The posterolateral corner of the knee is a very complex area with many important structures which are intricately related to prevent both increased lateral compartment gapping and rotation. There are many different tests which are utilized to assess for posterolateral rotatory instability of the knee. While some examiners feel that the increased amount of varus gapping and/or external rotation can be separated into the different components; in affect all of these structures in the posterolateral corner of the knee contribute to varus and rotatory instability, so one is primarily looking at injuries to a portion of this complex rather than looking at different ways to classify these injuries.

Posterolateral instability can be a very difficult problem to treat, diagnose, and for patients to function. It is not uncommon for patients to have difficulty with normal level gait with posterolateral instability.