Tissue Response to Injury

1. Tissue Response to Injury Lesson One – Introduction & Soft tissue Phase I Recovery

2. Acute vs. Chronic • Inflammatory response • The process of healing begins immediately after tissue is injured. • Altered metabolism occurs and Chemical mediators released which begins the inflammatory response

3. Cardinal Signs of Inflammation • Rubor – redness • Tumor – swelling • Color – heat • Dolar – pain • Functio laesa – loss of function

4. Soft Tissue Injuries • Phase I –Inflammatory Response Phase – (Acute) • Time table – time of injury (0 hour) to 48-72 hours • Critical stage for overall healing • Inflammation fundamental – • Reaction is to protect and localize • Help rid the body of some injurious agent • Prepare body for healing and repair

5. Steps of Inflammatory stage after injury • Step one • Soft tissue injury occurs • Blood vessels immediately vasoconstrict • This allows for quick repair of broken blood vessel • This lasts between 10-15 min • Activation of chemical mediators occurs

6. Steps of Inflammatory stage after injury • Step 2 • Mast Cells and Basophils arrive and release their chemicals mediators • Histamine released by mast cells • Causes blood vessel vasodilation • Causes changes in cell permeability • The more tissue damage the longer the permeability will last • Heparin released by both Mast cells and Basophils • Causes the blood to anticoagulant

7. Steps of Inflammatory stage after injury • Step 2 cont…. • This causes more fluid – exudate - to enter the area (swelling) • The exudate enters through the cells walls that are now open – this is called permeability • The more fluid that shows up, slows the bleeding down causing stasis – the blood and fluid stops and accumulates • The whole process attracts other leukocytes (aka – chemotaxis) – neutrophils and monocytes • Platelets help form a plug over the area by adhering to the vascular wall, this helps localize the injury • The process takes up to six hours to complete

8. Steps of Inflammatory stage after injury • Step 3 • Neutrophils show up, they begin the process of phagocytosis – destroying and eating dead tissue and bacteria • They are considered small phagocytes • The process of Phagocytosis causes a release of enzymes that irritate surrounding tissue that helps continue the inflammatory process. • We must control the amount of enzymes released – if we do not they may spill over into healthy tissue • RICE

9. Steps of Inflammatory stage after injury • Step 4 • Monocytes – the last and the largest leukocyte arrives • They finish the cleaning up • When complete the next stage may begin • A physical sign that the inflammatory process is complete is the absence of new swelling

10. Leukocyte review • Leukocytes – white blood cells – three types • Basophils – • bring anticoagulant substance – • present in acute and chronic inflammation • Neutrophils – • small phagocytosis • the process of ingesting cellular material • represent 60-70% of leukocytes • Monocytes – • large phagocytosis • show about 5 hours after injury • Enzymes released during during phagocytosis acts as an irritant and continue the inflammatory process.

11. Chronic inflammation • This occurs when the acute process does not get completed • This is usually caused my micro trauma occurred during the acute inflammatory phase • Can be resistant to physical and pharmacological treatments • Prominent features different than from acute • Proliferation of connective tissue and tissue degeneration • Primary cells are Lymphocytes, plasma cells, macrophages vs. neutrophils leukocytes (acute) • Major chemicals are kinins (especially bradykinins) which causes vasodilation, increased permeability and thus pain • prostaglandins are also present

12. Tissue Response to Injury Lesson Two – Soft tissue injuries – phase II and III recovery

13. Phase II • Repair and regeneration (end of acute stage to six weeks) • Repair – healing / Regeneration – restoration of destroyed tissue or lost tissue • Stage begins when area has been cleaned • No more swelling • The beginning of this stage depended on by three factors • Elimination of debris • Regeneration of endothelial cells • Production of fibroblasts • basis for scar tissue formation

14. Three Processes for tissue repair • Resolution – this is used when there is little damage and normal restoration occurs

15. Granulation – occurs when resolution is delayed • Two types of healing • Primary • takes place when wound has close opposed ends • example – incision • minimal granulation occurs • secondary • occurs when wound ends are gaping and large tissue loss • Example - laceration • scar tissue is needed to protect area • scar tissue is less viable than normal tissue • lays in spaghetti pattern

17. Regeneration • Increased by • Health of individual • Nutrition • Type of tissue that was injured • Controlled mobilization must start in this section • This stage is considered finished when there is no more point tenderness in the area.

18. Phase III • Remodeling • Overlaps repair stage and can last up to 3 months to two years after injury. • Scar tissue continues to increase • Ligament tissue can take up to a year to remodel properly • Wolff’s law – bone and soft tissue will respond positively to physical demands placed on them – causing them to remodel or realign along tensile forces.

