Module 5 Tissue Loading
stress fracture
*fracture caused by overuse low load conditions *functioanl ability often retained *could be warning of other nutritional or pathological conditions
trabecular bone
-bone type -high strain but low stress before fracture -deforms easily and lower stiffness
cortical bone
-bone type -stiffer --> HIGH MODULUS -accepts large loads but cannot deform much with out risking fracture -withstand more stress but less strain before fracture
cortical (compact) bone
-compact mineralized connective tissue -strong/dense -low porosity (60% non mineralized) -found in shafts and long bones
macrotruama
-from acute loading -ligament tear -bone fracture
microtrauma
-from repetitive loading -shin splints -stress fractures -tendonitis
trabecular (cancellous)/spongy bone
-less compact mineralized connective tissue -high porosity (30-90% non mineralized) -found in vertebrae and ends of long bones
factors for injury in spinal laoding
-load magnitude and direction: greater loads especially shear loads increase the risk for slippage and disc herniation -muscle tension: poor lifting form and increase load torque can cause tension which also contributes to excess loading of the spine -time dependent: under sustained land intervertebral discs lose water and height and more load is transmitted through the facets of the vertebrae
anistrophy of the bone
-loading angle matters -more axial the load the greater ability to withstand the load
high porosity
30-90% non mineralized
low porosity
60% non mineralized
bone hyertrophy
__ __ increase in bone mass w stress
longitudinal growth
__ ___: -growth at the epiphyseal plate (cartilaginous disc) -most fuse by age of 18 ending ____ ____
osteocytes
__ direct bone remodeling activity
yield point
__: end of the elastic region; if you put any more load to material you will begin to cause permanent damage to the material
rate of loading
___ __ ____ refers to how quickly a load is applied
bone atrophy
___ ___ decrease in bone mass w disuse
epiphyseal fracture
___ ___: -damage to the growth plate area of younger <18yrs -if hyaline cartilage is disrupted bone growth may end -can be difficult injury to treat, often with long term effects
circumferential growth
___ ____: -increases bone diameter -occurs throughout most of the lifespan -periosteum builds concentric layers of bone -bone is simultaneously reabsorbed on the medullary side
minerals water
___ and ___ contribute greatly to bones' compressive strength
linear
___ elastic material: stress is linearly proportional to strain
wolffs
___ law = bone (strength and mineral content) changes based on the stresses applied to the bone
bone
___ loss in jaw due to: -gum disease -dentures -loss of teeth
osteoclast
___ reabsorb bone
collagen
___: -type of bone composition -material constituent -protein, cable like and adds tensile strength
minerals
___: -type of bone composition -material constituent -calcium carbonate, calcium phosphate -stiffness = compression strength
plastic materials
___: deform instantaneously when they are subjected to externally applied loads and do not fully recover their shape when load is removed
elastic materials
___: deform instantaneously when they are subjected to externally applied loads and resume their shape when load is removed
anistrophy
___: some materials act better under different directions of load because of the microstructure of the material *bone has ____ *wolf's law - body will adapt to loads under which it is placed
collagen
____ allows for flexibility in the bone... maintains ductility in lifespan
osteoblast
____ deposit new bone
stress
____ is a function of strain only (no time dependent behavior) *___ doesn't necessarily need to be elastic
inverse
____ relationship between the magnitude of the load and the number of cycles/repetitions the tissue can withstand before there's a high likelihood for injury
water
____: -type of bone composition -material constituent -carries nutrients to and waste away and adds to compressive strength
ultimate stress
____: max load the material can withstand in the curve; not necessarily the same point as fracture point
fracture point
____: point at which the tissue will rupture; not necessarily the same as ultimate stress
ductile
able to yield at normal temps *large plastic deformation prior to failure (ex: steel)
strain
amount of deformation with respect to the structure *in compressive or tensile loading *normal ___ (greek e): ratio of the change in length (unitless) --> greek e = change in length /original resting length
acute loading
application of a single force of succulent magnitude to cause inury to a biological issue *macrotrauma
energy stored
area under the curve = ___ ___ in the tissue as it deformed
strain
as you get older not able to handle as much ___ before fracturing --> becomes more and more brittle
way to mitigate risk for injury
avoid twisting while lifting
compression
boens perform best with ____
composite
bone is a ___ material
axial
bone is much better at withstanding ___ loading than a load applied at an oblique angle
jaw
bone loss in jaw can lead to: -loss of teeth -non retentive dentures -mandibular fractures -inability to get implants -jaw joint issues due to abnormal loading
compressive tensile
bones can withstand ___ loads more than ___ loads
shear stress
bones perform least with ___
porous
containing pores or cavities
cortical, trabecular
cortical vs trabecular stress strain curve: ___ can withstand more stress ____ withstands less stress but more strain
modulus of elasticity
defines the slope of the linear region of the stress strain curve (E) = stress (omega) / strain (greek e) *uses Hooke's law for ONLY elastic region *represents the stiffness of material *where stress is directly proportional to strain
anistropic
exhibiting different mechanical properties in response to loads from different directions
stress strain curve
he relationship between the stress and strain that a particular material displays *Graphical representation of a material's mechanical properties. *help us predict how a material will deform w a given load *each material has its own curve
osteoporosis
low bone density; brittle bones that cannot undergo much stress without fracturing *lifestyle disease dependent on habits *no clear onset *peak bone mass during childhood is important predictor *weight bearing exercises in pre-puberty years can help *dietary calcium
way to mitigate risk for injury
maintain neutral spine
way to mitigate risk for injury
maintain upright posture
elastic
materials may exhibit ___ behavior up to certain loads beyond which they will exhibit plastic behavior
bone type
mechanical properties depend on ___ ___
spiral fracture
oblique break due to torsional loading
elastic, linear
on a stress strain curve: *graph becomes non linear — DOESN'T mean that it isnt _____anymore *during ____ portion — use the modulus of elasticity (slope of the curve)
decreasing
pressure in the L3 intervertebral disc changes with position -- listed in order of ____ internal pressure -sitting sloched -standing leaning forward -sitting erect -standing erect -lying flat
atrophy
problems related to ____: -loss of bone mineral density reduces bone strength --> increased likelihood of injury -space flight, bed-ridden patients and aging -osteoporosis
way to mitigate risk for injury
reduce moment arm of the load during lifting
repetitive loading
repeated application of a sub acute load that is usually of relatively low magnitude *microtrauma
buccal exostosis
results of clenching teeth
brittle
rupture occurs during elastic deformation *failure without undergoing plastic deformation (ex: cast iron, glass, stone) *can undergo a lot of stress -- just not plastic deformation before fracturing
combined loading
simultaneous action of more than one of the pure forms of loading
way to mitigate risk for injury
sustain intra-abdominal pressure during lifting
brittle
the FASTER you load bones the more ___ they are... more likely to rupture QUICKLY
ductile
the SLOWER you load bones the more ___ they are... will have plastic deformation without rupture
elasticity
the ability of a material to resume its original size and shape
brittle
the older you are the more brittle your bones are
ductile
the younger you are the more ____ your bones are
thoracic, sacral
to maintain upright position and have neutral spine which parts of the spine should be KYPHOTIC? cervical thoracic lumbar sacral *kyphotic is a a hump back shape
cervical, lumbar
to maintain upright position and have neutral spine which parts of the spine should be LORDOTIC? cervical thoracic lumbar sacral *lordotic is a C shape