Dose-dependent response of gamma irradiation on mechanical properties and related biochemical composition of goat bone-patellar tendon-bone allografts.
We studied the effects of gamma irradiation on the dimensions, mechanical and material properties, and mature hydroxypyridinium crosslink density of collagen in goat patellar tendon-bone specimens. Left and right patellar tendon-bone units were removed from 10 adult female goats and were bisected longitudinally. Each tendon half was frozen, and then the left halves were exposed to 4, 6, or 8 Mrad (40,000, 60,000, or 80,000 Gy) of gamma irradiation. The contralateral tendon halves served as controls (no irradiation). Each specimen then was loaded to failure in tension, and its soft-tissue midsubstance was processed to measure collagen content and hydroxypyridinium crosslink density. Dose-dependent reductions in the mechanical properties were found, including 46% (p < 0.01) and 18% (p < 0.05) reductions in maximum force and stiffness, respectively, at 4 Mrad. Similar reductions were noted in material properties, including 37% (p < 0.005) and 8% (p > 0.05) reductions in maximum stress and modulus, respectively, at 4 Mrad. These results are consistent with our previous report involving 2 and 3 Mrad (20,000 and 30,000 Gy) of exposure. We also found significant decreases in hydroxypyridinium crosslink density with 6 Mrad of irradiation (p < 0.05). However, since only one biomechanical parameter (modulus) correlated significantly with only one biochemical measure (hydroxypyridinium crosslink density) (p < 0.05), other possible mechanisms also are being explored to more fully explain these dose-dependent changes.
Noyes-Giannestras Biomechanics Laboratories, Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Ohio 45221-0048, USA.
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A
Salehpour
D L
DL
Butler
F S
FS
Proch
H E
HE
Schwartz
S M
SM
Feder
C M
CM
Doxey
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Ratcliffe
D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004548:Elasticity / Q000528:radiation effects; D005260:Female; D005720:Gamma Rays; D006041:Goats; D006614:Hindlimb; D010329:Patella / Q000528:radiation effects*; D011487:Protein Conformation / Q000528:radiation effects; D011725:Pyridines / Q000528:radiation effects; D013710:Tendons / Q000528:radiation effects* / Q000637:transplantation*; D014184:Transplantation, Homologous
D011725:Pyridines; D003094:Collagen