A Bionic Pneumatic Shoulder Exosuit for Subluxation Prevention and Load-Bearing Augmentation in Rehabilitation

Background: The shoulder joint is a pivotal articulation for upper-limb kinematics, yet it is prone to injury during rehabilitation exercises. Despite advances in assistive technologies, current rehabilitation exoskeletons still face challenges in reducing the risk of glenohumeral subluxation while also improving load-bearing capacity. Methods: This work proposes a novel Pneumatic Shoulder Exosuit (PSE), designed to protect the shoulder joint from subluxation while augmenting its load-bearing capability during rehabilitation. This dual functionality is enabled by two coupled, pouch-based pneumatic actuators configured into a bionic agonist/antagonist pair. Device performance was evaluated through experimental trials with 10 volunteers performing kinematic assessment, standardized trajectory-tracking, and static overhead weight-holding tasks. In addition, 7 participants with post-stroke hemiparesis were involved in evaluating the satisfaction with Activities of Daily Living (ADL) rehabilitation training using the device. Results: Experimental results showed that the PSE can provide dynamic gravity support with up to 24 Nm of torque. The device maintained the movement trajectory with a 96.5% similarity compared to unassisted. It also reduced agonist muscle activities (anterior, middle, and posterior deltoids and biceps brachii) by up to 65% with a 70% reduction in compensatory muscle (latissimus dorsi) activity, and a 45% reduction in peak lateral trunk tilt. The participants with post-stroke hemiparesis also provided positive feedback. Conclusions: This study demonstrates the strong potential of the PSE to effectively combine load-bearing augmentation with kinematic transparency, offering new insights into bionic soft actuator design. These findings suggest broad applicability in safe and effective rehabilitation across clinical and home settings. Future research should further explore adaptive assistance strategies during complex dynamic ADLs to refine the functional utility of such systems.