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Components of a stress-strain curve
Toe Region Elastic Range Elastic Limit Plastic Range Complete Failure (rupture) Resting length Length of Stretch New Resting Length After Stretch Hysteresis Loop Fiber "Necking"
In a stress-strain curve of musculotendinous tissue, what does the toe region represent?
straightening of collagen fibers
In a stress-strain curve of musculotendinous tissue, what does the elastic range represent?
fibers require substantial tension to deform and will return to original shape after stretch
Where is the index of tissue stiffness represented? What is considered to represent "stiffer" tissue?
slope of the curve in the elastic region is an index of tissue stiffness The steeper the curve the stiffer the tissue
In a stress-strain curve of musculotendinous tissue, what does the plastic range represent?
stretched fibers will not return to normal length (partial tearing of fibers) Fiber necking occurs in this region
In a stress-strain curve of musculotendinous tissue, what does the complete failure present?
rupture of the tendon
What is fiber necking?
When a set of parallel tendon fibers is stretched into the plastic range, there is a time where the fibers become thinner in the middle as they are tearing then at the ends of the fibers, creating a horizontal hour glass shape, or "fiber necking"
Hysteresis loop represents what?
heat loss during the stretch of the tendon
What does the x-axis of a stress strain curve represent?
Represents the amount of strain (% deformation)
What does the y-axis of a stress strain curve represent?
The amount of stress (load)
Does deformation cause damage?
deformation in the elastic range DOES NOT cause damage but, deformation in the plastic range and beyond WILL cause damage
What is microtrauma sometimes identified as?
Overuse syndromes Cumulative cell-matrix adaptive response
Define microtrauma
Tissue level tearing Micro does not necessarily mean small, it just indicates that the tearing/damage is at the tissue level
Repetitive maximal or submaximal stress (or movement in the elastic range) causes what?
It causes microscopic tears or lesions which creates inflammation and tissue malformation Overwhelming of cell metabolism means that the cell can't maintain structural integrity, which causes an increase in tissue synthesis
What is different about tissues formed in response to an overload stimulus?
tissues that are formed in response to overload stimulus are of inferior quality (scar tissue)
What percentage of sports injuries are microtrauma responsible for? Why?
responsible for 30%-50% of sports injuries so common because sports are the most common method to overuse your body
These types of injuries are characterized as what from person to person?
These types of injuries are very "individualistic" in nature
What are the structures most commonly affected in microtraumatic syndromes?
Bursa: synovial fluid sacs that decrease friction between skin-bone, tendon-bone, muscle-muscle Tendon Sheaths: paratenon - fat & areolar tissue - "extended bursa" surrounding tendon Tendons - tendonopathies Bones - stress fractures Muscle - delayed onset muscle soreness
Symptomology progression of microtraumatic overuse syndromes?
Phase 1: pain AFTER activity (immediate to 12 hours) which is palpable at injury site Phase 2: pain DURING & AFTER activity - no significant impairment - eventually resolves Phase 3: pain DURING & AFTER activity - significant impairment - eventually resolves Phase 4: pain all the…
What are the currently accepted theories as to the causes of DOMS?
Eccentric Contractions Prostaglandin & Histamine Increased Phospholipase and Protease Activity Phagocytes & Macrophages Cell Adaptations
How are eccentric contractions thought to cause DOMS?
eccentric contractions cause sarcomere inhomogeneities and sarcolemma (membrane) disruption
How are prostaglandin & histamine thought to cause DOMS?
prostaglandin and histamine cause edema and inflammation which cause the stimulation of free nerve endings
How are increased phospholipase and protease activity thought to cause DOMS?
increased phospholipase and protease activity begin to degrade the myofibril (by the protease) and associated membrane (by the phospholipase)
How are phagocytes and macrophages thought to cause DOMS?
Phagocytes and Macrophages invade cell 2-6 hours after the injury and continues for 2 to 3 days
How are cell adaptations thought to cause DOMS?
the cell adapts to cause future bouts of the same exercise cause less injury
Tendinitis
inflammation of tendon or tendon sheath
how common is tendinitis?
rarely occurs (for the tendon sheath)
what are the correct terms for inflammation of the sheath
tenosynovitis paratenonitis
Tendinosis
degeneration and deleterious changes in tendon without inflammation
What most clinicians in the past have termed as "tendonitis" is actually what?
it is actually "tendinosis" or more generally "tendinopathy" Both tendinitis and tenidnopathy can occur together
What types of tendon injuries can occur together?
