Je. Bechtold et al., THE EFFECTS OF FREEZE-DRYING AND ETHYLENE-OXIDE STERILIZATION ON THE MECHANICAL-PROPERTIES OF HUMAN PATELLAR TENDON, American journal of sports medicine, 22(4), 1994, pp. 562-566
Human patellar tendon allografts are used to replace injured anterior
cruciate ligaments. They are often stored by freeze-drying or freezing
before use and have been sterilized by gamma irradiation or ethylene
oxide gas. Studies comparing the mechanical properties of tendons pres
erved by freeze-drying and sterilized by ethylene oxide have yielded c
onflicting results. This study examined the effects of freeze-drying a
nd ethylene oxide sterilization on the mechanical properties of human
patellar tendons obtained from 11 human cadavers; all were free of mus
culoskeletal disease. The 22 patellar tendons were halved longitudinal
ly; 7 were frozen at -70-degrees-C for 8 weeks and served as controls;
8 were freeze-dried; and 7 were freeze-dried and sterilized with ethy
lene oxide gas. Ultimate tensile stress and longitudinal strain were g
reater for frozen than for freeze-dried, but not greater than freeze-d
ried, ethylene oxide-sterilized tendons (P < 0.05). The modulus of ela
sticity was similar in all tendon groups. The study suggests that some
in vitro mechanical properties of frozen tendons may be marginally su
perior to the properties of freeze-dried tendons, even after correctio
n for size difference. Ethylene oxide gas sterilization had no adverse
effect on tendon mechanical properties.