The achilles tendon is the big tendon at the back of the ankle.
Achilles tendon harvest
Tissue banks may 'harvest' this tendon from human donors and it is freeze-dried and stored for transplant (eg to the knee), where it can be used for a variety of purposes to strengthen areas in the recipient patient where their own natural body tissues have failed. Such a graft of human tissue from another person is called an allograft.
Survivorship of allograft ACL reconstruction in adolescent patients. Soneru A and Sarwark JF. J Orthop. 2018 Dec 6;16(1):11-13. doi: 10.1016/j.jor.2018.11.004. eCollection 2019 Jan-Feb.