Individuals with severe injuries to their lower limbs often require AFOs to return to normal activities. AFO alignment is key during the clinical fitting process and may be important during dynamic activities such as running.
To investigate how 3 degree changes in sagittal plane AFOs alignment affect running mechanics, during a laboratory study, 12 participants with unilateral lower-limb injuries ran over ground, and lower-limb running mechanics were assessed. Participants wore their passive-dynamic AFOs in three alignments: clinically fit neutral, 3 degree plantarflexed from clinically fit neutral, and 3 degree dorsiflexed from clinically fit neutral.
The 3 degree changes in sagittal alignment significantly influenced ankle mechanics during running, the study showed. The plantarflexed alignment significantly decreased the peak ankle plantarflexor moment, peak knee extensor moment, and peak ankle and knee power absorption and generation compared to more dorsiflexed alignments. Alignment also altered foot strike angle, with dorsiflexed alignments associated with a more dorsiflexed foot strike pattern and plantarflexed alignments toward a more plantarflexed foot strike pattern. However, alignment did not influence loading rate, according to the study.
The study found that small changes in AFO alignment significantly altered running mechanics, including foot strike angle and knee extensor moments. Understanding how AFO design parameters affect running mechanics may aid the development of evidence-based prescription guidelines and improve function for AFO users who perform high-impact activities.
Results of the study were published February 14 in Prosthetics and Orthotics International.