Module 2 - Injury Classification and Tissue Healing

Understanding the different ways in which forces act on the body is necessary to comprehend techniques to prevent injury

True

Forces applied to the body can act at different angles, over different surface areas, and over different periods of time

True

The body is composed of many different types of tissue which respond to applied forces the same

False, respond differently

Acceleration

change in velocity

Deformation

change in shape

Factors affecting the likelihood of injury

• size/magnitude of force

• force’s moment arm (amount of torque generated)

• direction force is applied

• material properties of tissues affected and their ability to sustain strain

• area over which force is applied

• magnitude of stress produced by force

Elastic response to force

• small load

• load is removed, materials return to original shape

Plastic response to force

• load reaching yield point

• load is removed, but some amount of deformation remains

Yield load

max load a material can handle without permanent deformation

Failure (force)

force resulting in loss of continuity, rupturing soft tissue or fracturing bone

Anistropic

structures are stronger in resisting forces from certain directions compared to other directions

Why are many tissues anistropic

• anatomical make-up of joint

• direction of collagen fibers

Axial force

force that acts on the long axis of a structure

MOI of axial force

• upright body position

• burner

Compressive force

axial load that produces a crushing or squeezing type force

MOI of compressive force

contusion

Tensile force

axial force in opposite direction, pulling/stretching the tissues

MOI of tensile force

sprain

Shear force

force parallel to a plane passing though the object

MOI of shear force

• sliding/displacement

• blisters

Bending (torque)

simultaneous application of forces from the opposite directions at different points along a structure (long bone)

MOI of bending (torque)

fracture

MOI of torsion (torque)

fracture

Torsion (torque)

twist along a longitudinal axis

Mechanical stress

force divided by the area over which the force acts

How does stress affect the level of injury

a given force over a large area vs small area results in different levels of injury

The amount of deformation relative to the amount of force applied

strain

Compression strain

shortening and widening

Tension strain

lengthening and narrowing

Shear strain

internal deformation

What does an acute injury the result of

a single force

What does a chronic injury the result of

repetitive loading

Causative factor of acute injury

macro-trauma

Causative factor of chronic injury

micro-trauma

What is an acute injury characterized by

a definitive moment of onset

What is a chronic injury characterized by

becoming more problematic over time

Healing of acute injury

predictable timeline

Healing of chronic injury

may persist for months or years

List some common MOIs in an athletic population

• Collision with another athlete

• Collision with objects

• Infringement of the rules

• Force overload

• Dangerous techniques

• Environmental factors

• Equipment factors

• Training error: under-recovery or over-training

• Change in training surface

• Change in equipment

• Change in technique or training

External injury

• skin

• wound is highly visible

Internal/unexposed injury

muscles, ligaments, bone, cartilage, nerves, joint capsule

Contusion

an area of tissue in which capillaries have been ruptured (bruise)

Hematoma

collection of blood that forms at the site of a contusion

MOI of contusion

compressive or direct blow

S+S of contusion

• onset acute

• pain localized

• ecchymosis (discolouration) present if superficial

• moderate to severe restrictions in ROM

• swelling

• nerve compression

Most frequently injures muscles for contusion

• rectus femoris

• vastus intermedius

Sprain

• stretch/tear of a ligament

• compromises ability of ligament to stabilize joint

MOI of sprain

tension force (overstretch/overload)

S+S of sprain

• onset acute

• pain localized

• joint instability

• often swelling and discolouration

• server may result in subluxation/dislocation

Strain

stretch/tear of muscle

MOI of strain

tension force (sudden induced lengthening)

S+S of strain

• onset acute

• pain localized

moderate to severe:

