Mechanism of Injury

Question 1

What are the most common mechanisms of injury (MOI)?

Answer 1

• all out exertion
• contact
• striking or throwing projectiles
• propulsion of body through air
• repetition of movement
• speed of sport
• extended periods of time/duration of activity
• large # of participants in small area

Question 2

What are the 3 classifications of trauma?

Answer 2

1. bacterial/viral
2. chemical
3. mechanical

Question 3

What is a mechanical injury?

Answer 3

result from force/mechanical energy that changes the state of rest or uniform motion of matter.

Question 4

What is trauma?

Answer 4

physical injury/wound produced by internal or external force

Question 5

What are the 4 tissue properties?

Answer 5

1. Load
2. Stiffness
3. Stress
4. Strain

Question 6

What is load?

Answer 6

an external force activing on the body causing internal reactions within the tissues

Question 7

What is stiffness?

Answer 7

The ability of a tissue to resist a load. Greater stiffness means greater magnitude a load can resist.

Question 8

What is stress related to mechanism of injury?

Answer 8

Internal resistance to a load.

Question 9

What is strain?

Answer 9

Internal changes in tissue (ex. length) resulting in a deformation.

Question 10

What are the 8 types of mechanical forces that can occur?

Answer 10

1. impact
2. shear stress
3. torsion stress
4. tension(stretch)
5. impingement
6. compression
7. bending
8. friction

Question 11

What is direct impact?

Answer 11

When injury occurs at the point of impact.

Question 12

What is indirect impact?

Answer 12

When injury occurs at a point away from point of impact.

Question 13

What types mechanical injuries are caused from tissue loading?

Answer 13

1. compression
2. tension
3. shearing
4. bending
5. torsion

Question 14

What happens during compression injuries?

Answer 14

trauma occurs along the long axis of a bone causing tissue failure due to excessive compressive loads.
ex. burst fracture of spine.

Question 15

What occurs in tension injury?

Answer 15

Ligaments or muscles are stretched linearly, causing tissue disruption along length of muscle/ligament.
ex. hamstring strain.

Question 16

What occurs during a shear stress injury?

Answer 16

two opposing bones that displace on each other in parallel to articular surface.
ex. spondylolisthesis

Question 17

How do bending injuries occur?

Answer 17

• two force pairs act at opposite ends of structure (4 points)
• three forces cause the bending (3 points)
• already bowed structures encounter axial loading.

Question 18

What occurs with torsion injuries?

Answer 18

a twisting force that causes the tissue to fail.

ex. anterior cruciate ligament (ACL)

Question 19

What occurs during an impingement injury?

Answer 19

pinching of intervening tissue between two bony structures.

ex. subdeltoid bursitis.

Question 20

What occurs during friction injuries?

Answer 20

repetitive friction between two structures or an intervening structure.
ex. Iliotibial band friction syndrome.

Question 21

What kind of condition would be caused on the skin by rubbing/friction, compression, and tearing?

Answer 21

blisters, bruises, lacerations.

Question 22

What are acute conditions to the muscle/tendon caused by compression and tension?

Answer 22

contusions, strains.

Question 23

What are chronic condtions caused by tension, tension/shearing, compression/tension to muscles and tendons?

Answer 23

tendonitis, myositis/fascitis, bursitis.

Question 24

What are acute conditions caused by tension/compression to capsules?

Answer 24

Sprains, dislocations, subluxations.

Question 25

What are chronic conditions caused by tension/compression/shearing to the capsule?

Answer 25

capsulitis/bursitis.

Question 26

What are acute conditions caused by tension/compression/shearing to the bone?

Answer 26

fractures.

Question 27

What occurs during foot to head direct impact?

Answer 27

Point of contact is distal at foot; energy is transmitted through legs and pelvis usually dissipating by the time it reaches spine. Minimizes injury

Question 28

What occurs during head to toe direct impact?

Answer 28

Due to cervical spine being weaker than lumbar the proximal to distal trauma has greater chance of injury.

Question 29

What are mechanical reasons for injury?

Answer 29

hereditary, congenital or acquired defects.

Question 30

What reasons could impact injury susceptibility?

Answer 30

Body build, structural make-up, repetitive incorrect application of skill.

Question 31

What are some determinates of injury severity?

Answer 31

direction, duration and magnitude of impact.

Question 32

What are the four types of injury that can occur from magnitude and duration?

Answer 32

1. low magnitude/long duration
2. high magnitude/short duration
3. low magnitude/short duration
4. high magnitude/long duration.

Question 33

What is considered during low mag/long dur. impact?

Answer 33

low energy of impact, long duration of contact time, tissue threshold could be exceeded over time.
ex. overuse injury, blister, callus, stress fracture.

Question 34

What is considered during high mag/short dur. impact?

Answer 34

high energy of impact, short duration of contact time, impact threshold of weaker structures may be exceeded, ex. blood vessels (bruise)
moderate potential for injury.

Question 35

What is considered during low mag/short duration impact?

Answer 35

low energy of impact, short contact time, impact threshold not exceeded which means potential for injury is low.

Question 36

What is considered for high mag/long duration impact?

Answer 36

high energy of impact, long duration of contact time, greatest potential for injury and to all structures involved.
ex. fractures/dislocation/ligament injuries.

Question 37

How are injuries classifed?

Answer 37

1. stage of injury or healing
2. severity of injury
3. type of tissue damaged/injured
4. type of mechanism

Question 38

What are sprains and how do they occur?

Answer 38

ligament injuries, usually involve traumatic joint twist and stretching/tearing of connective tissue.

Question 39

What are the sub-classifications of sprains?

Answer 39

1st, 2nd, 3rd degree.

Question 40

What occurs in first degree sprain?

Answer 40

ligament is stretched

Question 41

What occurs in second degree sprain?

Answer 41

ligaments torn slightly

Question 42

What occurs in third degree sprain?

Answer 42

ligaments are torn completely.

Question 43

What are strains?

Answer 43

injury to the musculotendenous unit, can be a partial tear or total rupture, or abnormal muscle contraction.

Question 44

When does a breaking point in a tendon occur?

Answer 44

at 6-8% of increased length

Question 45

What is tendinitis?

Answer 45

A gradual onset of tenderness due to repeated microtrauma and degenerative changes.

Question 46

What is tenosynovitis?

Answer 46

inflammation of the synovial sheath. Can be acute or chronic.

Question 47

What is a contusion?

Answer 47

injury from traumatic blow that compresses soft or boney tissues and creates hemorrhaging. AKA “bruise”

Question 48

How many grades or degrees of contusions are there?

Answer 48

4

Question 49

How can fractures occur?

Answer 49

Direct MOI (point of force) or indirect MOI (sudden violent/forceful muscle contraction)

Question 50

What are the types of fractures that can occur?

Answer 50

Dislocation, subluxation and separation.

Question 51

What is a disclocation?

Answer 51

complete disarticulation of joint, where stabilizing structures are disrupted.

Question 52

What is subluxation?

Answer 52

Brief transient injury involving partial dislocation and spontaneous joint relocation.

Question 53

What is separation?

Answer 53

separation of fibrous joint due to stretching/tearing of supporting tissues.