Editorial Commentary: A Positive "Half Dial Test" Is Seen in Anterior Cruciate Ligament Injury, so Get Out Your Goniometer.

Isolated anterior cruciate ligament (ACL)-deficient knees have roughly 7° of increased external rotation at both 30° and 90° of flexion compared with both the contralateral knee and the ACL reconstructed knee. This positive "Half Dial test" may be a new approach to confirming ACL injury but requires confirmation that the posterolateral corner itself is not injured. In the ACL-deficient knee, it is suggested that a greater cutoff (>15°) for the true Dial test be used to confirm posterolateral corner injuries. Goniometer measurements are reproducible and necessary for confirmation.