Stroke is a major cause of disability worldwide, with two-thirds of survivors experiencing upper limb (UL) impairments that limit their ability to perform daily activities. Effective UL rehabilitation is crucial for maximizing recovery and improving quality of life. To guide therapy selection and track patient progress, UL function assessment tests are commonly used. However, these assessment tests are subjective, lack detail, and are time-consuming. Moreover, the increasing stroke burden and healthcare workforce shortages highlight the need for innovative rehabilitation approaches, including more home-based rehabilitation solutions. Wearable sensor technology, particularly inertial measurement units (IMUs), offers a promising solution for objective, detailed UL assessment, enabling at-home monitoring. In response, the Towards@HomeRehab project, led by the Erasmus Medical Center, was established to develop and evaluate an IMU-based upper limb assessment tool for home use.

This thesis, as part of the Towards@HomeRehab project, had two main objectives: 1) to explore clinicians’ perspectives on an IMU-based assessment tool that uses a standardized drinking task to evaluate upper limb function, and 2) to examine the technical feasibility of extracting kinematic metrics from IMU data collected during the drinking task.

Chapter 2 presents a qualitative study on clinicians’ perspectives regarding the potential IMU-based assessment tool. Three different rehabilitation clinicians were interviewed, all recognizing the tool’s value in objectively and consistently tracking patient progress over time. However, they emphasized the important requirement for the tool to generate a simple, concise overview of clinically relevant movement deviations compared to normal performance. Determining the most relevant output measures remained challenging, as interpreting numerical data requires a shift from their traditional reliance on visual movement assessment.

Chapter 3 presents a pilot study with sixteen healthy subjects examining the technical feasibility of using QSense IMUs to extract kinematic metrics from a standardized drinking task. The results demonstrate that it is technically feasible to derive movement time and joint angle metrics from the IMU data collected during drinking tasks in healthy subjects. The analysis showed excellent relative consistency (ICC ≥ 0.9, SEM < 5% of the mean) and successfully captured different movement patterns, as demonstrated by significant differences between normal and stroke-mimicked drinking task data (p < 0.05). However, a preliminary validation test revealed notable errors in shoulder angle estimations (MAE > 10°).

Chapter 4 summarizes final conclusions, future perspectives, and recommendations. We have demonstrated the potential of an IMU-based upper limb assessment tool for post-stroke rehabilitation. However, the presented data processing methods require refinement to improve metric accuracy and should be extended with additional metrics. Future research should focus on the clinical validation of the extracted metrics, test-retest reliability, and responsiveness of the metrics to functional changes in stroke patients. Additionally, a simple and concise method of presenting the tool’s outcomes should be developed in collaboration with clinicians to ensure alignment with clinical needs, preferences, and workflows.

Trunk motor control is essential for the proper functioning of the upper extremities and is an important predictor of gait capacity in children with delayed development. Early diagnosis and intervention can potentially increase the trunk motor capabilities in later life. However, current tools used to assess the level of trunk motor control are largely observation-based and lack the sensitivity to change required to accurately monitor progress and effects of therapy in children below the age of 4. To the best of our knowledge, this is the first attempt to use trunk-attached inertial measurement units (IMUs) to differentiate different levels of trunk motor control in this population. We performed experiments with seven children to examine the applicability of the RMS of jerk as an outcome metric for the level of trunk motor control. This study showed that the root mean square (RMS) of jerk decreases for ages up to 24 months, is relatively independent of data segment and length, and shows results similar to a more established method: the centre of pressure (COP) velocity. These findings suggest that the RMS of jerk shows potential as a metric for the differentiation of different trunk motor control levels. However, due to the small sample size, a follow-up study is necessary to verify and validate these results.

Spinal cord injuries (SCI) occur when damage to any part of the spinal cord is sustained. Depending on what vertebrae segment the injury occurs, the patient will develop paraplegia or tetraplegia and have a complete or incomplete spinal cord injury. After sustaining a spinal cord injury, the patient must undergo rehabilitation.

For incomplete SCI patients, part of their rehabilitation is improving their mobility skills through gait training. To assess gait, the methods of the clinical eye and laboratory gait assessment are used. The starting goal of the project was to combine the quickness and easiness of conducting a gait assessment with the clinical eye with the objective data from a laboratory gait assessment into one system. This system consists of Xsens Awinda wireless motion trackers to collect the kinematic data and a user interface to view it.

User research was conducted in the form of questionnaires and focus groups. The research aimed to learn more about how physiotherapists and physicians within Rijndam Revalidatie currently assess gait, what features and parameters they would like in the user interface, and how they would prefer the selected parameters to be visualized (in numbers, graphs, or animations). Three physiotherapists and physicians were also interviewed to better understand the process incomplete SCI patients go through in gait rehabilitation and who is involved in each step.

From the results, a design direction and vision was created: “To develop an easy to use user interface that aids physicians and physiotherapists in selecting interventions for patients with incomplete spinal cord injuries in an objective and time efficient manner through intuitive data visualizations.”

Using design methods and tools, ideas for the data visualizations and the interface layout were formed, selected, and then made into concepts. The layout and visualizations concepts were evaluated through concept test sessions with physiotherapists and physicians. In the sessions, the interface layout was assessed in terms of usability and functionality. The data visualizations were evaluated based on if the participants, who had minimal pre-existing knowledge on gait analysis, could understand them. From the evaluation results, the final design of Gait Vision was created.

Gait Vision is an easy-to-use interface that allows physiotherapists and physicians to assess gait objectively and time-efficiently. It provides more accurate and objective information than can be obtained with the clinical eye, in a way that is more intuitive and comprehensible for clinicians with minimal gait assessment experience than laboratory gait assessment.

An interactive prototype of the final design was developed using Adobe XD. The interface prototype and the visualization concepts were evaluated through conducting individual user tests with seven physicians and physiotherapists. The interface and visualizations were tested with regard to usability, functionality, intuitiveness, and aesthetics. Overall positive feedback was received regarding the interface and visualizations. Testing was also conducted to compare gait assessment with the clinical eye versus with the interface. The interface was found to more objective than the clinical eye.

An implementation plan was developed to ensure Gait Vision survives in the long term. Future recommendations were also made to aid in the continuation of the development of Gait Vision.