AFO's Impact on Propulsive Force in Chronic Stroke Gait: A Detailed Four-Bin Stance Phase Analysis

Kimihiko Mori, Naoto Mano, Yuta Chujo, Takayuki Kuwabara, Masanori Wakida, Ayami Fujiwara, Kiichi Kajihara, Minami Rokutani, Tomotaka Morikawa, Kimitaka Hase, Jin Kuramoto, Hiroaki Tanaka
Purpose:

This study aimed to investigate the changes in anteroposterior ground reaction forces (A-P GRFs) with AFO use in individuals with stroke and identify the characteristics of those who demonstrated improved propulsive force.

Methods:

Sixty-nine chronic stroke survivors who could walk independently without orthosis were included. Immediate changes in gait with and without plastic AFO were compared. Outcomes included gait speed, spatiotemporal parameters, A-P GRFs, and lower limb joint angles. The stance phase of the paretic side was divided into four bins to analyze impulse generation during the gait cycle: (1) double support following initial contact, (2) the first 50% of single support, (3) the second 50% of single support, and (4) double support preceding the swing phase. A-P GRFs in each phase were compared between conditions using paired t-tests or Wilcoxon signed-rank tests. Bins 1-4 were used to categorize gait patterns using k-means clustering, and baseline gait characteristics were compared between clusters using Welch's two-sample t-test or Wilcoxon rank-sum test. Changes in A-P GRFs and joint angles between clusters with and without AFO were compared using Welch's two-sample t-test or Wilcoxon rank-sum test.

Results:

Overall, gait speed (0.62 vs 0.59 m/s) and bin 3 of A-P GRFs (39.6 vs 34.0 %BW*s) increased with AFO, while bin 1 of A-P GRFs (-91.3 vs -115.7 %BW*s) decreased. Participants were classified into two clusters: Cluster B (N=33) with a poor propulsive component, demonstrating slower gait speed (0.43 vs 0.76 m/s), less symmetric step length (0.59 vs 0.52 %), and smaller trailing limb angles (5.1 vs 16.0 degrees) and shank vertical angles (24.8 vs 39.2 degrees) during late stance compared to Cluster A (N=36) with a good propulsive component. The immediate change with AFO was greater in only bin 3 of A-P GRFs for Cluster B (10.9 %BW*s) than Cluster A (0.6 %BW*s).

Conclusion(s):

This study demonstrated that AFO use could partially increase the propulsive component of A-P GRFs during the latter half of the single support phase. The propulsive force was partially increased by the orthosis, particularly in individuals with post-stroke hemiplegia who walk slowly and have poor propulsive force on the paretic side.

Implications:

Tailoring orthotic prescriptions according to walking ability may lead to more effective outcomes for improving gait function.

Funding acknowledgements:
This work was partially supported by JSPS KAKENHI Grant Number JP23K19909.
Keywords:
ankle-foot orthosis
hemiparetic gait
anteroposterior ground reaction force
Primary topic:
Disability and rehabilitation
Second topic:
Neurology: stroke
Third topic:
Other
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
Institution: Kansai Medical University Hospital Ethics committee: Research Ethics Committee of Kansai Medical University Hospital
Provide the ethics approval number:
2022150
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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