To design effective rehabilitative technology, stakeholders (e.g., professionals from hospitals, universities, and industries) must empathize with end-user experiences and actively involve them throughout the design process. This approach can ensure the understanding of their complex needs. Yet end-user involvement is often limited to testing only. Technology developers often underestimate the valuable insights end-users gain during their recovery, which extend beyond technical knowledge. To address this, our international team of designers, engineers, and clinical personnel proposes a participatory design workshop involving acquired brain injury patients and their caregivers. Patients and caregivers work in groups with workshop participants to address specific needs and use methods like personas, MoSCoW prioritization, and prototyping to co-create solutions to meet those needs. We aim to illustrate the benefits of this approach and encourage participants to adopt participatory design in their future developments.

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In this research, we propose a novel method to estimate and monitor rotator cuff tendon strains during active robotic-assisted rehabilitation. This is a significant step forward from our previous work which estimated these tendon strains during passive exercises (i.e., no muscle activity). Physiotherapists adopt a cautious approach to rehabilitation treatment to prevent (re-) injury given the limited available information about the shoulder's internal condition. By leveraging a robotic device and a musculoskeletal model, our approach provides quantitative information on the risk of re-injury by monitoring the strains of the rotator cuff tendons during shoulder movements with the application of external loads. Muscle strains depend on the shoulder kinematic state and muscle activations, which makes it crucial to obtain physiologically realistic joint kinematics to estimate real-time muscle function. To obtain the strains, we utilize our muscle redundancy solver that incorporates constraints on model accelerations, the glenohumeral joint reaction forces, and active muscle dynamics. Using this algorithm along with force and pose data from a collaborative robotic arm, we demonstrate the ability to update our tendon strain estimates based on muscle activation during robotic-assisted rehabilitation exercises. The findings of our research pave the way for establishing improved therapy that considers the risk of injury to individual muscles and explores a broader and more personalized range of motion. By providing physiotherapists with valuable quantitative information on rotator cuff tendon strains, our method empowers them to optimize rehabilitation protocols and deliver more personalized and effective care. In addition, the system and method presented here comprise a tool capable of offering new insights into the relationship between the rotator cuff muscles, external forces, and shoulder kinematics.@en

The complexity of the human shoulder girdle enables the large mobility of the upper extremity, but also introduces instability of the glenohumeral (GH) joint. Shoulder movements are generated by coordinating large superficial and deeper stabilizing muscles spanning numerous degrees-of-freedom. How shoulder muscles are coordinated to stabilize the movement of the GH joint remains widely unknown. Musculoskeletal simulations are powerful tools to gain insights into the actions of individual muscles and particularly of those that are difficult to measure. In this study, we analyze how enforcement of GH joint stability in a musculoskeletal model affects the estimates of individual muscle activity during shoulder movements. To estimate both muscle activity and GH stability from recorded shoulder movements, we developed a Rapid Muscle Redundancy (RMR) solver to include constraints on joint reaction forces (JRFs) from a musculoskeletal model. The RMR solver yields muscle activations and joint forces by minimizing the weighted sum of squared-activations, while matching experimental motion. We implemented three new features: first, computed muscle forces include active and passive fiber contributions; second, muscle activation rates are enforced to be physiological, and third, JRFs are efficiently formulated as linear functions of activations. Muscle activity from the RMR solver without GH stability was not different from the computed muscle control (CMC) algorithm and electromyography of superficial muscles. The efficiency of the solver enabled us to test over 3600 trials sampled within the uncertainty of the experimental movements to test the differences in muscle activity with and without GH joint stability enforced. We found that enforcing GH stability significantly increases the estimated activity of the rotator cuff muscles but not of most superficial muscles. Therefore, a comparison of shoulder model muscle activity to EMG measurements of superficial muscles alone is insufficient to validate the activity of rotator cuff muscles estimated from musculoskeletal models.@en

Soft exosuits can help to prevent work-related musculoskeletal disorders by offloading human muscles through the application of external forces across the human joints. Many exosuits achieve this through tension producing elements called as exotendons. However, the design of these devices is based on intuition and experience. This leads to potentially sub-optimal or even harmful designs that could cause discomfort or injury to the wearer. This paper deals with automatically finding appropriate attachments and routing locations for exotendons. We propose to do that by accurate musculoskeletal modeling and design parameter optimization of soft exosuits. We focus here on a soft exosuit with a single passive exotendon to assist the shoulder. Using three arm raising-lowering and internal-external rotation motions as examples, we optimize the attachment point and rest-length of the exotendon to reduce overall muscle effort. We then fabricate the exosuit and validate the model predictions by testing with six participants. Supporting the predictions from simulations, measured muscle activity shows reductions in the deltoid and trapezius muscles. This work represents the first instance of explicitly optimizing functional and geometric parameters of exotendons in wearable assistive devices for minimizing human effort.

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