Lack of Definition of Chronic Ankle Instability With Arthrometer-Assisted Ankle Joint Stress Testing: A Systematic Review of In Vivo Studies

Despite extensive research on ankle instability a consensual and clear objective definition for pathological mechanical lateral ankle instability is yet to be determined. This systematic review aimed to summarize current available arthrometric devices, measuring methods and lateral ankle laxity outcomes in patients with chronic ankle instability that underwent objective arthrometric stress measurement. Sixty-eight studies comprising a total of 3,235 ankles with chronic ankle instability were included. Studies reported a wide range of arthrometric devices, testing position and procedures, and measuring methods. For the anterior drawer test, the average mean differences between injured and uninjured ankles ranged from -0.9 to 4.1 mm, and total translation in the injured ankle from 3.2 to 21.0 mm. Most common pathological threshold was ≥4 mm or ≥10 mm unilaterally and ≥3 mm bilaterally. For the talar tilt test, the average mean differences between injured and uninjured ankles ranged from 0.0° to 8.0°, and total tilt from injured ankle from 3.3 to 60.2°. Most common pathological threshold was ≥ 10° unilaterally and ≥ 6° mm bilaterally. It was found high heterogeneity in the scientific literature regarding the arthrometric devices, use of concomitant imaging and measuring methods of arthrometer-assisted anterior drawer and talar tilt tests which led to variable laxity outcomes in individuals with chronic ankle instability. Future studies should focus on standardizing the testing and measuring methods for an objective definition of mechanical ankle instability.