soft tissue injury

Question 1

what is a soft tissue injury?

Answer 1

Damage of the muscles, ligaments or tendons
Most occur from sudden or uncontrolled movements
Can result in pain, swelling, contusion and loss of function

Question 2

what is an acute injury?

Answer 2

Acute injuries result from a sudden trauma to the body/body parts
Examples are sprains, strains and contusions

Question 3

what is an overuse injury?

Answer 3

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)

Question 4

what is a sprain?

Answer 4

Occur from overstretching or stresses applied

Sprain is trauma to a ligament (attaches bone to bone)

Question 5

what is a strain?

Answer 5

Strain is trauma to muscles or tendons (fibrous tissue)

Question 6

how does an injury occur?

Answer 6

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

Question 7

what are the different types of stresses?

Answer 7

Tensile - pulling
Compressive - squashing
Shear-applied parallel to a specific plane
Bending
Torsion - twisting

Question 8

on the stress/strain curve explain the region where there is a linear relationship (Elastic/linear phase)?

Answer 8

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.

Question 9

explain the plastic phase on the stress/strain curve?

Answer 9

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.

Question 10

explain the toe phase on the stress/strain curve?

Answer 10

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.

Question 11

what is the failure region on the stress/strain curve?

Answer 11

tendon/ligament is stretched to more than 8-10% of its original length, macroscopic failure

Question 12

what is meant by viscoelasticity?

Answer 12

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

Question 13

what is regeneration?

Answer 13

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

Question 14

what is repair?

Answer 14

Lost tissue is replaced with granulation tissue

Matures to form scar tissue

Provides a ‘functional long term mend’

Question 15

what are the tissue repair phases?

Answer 15

Bleeding

Inflammation

Proliferation

Remodelling

Question 16

expand on the bleeding phase?

Answer 16

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

Question 17

overview of inflammatory phase?

Answer 17

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

Question 18

explain the vascular response of the inflammatory phase?

Answer 18

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

Question 19

explain the cellular response of the inflammatory phase?

Answer 19

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

Question 20

explain the proliferation phase ?

Answer 20

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

Question 21

what is meant by fibroplasia in proliferation phase?

Answer 21

Formation of granulation tissue
Fibroblasts produce collagen
As granulation tissue matures, less collagen type III is produced and more strong type 1

Question 22

what is meant by Angiogenesis in proliferation phase?

Answer 22

Formation of new blood vessels
Greater blood flow to wound
Increased healing factors

Question 23

explain the remodelling phase in tissue repair?

Answer 23

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

Question 24

factors known to delay healing?

Answer 24

Age

Protein deficiency & Low vitamin C

Temperature

Poor blood supply/ischemia

Continued inflammation

Adhesion to bone or underlying tissue

Excessive movement

Steroids & NSAID’s

Question 25

what is a ligament grade I?

Answer 25

Micro failure but no instability
Maintenance of normal end feel
Pain, tenderness and diffuse swelling

Question 26

what is a ligament grade II?

Answer 26

Partial rupture
Increased ‘gapping’ but maintenance of normal end feel
Minor laxity but may result in functional instability during high demand movement
Pain, tenderness and local swelling

Question 27

what is a ligament grade III?

Answer 27

A completed rupture
Loss of definite ‘end feel’
Severe pain initially, significant swelling and possible haemarthrosis