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 2/16/2010 2
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. 2/16/2010 3
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. 2/16/2010 4
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 2/16/2010 6
ProtectiveDevices 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 lesschance of disruption Tendon - Muscle to bone 2/16/2010 7
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 2/16/2010 9
2/16/2010 16 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.
OUCH !!!!!!!! Uhh- Yeah It’s Broken“ I don’t think that I’ll be going out tonight” 2/16/2010 18
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 2/16/2010 19
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 2/16/2010 20
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 2/16/2010 22
Types of Injuries and How they occur Contusions, Bruises, Hematoma By impact - Characterized by: local tenderness Swelling Discoloration Disabling I.E. vastusmedialis will limit walking ability "dead leg" 2/16/2010 23
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" 2/16/2010 24
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 2/16/2010 26
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 2/16/2010 28