Evaluation Of Smartphone-Based Assessment System In Chronic Ankle Instability

Abstract

Ankle sprains are the most common sports-related injury. About 80% subjects suffer recurrent sprains. Repeated injuries may cause chronic ankle instability, which will affect sports efficacy and postural control ability. In recent years, smartphones had become very popular and powerful devices, and been showed to have good validity on measuring range of motion and assessing gait patterns. The purpose of this study is to evaluate the feasibility of smartphone-based system in postural control ability assessment on chronic ankle instability. METHODS: Fifteen subjects (6 male, 9 female; age=23.4±5.28 y/o) who have at least one leg scoring lower than 27 points in Cumberland Ankle Instability Tool were recruited. ASUS Zenfone 2 smartphone was used to conduct the postural control assessment, by recording its built-in accelerometer data with an App developed using MIT App inventor. Subjects performed single leg stance for 20 seconds in eyes-open and eyes-closed conditions with each leg. The smartphone was fixed on the middle of shin with an exercise armband. The average of recorded acceleration data was used to represent the postural control performance, and the higher value indicated more instability. Data was analyzed with paired t-test with SPSS 17.0, and statistical significance was set as alpha < 0.05. RESULTS: Significant difference was found between sound leg and injured leg under both eyes-open and eyes-closed conditions (eyes-open: sound leg 0.051±0.018 vs injured leg 0.072±0.034, p=0.027; eyes-closed: sound leg 0.100±0.031 vs injured leg 0.123±0.038, p=0.001, unit: g). Significant difference was also found between eyes-open and eyes-closed conditions under both single leg standing with sound leg and injured leg (sound leg: eyes-open 0.051±0.018 vs eyes-closed 0.100±0.031, p<0.001; injured leg: eyes-open 0.072±0.034 vs eyes-closed 0.123±0.038, p=0.001, unit: g). The results demonstrate that the smartphone can be used to discriminate the different performance between sound leg and injured leg, and also between eyes-open and eyes-closed conditions. CONCLUSION: The study shows that smartphone may have the potential to be a convenient, easy-used and valid tool for assessment of postural control ability on chronic ankle instability.