mechanisms of injuries2010show1(2)
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Mechanisms of Injuries
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•No matter how much time is spent on injury prevention sooner or later an injury occurs
•Either acute or chronic in nature
•Acute injuries▫Result of trauma
•Chronic▫Caused by repetitive,
overuse activities
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INJURY MECHANISM
▫Mechanics of injuries Forces applied to the body
different angles, over different periods of time.
Different tissue types
respond differently to applied forces.
▫NOT an all or none
Phenomenon. injuries range in severity or grades.
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The Body Responds to Laws of Physics
• Movement through Space▫Accomplished by inefficient levers
The long levers must overcome considerable resistance. inertia muscle viscosity
▫More than 1/2 of the body's weight is in the upper body – ▫supported by rather thin bones. ▫center of gravity is relatively high in the human -
▫ requires energy to maintain posture.
▫Body can compensate• body may be lowered by widening stance to
decrease gravity.
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Sports Science
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FORCE AND ITS EFFECT
▫ Force Pushing or a pulling acting on a body. Numerous forces act on our bodies.
Gravity Terrain Weather Other bodies Equipment
▫ Balls▫ Bats▫ Clubs, etc
Bodies adjust when internal forces are produced by muscles. body absorbs forces body responds and adjusts
Two potential effects acceleration, or change in velocity deformation, or change in shape
▫ YOU TUBE VIDEOhttp://www.youtube.com/watch?v=P4PrTKwqeHY▫ http://www.youtube.com/watch?v=A_wnt84iyMk
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Protective Devices
•Musculature serves as a shock Muscle - affect movement of an organ or body
part. Cartilage pads - absorb shock.
•Ligaments - Maintains continuity of joints - bone to bone
•Muscle tone - Strength - again - the more flexible the muscle the less chance of disruption
Tendon - Muscle to bone
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Protective Devices
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Five Primary Tissue Stressors
• Tension=▫ Force that Pulls or Stretches Tissue
• Stretching=▫ Beyond Yield Point▫ Rupturing of soft tissue
• Compression=▫ Crushes Tissue
• Shearing▫ Force that moves across the parallel organization of tissue
Abrasions, Blisters ACL / PCL Tears
Tibia shears
• Bending=▫ Known as three point bending
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Ruptured Tissue
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Compression
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What is this????????
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Shearing
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More Shearing
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FRACTURES
• Interruptions in the continuity of a bone. • Classified as:
▫Simple break in a bone
▫Compound extended through the outer skin layers,
▫Fractures are one of the most serious hazards▫Causing factors:
Direct blow Torsion action Muscle / tendon stress causing avulsion fractures.
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OUCH !!!!!!!! Uhh- Yeah It’s Broken“ I don’t think that I’ll be going out tonight”
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Healing of a Fracture
▫Generally require immobilization for some period Approx. 6 weeks for bones of arms and legs 3 weeks for bones of hands and feet
▫Fracture healing requires osteoblast activity to lay down bone and form callus
▫Following cast removal, normal stresses and strains will aid in healing and remodeling process Osteoclasts will be called on to assist in re-
shaping of bone in response to normal stress
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Stress Fractures
No specific cause but with a number of possible causes Overload due to muscle contraction, altered stress distribution due to
muscle fatigue, changes in surface, rhythmic repetitive stress vibrations
· Switching to a harder running surface. · Rapid increase of speed or distance. · Returning to intense activity after a layoff. · Inadequate rest and excessive stress. · A change in footwear without proper adjustment period. · Improper shoe selection to accommodate foot type.
Begins with a dull ache and progressively becomes worse over time Initially pain during activity and then progresses to pain following activity
Early detection is difficult, bone scan is useful, x-ray is effective after several weeks Due to osteoblastic activity
If suspected – stop activity for 14 days Generally does not require casting
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Predisposing Factors
•Congenital (heredity) or Acquired •Kinesiological (way body moves through
space).•Pre-season physical examinations are very
important.▫Detect abnormalities▫Injuries not treated or Mistreated
•Nature of the Beast
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Types of Injuries and How they occur•Contusions, Bruises, Hematoma•By impact - •Characterized by:• local tenderness•Swelling•Discoloration •Disabling
▫I.E. vastus medialis will limit walking ability "dead leg"
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STRAINS• Involves Muscles or adjacent tendon.
▫ referred to as a "PULL“
• abnormal muscular contraction• imbalance between agonist and
antagonist muscles - Hams vs Quads• Fatigue
• Characterized by degrees of disruption of the muscle/tendon fibers
• A strain can range • Graded as 1st, 2nd, 3rd or• Mild, Moderate, Severe• Similar to contusion bleeding is
present and there may be some discoloration
• If severe - defect can be seen - Achilles "Roll Up"
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Explanation of Degrees
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SPRAINS• Over-extension of a joint. • Most common• Disabling injuries.• Forced beyond its normal anatomical
limits.• Microscopic and gross pathologies occur. • Injury to:
▫ Ligaments▫ articular capsule▫ synovial membrane
• Effusion (spreading) of blood and synovial fluid into the joint cavity
▫ inflammation (joint swelling)▫ point tenderness
• Laxity of joint
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Dislocations
• Disruption between the two articular surfaces.(Fingers and shoulders mostly)
• Divided into two classes
• Subluxations- partial dislocation wherein an imcompletet separation between 2 articulating bones occurs.
• Luxations- complete dislocations; total disunion of the bones.
• Characterized by▫ Loss of limb function; ▫ Obvious Deformity ▫ Swelling and point tenderness are
immediately present
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