cartilage Flashcards
What is hyaline cartilage?
- most common cartilage
- found on most non-articular surfaces such as the ends of ribs, nasal septum, lyarx, tracheal ring
- collage fibers are cross linked and loosely woven together
Where do you find elastic cartilage and how is it treated?
- not typically treated by PT
2. found in the exteranl ear, auditory canals, epiglottis, laryngeal cartilage, and walls of eustachian tubes
which is more dense elastic or hyaline cartilage
elastic
How is Fibrocartilage organized?
consists of alternating layers of hyaline cartilage and dense collagen fibers orientd in a directions of stress
Where do you typically find fibrocartilage?
intervertebral discs, articular cartilage, pubic symphysis, capsules, ligaments, enthesis
What is the functional cell of cartilage?
Chondrocytes
What is the root function of chonrocytes?
- produce and control ECM
2. immature chondrocytes know as chondroblasts produce GAG and type II collagen
What are the metabolic properties of cartilage?
- by nature cartilage is devoid of nerve supply, blood vessels and lymphatic vessels
- anaerobic metabolism is used by cartilage in its low oxygen environment
How does cartilage have both solid and flexible properties?
the ground substance of glycoprotiens imbibies water giving it viscoelastic properties
What is cartilage made of?
- half the dry weight is type II collagen
2. proteoglycans make up about 4-7% of the ECM
What are proteoglycans?
complex macromolecules comprised of a protein core joined to a long non-branching polysaccride such as GAG
How does cartilage resist high tensile loads?
since it is made of 65-80% water it is essentially noncompressable and is able to take high tensile loads
What are the layers of articular cartilage?
- superfiscial
- middle
- deep
- calcified
What is the superficial layer of articular cartilage?
- collagen in oriented parallel to joint surface
- rich in collagen
- low in proteoglycans
- high in tensile loads
What is the middle layer of articular cartilage?
- less organized collagen
2. greater proteoglycan content than the superficial layer
What is the deep layer of articular cartilage?
- highest concentration of proteoglycans
- collagen organized to resist shear
- compression improves in capacity for resisting shear
What is the calcified zone of articular cartilage?
- large content of apatite salt
- minimal blood supply
- transports nutrients to other layers
How is the metabolic rate of collagen regulated?
- hydrostatic pressures
- growth factor
- interleukins
- matrix make up
- electric fields
How is fluid imbibed into cartilage?
1donnan osmotic pressure- differences in intra and extra cellar ionic charge creates a magnetic effect
- electroastic repulsion forces- proteglycans have a negative charge creating metabolic movement
- entropic tendency of proteoglycans to gain volume
How are proteteoglycans produced?
- compression of cartilage triggers production
- the rough endoplasmic reticulum produces a protein core
- as the protein core leaves the RIR it is sulfated by the Golgi apparatus
- the sulfated protien core passes through the membrane and attaches to hylauronic acid
How does compression benefit from cartilage?
- triggers production of GAG
2. increase rate solutes move towards and away from cells deep within cartilage
How does joint gliding benefit cartilage?
gliding causes the synovial fluid to become less viscous which facilitates imbibition of the cartilage
How do you decrease synovial fluid viscosity?
- joint gliding
2. the fast the movement the less viscose the synovial fluid
What characteristic of cartilage allows it to manage the high reps?
It has biphasic properties
- sold under compressions
- fluid for nutrient exchange
How is nutrition and wast removal regulated by cartilage?
the chondrosynovial membrane
- a thing permeable membrane covering the surface of cartilage
- prevents rapid fluid exudation under loading
What is the optimal stimulus for repair of collagen?
compression decompression with gliding
- compression/decompression stimulates chondroblast and increased nutrient exchange
- gliding decreases synovial fluid viscosity
What is the only non-blast cell to produce collagen
chondrocyte
What joint in the body does not receive cartilage OSR with gravitational loading?
Lumbar spine due to the orientation of the facets
- rotation- creates contralateral facet opposition
- flex and provide gliding
How do you provide facet cartilage OSR?
- compression/decompression via rotation
2. gliding- flexion and extension
What are some intrajoint mechanical structures that help attenuate force?
1.fat pads that move in and out of the joint such as infrapetellar, pulvinar acetabulum and facet
How does hyaline cartilage change when it heals?
it is usually replaced by fibrocartilage which has poor mechanical properties
How does immobilization impact muscle?
immobilization in a shorted position causes 40% loss of sacrcomers and in a lengthened position causes a 20% gain
How does recovery time after immobilization and damage during immobilization compare?
