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Chapter 14

Chapter 14. Injuries to the Tissues. OA 10.21. Differentiate between a primary injury and secondary injury. Objectives. Introduce the terminology associated with injury classification Introduce biomechanical forces that cause injuries Explain biomechanical concepts for various tissues.

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Chapter 14

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  1. Chapter 14 Injuries to the Tissues

  2. OA 10.21 • Differentiate between a primary injury and secondary injury

  3. Objectives • Introduce the terminology associated with injury classification • Introduce biomechanical forces that cause injuries • Explain biomechanical concepts for various tissues

  4. Injury classification • Intrinsic • Infection (viral, bacterial) • Extrinsic • Tissue stressed to the point of mechanical failure due to excessive force

  5. Extrinsic injury classification • Primary Injury • Direct immediate consequence of excessive force (trauma) • Secondary Injury • Delayed injury some time after initial trauma • An accommodation to the primary injury

  6. Extrinsic injury classification • Acute Injury • Mechanical failure of soft tissue due to excessive force occurring in a single bout • Sudden onset of short duration

  7. Extrinsic injury classification • Chronic Injury • Mechanical failure of soft tissue due to repeated micro-trauma occurring over an extended period of time • Gradual onset and are of prolonged duration

  8. Injury classification • Microtrauma • Occurs with repeated submaximal forces over time, and the tissues are unable to adapt • Macrotrauma • Occurs when a single force exceeds the tissue’s failure point

  9. Open vs. closed • Open • Exposed • Breaks the surface of the skin • Closed • Unexposed • Any injury that does not involve disruption of the skin surface

  10. Mechanical stresses • Load/Stress • External/internal force acting on the tissue • Force = Mass x Acceleration (F=ma) • Deformation/Strain • Extent of deformation under loading

  11. Load Deformation load/deformation • Mechanical force causes deformation • Degree of deformation depends on: • Tissue composition • Speed of applied load • Frequency of loading • Direction of loading

  12. Yield point • Load is greater than mechanical capabilities of the tissue • Elastic limit of the tissue has been reached • Mechanical failure occurs Ultimate Failure Point Load Yield Point Elastic Region Plastic Region Deformation

  13. Tissue stresses • Five primary mechanical forces that cause injury • Tension • Compression • Bending • Shear • Torsion

  14. Tissue stresses • Can occur alone or in combination • Type of force = Mechanism of Injury (MOI)

  15. tension • Creates a pulling action trying to elongate the structure • Longitudinal “tearing” stress • Overstretched tissue (i.e. valgus force)

  16. Valgus force

  17. compression • Creates a pushing action tending to shorten the structure • Stress is applied at each end (i.e. FOOSH)

  18. FOOSH

  19. bending • Loading about an axis – Combination of tension and compression

  20. Shear force • Force that acts perpendicular to the surface of a structure

  21. Shear force

  22. torsion • Load applied causing structure to twist about an axis

  23. Combined loading • Tissue is seldom loaded in one mode only • Subjected to multiple indeterminate loads • Geometric structure is irregular

  24. forces

  25. OA 10.22 • Give an example of each of the 5 mechanical forces that cause injury.

  26. Superficial injuries

  27. Integumentary System • Skin and structures derived from it • Hair, nails, sweat and oil glands

  28. Functions • Regulate body temperature • Protects body • Receives stimuli • Temp, pressure, pain • Eliminates waste • Sweat

  29. Three Layers • Epidermis: • Most Superficial

  30. Three Layers • Dermis: • Tough, Leathery Fibrous Connective Tissue • Partly Vascularized

  31. Three Layers • Subcutaneous (Hypodermis): • Superficial Fascia • Mostly Fat (Insulate & Absorb Shock) • Anchors Skin to Underlying Structures

  32. Three Layers

  33. Injurious Mechanical Forces • Friction • Scraping • Compression • Tearing • Cutting • Penetrating

  34. Open Vs. Closed • Open • Exposed • Breaks the surface of the skin • Closed • Unexposed • Any injury that does not involve disruption of the skin surface

  35. Abrasions • Scraping away of the superficial tissue • Sliding or skidding across a surface • Superficial in depth, large in area • Bleeding is minimal, risk of infection is great

  36. Laceration • Irregular cut caused by tearing forces • Jagged wound edges • Can be minor or very deep

  37. Puncture • Penetration of the skin by an object • Most susceptible to infection– why? • Impaling = object is embedded & partially sticks out

  38. Incision • A clean, straight, knife-like cut • Commonly caused by a surgeon

  39. Avulsion • Tearing away of tissue, commonly paired with a laceration. • Flap avulsion – tissue is still connected

  40. Calluses • Skin thickening due to increased friction or intermittent pressure

  41. Blister • Excessive friction combined with shear forces causing fluid build-up under the skin

  42. General Principles Of Wound Care

  43. Chain of infection pathogen

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