Objective: The purpose of this study was to evaluate the effect of a single treatment vs serial dry needling (DN) treatments of the fibularis longus on individuals with chronic ankle instability and to determine the longevity of any effect found.

Methods: Thirty-five adults with chronic ankle instability (24.17 ± 7.01 years, 167.67 ± 9.15 cm, 74.90 ± 13.23 kg) volunteered for a university laboratory repeated-measures study. All participants completed patient-reported outcomes and were objectively tested using the Star Excursion Balance Test (SEBT), threshold to detect passive motion (TTDPM) measurements, and single limb time-to-boundary measurements. Participants received DN treatment to the fibularis longus once weekly for 4 weeks on the affected lower extremity by a single physical therapist. Data were collected 5 times: baseline 1 week before initial treatment (T0), pre-treatment (T1A), immediately after the first treatment (T1B), after 4 weekly treatments (T2), and 4 weeks after the cessation of treatment (T3).

Results: Significant improvements were found for clinician-oriented (SEBT-Composite P < .001; SEBT-Posteromedial P = .024; SEBT-Posterolateral P < .001; TTDPM-Inversion P = .042) and patient-oriented outcome measures (Foot and Ankle Ability Measure-Activities of Daily Living P < .001; Foot and Ankle Ability Measure-Sport P = .001; Fear Avoidance Belief Questionnaire P = .021) following a single DN treatment. Compounding effects from additional treatments exhibited improvement of TTDPM (T1B to T2). No significant losses were noted 4 weeks after cessation of treatment (T2 to T3).

Conclusion: For the participants in this study, outcomes improved immediately following the first DN treatment. This improvement was sustained but not further improved with subsequent treatments.