Dynamic AFOs may improve gait outcomes in stroke patients

A study of patients with post-stroke hemiparesis who used a dynamic ankle-foot orthosis with plantar flexion resistance found that a medium PFR grade showed near-normal maximal peak ankle dorsiflexion. Researchers noted in the journal Gait & Posture that medium PFR grade can improve path length and average velocity of center of pressure, as well as boost cadence and average velocity.

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Highlights

Changes in resistive moment of plantar-flexion affects gait and balance in stroke.
The influence of PFR moment on ankle kinematics, gait and balance was examined.
Dynamic AFOs with dorsiflexion assist Klenzak joints allow for adjustable PFR.
Moderate PFR setting may improve the ankle kinematics, gait and balance parameters.
High PFR may increase non-symmetrical ankle dorsiflexion during swing.

Abstract

Background

An ankle-foot orthosis (AFO) with plantar flexion resistance (PFR) can improve the first rocker function during gait, but the incremental changes in the resistive moment on balance and gait have not been well identified.

Objectives

To investigate the effect of changing the PFR moment of dynamic AFO (DAFO) on measures of the center of pressure (COP) and clinical gait outcomes in individuals with post-stroke hemiparesis.

Method

In this randomized repeated measure study of 36 stroke individuals, the customized DAFO using foot drop ankle units set in three PFR situations (low, medium, and high) was evaluated. The balance parameters for COP measures were investigated by HUMAC® Balance & Tilt System. Gait parameters and ankle kinematics were recorded using the 3D motion analysis through force platform and optoelectronic system. The comparison was made using a parametric ANOVA test and the P value was set at 0.05 for statistical significance.

Results

Significant differences were observed for COP average velocity (1.30 ± 0.64, 1.10 ± 0.05, and 1.37 ± 0.43), COP path length (43.3 ± 4.6, 33.4 ± 4.3, and 36.3 ± 5.4), walking velocity (11.0 ± 3.1, 13.2 ± 4.4, and 9.9 ± 3.5), and cadence (31.5 ± 2.0, 33.0 ± 3.1, and 29.0 ± 1.6) respectively for low, medium and high PFR settings (P < 0.05). Except for the COP path length and cadence, posthoc multiple comparisons revealed significant differences between low and medium (P < 0.05) and medium and high (P < 0.05) PFR grades. PFR with medium resistance demonstrated near-normal maximal peak ankle dorsiflexion (mean deviation of 8 degrees, P < 0.05).

Conclusion

Medium PFR grade should be encouraged since it can enhance balance parameters like path length and average velocity of COP, increase cadence and average velocity during gait, and improve maximal peak ankle dorsiflexion.

References

Impact of plantar flexion resistive moment of dynamic ankle foot orthosis on measures of center of pressure and clinical gait outcomes in individuals with post-stroke hemiparesis, Pradhan D, Mohanty RK. Gait Posture. 2024 May 28;113:58-66. doi: 10.1016/j.gaitpost.2024.05.024. Epub ahead of print. Summary