In the past years, there have been several experimental studies that aimed at quantifying the material properties of articular ligaments such as tangent modulus, tensile strength, and ultimate strain. Little has been done to describe their response to mechanical stimuli that lead to damage. The purpose of this experimental study was to characterize strain-induced damage in medial collateral ligaments (MCLs). Displacement-controlled tensile tests were performed on 30 MCLs harvested from Sprague Dawley rats. Each ligament was monotonically pulled to several increasing levels of displacement until complete failure occurred. The stress–strain data collected from the mechanical tests were analyzed to determine the onset of damage and its evolution. Unrecoverable changes such as increase in ligament's elongation at preload and decrease in the tangent modulus of the linear region of the stress–strain curves indicated the occurrence of damage. Interestingly, these changes were found to appear at two significantly different threshold strains (P<0.05). The mean threshold strain that determined the increase in ligament's elongation at preload was found to be 2.84% (standard deviation (SD) = 1.29%) and the mean threshold strain that caused the decrease in the tangent modulus of the linear region was computed to be 5.51% (SD = 2.10%), respectively. The findings of this study suggest that the damage mechanisms associated with the increase in ligament's elongation at preload and decrease in the tangent modulus of the linear region in the stress–strain curves in MCLs are likely different.

References

References
1.
Fung
,
D. T.
,
Wang
,
V. M.
,
Laudier
,
D. M.
,
Shine
,
J. H.
,
Basta-Pljakic
,
J.
,
Jepsen
,
K. J.
,
Schaffler
,
M. B.
, and
Flatow
,
E. L.
,
2009
, “
Subrupture Tendon Fatigue Damage
,”
J. Orthop. Res.
,
27
(
2
), pp.
264
273
.10.1002/jor.20722
2.
King
,
G. J. W.
,
Pillon
,
C. L.
, and
Johnson
,
J. A.
,
2000
, “
Effect of In Vitro Testing Over Extended Periods on the Low-Load Mechanical Behaviour of Dense Connective Tissues
,”
J. Orthop. Res.
,
18
(
4
), pp.
678
681
.10.1002/jor.1100180422
3.
Pollock
,
R. G.
,
Wang
,
V. M.
,
Bucchieri
,
J. S.
,
Cohen
,
N. P.
,
Huang
,
C. Y.
,
Pawluk
,
R. J.
,
Flatow
,
E. L.
,
Biqilani
,
L. U.
, and
Mow
,
V. C.
,
2000
, “
Effects of Repetitive Subfailure Strains on the Mechanical Behavior of the Inferior Glenohumeral Ligament
,”
J. Shoulder Elbow Surg.
,
9
(
5
), pp.
427
435
.10.1067/mse.2000.108388
4.
Schechtman
,
H.
, and
Bader
,
D. L.
,
2002
, “
Fatigue Damage of Human Tendons
,”
J. Biomech.
,
35
(
3
), pp.
347
353
.10.1016/S0021-9290(01)00177-4
5.
Thornton
,
G. M.
,
Schwab
,
T. D.
, and
Oxland
,
T. R.
,
2007
, “
Fatigue Is More Damaging Than Creep in Ligament Revealed by Modulus Reduction and Residual Strength
,”
Ann. Biomed. Eng.
,
35
(
10
), pp.
1713
1721
.10.1007/s10439-007-9349-z
6.
Wang
,
X. T.
,
Ker
,
R. F.
, and
Alexander
,
R. M.
,
1995
, “
Fatigue Rupture of Wallaby Tail Tendons
,”
J. Exp. Biol.
,
198
(
Pt 3
), pp.
847
852
.
7.
Wren
,
T. A. L.
,
Lindsey
,
D. P.
,
Beaupre
,
G. S.
, and
Carter
,
D. R.
,
2003
, “
Effects of Creep and Cyclic Loading on the Mechanical Properties and Failure of Human Achilles Tendons
,”
Ann. Biomed. Eng.
,
31
(
6
), pp.
710
717
.10.1114/1.1569267
8.
Zec
,
M. L.
,
Thistlethwaite
,
P.
,
Frank
,
C. B.
, and
Shrive
,
N. G.
,
2010
, “
Characterization of the Fatigue Behavior of the Medial Collateral Ligament Utilizing Traditional and Novel Mechanical Variables for the Assessment of Damage Accumulation
,”
ASME J. Biomech. Eng.
