Injury and the Healing Process

1. Injury and the Healing Process

2. Introduction to Injury • When an injury takes place some responses are predictable, but others are unexpected • It is not clear if the stages are the same in acute and chronic injuries • An athletes point of view of an injury • Painful problem that prevents or hampers sport performance

3. Tissue Damage • Microscopic trauma • Involves damage to a structure at a microscopic level • Macroscopic trauma • Is obvious, visible damage to a structure • Individual cell holds the key to the regulation of the body’s trauma response

4. Sports Medicine Goals • When an injury occurs the sports med team • Minimize the adverse effects of traumatic inflammatory response • Promoting tissue repair • Expediting a safe return to performance • Challenged to understand and anticipate the cellular response in predicting the recovery from injury

5. Injury Mechanisms • Human movement during sport and exercise is typically faster and or produces greater force • As a result, the potential for injury is also heightened • Understanding the different forces that act upon the body- you can understand how to prevent injuries

6. Force • Defined as a push or a pull acting on the body • When a force is sustained by body tissue, two factors help determine if injury occurs • The size and magnitude of the force • The material properties of the involved tissues

7. Small forces The response of the loaded structure is elastic When the load is removed the material will return to its original size and shape Large forces Exceeds the materials elastic limits- the structure is unable to elastically rebound to its original shape Some amount of deformation results Magnitude of Force

8. Magnitude of Force • Larger forces • Exceed the material’s ultimate failure limit • Produces mechanical failure of the structure • Translates to a bone fracture or rupturing of a soft tissue

9. Direction • The direction of force is applied has important implications for injury potential • Many tissues are stronger in resisting force from some directions than from others • Lateral ankle sprains are much more common than medial ankle sprains, because ligament support of the ankle is much stronger on the medial side

10. Categories of Force • Force acting along the long axis of a structure is an Axial force • 4 categories of force • Compression • Tension • Shear • Torque

11. Compressive Force • Axial load that produces a squeezing or crushing effect is a compressive force • Weight of the human body constantly produces compression on the bones • When a football player is sandwiched between two tacklers, the force upon the player is compressive • Often result in bruises or contusions

12. Tensile Force • Axial loading in the direction opposite of that of compression in called tension • Pulling force that stretches the object to which it is applied • Muscle contraction produces a tensile force on the attached bone, enabling movement • When the ankle is inverted, the tensile force results in an ankle sprain

13. Shear Force • Force that acts parallel or tangent to a plane passing through an object • Tends to cause one part of the object to slide, displace, or shear with respect to another part of the object

14. Torque • A rotary or twisting force is termed torque or torsion • Excessive torque's can produce injury • Usually generated by forces external to the body rather than by the muscles • Torsion results in the creation of shear stress throughout a structure • Causing such injuries as a spiral fracture

15. Stress • When a given force is distributed over a larger area, the resulting stress is less than if the force where distributed over a smaller area • If a force is concentrated over a small area, the mechanical stress is relatively high • Football and hockey pads- distribute any force sustained across the entire pad, thereby reducing the stress acting on the player

16. Strain • The amount of deformation an object undergoes in response to an applied force • Application of a compressive force to an object produces shortening and widening of a structure • Tensile force produces lengthening and narrowing of a structure • Shear results in internal changes in the structure acted upon

17. Acute Injury Caused by a single traumatic force Force is of large magnitude Definitive moment of onset Predictable process of healing Macrotrauma Ruptured ACL Fractured Humerus Chronic Injury Cased by repeated forces Force is of small magnitude Over a period of time Stress injury Microtrauma Starts when pain and inflammation become evident May persist for months or even years Acute vs. Chronic

18. Body’s Response to Force • Tendon, ligament, muscle and bone respond to gradually increased stress by becoming larger and stronger • Overuse syndromes and stress fractures result from the body’s inability to adapt to an increased training regimen

19. Soft Tissue Injuries • Behave in characteristic ways when subjected to different forms of loading • Skin • Tendon • Ligament • Muscle

20. Collagen • Major building block of soft tissue • Protein that is strong in resisting tension • Allows tissues to stretch slightly under tensile loading, providing flexibility

21. Skin Injuries • Skin is the body’s first layer of defense against injury • Most frequently injured body tissue • Different Types of Skin Injuries • Abrasions • Blisters • Skin Bruises • Incision • Laceration • Puncture Wound

22. Abrasions • Minor skin injuries • Caused by a shear force • Skin is scraped with sufficient force, usually in one direction, against a rough surface • The greater the applied force, the more layers of skin that are scraped away

23. Blisters • Minor skin injuries • Caused by repeated application of shear in one or more directions • Occurs when a shoe rubs back and forth against foot • Result is the formation of a pocket of fluid between the multiple layers of skin

24. Skin Bruises • Contusion • Injuries resulting from compression sustained during a blow • Damage of the underlying capillaries • Causes the accumulation of blood within the skin

25. Incision Clean cut Produced by the application of a tensile force to the skin as it is stretched along a sharp edge Laceration Irregular tear in the skin Typically results from a combination of tension and shear Incision and Laceration

26. Puncture Wound • Formed when a sharp object penetrates the skin and underlying tissues with tensile loading • Puncture wound can come from: • Shoe spike • Nail

