soft tissue injury Flashcards
what is a soft tissue injury?
Damage of the muscles, ligaments or tendons
Most occur from sudden or uncontrolled movements
Can result in pain, swelling, contusion and loss of function
what is an acute injury?
Acute injuries result from a sudden trauma to the body/body parts
Examples are sprains, strains and contusions
what is an overuse injury?
Overuse injuries occur when an activity is repeated without enough rest between. This can result in overly fatigued structures becoming injured. Example tendinitis (inflammation of tissue)
what is a sprain?
Occur from overstretching or stresses applied
Sprain is trauma to a ligament (attaches bone to bone)
what is a strain?
Strain is trauma to muscles or tendons (fibrous tissue)
how does an injury occur?
During an activity the tissue is subject to loading forces (stress) which causes it to deform (strain)
An injury depends upon the stress and strain within the tissue
what are the different types of stresses?
Tensile - pulling Compressive - squashing Shear-applied parallel to a specific plane Bending Torsion - twisting
on the stress/strain curve explain the region where there is a linear relationship (Elastic/linear phase)?
Tendon deforms in a linear fashion due to the inter-molecular sliding of collagen triple helices.
If strain is less than 4%, the tendon will return to its original length when unloaded, therefore this portion is elastic and reversible and the slope of the curve represents an elastic modulus.
explain the plastic phase on the stress/strain curve?
tendon/ligament is stretched beyond physiological limits, some fibrils begin to fail.
Micro failure accumulates, stiffness is reduced and the ligament/tendon begins to fail.
Intramolecular cross-links between collagen fibres fail.
Tendon undergoes irreversible plastic deformation.
explain the toe phase on the stress/strain curve?
represents “un-crimping” of the collagen fibrils. Relatively low stiffness compared to linear portion as easier to stretch out the crimp of the collagen fibrils.
The toe region ends at about 2% strain when all crimpled fibres straighten.
what is the failure region on the stress/strain curve?
tendon/ligament is stretched to more than 8-10% of its original length, macroscopic failure
what is meant by viscoelasticity?
Biological materials are neither perfectly plastic nor perfectly elastic
Amount of deformation depends upon rate of loading
load applied rapidly meets with a rapidly increasing resistance and allows little deformation before failure: plastic
Load applied slowly meets less resistance and allows greater deformation to take place: elastic
what is regeneration?
This is replacement of damaged tissue with the same tissue
In minor muscle injuries the muscle fibres may regenerate
Tendon has a limited ability to regenerate
Peripheral nerves can regenerate provided that the cell body is intact
what is repair?
Lost tissue is replaced with granulation tissue
Matures to form scar tissue
Provides a ‘functional long term mend’
what are the tissue repair phases?
Bleeding
Inflammation
Proliferation
Remodelling
expand on the bleeding phase?
Relatively short lived phase
More vascular tissues bleed longer e.g. muscle
Average is 6-8 hours
Be aware bleeding can carry on for longer periods for example up to 24 hours in a blunt soft tissue trauma or longer
overview of inflammatory phase?
Goal is to stop bleeding phase
Vasoconstriction, retraction of injured blood vessels, fibrin deposition and clotting
Increase in blood supply occurs = oedema (build up of fluid) and redness
Essential component of healing with a rapid onset and gradual increase in magnitude 2-3 days
Generates exudates- fluid that filters from circulatory system to tissue
Composed of protein and leukocytes
explain the vascular response of the inflammatory phase?
Chemical mediators are released and result in:
Increased vasodilation
Increased velocity of blood flow
Increased vasopermeability
combination of the vasodilation and vasopermeability =increased flow through vessels =an increased exudate production.
exudate dilutes irritant substances and contains a high level of fibrinogen
explain the cellular response of the inflammatory phase?
Variety of cells emigrate from vessels including Polymorphonucleocytes (PMN’s)
PMN’s act as early debriders of the wound
Chemical mediators have a Chemotatic role (attraction): including platelet derived growth factor, C3a, C5a, macrophages & mast cells
These cells exhibit a strong phagocytic activity and the essential debridement of dead and dying cells, fibrin mesh & clot residue
explain the proliferation phase ?
Collagen is produced to form scar tissue
Starts between 24-48 hours after injury, but lasts up to 2-3 weeks
Formation of granulation tissue is a imperative
Granulation tissue composed of new capillaries which grow into damaged area
Contains phagocytes- dispose of blood clot
Contains fibroblasts (connective tissue cells)- building blocks of collagen fibres (scar tissue)
Deposition of granulation tissue which matures to form scar tissue
Capillaries bud: form loops around injured site re-establish oxygen & nutrient delivery required for collagen production
Fibroplasia: fibroblasts produce grade III collagen N.B vitamin C
Fibroblastic activation is mediated by macrophage derived growth factors. Myofibroblasts initiate wound contraction
what is meant by fibroplasia in proliferation phase?
Formation of granulation tissue
Fibroblasts produce collagen
As granulation tissue matures, less collagen type III is produced and more strong type 1
what is meant by Angiogenesis in proliferation phase?
Formation of new blood vessels
Greater blood flow to wound
Increased healing factors
explain the remodelling phase in tissue repair?
Dynamic system involving the orientation of collagen fibres
N.B. physical stress important
Re-absorption of type III collagen
Replaced with type I collagen
New evidence suggests the scar is remodelled as it is constructed
Organised and functional scar capable of behaving in a similar way to parent tissue
factors known to delay healing?
Age
Protein deficiency & Low vitamin C
Temperature
Poor blood supply/ischemia
Continued inflammation
Adhesion to bone or underlying tissue
Excessive movement
Steroids & NSAID’s
