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.

Background: Stroke contributes significantly to the global rates of disability and mortality. A widely recognised consequence of a stroke is motor impairment, including upper extremity impairments. Rehabilitation has a significant role in the improvement of upper extremity functioning. However, the field of rehabilitation care is currently confronted with several challenges. Telerehabilitation, which includes wearable motion sensors such as Inertial Measurement Units (IMUs), offers a promising solution to improve rehabilitation care in a home-based environment. Therefore, the ArmCoach4Stroke (AC4S) project, initiated by the Erasmus Medical Centre and Rijndam Rehabilitation Institute, was established to develop and evaluate a wearable system for upper extremity rehabilitation at home for post-stroke patients.

Aim: As part of the AC4S project, the aim of this thesis was to investigate the test-retest reliability and criterion validity of an IMU-sensor based method, compared to an optoelectronic system, for measuring kinematic metrics of the upper extremity in post-stroke patients.

Methods: The data from two protocols were subjected to analysis: a reliability and validity protocol. During both protocols, participants were equipped with IMUs and executed predefined calibration movements, as well as reaching and lifting exercises. For the validity protocol, patients also wore markers of the gold standard marker-based Vicon system. The measurements of the validity protocol were performed in a laboratory setting, whereas the reliability protocol simulated measurements in an ecological environment. The indices of calibration movements and exercises were selected manually. The orientations of the IMU sensor were estimated and joint angle metrics were calculated for the reaching and reach-and-return phase of movements. A statistical analysis of the metrics was performed to investigate test-retest reliability and criterion validity separately. This involved the use of the intraclass correlation coefficients (ICC) and Spearman correlation coefficients, respectively.

Results: Eventually, 18 participants were analysed for the reliability protocol and 7 for the validity protocol. The reliability protocol yielded ICCs indicating both good reliability (values >0.75) and poor reliability (values <0.5) for some metrics. Significant test-retest differences were identified for certain metrics. The Spearman correlation coefficients for the validity protocol indicated strong correlations (values >0.7). However, the p-values were above the level of significance. The results further demonstrated considerable differences in absolute values between IMU and Vicon joint angles across various metrics.

Conclusion: A large variability and poor-moderate reliability were observed for multiple metrics, indicating underlying issues with the measurements or metric calculations. Substantial differences in absolute joint angle values were evident, not only between Vicon and IMU, but also between test-retest sessions or between patients. This indicates suboptimal orientation estimation, angle definitions or other fundamental problems that need further investigation.