A preliminary study of an ultrasound-based method for measuring talar displacement during the anterior drawer stress test using a Telos device

Abstract Background Conventionally, X-ray examination has been performed to quantify the instability of the ankle joint. The aim of this study was to evaluate the reliability and validity of a new ultrasound-based examination for the quantitative detection of ankle instability, and whether the present examination could replace the conventional X-ray test. Methods Thirteen adults were recruited for this validation study and were divided into two groups: a control group (eight adults, 16 feet) and an ankle instability (AI) group (five adults, eight feet). The control group had Cumberland Ankle Instability Tool (CAIT) scores ≥ 25 points, and the AI group had CAIT scores < 25 points. Anterior drawer stress tests were performed using a Telos device with ultrasound (0–150 N) and X-ray (0, 120, and 150 N). The stress ultrasound was performed by two examiners, and changes in the anterior talar displacement were measured by two measurers. The inter-examiner and inter-measurer reliabilities were calculated in the control group, and correlations between stress ultrasound and conventional stress X-ray imaging results were examined at 120 and 150 N in both the control and AI groups. Results Ultrasound imaging detected changes in the anterior talar displacement under loads greater than 70 N. The inter-examiner and inter-measurer reliability of the ultrasound-based method were moderate and excellent, respectively, at 150 N. The tibiotalar distances observed with X-ray and ultrasound imaging at 120 N were highly correlated in the AI group. Conclusion The ultrasound-based method was comparable to the conventional X-ray method and represents a novel radiation-free method for the detection of ankle instability. This method has the potential for clinical application to quantitatively evaluate mechanical instability.