Cortical and trabecular bone have similar creep behaviors that have been described by power-law relationships, with increases in temperature resulting in faster creep damage accumulation according to the usual Arrhenius (damage rate ~ exp (−Temp.−1)) relationship. In an attempt to determine the phase (collagen or hydroxyapatite) responsible for these similar creep behaviors, we investigated the creep behavior of demineralized cortical bone, recognizing that the organic (i.e., demineralized) matrix of both cortical and trabecular bone is composed primarily of type I collagen. We prepared waisted specimens of bovine cortical bone and demineralized them according to an established protocol. Creep tests were conducted on 18 specimens at various normalized stresses σ/E0 and temperatures using a noninvasive optical technique to measure strain. Denaturation tests were also conducted to investigate the effect of temperature on the structure of demineralized bone. The creep behavior was characterized by the three classical stages of decreasing, constant, and increasing creep rates at all applied normalized stresses and temperatures. Strong (r2 > 0.79) and significant (p < 0.01) power-law relationships were found between the damage accumulation parameters (steady-state creep rate dε/dt and time-to-failure tf) and the applied normalized stress σ/E0. The creep behavior was also a function of temperature, following an Arrhenius creep relationship with an activation energy Q = 113 kJ/mole, within the range of activation energies for cortical (44 kJ/ mole) and trabecular (136 kJ/mole) bone. The denaturation behavior was characterized by axial shrinkage at temperatures greater than approximately 56°C. Lastly, an analysis of covariance (ANCOVA) of our demineralized cortical bone regressions with those found in the literature for cortical and trabecular bone indicates that all three tissues creep with the same power-law exponents. These similar creep activation energies and exponents suggest that collagen is the phase responsible for creep in bone.

1.
Bonar
L. C.
, and
Glimcher
M. J.
,
1970
, “
Thermal denaturation of mineralized and demineralized bone collagens
,”
J. Ultra. Res.
,
32
,
545
551
.
2.
Bowman
S. M.
,
Keaveny
T. M.
,
Gibson
L. J.
,
Hayes
W. C.
, and
McMahon
T. A.
,
1994
, “
Compressive creep behavior of bovine trabecular bone
,”
J. Biomech.
,
27
,
301
310
.
3.
Bowman, S. M., Gibson, L. I., Hayes, W. C., and McMahon, T. A., 1996a, “The creep behavior of trabecular bone is temperature dependent,” Trans. ORS, 21, 80.
4.
Bowman
S. M.
,
Zeind
J.
,
Gibson
L. J.
,
Hayes
W. C.
, and
McMahon
T. A.
,
1996
b, “
The tensile behavior of demineralized bovine cortical bone
,”
J. Biomech.
,
29
,
1497
1501
.
5.
Bowman
S. M.
,
Guo
X. E.
,
Cheng
D. W.
,
Keaveny
T. M.
,
Gibson
L. J.
,
Hayes
W. C.
, and
McMahon
T. A.
,
1998
, “
Creep contributes to the fatigue behavior of bovine trabecular bone
,”
ASME JOURNAL OF BIOMECHANICAL ENGINEERING
, Vol.
120
, pp.
647
654
.
6.
Caler
W. E.
, and
Carter
D. R.
,
1989
, “
Bone creep-fatigue damage accumulation
,”
J. Biomech.
,
22
,
625
635
.
7.
Carter
D. R.
, and
Caler
W. E.
,
1983
, “
Cycle-dependent and time-dependent bone fracture with repeated loading
,”
ASME JOURNAL OF BIOMECHANICAL ENGINEERING
,
105
,
166
170
.
8.
Cohen
R. E.
,
Hooley
C. J.
, and
McCrum
N. G.
,
1976
, “
Viscoelastic creep of collagenous tissue
,”
J. Biomech.
,
9
,
175
184
.
9.
Dieter, G. E., 1986, Mechanical metallurgy, 3rd ed., McGraw-Hill, New York.
10.
Derwin
K. A.
,
Soslowsky
L. J.
,
Green
W. D. K.
, and
Elder
S. H.
,
1994
, “
Technical note: a new optical system for the determination of deformations and strains: calibration characteristics and experimental results
,”
J. Biomech
.,
27
,
1277
1285
.
11.
Fondrk
M.
,
Bahniuk
E.
,
Davy
D. T.
, and
Michaels
C.
,
1988
, “
Some viscoplastic characteristics of bovine and human cortical bone
,”
J. Biomech.
,
21
,
623
630
.
