Knee tissue that's prone to tearing, for short

ACL

This key ligament connects the thigh bone to the shin and is often injured during sudden stops or direction changes in sports.

This clue refers to the anterior cruciate ligament, a key tissue in the knee that stabilizes the joint and is commonly injured in sports. The "for short" hint signals that the answer is an abbreviation, so instead of spelling out the full name, you use its three-letter initials: ACL. Athletes and doctors often talk about "tearing an ACL," making it a well-known term even outside medical circles.