People sometimes refer to ACL reconstruction surgery as “ACL repair.” Unfortunately, we can’t surgically repair a torn ACL.
ACL reconstruction surgery involves drilling bone tunnels into the tibia and femur, removing the torn ACL fibers, harvesting a tendon from your body (or from a cadaver), and affixing that tendon to your tibia and femur in place of what was previously your ACL.
As I understand it the tendon forms a matrix that allows a ligament to regrow along it. At around 3 months the tendon graft dies off and the ligament tissue continues to grow.
ACL reconstruction surgery involves drilling bone tunnels into the tibia and femur, removing the torn ACL fibers, harvesting a tendon from your body (or from a cadaver), and affixing that tendon to your tibia and femur in place of what was previously your ACL.