12.
Glimcher
M. J.
, and
Katz
E. P.
,
1965
, “
The organization of collagen in bone: the role of noncovalent bonds in the relative insolubility of bone collagen
,”
J. Ultra. Res.
,
12
,
705
729
.
13.
Holden
J. L.
,
Clement
J. G.
, and
Phakey
P. P.
,
1995
, “
Age and temperature related changes to the ultrastructure and composition of human bone mineral
,”
J. Bone Miner. Res.
,
10
,
1400
1409
.
14.
Keaveny
T. M.
,
Guo
X. E.
,
Wachtel
E. F.
,
McMahon
T. A.
, and
Hayes
W. C.
,
1994
, “
Trabecular bone exhibits fully linear elastic behavior and yields at low strains
,”
J. Biomech.
,
27
,
1127
1136
.
15.
Lakes
R. S.
, and
Saha
S.
,
1979
, “
Cement line motion in bone
,”
Science
,
204
,
501
503
.
16.
Mauch
M.
,
Currey
J. D.
, and
Sedman
A. J.
,
1992
, “
Creep fracture in bones with different stiffnesses
,”
J. Biomech.
,
25
,
11
16
.
17.
Melnis
A. E.
,
Ozola
B. O.
, and
Moorlat
P. A.
,
1981
, “
Comparative characteristics of the creep properties of human compact bone tissue under various specimen storage and testing conditions
,” translated from
Mekhanika Kompozitnykh Materialov
,
3
,
515
521
.
18.
Morchio
R.
, and
Ciferri
A.
,
1969
, “
The role of calcium and of in vitro aging on the creep behavior of collagen tendons
,”
Biophysik
,
5
,
327
330
.
19.
Mow
V. C.
,
Kuei
S. C.
,
Lai
W. M.
, and
Armstrong
C. G.
,
1980
, “
Biphasic creep and stress relaxation of articular cartilage in compression: theory and experiments
,”
ASME JOURNAL OF BIOMECHANICAL ENGINEERING
,
102
,
73
84
.
20.
Park
H. C.
, and
Lakes
R. S.
,
1986
, “
Cosserat micromechanics of human bone: strain redistribution by a hydration sensitive constituent
,”
J. Biomech.
,
19
,
385
397
.
21.
Reilly
D. T.
, and
Burstein
A. H.
,
1975
, “
The elastic and ultimate properties of compact bone tissue
,”
J. Biomech.
,
8
,
393
405
.
22.
Rimnac
C. M.
,
Petko
A. A.
, and
Wright
T. M.
,
1991
, “
Creep of compact bone: effects of temperature and stress on bovine lamellar microstructure
,”
Trans. ORS
,
18
,
152
152
.
23.
Rimnac
C. M.
,
Petko
A. A.
,
Santner
T. J.
, and
Wright
T. M.
,
1993
a, “
The effect of temperature, stress, and microstructure on the creep of compact bovine bone
,”
J. Biomech.
,
26
,
219
228
.
24.
Rimnac
C. M.
,
Petko
A. A.
,
Santner
T. J.
, and
Wright
T. M.
,
1993
b, “
Creep of compact human bone
,”
Trans. ORS
,
18
,
172
172
.
25.
Schmidt
M. B.
,
Mow
V. C.
,
Chun
L. E.
, and
Eyre
D. R.
,
1990
, “
Effects of proteoglycan cxtraction on the tensile behavior of articular cartilage
,”
J. Orthop. Res.
,
8
,
353
363
.
26.
Simon
B. R.
,
Coats
R. S.
, and
Woo
S. L.-Y.
,
1984
, “
Relaxation and creep quasilinear viscoclastic models for normal articular cartilage
,”
ASME JOURNAL OF BIOMECHANICAL ENGINEERING
,
106
,
159
164
.
27.
van Rietbergen
B.
,
Weinans
H.
,
Huiskes
R.
, and
Odgaard
A.
,
1995
, “
A new method to determine trabecular bone elastic properties and loading using micromechanical finite-element models
,”
J. Biomech.
,
28
,
69
81
.
28.
Vogel
H. G.
,
1977
, “
Strain of rat skin at constant load (creep experiments) influence of age and desmotropic agents
,”
Gerontology
,
23
,
77
86
.
29.
Zar, J. H., 1984, Biostatistical Analysis, 2nd cd., Prentice Hall, Englewood Cliffs, NJ.
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