Uneven Treadmill Training for Rehabilitation of Lateral Ankle Sprains and Chronic Ankle Instability: Protocol for a Pragmatic Randomized Controlled Trial

Abstract

Background: Lateral ankle sprains (LASs) are common injuries among military service members. Approximately 40% of individuals with an LAS progress to develop chronic ankle instability (CAI), a condition that results in substantial mechanical and neurophysiological impairment and activity limitation. Since proprioceptive and balance training improve functional outcomes and prevent secondary injury following LAS, they are recommended in clinical practice. Uneven treadmills are an innovative modality that challenge the sensorimotor system while performing an ecologically valid task simulating environments frequently encountered by service members with LAS and CAI.

Objective: The aim of this study is to evaluate whether the inclusion of uneven treadmill training in standard rehabilitation can improve clinical, functional, biomechanical, and patient-reported outcomes compared with the standard of care alone in service members with LAS and CAI. The prophylactic effects of treatment on secondary injury and identification of any contributing or mediating factors that influence outcomes following treatment will also be evaluated. We hypothesize that service members receiving uneven treadmill training will demonstrate greater improvements in clinical and instrumented measures of impairment, patient-reported function, and lower risk of injury recurrence than the control group immediately post and 18 months following treatment.

Methods: A multisite, parallel randomized clinical trial will be performed among service members aged 18-49 years being treated for LAS and CAI in military treatment facilities in the United States. Participants randomly assigned and allocated to receive the experimental intervention will be provided up to 12 sessions of training on an uneven terrain treadmill over a 6-week treatment course to supplement standard rehabilitation care. Treatment intensity of the rehabilitation exercises and treadmill training will be progressed on the basis of patient-perceived intensity and treatment responses. Outcome measures will include patient-reported outcomes, functional assessments, performance measures, and biomechanical measures. Investigators collecting outcome measures will be blinded to treatment allocation. Reinjury rates and patient-reported outcomes of function will be tracked over 18 months following treatment.

Results: The project was funded in September 2020. Patient recruitment began in November 2021, with 3 participants enrolled as of February 2022. Dissemination of the main study findings is anticipated in 2024.

Conclusions: This study will assess the impact of an innovative uneven-terrain treadmill on treatment outcomes in the rehabilitation of service members with LAS and CAI. The results of this study will be used to inform rehabilitation practices and to potentially improve functional outcomes and secondary prevention in this patient population.

Trial registration: ClinicalTrials.gov NCT04999904; https://ichgcp.net/clinical-trials-registry/NCT04999904?term=NCT04999904.

International registered report identifier (irrid): DERR1-10.2196/38442.

Keywords: ankle injuries; ankle sprain; military personnel; recovery of function; rehabilitation; secondary prevention; treadmill.

Conflict of interest statement

Conflicts of Interest: None declared.

©Elizabeth Russell Esposito, Shawn Farrokhi, Benjamin R Shuman, Pinata H Sessoms, Eliza Szymanek, Carrie W Hoppes, Laura Bechard, David King, John J Fraser. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 22.06.2022.

Figures

Figure 1

The custom uneven-terrain treadmill. Participants allocated to the experimental treatment will be provided a progressive gait retraining program in addition to standard rehabilitation care.

Figure 2

The CONSORT (Consolidated Standards of Reporting Trials) flow diagram. ADL: activities of daily living subscale, CAIT: Cumberland Ankle Instability Tool, EMG: electromyography, FAAM: Foot and Ankle Ability Measure, Godin: Godin-Shepard Leisure-Time Physical Activity Questionnaire, LEFS: Lower Extremity Functional Scale, NPRS: numeric pain rating scale, SEBT: Star Excursion Balance Test, TSK: Tampa Scale of Kinesiophobia.

Figure 3

The direct acyclic graph of the Bayesian model acts like a causal diagram. In the model, the explanatory variables {X1, . . . , X6}: age, sex, BMI, pain intensity, weight-bearing status, and initial injury severity. These variables causally affect the subject-specific slopes and the y-intercepts. However, the slopes and y-intercepts of the responses are not directly observed, so they are considered latent variables. In the diagram, the shaded circles are directly observed variables, and the unshaded circles are latent variables. The Bayesian model has 2 levels of hierarchy: the first one establishes the best fit line that goes through the observed subject responses; the second one establishes how the explanatory variables {X1, . . . , X6} affect the slopes and y-intercepts. The regression parameters {η0, . . . , η6} are those that affect the slope of the subject responses and, as such, are particularly important because they affect the healing rate. Variables that significantly affect the healing rate will be retained in the model if the credible intervals for the regression parameters {η0, . . ., η6} do not include 0.