Ulnar Collateral Ligament Sprains (Gamekeeper's Thumb; Skier's Thumb) By Danielle Campagne, MD, University of California, San Francisco Reviewed / Revised Mar 2021 | Modified Sep 2022 View Patient Education Diagnosis Treatment Topic Resources Torn ulnar ligament Thumb spica splint Ulnar collateral ligament sprains of the thumb are common and sometimes disabling.