Tendonopathy and tendinitis can occur together
What are observations common among most if not all tendonopathy patients?
The problem is most often accompanied by: tissue degeneration (necrosis) and vascular abnormalities (disorganized vascularization) collagen disorganization and fiber separation by mucoid or lipoid (inferior) ground substance
Tendonopathy may contribute to what other problem that is much worse? How does it contribute?
The problem may lead or contribute to complete or partial tendon rupture Chronic tendonopathy causes fibrinous adhesions which causes diminished tissue strength & function which leads to complete or partial tendon rupture
Although cause & etiology are debatable, recent opinions purport causes of tendonopathy to be related to:
The sliding of tendon over other structures (compressive forces) Subjecting the tendon to loads close to tensile strength & exceeding anabolic capabilities Eccentric Contractions -negative direction on force velocity curve Chronic anabolic steroid use causes a decrease in tissu…
What are the general steps in the healing of microtrauma pathology including time frames for each stage?
INFLAMMATION: day 0-6 (if present), Some authors say day 1 or 2 only FIBROPLASTIC PROLIFERATION: days 5-21 REMODELING/MATURATION: 20 days - 6 months
What are the pathology, healing, and objectives of the healing stage for microtrauma including inflammation?
INCREASE GAG & COLLAGEN SYNTHESIS Prevent prolonged course of inflammation (if present) Prevent injury to developing collagen
What are the pathology, healing, and objectives of the healing stage for microtrauma including fibroplastic proliferation?
Increase rate of collagen synthesis by fibroblasts SYNTHESIZED COLLAGEN FIBERS NEED TO BE ALIGNED
What are the pathology, healing, and objectives of the healing stage for microtrauma including remodeling/maturation?
increase rate of crosslinkage formation and fibril size replacement of initial and/or inferior tissues
What are the treatment implications of the healing stage for microtrauma including inflammation?
REST nsaid's, oral corticosteroids low level ROM exercises cryogenic therapy? load reducing devices (casting, bracing, heel lifts, etc.)
What are the treatment implications of the healing stage for microtrauma including fibroplastic proliferation?
low level/low duration exercise STRETCHING ALIGNS THE COLLAGEN Cryogenic-thermogenic therapy? Ultrasonography? Laser? Electricity causes increase in fibroblast electricity?
What are the treatment implications of the healing stage for microtrauma including remodeling/maturation?
strengthening exercises increase in intensity and duration eccentric exercises to further stimulate collagen alignment
Not about the general steps of healing of tendon microtrauma pathology was?
Almost all body tissues follow this paradigm of healing only with a different time frame
Effects of immobilization on injured tendinous tissue
Protein degradation exceeds protein synthesis causing a net decrease in collagen quantity Reduction in the number of collagen crosslink bonds Atrophy of tissues at myotendinous (muscle-tendon) junction -2% loss of total collagen mass at 9 weeks, 27% loss at 12 weeks
Benefits of mobilization (movement) on injured tendinous tissue
Greater cross-sectional area of the healed tendon Improvement in collagen fiber type and fiber arrangement in the replacement Greater number of crosslink bonds Better quality of ground substance in the tendon
Collagen Type I
most abundant type for humans has the highest tensile strength of the 3 types, and is in tendons, muscle endomysium, fibrocartilage, bone, "final" scars
Collagen Type II
found in hyaline cartilage
Collagen Type III
found in granulation tissue, reticular tissue, and basement membranes
Common Therapies for Tendon Microtrauma
NSAID drugs Corticosteroids Surgery
How are NSAID drugs used as a therapy for tendon microtrauma?
Previous reviews conclude approximately 73% of studies show NSAID's to be effective They decrease healing time and decrease inflammation Other, more recent studies show NO MEASURABLE BENEFIT OF NSAIDs Note: approx. half of those using NSAIDs will have adverse side effects

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