An allograft is transplant of tissue that did not originate from the patient but from another person.
Allografts in knee surgery
An allograft is in reality a 'transplant' - where a graft is 'harvested' (taken) from one person ('the donor') and put into another person ('the recipient'). In knee surgery, we usually refer to allografts in the context of the menisci or cruciate ligament. In the latter, hamstrings tendon, fascia lata, patellar tendon or achilles tendon may be taken taken from the donor and freezedried to eventually replace a damaged cruciate ligament in the recipient.
(NB. The word is never spelled or pronounced 'allograph' - this is a typo that is often found in consumer bulletin boards.)
Anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone allograft: matched case control study Kwak Y-H, Lee S, Lee MC and Han H-S. BMC Musculoskelet Disord. 2018; 19: 45.
Impact of storage conditions on electromechanical, histological and histochemical properties of osteochondral allografts. Mickevicius T, Pockevicius A, Kucinskas A, Gudas R, Maciulaitis J, Noreikaite A and Usas A. BMC Musculoskelet Disord. 2015; 16: 314.