Fellowship for Jennifer Mullins: The Effect of Dry Needling on Clinical and Neurophysiologic Components of Balance in Individuals with Chronic Ankle Instability

Ankle injuries decrease the U.S. Army's deployment readiness resulting in an average of 16.7 duty days lost per ankle sprain and an associated cumulative annual loss of 25 million operational duty days [1, 2]. The incidence of ankle sprains is five times higher among US Service Members than their civilian counterparts. This significantly contributes to rising military healthcare costs that was estimated to represent 12% of entire the US defense budget in 2015, nearly double what it was in 2014 [3, 4]. Despite the loss of training days and current best-evidence rehabilitative care, it is widely accepted that ankle injures frequently result in chronic pain, muscular weakness, functional deficits and chronic instability. The overall objective of the proposed research study is to empower physical therapists to return Soldiers to their assigned duties faster following an ankle sprain and keep them there longer by reducing the likelihood for recurrent sprains through the evidenced application of dry needling (DN). This study will build on established research that will provide therapists with evidence-based rehabilitation regarding the applicability and prescription of DN for chronic ankle instability (CAI). Quiet standing and the Star Excursion Balance Test (SEBT) are well represented in the literature as valid and reliable ways of measuring balance and have demonstrated deficits in those with CAI [5-8]. Additionally, this study will further our understanding of the neurophysiological mechanisms that explain the clinical benefit of DN for broad therapeutic applicability across a myriad of musculoskeletal conditions frequently seen by physical therapists. Hoffmann's Reflex (H-Reflex) is an electromyographic measure of motor neuron pool excitability which is shown to be decreased in individuals with CAI [9-14]. Army physical therapists operate at the top of their license with privileges to operate direct access clinics, order advanced imaging and medication, and treat with DN. DN is a field-expedient treatment tool for various musculoskeletal pain and dysfunctions currently utilized by Army physical therapists. Despite its growing popularity, there is a lack of understanding of the mechanisms behind its positive outcomes and the appropriate applications in the lower extremity. The goal of this study to further the body of evidence regarding DN by quantifying changes in functional outcomes and furthering our understanding of DN's neurophysiological effects in individuals with CAI. A recent study demonstrated that the addition of DN therapy to current standard of care proprioceptive exercises, produced significantly improved patient reported outcomes at four weeks [15]. Despite the well-established problem of CAI and the emerging knowledge of the positive effects of DN, there exists a critical need for determining the neurophysiologic mechanistic effects of DN to ensure its appropriate and most clinically useful application. Without this knowledge the utility of DN will be limited or misused, perpetuating chronic ankle instability and thereby decreasing the strength of our military forces. The following Specific Aims will address each facet of my research. Aim 1: Quantify the immediate effects of DN on components of balance to include H-Reflex, Quiet Standing and SEBT in healthy and individuals with CAI Hypothesis: Healthy individuals will demonstrate no change following DN while individuals with CAI will demonstrate improved functional balance and individuals with CAI will demonstrate improved H-Reflex. Aim 2: Measure the dosing effect of DN on the above components of balance after once weekly treatment for four weeks and four weeks after cessation of treatment if there is a dosing effect of dry needling on the above components of balance after 4 weeks of weekly DN treatment in individuals with CAI. Hypothesis: Improvements will be seen in functional balance and H Reflex after 4 weeks of treatment in individuals with CAI. Sustainment of improvements in balance and H Reflex as a result of DN will be demonstrated in individuals with CAI. Aim 3: Decrease the incidence of sprains in individuals with CAI measured eight weeks following initiation of DN treatment.