Repairing a ruptured anterior cruciate ligament (ACL) depends on ligament substitutes. Tissue from some other part of the body or from a donor is needed to take the place of the torn ACL.

Most often the graft tissue is taken from the patient's hamstrings muscle or the patellar tendon. This is called an autograft.

When the hamstring is used, the harvested tissue is folded in half twice to make a stronger graft. When the patellar tendon is harvested, a small plug of bone is taken on both ends and used in the repair process.

Donor tissue from a cadaver is also possible. This is referred to as an allograft. It can be taken from the patellar tendon, hamstrings, or Achilles tendon.