27. Categories of Injury • Muscle bruises or contusion • Result from compression sustained from heavier blows • Injuries vary in severity according to the area and depth over which blood vessels are ruptured • Rated according to the extent to which associated joint range of motion is impaired

28. Categories of Injuries • Strain and Sprains • Caused by an abnormally high tensile force that produces rupturing of the tissue and subsequent hemorrhage and swelling • Categorized as first, second, and third degree injuries

29. First Degree Injuries • Some pain • Only involve micro-tearing of the fibers • No readily observable symptoms • Mild discomfort • Local tenderness • Mild swelling • Ecchymosis • NO loss of function

30. Second Degree Injury • More severe pain • More extensive rupturing of the tissue • Detectable joint instability • Muscle weakness • Limited joint range of motion

31. Third Degree Injury • Produce severe pain • Major loss of tissue continuity • Loss of range of motion • Complete instability of the joint

32. Tendonitis • Chronic condition • Characterized by pain and swelling with tendon movement • Prolonged chronic inflammation of muscle or tendon can result in the accumulation of mineral deposits, known as calcification

33. Bursitis • Involves irritation of one or more bursa, the fluid filled sacs • Serve to reduce friction in the tissues surrounding joints • Can be acute or chronic

34. Soft Tissue Healing • Normal healing process takes place in a regular and predictable fashion • Three Phases • Acute Response • Repair and Regeneration • Remodeling

35. Acute Phase • Also known as the reaction phase • Lasts for the first several days following an injury • Inflammation is major reaction in this phase • Characteristics of the inflammatory process: • Redness, Local Heat, Swelling • Pain and Loss of Function

36. Vasoconstriction • Vasoconstriction occurs in the acute phase • Curtails the loss of blood • Enables initiation of clotting • Hypoxia and Necrosis occur due to lack of oxygen and blood in the area • Hypoxia • Reduced oxygen in tissue • Necrosis • Death of tissue

37. Vasodilatation • Vasodilatation also occurs in the acute phase • Occurs after vasoconstriction • Brought on by chemicals released by the body • Increased blood flow causes swelling in area of injury • Broken blood vessels and damaged cells form a hematoma • Speeds the arrival of specialized cells that will ingest dead cells and any foreign material or infectious agents • The resulting swelling also stimulates nerve endings to cause pain

38. Repair and Regeneration Phase • Takes place from about 2 days following the injury through the next 6-8 weeks • Begins when hematoma has diminished in size allowing room for growth of new tissue • Except for skin, all other soft tissues replace damaged cells with scar tissue • Healing begins with the accumulation of fibroblasts to produce scar tissue

39. Repair and Regeneration Phase Cont… • Fibroblasts begin to produce immature collagen • The scar tissue that is formed is less strong and less functional than the original tissue • Development of the scar also causes the wound to shrink in size, resulting in decreased flexibility of the affected tissue

40. Remodeling Phase • Begins about 3 weeks post injury, overlapping the repair and regeneration phase and continues for a year or more • Maturation of the newly formed tissue • Decreased fibroblast activity • Organization of the tissues increases and normal chemical activity resumes

41. Severe Muscle Injuries • Severe muscle injuries can result in scarring or the formation of adhesions • After severe injury, muscle may regain only about 50% of its pre-injury strength • Adhesions • Tissues that bind the healing tissue to adjacent structures • Happens within the muscle • Inhibits muscle fiber regeneration

42. Tendon and ligament injuries • Have few reparative cells • Healing may take more than a year • If these tissues undergo abnormally high tensile stress before scar formation is complete, the newly formed tissues can be elongated • This may result in permanent joint instability

43. Bone Injury Healing • Three Phases Process • Acute Phase • Repair and Regeneration • Remodeling Phase

44. Acute Phase • Last approximately 4 days • Hematoma is formed • Vasodilatation occurs • Edema • Tissue chemical changes

45. Repair and Regeneration Phase • Osteoclasts come to the area of injury to reabsorb damaged bone tissue • Osteoblasts build new bone • A callus is forms between the fractured bone ends • A callus is a fibrous vascularized tissue containing immature bone • Strengthens with time through remodeling phase • Fixation devices are only implanted when it appears unlikely that the fracture will not heal properly

46. Remodeling Phase • Osteoblasts and Osteoclasts activity continues until normal shape and strength has restored • Time is the largest requirement for proper none union to take place • Complete remodeling may take many years

47. Nerve Injuries • Most commonly injured by tensile or compressive forces • When a nerve is loaded with tension, the nerve fibers tend to rupture prior to the rupturing of the surrounding tissue • The nerve roots on the spinal cord are not protected by connective tissue and are particularly susceptible to tensile injury, especially stretching of the brachial and cervical plexus

48. Compression Injury to Nerves • More complex • Severity depends on the magnitude and duration of the loading force • Nerve function is highly dependent on oxygen provided by blood vessels • Damage to the blood supply caused by a compressive injury results in damage to the nerve

49. Nerve Injuries • Symptoms can range • Pain • Discomfort • Complete loss of sensation • Chronic irritation/inflammation • Lead to chronic pain along the nerve’s path • Pinching of a nerve • Results in a sharp wave of pain that is transmitted through a body segment

50. Nerve Healing • Completely severed nerve • Healing does not occur • Loss of function is typically permanent • Incomplete nerve injury • Sometimes possible for regeneration • Regeneration is relatively slow