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The flashcards below were created by user
hgienau
on FreezingBlue Flashcards.
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Three types of forces
- Shear: opposite directions
- Tensile: both directions
- Compressive: same direction
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Compressive Force
- Naturally occurring forces
- force applied perpendicular to articulating surface
- Weight Bearing In LE's or with muscle contractions
- Therapeutically called "joint Approximation"
- Good for joint to a point
- Increase osteoblastic activity
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Tensile Forces
- Foce applied perpendicular to the joint surface
- Therapeutically called "distraction" used in mobilization and ROM activities
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Shear Forces
- Force is parallel to the joint surface
- When load is applied there will be a combination of approximation and shear
- If force applied at an angle and not perpendicular it will add shear - this can lead to injury
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Connective Tissue
- Bone
- SKin
- Ligaments
- tendons
- Fascia
- Tissue make up and orientation gives it it's strength and ability to withstand different forces
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Structural Components of Connective Tissue
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Cellular Component
- Fibroblast and fibrocytes
- produce fibers of connective tissues and specialized cells
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fibrous component
- Collagen fibers: responsible for strength and stiffness
- Elastin: flexibility and extensibility
- Reticulin fibers: provide bulk to connective tissue
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Ground Substance
- Fluid component of tissues
- Serves to: reduce friction between fibers
- form lkinks between collagen fibers
- resists compressive forces
- helps dissipate tensile forces
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Strength
- Collagen is 5 times stronger than elastin
- increased collagen= increased strength and decreased flexibility
- Increased elastin = greater flexibility and decreased strength
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Orientation of fibers
- Parallel: Resists tensile forces in that direction (tendon)
- Random: withstand forces in a varisty of diretions (ligaments in foot)
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Stress-strain curve
Mechanical response of a selected internal structure to a deforming stress can be graphically representaed
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Stress
Magnitude of force of load being applied to internal structure
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Strain
amount of deformation that occures to the structure in reponse to stress applied
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Elastic Range
Structure can return to original shape after deforming load
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Yield Point
Point between elastic and plastic where changesa from one to the other
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Plastic range
the ability of a structure being loaded to permanently obtain a new length after load is removed
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Failure point
Tissue is unable to withstand anymore load without damage
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Mechanical failure
- Injury
- Point to where stress is too excessive and reaches a point at which internal structure can't withstand it
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Remodeling of Bone
- Ongoing preocess thoughtout life adjust to stresses presented in everyday life
- Osteoblast - build up bone
- Osteoclast - break down bone
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Wolffs law
- Law is the phenonmenon that describes the remodeling of bone occuring in reponse to physical stress
- Bone will be desposited and align along lines of stress and reasborbed or no stress is present
- have to have stess on bone inorder for it to grow
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Bone Deposition
- Developmentally if unable to weight bear will have difficulty maturing sufficiently
- need to weight bearing activities as we grow
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Recovery after fracture
Bone developed throught early closed chain approximation activities
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Effects of Immobilization
- Muscle: loss of strength, loss of muscle size and decreased in tension per unit of muscle cross sectional area
- Connective Tissue: fibrosis and tightening
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Ligament Sprain Grades
- Grade 1: microscopic tear, no joint laxity
- Grade 2: tearing of some fibers, moderate laxity (5-10mm)
- Grade 3: near complete or complete rupture progound laxity, unstable (greater than 10mm)
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Ligament Healing
- Three key conditions must be present for ligaments to properly remodel or heal
- Torn ligament ends must be in contact wiht each other
- Progressive contreolled stress must be applied to the healing tissue to orient scar tissue formation
- the ligament must be protected against excessive forces during the remodeling phase
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Ligament effects of immobilization
- Joint stiffness immobilizaion is related to adhesion formation active shortening of dense connective tissue and decreases in water contect
- gradual deterioration in ligament strength, loss of bone, weakenin gor cartilage and tendons, significant muscles atrophy and negatie effects on joint mechanics
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Muscle disorders
- Occur within the contractile unit
- Consists of the muscle belly, the musulotendinous junction, the tendon and the tendons bony attachemnt
- Tendons heal slow
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Grades of Muscle Strains
- Grade 1: less the 50% of damage
- Grade 2: more than 50% damage
- Grade 3: complete tear
- also caleed muscles stress, pull or rupture
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