Neuromodulation with a 3D-printed, patient-specific hand orthotic in stroke: A proof-of-concept fMRI case series on clinical application

Three-dimensional (3D) printing holds great promise for creating patient-specific rehabilitative devices. While previous studies have demonstrated that behavioral interventions can induce cortical reorganization in stroke, direct evidence that a device alone—specifically, a patient-specific 3D-printed orthotic—can modulate brain function remains lacking. This proof-of-concept case series bridges this gap by integrating a complete digital workflow—from upper limb 3D scanning to stereolithography (SLA) fabrication of a custom hand orthotic—with longitudinal multimodal functional magnetic resonance imaging (fMRI) to assess cortical reorganization in chronic stroke. Four patients participated, with two index cases wearing the 3D-printed orthosis daily for four months alongside conventional rehabilitation, while two reference patients underwent conventional therapy only. Pre- and post-intervention neuroimaging revealed consistent, orthosis-associated neural changes: enhanced activity in the primary somatosensory cortex and greater functional integration within sensorimotor networks. Structural adaptations in motor regions were also observed in both index cases. Quantitatively, the index cases exhibited functional changes in nine brain regions and structural changes in six regions, substantially exceeding the minimal changes observed in the reference cases. This work provides the first direct evidence that a 3D-printed, patient-specific orthotic can drive targeted neuroplasticity independent of intensive behavioral coaching, validating its role not merely as a passive assistive device but as an active neuromodulatory tool. It establishes a translational framework for using objective neuroimaging biomarkers to guide the development and personalization of 3D-printed interventions in neurorehabilitation.