500 Section - Passive Knee Actuation for Functional Pediatric Gait Orthosis: Prototype Development, Biomechanical Testing, and Clinical Implementation

Many children with gait disorders rely on wheelchairs for daily mobility. However, even when independent walking is difficult, maintaining opportunities for standing and ambulation is essential for promoting physical development. Thus, the need for pediatric gait orthoses remains consistently high. Despite this demand, existing orthoses for paraplegic children face substantial barriers to widespread use: high cost, heavy weight, difficulty with donning/doffing, and limited adaptability to growth-related size changes. To address these issues, we have been developed a pediatric gait orthosis incorporating a non-powered knee flexion–extension mechanism and an adjustable sizing system, alongside a fundamental redesign of manufacturing methods and cost structure. We here describe the development process leading to the final product-level prototype, results of user test, and the future vision for clinical implementation.

Design:

The orthosis allows fine size adjustment for growing children and improves gait assistance by reciprocal hip flexion–extension movement. Structural modifications were made to enhance standing stability and walking ease. Simplifying structural elements, optimizing material selection, and refining the design enabled reductions in both weight and manufacturing cost, supporting feasible small-batch production and affordability for clinical settings.

Results:

After a three-year development process, gait evaluation was conducted in an 11-year-old boy using the final prototype. Three-dimensional motion analysis revealed approximately 20° of knee flexion during swing phase. Notably, electromyography detected synchronized activities even in completely paralyzed lower-limb muscles, including phase-specific activation in the rectus femoris and gastrocnemius corresponding to knee flexion–extension. These findings indicate that walking with the developed orthosis can induce physiological locomotor-like muscle activity in paralyzed limbs.

Conclusion:

Having completed the final prototype, the next step is to establish small-scale production processes and advance toward product commercialization and clinical application in multiple collaborating hospitals.