A 3D printed Ankle Foot Orthosis (AFO) for personalised form and function in patients with movement disorders

Participants in this study will be individuals with movement disorders who experience gait impairments such as reduced push-off and ankle plantar flexor weakness, who have been prescribed with Ankle-Foot Orthoses (AFOs). These gait patterns may be associated with neurological, congenital, or musculoskeletal conditions that affect lower-limb control. As part of the study procedures, participants will be exposed to controlled walking conditions on an instrumented treadmill, including different walking speeds and inclines, while wearing custom modular 3D-printed AFO. Motion capture and force measurements will be recorded to evaluate gait biomechanics. The duration of observation and exposure is limited to the gait assessment session (second session of the study), which typically lasts 60–120 minutes, including rest breaks and setup time. The study includes two sessions: Session 1 (3D scanning + interview): Session 1 will involve 3D scan of the participant’s lower limb (ankle and foot) for the purpose of designing a modular, patient-specific 3D-printed AFO for research observation. In the same session, a semi-structured open-ended question interview will be conducted to explore the participant’s experience using their prescribed AFOs. For paediatric participants, a parent/guardian will also be invited to contribute to the interview. Session 1 will be conducted by the PhD student (biomechanics researcher), who will complete both the interview and the 3D scanning. Session 2 (gait analysis): Session 2 will involve a treadmill-based gait analysis while the participant wears the study AFO under different stiffness (maximum four different stiffnesses) and walking conditions. Data collection will be conducted by the PhD student under supervision from the Principal Investigator and an experienced biomechanics laboratory technician. Location/setting: Both sessions will take place at the biomechanics laboratory, Department of Exercise Sciences, The University of Auckland. Interviews will be conducted in a private room within the department. 3D scanning and gait assessment will be conducted in the biomechanics laboratory. Walking speeds and inclines assessed: During Session 2, participants will first complete a treadmill familiarisation period, during which their self-selected walking speed will be identified. Testing will then be performed at four speeds: 10% below self-selected speed self-selected speed 10% above self-selected speed 10% above the previous speed (i.e., approximately 20% above self-selected) Three incline conditions will be assessed: 0% incline at self-selected speed 5% incline at self-selected speed 10% incline at self-selected speed Use of the study AFO after Session 2: The modular 3D-printed AFO is used only during the gait assessment session for research measurement. Participants will not be asked to wear the study AFO after Session 2. The study data collection will be finished after second session and there is no anticipated duration of use beyond the supervised testing session. The study AFO will be retained by the research team at the completion of data collection. In New Zealand and Australia, individuals may receive similar modular, patient-specific 3D-printed AFOs with adjustable stiffness through routine clinical pathways if they require a new AFO depending on regulatory requirements and the orthotic provider they attend. Access to similar AFOs is therefore not dependent on participation in this study. The modular 3D-printed AFO used in this study is not provided as a treatment device and is not issued for ongoing use. It will be used only temporarily during a supervised gait analysis session (approximately 2 hours). Participants will continue to use their own clinically prescribed AFOs before and after the second research session. Therefore, participation in this study does not alter the participant’s clinical treatment, prescription, or standard care pathway.