Leg stiffness control during drop landing movement in individuals with mechanical and functional ankle disabilities

ABSTRACT

Purpose: Individuals with mechanical ankle instability (MAI) and functional ankle instability (FAI) present with residual movement dysfunctions after an initial lateral ankle sprain. This study investigated leg stiffness control to determine how behavioural characteristics between MAI and FAI differ during single-leg drop landing movement. Methods: Thirty individuals (10 with MAI, 10 with FAI, and 10 healthy controls) participated in this study. During single-leg drop landing movement, we estimated dimensionless leg stiffness, peak vertical force (PVF), change in the displacement of leg movement, loading rate, angular joint movement, and internal joint moment for impaired and unimpaired legs, respectively. Univariate one-way analysis of variance was used for each dependent variable across leg conditions. Results: The MAI group had lower dimensionless leg stiffness with greater change in the displacement of leg movement for the impaired leg than the FAI and control groups. Moreover, reduced leg stiffness was associated with greater hip joint flexion movement in the MAI group, whereas ankle dorsiflexion movement increased to decrease the leg stiffness in the FAI and control groups. Conclusion: These findings indicate that lower leg stiffness in the MAI group than in the FAI group may be attributed to compensatory actions to minimise reliance on their ankle movement after landing.

KEYWORDS:

• Leg stiffness
• chronic ankle instability
• mechanical ankle instability
• functional ankle instability
• drop landing

Acknowledgments

The authors would like to thank the participants for their time and commitment to this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by Incheon National University Research Grant [2018-0468].