• restrictions in ROM and strength

• swelling

• discolouration

Most common site of strain

muscle portion of musculotendinous junction

Key factors of a strain

• magnitude of force

• structure’s cross-sectional area

• yield point: 8-10% beyond normal length

Cramp

biochemical imbalance or fatigue

Types of cramps

• clonic: alternating contraction/relaxation

• tonic: constant

Spasm/spasticity

reflection action caused by biochemical or mechanical blow to nerve/muscle

Myositis

inflammation of connective tissue

Fasciitis

inflammation of fascia surrounding portions of muscle

Tendinitis

inflammation of tendon

Tendinosis

degenerative change to a tendon

Characteristics of tendinosis

• onset - chronic

• MOI - overuse/repetitive overload

• pain on palpation over tendon

• minor swelling, possible thickening

• crepitus possible

• pain at extreme ROMs

Tenosynovitis

inflammation of synovial sheath

S+S of tenosynovitis

• acute: rapid onset, crepitus, local swelling

• chronic: thickened tendon, nodule formation in sheath

Myositis ossificans

prolonged inflammation in a muscle/tendon may result in mineral deposits in affected tissue

MOI of myositis ossificans

often macro-trauma but can be micro

Common site or myositis ossificans

quad region

Dislocation/subluxation

joint is forced beyond its normal limits

MOI of dislocation/subluxation

tension

S+S of dislocation/subluxation

• onset - acute but may become chronic

• loss of limb function

• deformity present

• swelling

• point tenderness

• acute dislocation often result in fracture and/or nerve injury

Bursitis

inflammation of a bursae

MOI of bursitis

compression

S+S of bursitis

• onset - acute of chronic

• swelling

• pain localized

• may result in loss of function

• may result in degeneration

Fracture

a disruption in the continuity of the bone

MOI of fracture

different forces result in different fractures

Simple fracture

closed

Compound fracture

open

Epiphyseal injuries

injury to growth plate, may result in alteration in normal bone growth

Osteochondrosis

• disruption of blood supply

• idiopathic

Apophysitis

• Osteochondrosis of apophysis

• idiopathic

Nerve injuries may result in both sensory and motor changes

True

MOI of nerve injuries

result of tensile or compressive forces

Neuropraxia (Gr 1)

temporary loss of sensation and/or motor conduction with no nerve damage (resolves in days)

Axonotomesis (Gr.2)

significant motor and mild sensory deficits (resolves in 2 + weeks)

Neurotomesis (Gr 3)

total degeneration of the nerve, Motor and sensory loss (1 year)

List she different afferent symptoms caused by nerve injuries

• Hyperesthesia: heightened sensation

• Hypoesthesia: a reduction in sensation

• Paresthesia: a sense of numbness, prickling, or tingling

• Neuralgia: chronic pain along a nerve’s course

A completely severed nerve can still heal

False, if a nerve is completely severed, healing will not occur!

Exposed injuries

injuries that involve disruption to the skin surface

MOI of exposed injuries

friction, blunt or sharp trauma

Exposed injures are not susceptible to infection so should be monitored closely for pus, pain, redness, swelling, heat

False, are susceptible

Exposed injury examples

• abrasion

• laceration

• incision

• puncture wound

• blister

Phases of soft tissue healing

• inflammatory phase

• proliferative phase

• maturation phase

Inflammatory phase of soft tissue healing

Time: 0-6 days

1. vasoconstriction

2. platelet reaction

3. coagulation cascade

Vasoconstriction

• decreased blood flow doe to platelets and serum releasing serotonin and catecholamines

• lasts up to 10 minutes

Platelet reaction

• promotes clotting as individual cells & connect to form a plug

• chemical mediators also produce serotonin, adrenaline, noradrenaline, histamine, adenosine triphosphatose

Coagulation cascade

• fibrinogen converts to fibrin which can extrinsically and intrinsically form clots

• these two paths result in a prothrombin activator converting prothrombin into thrombin

Why is there vasodilator following vasoconstriction in the inflammatory response

Vasodilation brings neutrophils and macrophages to clean the area via phagocytosis

What mast cells are released during inflammatory response and what do they do

• Heparin: thins the blood and prolongs clotting

• Histamine: promotes further vasodilation

• Bradykinin: opens the blood vessel walls (increases permeability); results in pain

Inflammatory response: zone of primary injury

• Edema: increased permeability and pressure within the vessels forces a plasma exudate into the interstitial tissue

• Hematoma combined with necrotic tissue

Inflammatory response: zone of secondary injury

• Tissue affected by inflammation, edema and hypoxia

• Prostaglandins: promote further healing and clearing of debris