Effect of internal rotation of the hindfoot on diagnosis of anterior talofibular ligament injury: An in vitro simulation study.

BACKGROUND

The anterior drawer test of the ankle is widely used to diagnose anterior talofibular ligament injuries caused by ankle sprains; however, low sensitivity has been reported. The braking effect of the deltoid ligament is likely responsible for this low sensitivity. This study aimed to examine the effect of consistent and mandated internal rotation of the hindfoot, which leads to relaxation of the deltoid ligament, on the conventional anterior drawer test.

METHODS

Seven cadaveric ankle specimens were subjected to quantitative analysis with a stretchable strain sensor at 30° plantarflexion, with or without 10° internal rotations, under accurate three-axial joint angle monitoring using inertial measurement units. The anterior drawer distance (mm) was calculated from the measured change in the capacitance value (picofarad) detected using the stretchable strain sensor and compared with that measured with the anterior talofibular ligament detached.

FINDINGS: A two-way repeated measures analysis of variance and post-hoc pairwise analysis revealed that the anterior drawer test with internal rotation revealed a significantly greater mean value than the conventional anterior drawer test (4.7 ± 1.6 mm vs. 2.2 ± 1.5 mm) in anterior talofibular ligament-detached samples (P < 0.001). The capacitance data revealed an intraclass correlation coefficient (1,1) of 0.903.

INTERPRETATION: Present findings suggest that our modified anterior drawer test with consistent and mandatory internal rotation, prevents the braking effect of the deltoid ligament and is expected to improve the sensitivity in assessing anterior talofibular ligament injuries.