Blog Post Author Biography: Luke Donovan is an Associate Professor at the University of North Carolina at Charlotte in the Department of Applied Physiology, Health, and Clinical Sciences and a certified athletic trainer. Dr. Donovan’s research aims to develop clinical measurement techniques for assessing gait and rehabilitation strategies among patients with chronic ankle instability.

Citation: Shein Lumbroso D, Gottlieb U, Zimmerman DR, Springer S. Functional tests as predictors of ankle instability six months after an acute lateral ankle sprain. J Sports Med Phys Fitness. 2023 Apr;63(4):570-579. doi: 10.23736/S0022-4707.22.14395-1.

Take-to-the-clinic message: Following an acute lateral ankle sprain, balance performance on foam in tandem stance, willingness to perform a single-limb drop landing task, and limb-dominance of the injured ankle were associated with the development of ankle instability 6-months after the initial injury. Clinicians can use these functional tasks and descriptive information to identify patients that may be at a greater risk of experiencing residual symptoms following a lateral ankle sprain. 

Background: Lateral ankle sprains (LAS) are one of the most common musculoskeletal injuries among individuals who are physically activity. It has been estimated that as high as 2 out of 3 individuals who experience a LAS develop a long-term condition characterized by repetitive ankle sprains and/or feelings of instability known as chronic ankle instability (CAI). Identifying individuals at risk of developing CAI as close to the initial injury as possible may help clinicians implement rehabilitative strategies to mitigate the development of the chronic condition. Given the sensorimotor disruption affiliated with CAI, the authors hypothesized that functional tasks that require attention and cognitive demand would be capable of discriminating between individuals who recover from the LAS (copers) vs individuals who do not (ankle instability).

Purpose: The purpose of this study was to prospectively determine whether performance on various functional tasks within 3-weeks of an acute LAS, as well as other demographic information could predict ankle instability outcomes 6-months after the initial injury. Specifically, the authors evaluated performance on the balance error scoring system (BESS) with a dual-cognitive task (Modified-BESS), a single-limb drop landing (SLDL) task and drop-vertical jump (DVJ) task.

Methods: The authors completed a prospective study of individuals who experienced a LAS within 3-weeks of data collection. To be included in the study, participants were required to be between the ages of 18 and 35. In addition, the LAS must have been associated with inflammatory symptoms and caused at least 1-day of interruption in their physical activity. 

Participants who enrolled in the study completed a one-hour data collection session. During this session, participants provided demographic information (age, gender, weight, height, injured leg, dominant leg, and physical activity). Next, participants completed the Modified-BESS, the SLDL, and the DVJ tasks. The Modified-BESS task reflected the previously reported BESS procedures (eyes closed balancing on firm/foam surfaces during double-limb, single-limb and tandem stance), but also included a dual-task component (Backward Digits Span Task). A 40-cm box was used for both the SLDL and DVJ tasks. After completing the data collection sessions, participants were contacted every month to determine whether they re-injured the involved ankle. After 6-months, participants completed the Cumberland Ankle Instability Tool (CAIT) to determine their status as either potential ankle instability or potential copers. Since a patient is not considered to be diagnosed with CAI until 12-months post-injury, the authors found the term ‘potential’ to be most appropriate.  Individuals who scored lower than a 24 on the CAIT and/or experienced any re-sprain during the follow-up period were classified as ‘potential ankle instability’. Participants who scored 24 or greater on the CAIT and did not experience any re-sprains were classified as ‘potential copers’. 

Results: Thirty-three individuals completed the study where 21 of the individuals met the potential ankle instability criteria 6-months following their initial injury. Specific to the main outcome measures, the authors found that for every 1-point increase observed on the Foam-Tandem stance task (part of the Modified BESS) increased the odds of developing ankle instability by 1.5. In addition, participants who were unwilling to complete the SLDL increased their odds of developing ankle instability by 10. Finally, individuals who sustained a LAS to their non-dominant limb had a 6 times greater odds of developing ankle instability when compared to individuals who sprained the ankle on the dominant limb. 

Rolling the field forward: The authors report that various functional tests, as well as demographic information may help clinicians prospectively identify individuals at a heightened risk of developing ankle instability 6-months after the initial injury. Clinicians can incorporate functional tasks as an evaluation tool to help guide the return to activity process.

Question for the researchers: The criteria required participants to be within 3-weeks of the LAS at the time of data collection; however, the time since injury was not reported. Did the authors observe differences in time since ankle sprain among participants? Do the authors have a recommendation as to when clinicians should incorporate these functional tasks as part of their evaluation?