Passive-dynamic ankle-foot orthoses change post-stroke lower extremity constituent work profile

Area of Science:

• Biomechanics
• Neurorehabilitation
• Orthotics

Background:

• Passive-dynamic ankle-foot orthoses (PD-AFOs) customized for stiffness can decrease the mechanical cost of transport (COT) in individuals post-stroke.
• The underlying mechanisms responsible for this observed reduction in COT are not yet fully understood.
• Identifying these mechanisms is crucial for optimizing PD-AFO design and rehabilitation strategies.

Purpose of the Study:

• To investigate the specific factors contributing to the reduction in COT when using stiffness-customized PD-AFOs in individuals post-stroke.
• To determine the relationship between changes in limb work, stride length, and COT with PD-AFO use.

Main Methods:

• Comparison of COT, limb work, and stride length between PD-AFOs, no orthosis (No AFO), and standard-of-care (SOC) AFO conditions.
• Statistical analysis using Kendall's tau correlation to assess relationships between variables in paretic and non-paretic limbs.

Main Results:

• Changes in limb work strongly correlated with changes in COT for both paretic and non-paretic limbs when comparing PD-AFO to No AFO and SOC AFO.
• No significant correlation was found between changes in stride length and changes in COT.
• A moderate correlation existed between reduced COT and a decrease in mechanical work performed by lower limb constituents, particularly in the paretic limb.

Conclusions:

• PD-AFOs reduce COT in individuals post-stroke mainly through minor alterations in mechanical work across numerous lower limb components.
• The findings suggest that PD-AFOs influence gait mechanics by redistributing work rather than significantly altering stride parameters.
• Understanding these mechanisms can guide the refinement of PD-AFO technology and other post-stroke interventions for improved mobility.