Can a single question replace the Cumberland Ankle Instability Tool? Diagnostic accuracy of the Simple Foot and Ankle Value for screening functional ankle instability: a multicentre cross-sectional study
In a multicentre cross-sectional study of 717 adults, the single-question Simple Foot and Ankle Value (SFAV) demonstrated superior diagnostic accuracy compared to the 21-item Cumberland Ankle Instability Tool (CAIT) and other questionnaires for screening functional ankle instability, supporting a score below 90 as an efficient first-line triage rule that significantly reduces the need for lengthy assessments.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Ankle sprains are among the most common injuries people suffer, yet for many, the problem does not end when the swelling goes down. Instead, the joint may feel unreliable, giving way during a simple step or a turn, even years after the initial injury. This lingering sense of instability, known as functional ankle instability, is widespread and often goes unnoticed in the general population. Because it is so common, doctors and physical therapists have long sought a quick way to identify who is struggling with this issue so they can offer simple, low-cost exercises to prevent future falls and injuries. The standard tool for finding these cases, however, is a detailed questionnaire that takes several minutes to complete for each foot, making it impractical to use during a brief visit with a busy physician. The question facing researchers was whether a single, simple question could do the same job as this lengthy test, allowing for a rapid check that could be done almost anywhere.
A team of researchers in France set out to answer this question by testing a new, one-question screening method against the established standard. They gathered a large group of adults who were visiting orthopedic clinics not for their own ankle problems, but to accompany patients. This approach was chosen to ensure the group represented a broad cross-section of the community rather than just people already complaining of ankle pain. Each participant filled out a questionnaire that included the standard nine-question test for ankle instability, a longer twenty-one-question survey about daily activities, and the new single question. The new question asked people to rate their ankle's function as a percentage of normal, where one hundred percent meant perfect function and zero meant no function at all. The researchers defined a case of instability based on the standard test, looking for scores that indicated the ankle felt untrustworthy.
The results showed that the single question was remarkably effective at identifying people with functional ankle instability. In a group of over seven hundred people, the researchers found that nearly twenty-eight percent had signs of instability according to the standard test. When they looked at how well the single question performed, it correctly identified more than ninety percent of these cases. The researchers determined that if a person rated their ankle function at less than ninety percent, they should be considered for further testing. Using this simple cutoff, the screening process would have saved time by avoiding the longer, nine-question test for about sixty-one percent of the people in the study. In other words, for the majority of people who answered the single question with a high score, no further investigation was needed. For the smaller group who scored lower, the longer test would then be administered to confirm the diagnosis.
This single-question method actually performed better than the longer, twenty-one-question survey that is often used to measure foot and ankle health. The longer survey struggled to distinguish between people with mild instability and those with no issues at all, largely because many people in the general population scored the maximum possible points on it, creating a ceiling effect where the test could not detect subtle problems. The single question, by contrast, was sensitive enough to pick up on the feeling of unreliability even in people who did not consider themselves severely disabled. The study confirmed that this quick check works well across different ages, genders, and activity levels, and it remains reliable even if the definition of instability is adjusted slightly.
The researchers were careful to note that this finding applies specifically to the feeling of instability, which is what the standard test measures. It does not yet prove that this single question can diagnose the more complex condition of chronic ankle instability, which requires a documented history of specific injury events that were not recorded in this study. However, for the purpose of a first-line screen in a busy clinic, the evidence is strong. A single question asking for a percentage rating of ankle function can efficiently sort people into two groups: those who are likely fine and those who need a closer look. This approach offers a practical way to bring attention to a common, often hidden problem, ensuring that more people can receive the simple balance training that helps prevent future injuries.
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