CT Response to Load

epithelial, nervous, muscle, connective

what are the types of CT?

Cells and ECM

what are the components of CT

resident and non-resident

what are the types of cells in CT?

ECM

what defines the type of CT

fibers, proteoglycans, glycoproteins, water

what are the components of the ECM

GAGs

what part of proteoglycans attracts water and attaches to the proteins?

collagen molecule, fibril, fiber, primary fiber bundle, secondary/fascicle, tertiary, tendon

what is the progression of collagen structure that builds to make CT?

enthesis

what is the name for the bone-tendon junction?

1- end of the tendon

2- unmineralized fibrocartilage

3- mineralized fibrocartilage

4- bone

what are the zones of the enthesis?

mid-tendon

this part of the tendon has less frequent injuries, but if there is one it is usually due to overuse

Musculotendonus Junction

which area is the most common site of injury?

parallel

tendons and ligaments have dense regular CT, meaning their fibers are...

bone, ligament, tendon, and capsule

what types of tissues are composed primarily of type 1 collagen?

cartilage

what type of CT is composed of type 2 collagen?

elastin, allows for support through ROM

the joint capsule has more of what type of fiber? why?

ligament

when comparing tendon to ligament, which fibers are more irregular?

tensile

what types of forces do ligaments resist

stabilize a joint, prevent excessive motion, guide motion, proprioception

what is the function of a ligament

from proximal and distal attachments

where do ligaments receive their blood supply?

fiber that allows deformation to return back to original state

what is elastin?

mass*acceleration

force=

stress

force on an area during movement results in

force/area

stress=

toe region, elastic zone, plastic zone, failure

in a stress/strain curve, what are the regions?

the slope of the elastic zone

what part of the stress/strain curve is used to calculate stiffness

yield pt

what point marks the change from the elastic zone to the plastic zone?

stiffer

tissues with a higher slope in the elastic zone are...

it has sold and semisolid components

how is biological tissue an example of heterogenous material

extensibility is the ability to stretch, elasticity is the ability to return to original length

what is the difference between extensibility and elasticity

adaptations

how does CT respond to stresses (both internal and external) placed on it?

structural tension, joint compression, joint shear forces

what are examples of internal forces, loads, and forces?

gravity, GRF, contact force (weights/manual)

what are examples of external forces, loads, and forces?

magnitude, duration, and frequency of the force

response to stress is different based on what characteristics about the force?

tension, compression, shear, torsion, bending, combined

what are the types of loading?

tension

this load is directed away from the center

sprains, strains, tears

what are mechanisms of injury related to tension

compression

this load is directed inward toward the center

falls, trauma

what are mechanisms of injury related to compression

shear

2 forces applied parallel to each other but at different levels and opposite sides

torsion

this load is applied and results in twisting along the longitudinal axis

bending

tension

due to bending load, what force is created on the opposite side of the bend? (the bulging side)

compression

due to bending load, what force is created on the opposite side of the bend? (the indented side side)

stress/load

this is the term used to describe the force applied to a structure, it is directly related to the magnitude and inverse to the area (F/a)

strain/deformation

this is the product of applied force that presents as a change in shape or length due to that force

load/deformation curve

what can be made from the stress/strain results?

proteoglycan concentration

what part of the ECM is responsible for the mechanical properties of the tissue?

length change

if load is applied in a linear direction, what is the resulting deformation?

angular change

if load is applied in a shearing direction, what is the resulting deformation?

strength, elasticity, plasticity, stiffness, strength

what type of information can a load/deformation curve tell us

load sustainability, deformation sustainability, energy storage before failure

the strength of a structure is determined by...

stress vs strain

stiffness is a ratio of...

measurement of elasticity/definition of rigidity

modulus of elasticity/Young's modulus is...

toe region

this part of the stress/strain curve is the initial curve when the crimp is removed from CT

elastic region

this part of the stress/strain curve has a linear relationship with stress/strain, if stress is removed the structure will return to its original length

plastic region

in this region of the stress strain curve, there is tearing which results in permanent deformation. this deformation can recover over time depending on synthesis and reorganization of new tissue

fluid and solid (viscoelastic)

what behaviors does all CT exhibit

rate of loading

what influences the properties (fluid/solid) of CT

results in a steeper slope, meaning it is more stiff and a greater load is needed for failure

how does increased loading effect the slope of the elastic range, what does this mean for stiffness and failure pt

ECM is able to disperse, resulting in lower load needed for failure, but it will occur at an increased point of displacement

what happens in CT with slow loading rates

Creep and Load/stress relaxation

what are the two characteristics of viscoelastic properties?

creep

this viscoelastic property is time dependent (>15min) using a constant load resulting in deformation over time

stress relaxation

this viscoelastic property is when tissue is deformed and fixed over time resulting in decreased force over time due to relaxation

hysteresis

loss of energy during plastic deformation as the result of broken bonds in CT due to the application of stress/load

greater stiffness and strength

the result of increased cross sectional area in the fibers of ligaments and tendons results in..

the same

elongation to achieve failure is ______________ with increased cross sectional area

increased length until failure and decreased stiffness

if the length of fibers increases, how does it effect the length till failure? what does this mean about stiffness

magnitude

a longer fiber would have the same _________________ of force required to cause failure

aging, exercise, immobilization

what factors affect the joint capsule, tendon, and ligament tissue properties?

20

increases strength, diameter, and cross sectional area

number of cross links between fibers increases until what age? what does this result in?

20-60

from what ages does the diameter of fibrils in CT decrease?

increases vascularity, strength and diameter

how does exercise effect the properties of jt capsule, tendons, and ligaments?

it decreases stregnth

how does immobilization effect the properties of jt capsule, tendons and ligaments

no

if a pt is 12 months reconditioned post immobilization, are they 100% back to pre-immobilization levels?

bone

which type of CT is the most stiff/rigid and ductile

self-repair, aging, immobilization

in what ways does bone change throughout life?

osteoblasts

osteoclasts

osteocytes

what is the name of the bone cells that build bone? break it down? maintain?

osteon

structural unit of cortical bone that is in a haversian system

haversian canal

the center of the osteon containing blood vessels and nerves

lamellae

a series of concentric rings around each haversian canal

lacunae

cavity type area that houses the osteocytes

canuliculi

small channels that connect lacunae, but doesn't cross cement lines

volkman canal

canals from haversian canals to canuliculi, does cross cement lines

cement line

periphery of the osteon that is the weakest area of bone strucutre

80%

what % of bone mass is cortical bone?

cortical bone

this type of bone is dense and surrounds trabecular bone, it has a haversian system

cancellous bone (trabculae)

this type of bone has thin plates in a mesh like structure, spaces between the plates is filled with red marrow. there is no hversian system

woven bone

immature bone at a growth plate or fracture that is made up of cells and collagen in random arrangement

lamellar bone

mature bone that organized and replaces wocen bone

heterogenous

bone is composed of collagen and hydroxyapatite, making it...

it resists many forces, but responds differently to each

because bone is anisotropic and not isotropic, how does it respond to different forces

in the direction that the force is applied

when bone responds to stresses, its strength and stiffness is greatest...

compression and tension

what forces is bone the strongest in?

shear

what force is bone the weakest in?

less dense

less stiff

way more ductile

how does trabecular bone compare to cortical bone in regards of density, stiffness, and ductility

at the cement line, resulting in fracture

how does bone failure occur with tension

within the structure

where is the stress and strain occurring with compression in bone occurring inward

shorten and widen

forces in the same line on opposite sides of the structures causes the structure to...

vertebrae

where in bone are compression injuries most likely to occur

bone deformation at an angular manner

shear forces on bone usually result in...