Triggered Electrical Stimulation Cueing to Address Hypofunctioning Peroneus Muscle in the Treatment of Chronic Ankle Instability: Two Repeated Single Case Designs

Background: Approximately two million ankle sprains occur in the United States annually. Lateral ankle sprains (LAS) account for 85% of all ankle sprains, 74% of those individuals report continued symptoms following the initial insult. Persistent pain and instability following ankle sprain is indicative of chronic ankle instability (CAI). There are many interventions to address hypofunctioning muscle including electrical stimulation (ES) and it is known that peripheral ES changes muscle behavior. The purpose of this pilot study was to investigate the effect of electrical stimulation of the peroneal muscles combined with 3 exercises for the treatment of CAI.
Methods: Two participants with CAI were recruited for this repeated single case design. The Cumberland Ankle Instability Tool (CAIT), the modified Star Excursion Balance Test (mSEBT), and center of pressure (CoP) was measured. A single limb hop to stabilization protocol and single limb stance activities were combined with manual triggered electrical stimulation for six sessions.
Results: Improvements in CAIT scores for both patients were observed. There was no statistically significant change in mSEBT scores. Center of Pressure measurement improvements varied between subjects. For subject 1, there was no significant change in CoP in eyes open and eyes closed conditions. For subject 2, there was a significant change in the anterior/posterior CoP data points in both conditions.
Discussion: In individuals with CAI, the addition of electrical stimulation to a single limb stance and hop stabilization protocol for hypofunctioning peroneal muscles led to positive CAI outcomes as measured by improved CAIT scores and improved CoP measurement in one subject.