Segmental spinal reflex adaptations associated with chronic ankle instability

Sefton JM, Hicks-Little CA, Hubbard TJ, Clemens MG, Yengo CM, Koceja DM, Cordova ML. Segmental spinal reflex adaptations associated with chronic ankle instability.

Objective

To further understanding of the role that segmental spinal reflexes play in chronic ankle instability (CAI).

Design

A 2 × 2 repeated-measures case-control factorial design. The independent variables were ankle group with 2 levels (healthy, CAI) and stance with 2 levels (single, double legged).

Setting

University research laboratory.

Participants

Twenty-two participants with CAI and 21 matched healthy controls volunteered.

Interventions

Not applicable.

Main Outcome Measures

The dependent variables were 2 measures of motoneuron pool excitability: paired reflex depression (PRD) and recurrent inhibition.

Results

A 2 × 2 repeated-measures multivariate analysis of variance revealed a significant interaction between group and stance on the linear combination of PRD and recurrent inhibition variables (Wilks λ=.808, F_2,40=4.77, P=.014). Follow-up univariate F tests revealed an interaction between group and stance on the PRD (F_1,41=9.74, P=.003). Follow-up dependent t tests revealed a significant difference between single- and double-legged PRD in the healthy participants (t₂₀=-3.76, P=.001) with no difference in CAI participants (t₂₁=-0.44, P=.67). Finally, there was a significant difference in recurrent inhibition between healthy (mean, 83.66) and CAI (mean, 90.27) (P=.004).

Conclusions

This study revealed that, compared with healthy participants, CAI participants were less able to modulate PRD when going from a double- to a single-legged stance. Additionally, CAI participants showed higher overall levels of recurrent inhibition when compared with healthy matched controls.