The anterior cruciate ligament (ACL) is not so named to reflect a preoccupation with an anatomic structure. It is the crucia/ligament. Crucial, not because the knee cannot function without it, but because it stands as a challenge to the soft tissue surgeon. When the repair or reconstruction of this ligament is solved, then the soft tissue surgeon can approach his task with the same confidence, same aggressiveness, and the same certainty as we now approach hard tissues - thanks to the contributions of Charnley, Wagner, Weber, and the AO school.