- the damage occurs on an exponential rate
2. recovery occurs on a linear rate
What is the pattern of collagen loss with immobilization
- 9 weeks 14% loss with a 2 % loss
- 12 weeks 28% loss with a 27% net loss
- in other words you have an exponential loss
Describe the healing process following a cartilage injury through to the subcondral bone
- cells travel through subcondral vessels to initiate the healing process
- fibrin clot forms a framework from mesenchymal cells from the marrow to produce a fibrocartilagenous base
- growth factor such as platelet derived GF and transforming GF beta can attract undifferentiated cells to the fibrin clot
What extrinsic variable effects cartilage permeability the most?
- rate of loading due to the viscoelastic properties
- fast loading has less fluid movement
- prolonged or slowly applied loads move fluids best
Describe the repair process of a superficial laceration of the cartilage?
There isn’t one because there is no vascularization
How does immobilization effect cartilage enzyme function?
- lactic dehydrongenase and malic dehydrogense decrease so you have less production
- lysosomal hydrolase increase activity degrading GAG
How does immobilization effect cellular alignment?
distorts alignment and you lose mechanical tensile properties
How does immobilization effect collagen bundle width?
- decreases it via loss of total number of bundles
- 14% at 9 weeks
- 38% at 12 weeks
How does immobilization effect muscles?
- weakening of boney insersion
- decreased muscle belly circumfrence
- decreased extensibility
- muscle fiber atrophy (slow>fast)
- either a loss or gain of sarcomes depending on the position
What does type III collagen usually show up first at an injury site (2 reasons)?
- it has the ability to rapidly form cross links to establish an early fragile stability at the repair site
- cell that normally produce type I collagen produce type III at the time of injury
What did Salter’s study in 1980 demonstrate about cartilage?
CPM helps with heeling.
Why is cartilage healing difficult?
cartilage is avasuclar , anueral, alympathic and has a low metabolic rate
How come rehabing healed articular cartilage is difficult?
Repaired articular cartilage is usually type III collagen
- it lacks cross bonding of normal cartilage
- leads to weakness and tendency for repair site to swell more than surrounding tissue
- more susceptible to damage because gaps form in the tissue and it has a reduced quality of matrix
What general dosing is used for cartilage exercises?
- very high reps
- low resistance starting NWB
- restore joint mobility
- restore muscle tone and balance
- endurance
- strength
- motor control
How does over stressing articular cartilage effect its properties?
- articular cartilage become stiffer
- decreased ability to attenuate force across a greater area
- focal points of impact can lead to sclerotic changes
- leads to diminished nutrient flow from subcondral bone
What nutritional supplements benefit cartilage?
- 1.5 g Glucosamine
2. 2g day Omega 3
A change in varus knee position of 4-6 degree can change the internal knee pressures by how much?
1.medial compartment loading 70-90%
How does NSAID work?
inhibits cyclo-oxygenase enzyme in the synthesis of prostiglandins from arachondonic acid
How do NSAIDs negatively effect joint healing?
- inhibit the production of proteoglycans
- impaired protein synthesis
- the inflammatory process produces cytokines interlukin that clear the broken down
How does a menisectomy impact effect knee joint cartilage?
- it disrupts normal normal anabolic and catabolic processes
- also signs of degenerative cartilage loss
How does age impact cartilage regeneration?
- decreased capacity of chondrocytes to link protein
- decreased rate of histological events
- decreased energy stores so dosing considerations must be made
- calcification of subchondral bone decreasing nutrient exchange increasing the importance of imbibition
What is the optimal stimulus for chondrocytes to produce cartilage?
- compression
- decompression
- shearing
Hoe are progenitor cells used in tissue repair?
1.osteochondral progenitor cells can be grown in vitro from autologeus bone marrow and transplanted surgically to trigger conventail repair of cartilate
What is a periosteal graft?
periosteal or periochondral tissue is harvested from a remote site and implanted in other joints
Why should pain be avoided with exercise?
- its a signal of excessive tissue deformity
- chronic inflammation produces more scar tissue
- pain alters normal circulation via sympathetic response
- muscle recruitment patterns are altered
How will exceeded the tolerance of cartilage present clinically?
- cartilage is not innervated so it will not have a pain response
- secondary edema within 24 hours
- loss of ROM
