With a valgus stress test at 0°, one is assessing for the potential of a combined medial knee and cruciate ligament injury. When one applies a valgus force to the knee in full extension, the amount of medial gapping which occurs with an isolated medial knee injury is only 1-2 mm. When there is more gapping than this, one must be concerned that there is a combined ACL or PCL injury.
The valgus stress testat 0° is performed with the knee in extension. Ones fingers should be directly applied over the joint line. A valgus force is then applied through the foot or ankle to apply stress to the knee to determine if there is any gapping present. position valgus stress test at 0° in concerning because it has been reported that patients with this instability have a lower likelihood of healing their medial knee injury.