(English captions by Jade Cheng from the Universtiy of Michigan)

Ulnar collateral ligament stability can be
tested at zero and thirty degrees of flexion

by applying a valgus force to the finger.

Radial collateral ligament stability can also
be tested at zero and thirty degrees of flexion

by applying a varus force to the finger.

Laxity indicates a partial or complete ligament
tear.