,
132
(
1
), p.
011001
.10.1115/1.4000108
9.
Panjabi
,
M. M.
, and
Courtney
,
W.
,
2001
, “
High-Speed Subfailure Stretch of Rabbit Anterior Cruciate Ligament: Changes in Elastic, Failure and Viscoelastic Characteristics
,”
Clin. Biomech.
,
16
(
4
), pp.
334
340
.10.1016/S0268-0033(01)00007-9
10.
Panjabi
,
M. M.
,
Yoldas
,
E.
,
Oxland
,
T. R.
, and
Crisco
,
J. J.
, III
,
1996
, “
Subfailure Injury of the Rabbit Anterior Cruciate Ligament
,”
J. Orthop. Res.
,
14
(
2
), pp.
216
222
.10.1002/jor.1100140208
11.
Provenzano
,
P. P.
,
Heisey
,
D.
,
Hayashi
,
K.
,
Lakes
,
R.
, and
Vanderby
,
J. R.
,
2002
, “
Subfailure Damage in Ligament: A Structural and Cellular Evaluation
,”
J. Appl. Physiol.
,
92
(
1
), pp.
362
371
.
12.
Panjabi
,
M. M.
,
Huang
,
R. C.
, and
Cholewicki
,
J.
,
2000
, “
Equivalence of Single and Incremental Subfailure Stretches of Rabbit Anterior Cruciate Ligament
,”
J. Orthop. Res.
,
18
(
5
), pp.
841
848
.10.1002/jor.1100180524
13.
Sengupta
,
P.
,
2013
, “
The Laboratory Rat: Relating Its Age With Human's
,”
Int. J. Prev. Med.
,
4
(
6
), pp.
624
630
.
14.
Provenzano
,
P. P.
,
Martinez
,
D. A.
,
Grindeland
,
R. E.
,
Dwyer
,
K. W.
,
Turner
,
J.
,
Vailas
,
A. C.
, and
Vanderby
,
R.
, Jr.
,
2003
, “
Hindlimb Unloading Alters Ligament Healing
,”
J. Appl. Physiol.
,
94
(
1
), pp.
314
324
.10.1152/japplphysiol.00340.2002
15.
Thornton
,
G. M.
,
Shrive
,
N. G.
, and
Frank
,
C. B.
,
2002
, “
Ligament Creep Recruits Fibres at Low Stresses and Can Lead to Modulus-Reducing Fibre Damage at Higher Creep Stresses: A Study in Rabbit Medial Collateral Ligament Model
,”
J. Orthop. Res.
,
20
(
5
), pp.
967
974
.10.1016/S0736-0266(02)00028-1
16.
Wei
,
X.
, and
Messner
,
K.
,
1996
, “
The Postnatal Development of the Insertions of the Medial Collateral Ligament in the Rat Knee
,”
Anat. Embryol.
,
193
(
1
), pp.
53
59
.10.1007/BF00186833
17.
Su
,
W. R.
,
Chen
,
H. H.
, and
Luo
,
Z. P.
,
2008
, “
Effect of Cyclic Stretching on the Tensile Properties of Patellar Tendon and Medial Collateral Ligament in Rat
,”
Clin. Biomech.
,
23
(
7
), pp.
911
917
.10.1016/j.clinbiomech.2008.04.002
18.
Crowninshield
,
R. D.
, and
Pope
,
M.
,
1976
, “
The Strength and Failure Characteristics of Rat Medial Collateral Ligaments
,”
J. Trauma Acute Care Surg.
,
16
(
2
), pp.
99
105
.10.1097/00005373-197602000-00004
19.
Yiannakopoulos
,
C. K.
,
Kanellopoulos
,
A. D.
,
Dontas
,
I. A.
,
Trovas
,
G.
,
Korres
,
D. S.
, and
Lyritis
,
G. P.
,
2005
, “
The Symmetry of the Medial Collateral and Anterior Cruciate Ligament Properties. A Biomechanical Study in the Rat Hind Limb
,”
J. Musculoskeletal Neuronal Interact.
,
5
(
2
), pp.
170
173
.
20.
Viidik
,
A.
, and
Ekholm
,
R.
,
1968
, “
Light and Electron Microscopic Studies of Collagen Fibers Under Strain
,”
Z. Anat. Entwickl. Gesch.
,
127
(
2
), pp.
154
164
.10.1007/BF00521981
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