1. Chapter 3 §Mechanism of Injury- how an injury occurs §Severity of Injury depends on: l Type and angle of force; different periods of time l Tissue affected- bone, muscle, tendon, ligament

2. Force and Its effects §Force = the push or pull acting on a body l Two possible outcomes: Athletes can apply force Athletes can absorb force §Types of force-Fig 3-1 l Axial = acting along the long axis of a structure, Compressive = squeezing or crushing a structure Tension = pulling or stretching on an object l Shearing = parallel or tangent to a structure-spine l Torque = force around an axis-elbow/shoulder

3. Force and Its effects §Failure = the loss of continuity of a tissue resulting in rupture or fracture §Stress = distribution of force within a body l Force/area – Fig 3-2 l Force has a greater stress on a smaller area of the body l A higher amount of stress, rather than a higher amount of force usually c/s injury

4. Force and Its effects §Types of injury l Acute = mactrotrauma-fracture, sprained ankle Definitive moment of onset and single force l Chronic = microtrauma-stress fractures, arthritis Repeated chronic loading over a period of time Can persist for months or even years Acute injuries can turn into chronic injuries

5. Healing of Soft Tissue (1) §Three phases §Phase 1 = acute inflammatory - 0-6 days §Phase 2 = repair and regeneration 3-21+ days (Proliferation) §Phase 3 = remodeling up to 1+ year (Maturation)

6. Tissue Healing Phases

7. Acute Inflammation Phase §First several days after injury §Key signs: l Redness, heat, swelling, pain, loss of function §Key events: l Vasoconstriction --- tissue death (necrosis)-last secs to 10 minutes- reduces blood loss at a tissue site b/c blood thickens Blood Clotting Mechanism- Platelet reaction-Fig 3-3 Chemical mediator release- aid in the inflammation process- cause pain by stimulates nerve endings

8. Inflammation Process Continued l Vascular permeability increases/ vasodilation of cells which allows exudate to cleanse the site of debris and infectious materials l Exudate-plasma like substance that is made up of protein and WBC l Hematoma and Edema formation

9. Repair and Regeneration §3 days – 6 to 8 weeks §Begins when hematoma is diminished to allow for growth of new tissue §Key events: l Scar tissue formation begins l Improved vascularization l Collagen is laid down

10. Remodeling Phase §3 weeks after injury – up to one year §Mobilization vs immobilization §Key events: l Maturation of tissue-increases strength l Collagen fibers oriented along lines of stress l Decreased Flexibility l Return to normal chemical activity within body