The effect of donor age and low-dose gamma irradiation on the initial biomechanical properties of human tibialis tendon allografts.
BACKGROUND
Most tissue banks recover and irradiate tibialis tendon allografts from donors aged up to 65 years. It is unknown whether donor age and low-dose gamma irradiation affect the initial biomechanical properties of tibialis allografts.


OBJECTIVE
Donor age up to 65 years and low-dose gamma irradiation do not significantly affect the initial biomechanical properties of tibialis allografts.


METHODS
Controlled laboratory study.


METHODS
One hundred twenty-six tibialis tendon allografts (63 pairs, 37 human donors) were divided into 3 age groups: young (<45 years), middle (46-55 years), and old (56-65 years). Within each age group, half of the paired tendons underwent tensile testing as single-strand grafts and the other half as double-strand grafts. One tendon from each donor pair was randomly assigned to undergo terminal sterilization with an absorbed dose of 1.46 to 1.80 Mrad (14.6-18.0 kGy) gamma irradiation, whereas the other tendon received no irradiation. All tendon grafts were preconditioned with a cyclic load and tested to failure in tension.


RESULTS
Irradiated single-strand tendons in the old age group had a longer displacement at failure compared to the middle but not the young age group. Nonirradiated double-strand tendons in the old age group had a lower failure stress. Single-strand irradiated old tendons had a lower stiffness, and all irradiated young tendons and old double-strand tendons had a higher failure stress compared to nonirradiated tendons.


CONCLUSIONS
Donor age up to 65 years does not significantly affect the initial failure load, stiffness, or displacement at failure of tibialis allografts. An age-related decrease in failure stress was observed among nonirradiated tendons but not in tendons subjected to irradiation.


CONCLUSIONS
The results provide biomechanical evidence for use of tibialis allografts from donors up to 65 years of age. Low-dose gamma irradiation does not negatively influence the initial biomechanical properties of tibialis allografts. Further studies examining age and irradiation effects after submaximal cyclic loading conditions are recommended.
Greaves
Laura L
LL
Division of Orthopaedic Engineering Research, Department of Mechanical Engineering, University of British Columbia and Vancouver General Hospital, 828 West 10th Ave, Room 500, Vancouver, BC V5Z 1L8, Canada. lauragreaves@gmail.com
Hecker
Aaron T
AT
Brown
Charles H
CH
D000328:Adult; D000367:Age Factors; D000368:Aged; D001696:Biomechanical Phenomena; D005720:Gamma Rays; D006801:Humans; D008875:Middle Aged; D011829:Radiation Dosage; D013710:Tendons / Q000502:physiology* / Q000528:radiation effects*; D009927:Tissue and Organ Procurement; D014184:Transplantation, Homologous