Two Cases of Isolated Lateral Collateral Ligament Knee Strain in Footballers Presenting with a Novel Mechanism of Injury and Novel Examination Findings

We describe a previously unknown mechanism of injury for isolated lateral collateral ligament strain as well as a novel clinical sign. The mechanism of injury is poorly understood and testing of the LCL is challenging and so we aim to add to the evidence base in this area. We present two cases in professional football where LCL injury occurred after passing the ball laterally using forced external rotation of their feet with the knee in extension. Varus stress test was negative in both cases, but the pain was reproduced in long-legged sitting with the left leg crossed over the right at the ankle. This is a novel mechanism of injury with potential for a new clinic sign. Increased awareness of this mechanism of injury may allow clinicians to identify other cases in the future. Furthermore, with additional investigation, this provocative position could give rise to a new clinical sign.