Cyclic loading causes faster rupture and strain rate than static loading in medial collateral ligament at high stress

Thornton, Gail M.; Schwab, Timothy D.; Oxland, Thomas R.

doi:10.1016/j.clinbiomech.2007.05.004

Cited by 45 publications

(48 citation statements)

References 21 publications

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“…In vitro studies have reported that preconditioning usually shifts the load-elongation curve to the right, and that afterward, the load-elongation relation of the soft tissues reaches a steady state. The warm-up used in our in vivo experiments should have moved beyond the primary strain stage (in this stage, loading causes a rapid increase in strain amplitude but a decrease in strain rate over time) (25) into the secondary strain stage, where the strain rate reaches a steady state over time.…”

Section: Tendon Plasticity To Short-term Mechanical Loading In Vivomentioning

confidence: 99%

“…A lower proteoglycan concentration, changes in its composition, and a decrease in glycosaminoglycan content in older tendons could induce an age-related effect of static or cyclic mechanical loading on the tendon mechanical properties, resulting in a reduced resistance to creep in tendons of older adults. Static loading and cyclic loading were compared because it has been reported that these induce different creep responses in collagenous tissues (ligament) (25).…”

Section: Tendon Plasticity To Short-term Mechanical Loading In Vivomentioning

confidence: 99%

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Plasticity of the Human Tendon to Short- and Long-Term Mechanical Loading

Arampatzis

Karamanidis

Mademli

et al. 2009

Exercise and Sport Sciences Reviews

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Section: Tendon Plasticity To Short-term Mechanical Loading In Vivomentioning

confidence: 99%

Section: Tendon Plasticity To Short-term Mechanical Loading In Vivomentioning

confidence: 99%

Plasticity of the Human Tendon to Short- and Long-Term Mechanical Loading

Arampatzis

Karamanidis

Mademli

et al. 2009

Exercise and Sport Sciences Reviews

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“…3). Strain-time profiles follow the three strain stages traditionally assigned to creep 15 (Fig. 3b): (primary) decreasing strain rate, (secondary) steadystate strain rate, and (tertiary) increasing strain rate.…”

Section: Modulus Ratio and Increase In Strainmentioning

confidence: 99%

Fatigue is More Damaging than Creep in Ligament Revealed by Modulus Reduction and Residual Strength

2007

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Following injury of a complementary joint restraint, ligaments can be subjected to higher than normal stresses. Normal ligaments are exposed to static (creep) and cyclic (fatigue) loading from which damage can accumulate at these higher than normal stresses. This study tracked damage accumulation during creep and fatigue loading of normal rabbit medial collateral ligaments (MCLs) over a range of stresses, using modulus reduction as a marker of damage. Creep tests were interrupted occasionally with unloading/reloading cycles to measure modulus. Test stresses were normalized to ultimate tensile strength (UTS): 60%, 30%, and 15% UTS. Not all creep and fatigues tests progressed until rupture but were stopped and followed by an assessment of the residual strength of that partially damaged ligament using a monotonic failure test. Fatigue loading caused earlier modulus reduction than creep. Modulus reduction occurred at lower increases in strain (strain relative to initial strain) for fatigue than creep. In other words, at the same time or increase in strain, fatigue is more damaging than creep because the modulus ratio reduction is greater. These findings suggest that creep and fatigue have different strain and damage mechanisms. Ligaments exposed to creep or fatigue loading which produced a modulus reduction had decreased residual strength and increased toe-region strain in a subsequent monotonic failure test. This finding confirmed that modulus reduction during creep and fatigue is a suitable marker of partial damage in ligament. Cyclic loading caused damage earlier than static loading, likely an important consideration when ligaments are loaded to higher than normal magnitudes following injury of a complementary joint restraint.

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“…During creep and fatigue in normal ligaments, modulus ratio versus time curves had three characteristic regions (Thornton et al, 2007a): increasing; constant; and decreasing modulus. These three regions of modulus were related to three regions of strain (Thornton et al, 2007a(Thornton et al, , 2007b: decreasing; steadystate; and increasing strain rate. Modulus reduction occurred at the transition from constant to decreasing modulus and was related to the transition from steady-state to increasing strain rate (Thornton et al, 2007a).…”

Section: Introductionmentioning

confidence: 99%