Mechanism of Injury Flashcards
What are the most common mechanisms of injury (MOI)?
- 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
What are the 3 classifications of trauma?
- bacterial/viral
- chemical
- mechanical
What is a mechanical injury?
result from force/mechanical energy that changes the state of rest or uniform motion of matter.
What is trauma?
physical injury/wound produced by internal or external force
What are the 4 tissue properties?
- Load
- Stiffness
- Stress
- Strain
What is load?
an external force activing on the body causing internal reactions within the tissues
What is stiffness?
The ability of a tissue to resist a load. Greater stiffness means greater magnitude a load can resist.
What is stress related to mechanism of injury?
Internal resistance to a load.
What is strain?
Internal changes in tissue (ex. length) resulting in a deformation.
What are the 8 types of mechanical forces that can occur?
- impact
- shear stress
- torsion stress
- tension(stretch)
- impingement
- compression
- bending
- friction
What is direct impact?
When injury occurs at the point of impact.
What is indirect impact?
When injury occurs at a point away from point of impact.
What types mechanical injuries are caused from tissue loading?
- compression
- tension
- shearing
- bending
- torsion
What happens during compression injuries?
trauma occurs along the long axis of a bone causing tissue failure due to excessive compressive loads.
ex. burst fracture of spine.
What occurs in tension injury?
Ligaments or muscles are stretched linearly, causing tissue disruption along length of muscle/ligament.
ex. hamstring strain.
What occurs during a shear stress injury?
two opposing bones that displace on each other in parallel to articular surface.
ex. spondylolisthesis
How do bending injuries occur?
- two force pairs act at opposite ends of structure (4 points)
- three forces cause the bending (3 points)
- already bowed structures encounter axial loading.
What occurs with torsion injuries?
a twisting force that causes the tissue to fail.
ex. anterior cruciate ligament (ACL)
What occurs during an impingement injury?
pinching of intervening tissue between two bony structures.
ex. subdeltoid bursitis.
What occurs during friction injuries?
repetitive friction between two structures or an intervening structure.
ex. Iliotibial band friction syndrome.
What kind of condition would be caused on the skin by rubbing/friction, compression, and tearing?
blisters, bruises, lacerations.
What are acute conditions to the muscle/tendon caused by compression and tension?
contusions, strains.
What are chronic condtions caused by tension, tension/shearing, compression/tension to muscles and tendons?
tendonitis, myositis/fascitis, bursitis.
What are acute conditions caused by tension/compression to capsules?
Sprains, dislocations, subluxations.
What are chronic conditions caused by tension/compression/shearing to the capsule?
capsulitis/bursitis.
What are acute conditions caused by tension/compression/shearing to the bone?
fractures.
What occurs during foot to head direct impact?
Point of contact is distal at foot; energy is transmitted through legs and pelvis usually dissipating by the time it reaches spine. Minimizes injury
What occurs during head to toe direct impact?
Due to cervical spine being weaker than lumbar the proximal to distal trauma has greater chance of injury.
What are mechanical reasons for injury?
hereditary, congenital or acquired defects.
What reasons could impact injury susceptibility?
Body build, structural make-up, repetitive incorrect application of skill.
What are some determinates of injury severity?
direction, duration and magnitude of impact.
What are the four types of injury that can occur from magnitude and duration?
- low magnitude/long duration
- high magnitude/short duration
- low magnitude/short duration
- high magnitude/long duration.
What is considered during low mag/long dur. impact?
low energy of impact, long duration of contact time, tissue threshold could be exceeded over time.
ex. overuse injury, blister, callus, stress fracture.
What is considered during high mag/short dur. impact?
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.
What is considered during low mag/short duration impact?
low energy of impact, short contact time, impact threshold not exceeded which means potential for injury is low.
What is considered for high mag/long duration impact?
high energy of impact, long duration of contact time, greatest potential for injury and to all structures involved.
ex. fractures/dislocation/ligament injuries.
How are injuries classifed?
- stage of injury or healing
- severity of injury
- type of tissue damaged/injured
- type of mechanism
What are sprains and how do they occur?
ligament injuries, usually involve traumatic joint twist and stretching/tearing of connective tissue.
What are the sub-classifications of sprains?
1st, 2nd, 3rd degree.
What occurs in first degree sprain?
ligament is stretched
What occurs in second degree sprain?
ligaments torn slightly
What occurs in third degree sprain?
ligaments are torn completely.
What are strains?
injury to the musculotendenous unit, can be a partial tear or total rupture, or abnormal muscle contraction.
When does a breaking point in a tendon occur?
at 6-8% of increased length
What is tendinitis?
A gradual onset of tenderness due to repeated microtrauma and degenerative changes.
What is tenosynovitis?
inflammation of the synovial sheath. Can be acute or chronic.
What is a contusion?
injury from traumatic blow that compresses soft or boney tissues and creates hemorrhaging. AKA “bruise”
How many grades or degrees of contusions are there?
4
How can fractures occur?
Direct MOI (point of force) or indirect MOI (sudden violent/forceful muscle contraction)
What are the types of fractures that can occur?
Dislocation, subluxation and separation.
What is a disclocation?
complete disarticulation of joint, where stabilizing structures are disrupted.
What is subluxation?
Brief transient injury involving partial dislocation and spontaneous joint relocation.
What is separation?
separation of fibrous joint due to stretching/tearing of supporting tissues.
