Neural Excitability and Joint Laxity in Chronic
Ankle Instability, Coper, and Control Groups

Bowker, S, Terada M, Thomas AC, Pietrosimone BG, Hiller CE, Gribble PA. J Athl Train. 2016 Apr 11 [Epub ahead of

Take Home Message: A group of individuals with
chronic ankle instability have sensorimotor system deficits compared with a
group of healthy controls and copers; however, the authors found no mechanical
differences between any of the groups.

One of the most common sports injuries are ankle
sprains. Unfortunately, many individuals that suffer an ankle sprain develop
prolonged ankle dysfunction, which is known as chronic ankle instability. A
better understanding of the differences between individuals that develop
chronic ankle instability and those that do not (copers) could provide
clinicians with better evidence-based decisions when evaluating and treating
initial ankle sprains. Therefore, Bowker and colleagues conducted a
case-control study of individuals with chronic ankle instability, copers that
did not report chronic dysfunction following an initial ankle sprain, and a
group of healthy controls to investigate the differences in ankle laxity and
neural excitability. Ninety-three physically active volunteers participated in
the study. Thirty-seven (18 male) volunteers had chronic ankle instability
based upon
recommendations from the International Ankle Consortium, 30 (13 male) volunteers
were copers who were defined as individuals with a history of ankle sprains
that were not accompanied with episodes of the ankle giving way, perceived
instability, or loss of function. Additionally, 26 (9 male) were healthy
controls. The authors assessed ankle laxity using an instrumented ankle
arthrometer that measured the total displacement in the anterior-posterior (mm)
directions and total rotation in the inversion-eversion (°) directions. To assess neural
excitability, they measured spinal reflex excitability of the soleus muscle
using the
Hoffmann reflex to determine the maximum Hoffmann reflex to maximum muscle response
(H:M ratio) ratio. The authors showed that participants with chronic ankle instability
had less spinal excitability in the soleus muscle compared with the coper and
healthy control groups. However, spinal reflex excitability was not different
between the copers and healthy controls. There were no differences between any
of the groups for either of the ankle laxity measures.

The data from this study support
the idea that the differences between individuals with chronic ankle
instability versus those that who cope after an ankle sprain may have more to
do with changes in the sensorimotor system than ankle laxity. Other studies
have reported neural excitability deficits in people with chronic ankle
instability; but, this study highlights the potential need for appropriate
interventions to address neural excitability deficits. Potentially, certain
therapeutic interventions that affect nervous system excitability such as joint
mobilizations and manipulations, muscle energy technique, cryotherapy, and
transcutaneous electrical stimulation could be used for patients with chronic
ankle instability. However, we don’t know if or how these common clinical
interventions would impact the neural excitability changes of the soleus in
patients with chronic ankle instability. It is also difficult for most
clinicians to easily assess spinal reflex excitability and may force them to
rely upon subjective clinical complaints. Additionally, we also need
prospective studies because we do not know if the presence of these neural
deficits can predict who will struggle with chronic ankle instability or those
that will be able to cope effectively.
Fortunately, many of the interventions that
could help are low cost, low risk, and many of them are already commonplace in
clinical settings. Therefore, it may be a good idea for clinicians to
incorporate some of these techniques into rehabilitation protocols of patients
with a history of recurrent ankle sprains or chronic ankle instability.

Questions for Discussion: Do you focus your
rehabilitative efforts on both potential mechanical and neurological changes
for ankle sprains? Have you used manual therapies with a non-mechanical model
of efficacy? How do you implement neural training into your rehabilitation

Written By: Adam Kelly, MS, ATC
Reviewed By: Jeffrey Driban

Related Posts:

Bowker S, Terada M, Thomas AC, Pietrosimone BG, Hiller CE, & Gribble PA (2016). Neural Excitability and Joint Laxity in Chronic Ankle Instability, Coper, and Control Groups. Journal of athletic training PMID: 27065189