(English captions by Jade Cheng from the Universtiy of Michigan)
Ulnar collateral ligament testing of the thumb is performed to evaluate for instability found
on a gamekeeper's or skier's thumb.
After stabilizing the first metacarpal, a valgus stress is applied to the thumb at the
metacarpophalangeal joint.
Laxity indicates a partial or complete ulnar collateral ligament tear.