Knee ligament tests are physical examinations used to assess the integrity of the knee's ligaments, which can be injured by sprains or tears. These tests help determine if there is damage to the anterior cruciate ligament (ACL), medial collateral ligament (MCL), lateral collateral ligament (LCL), or posterior cruciate ligament (PCL). Common tests include the Lachman test, anterior drawer test, posterior drawer test, valgus stress test, and varus stress test.