10-21a Connective Tissue Physiology and Response to Immobilization Flashcards
What is the structure of tendon fibers?
mostly in parallel
What is the structure of ligament fibers?
somewhat parallel
What is the role of type I collagen fibers?
absorb tensile forces
What is the role of type III collagen? function?
flexibility/mesh
cross links to help with sliding motion and strength
What cells lie within collagen?
fibroblast cells
trauma causes fibroblasts to turn into fibrocytes to become part of the healing process
What are the other components of CT cells?
ECM: consistency and properties needed to function
water
elastin
GAGs: negatively charged, water-attracting, proteoglycans that help with lubrication and provide viscoelastic properties
What is stress?
force/cross sectional area
What is strain/deformation relationship?
how much can the tissue elongate as you apply stress to the tissue
what is the toe stage and its properties?
□ Tissue is slack and crimped and begins to uncrimp here
□ Non-linear part of the stress strain curve
□ Where we are when stretching ligaments for daily motion
what is the linear physiological range and its properties?
□ Elastic portion of stress strain curve
□ Can still return back to original length
□ Young’s modulus = slope of linear region/tissue stiffness
what is the primary failure point and its properties?
loss of mechanical properties
□ Amount of stress goes beyond elastic threshold
□ Cannot return to original state
□ Plastic phase
® Once it goes beyond threshold (yield point), it cannot return to original length; elasticity reduces
□ Cross links are starting to break down and there is some micro failure within the ligaments and tendons
What does complete failure involve?
reaching the ultimate failure point
tissues fail and lose their mech. properties
CI: how much load can the tissue take?
What is creep?
the constant load that deforms the tissue over time
within tissues’ normal properties
applied within elastic range
What is cyclic loading?
as you load and unload the tissues, they may follow a different pattern
What is the clinical importance of cyclic loading?
measure of knee extension and then do it ten times/repeat the motion = better ROM
more reproducible after a few repetitions
What is a grade I strain or sprain?
Grade I: some swelling, microtrauma, fatigue failure, constant repetitive loading of the tissues causes minor tear in collagen fibers, bonds break down
tendinopathy
What does the grade of an injury tell you?
the degree of loading
What is grade II?
no instability, continuity of tissues, beginning of breakdown and loss of parallel nature; addition of swelling and pain
What is grade III?
unnatural trauma
breaking down of collagen fibers, mechanical properties change, macro-trauma, swelling, more instability of the joint
What is microtrauma?
normal, parallel arrangement but reduced tensile properties
what is macrotrauma?
ultimate failure point
over time, ultimate stress is greatly reduced
What does the physical stress theory say?
injury causes changed thresholds
more activity can increase the tolerance of the tissue
loads applied to tissue before injury will be more harmful than you think after (dosing)
