metrics include for example: reaching distance, walking speed, and hand distribution plots. The latter shows a density plot of the hand position in the transversal plane. The objective of this study is to investigate the opinions of care professionals in using these metrics obtained from INTERACTION and its usability. Methods By means of a semi-structured interview, guided by a presentation, presenting two patient reports. Each report includes several QoM metric (like reaching distance, hand position density plots, shoulder abduction) results obtained during daily-life measurements and in clinic and were evaluated by care professionals not related to the project. The results were compared with care professionals involved within the INTERACTION project. Furthermore, two questionnaires (5-point Likert and open questionnaire) were handed over to rate the usability of the metrics and to investigate if they would like such a system in their clinic. Results Eleven interviews were conducted, where each interview included either two or three care professionals as a group, in Switzerland and The Netherlands. Evaluation of the case reports (CRs) by participants and INTERACTION members showed a high correlation for both lower and upper extremity metrics. Participants were most in favor of hand distribution plots during daily-life activities. All participants mentioned that visualizing QoM of stroke survivors over time during daily-life activities has more possibilities compared to current clinical assessments. They also mentioned that these metrics could be important for self-evaluation of stroke survivors. Discussion The results showed that most participants were able to understand the metrics presented in the CRs. For a few metrics, it remained difficult to assess the underlying cause of the QoM. Hence, a combination of metrics is needed to get a better insight of the patient. Furthermore, it remains important to report the state (e.g., how the patient feels), its surroundings (outside, inside the house, on a slippery surface), and detail of specific activities (does the patient grasps a piece of paper or a heavy cooking pan but also dual tasks). Altogether, it remains a questions how to determine what the patient is doing and where the patient is doing his or her activities.