Clinical measurement of mechanical ankle instability

Clinicians commonly use the anterior draw test (ligament laxity) and distal fibular position (lateral malleolus displacement), to measure ankle instability. The purpose of this study was to establish intra-rater and inter-rater reliability for the anterior draw test and distal fibular position in a clinical setting. The anterior draw test (AD) was measured with a plastic Goniometer, and was defined as the linear displacement of the foot as it is drawn anteriorly with the ankle held in 20 degrees of plantar-flexion. Distal fibular position (DFP) was measured in standing using a digital vernier caliper and was the relative linear distance between the lateral and the medial malleoli. 20 participants aged 21-28 volunteered for the study and were measured on both ankles. It was found that Intra-tester reliability (ICC) ranged from 0.88 to 0.97 for AD and DFP; while inter-tester reliability (ICC) was 0.6 for AD and 0.77 for DFP. In addition for measures across trials, the standard error of the measurement (SEM) was, on average 0.66 mm for AD and 1.7 mm for DFP. While the limits of agreement (LOA) was ±0.17 mm for AD and ±4.03 mm for DFP. However, the SEM and LOA between testers was 2.27 mm and ±2.27 mm respectively for AD; and for 3.1 mm and ±10.4 mm for DFP. Overall the results suggest that both measures, as defined in this study exhibit moderate to good reliability and low standard error of measurement, suggesting a high degree of repeatability across trials.