Validation of a Chinese Translation of the Identification of Functional Ankle Instability Questionnaire
Ankle sprains are among the most common sports injuries, accounting for approximately 40% of all sports-related injuries. Among these, 20% to 33% result in ankle instability, a condition that can significantly impair an individual’s mobility and quality of life. Functional ankle instability (FAI) is a specific type of ankle instability that lacks a precise and widely accepted measurable definition. Despite this, FAI is often treated by surgeons, particularly when it is associated with injuries to the anterior talofibular ligament, calcaneofibular ligament, or both. In China, the absence of a validated tool to assess FAI has led to unnecessary ligament-repair surgeries based solely on imaging evidence of ligament injury and potential FAI, often resulting in unsatisfactory outcomes.
The International Ankle Consortium has recommended several self-reported questionnaires to assess FAI, including the Ankle Instability Instrument, the Cumberland Ankle Instability Tool, and the Identification of Functional Ankle Instability (IdFAI) questionnaire. The IdFAI, which is based on the first two questionnaires, has been shown to have the highest accuracy among the three. While the original English version of the IdFAI has been translated into multiple languages and validated in Japanese, Korean, Brazilian, and Persian, no validated Chinese version existed until this study. Given that China has the highest number of patients with FAI, the development of a Chinese version of the IdFAI (IdFAI-C) is of significant clinical importance.
The process of translating the IdFAI into Chinese followed established guidelines for the cross-cultural adaptation of self-report measures. The translation process involved several steps to ensure accuracy and cultural relevance. First, two independent bilingual translators—a foot-and-ankle surgeon and an English teacher, both native Chinese speakers—separately translated the IdFAI into Chinese. They then met to resolve any differences in their translations. Next, two independent bilingual translators, both native English speakers, back-translated the initial Chinese version into English. This back-translated version was compared to the original English version to confirm the accuracy of the translation. A preliminary version of the IdFAI-C was then created by a panel that included two additional foot-and-ankle surgeons, two experienced English teachers (native Chinese speakers), and the initial four translators. Finally, 20 Chinese college students completed the preliminary version and were interviewed to ensure that each question was understood correctly. The final version of the IdFAI-C was made available in Supplementary Table 1.
To validate the IdFAI-C, college students were recruited through the Internet from March 17 to 29, 2019. The recruitment statement encouraged sports-active volunteers to participate, as the study aimed to include individuals with symptoms of instability. Exclusion criteria included: (1) students who had undergone lower-limb surgeries or had lower limb fractures; (2) students who had suffered severe leg injuries in the previous three months that required more than one day of rest. All enrolled students were asked to complete the IdFAI-C within 10 minutes. One month later, 100 of these students were asked to complete the IdFAI-C a second time, also within 10 minutes.
The validation process used the widely accepted “minimal acceptable criteria” for FAI as the discriminative measure. These criteria require that an individual must have suffered at least one ankle sprain in the affected limb and must describe symptoms or incidences of “giving way” in that same limb. Students who met these criteria were expected to score higher on the IdFAI-C. The Youden index (sensitivity + specificity – 1) was calculated for each cutoff score to determine the optimal diagnostic score. A receiver operating characteristic curve was also calculated to assess discriminative validity. Diagnostic accuracy was reported as the percentage of true positive results among all results at the optimal cutoff score. The internal consistency of the IdFAI-C was evaluated using Cronbach’s alpha, and test-retest reliability was assessed using the intra-class correlation coefficient from scores provided by the same 100 volunteers who completed the questionnaire again after one month.
Of the 358 volunteers from 51 different colleges and 21 different cities across China, 74 were excluded based on the exclusion criteria: 20 students had undergone lower-limb surgeries, 28 had suffered lower limb fractures, and 50 had experienced severe leg injuries in the previous three months that required more than one day of rest. Additionally, 16 invalid questionnaires were excluded due to inconsistent answers. The remaining 268 students (mean age, 25 ± 6 years old; 142 women) were eligible for the study. Among these, 126 exercised more than three times a week for more than 90 minutes a week, and 176 had a history of ankle sprain.
The Youden index indicated that a cutoff score of 7 was optimal for defining FAI. Students with FAI typically scored 8 or above, while those without FAI scored 7 or below. The area under the receiver operating characteristic curve for this cutoff score was 0.89 (95% confidence interval, 0.86–0.93), indicating that the questionnaire can adequately distinguish between students with and without FAI. The optimal cutoff value of 7 was 94% sensitive and 73% specific for FAI. The diagnostic accuracy of the translation was 0.79. Cronbach’s alpha was 0.80, indicating high internal consistency, and the intra-class correlation coefficient was 0.98, indicating high test-retest reliability.
The Chinese translation of the IdFAI exhibited higher sensitivity and lower specificity compared to the original English version. The cutoff point of 7 was lower than that used in other versions, which may be attributed to cultural differences in seeking medical care after sports injuries. Many Chinese individuals prefer to rest at home and use traditional Chinese patent medicine rather than visiting a doctor unless severe symptoms are present. This tendency was reflected in the responses to question 3 of the IdFAI-C, where nearly half of the participants with a history of ankle sprain (84/176) reported not having seen a professional. Additionally, the translation process faced challenges in capturing the nuance of certain idiomatic expressions, such as “giving way.” The chosen Chinese term, “Shi Kong Gan,” was not universally understood by all participants, leading to the inclusion of an explanatory sentence in the final version of the questionnaire.
Despite its strengths, the study had some limitations. It focused exclusively on college students, and the discriminative ability of the IdFAI-C may vary across different age groups and professions. Additionally, the study relied on volunteers, which may have introduced bias. However, the IdFAI-C demonstrated high discriminative validity, reliability, and accuracy, making it a suitable tool for Chinese physicians and foot-and-ankle surgeons to use in clinical practice.
In conclusion, the development and validation of the Chinese translation of the Identification of Functional Ankle Instability questionnaire represent a significant advancement in the assessment of FAI in China. The IdFAI-C provides a reliable and accurate tool for identifying individuals with FAI, potentially reducing the incidence of unnecessary surgeries and improving patient outcomes.
doi.org/10.1097/CM9.0000000000001020
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