19. Phase III cont… • For proper healing many factors must be evaluated • Balance between synthesis/lysis – avoids unyielding scar • Must be a balance also between immobilization and Controlled mobilization • Proper forces applied during rehab – if done at right time strength will develop properly along stress lines • Tensile strength of collagen is specific to mechanical forces applied • If done at wrong time healing will take longer.

20. Extent of injury Edema Hemorrhage Poor vascular supply Separation of tissue Muscle spasm Atrophy Corticosteriods Keloids and hypertrophic scars Infections Humidity, climate oxygen tension O2 and keeping wound moist helps tissue grow twice as fast vs. having a scab Health, age, nutrition Factors that impede healing

21. Healing of soft tissue types • Cartilage healing • Articular cartilage has poor blood supply and heals slowly if at all. • If sub-chondral bone is affected healing may occur as normal due to greater blood supply • due to blood supply granulation will occur • Ligament healing • Extra-articular ligaments heals like any other vascular tissue • Surgically repaired ligaments show faster recovery but overtime the non surgical repaired ligaments catch up • Intra-articular ligament may not heal well because synovial fluid impedes clot formation • During repair phase collagen or connective tissue fibers are arranged in a random woven pattern with little organization. • scar forms gradually • If stressed properly scar will realign along stress lines (per Wolff’s Law) • May take up to 12 months to heal

22. Healing cont. • Nerve tissue • If nerve cells are involved – no chance for regeneration. • If nerve fibers are involved – regeneration possible (closer to the nerve cell the less likely) • regenerate 3-4 mm per day • Peripheral nerves regenerate faster than CNS nerves.

23. Management of healing • Management in healing • Nutrition • good nutrition will help healing • Older athletes healing slower than younger athletes • OTC Drugs • Pain medications – acetaminophen • Anti-inflammatory – ibuprofen and naproxen • Physical modalities • Heat and cold • Electrical stimulation • Exercise • Must be pain free.

24. Tissue Response to Injury Lesson Three – Fracture healing

25. Phase I • Phase I – acute stage – • Lasts about four days • Stage 1 – hematoma formation • Trauma • hemorrhage – forms within first 48-72 hours • Bone death • Causes inflammatory response – vasodilation, ect.

26. Phase II • Phase II – repair and regeneration • Stage 2 – cellular formation (lasts from day 5-10 approx) • Hematoma begins forming • forms fibrous bridge between the fractured ends • Major influx of capillaries that carry endosteal cells • These cells produce fibrous callus, cartilage, and woven bone

27. Phase II cont… • Stage 3 – callus formation • soft callus – begins in week 2 • unorganized network of woven bone bridging the fracture site • internal and external calluses • brings influx of osteoblasts • grow towards each other • Osteoclasts also show up helping remove broken bone and helping shape the bone • hard callus • begins forming in week 3 or 4 and lasting 3-4 months • gradual connection of bone filament • important that proper immobilization occurs or cartilaginous rather than bony union will occur • In most cases when the callus is 2-4 weeks strong then a cast may be removed (usually occurs around 6-8 weeks)

28. Phase III • Phase III – remodeling stage • Stage 4 - Ossification • Formation of new Haversion system • This leads to laying of new primary bone • Completed when new bone is laid down and excess callus is reabsorbed by osteoclasts

29. Phase III cont… • Stage 5 – Remodeling • Begins after callus is reabsorbed and bone is laid down along stress lines • May take many years • completed when bone has restored normal shape or a shape that can withstand imposed stresses

31. Management of acute fractures • Conditions that interfere with healing • Poor blood supply • Causes aseptic necrosis – bone death • Common places • head of femur • scaphoid of wrist • talus of ankle • poor immobilization • improper union • deformity develops • infection • compound fracture • staphylococcal or streptococcal infection • closed fracture not immune

32. Healing of a stress fracture • closed fracture not immune • Stress fracture caused by an imbalance of Osteoclasts (greater)/ osteoblast (lesser) activity • Must achieve balance again • If not healed will lead to full fracture

33. Tissue Response to Injury Lesson Four - Pain

34. Pain • Pain is both psychological and physiological. • Pain is subjective. • Nociceptors, are pain receptors (aka free nerve endings) • Sensitive to extreme mechanical, thermal, and chemical energy • They are found in the meninges, periosteum, skin, teeth, and some organs.

35. Transmission and Stimulation • Pain is transmitted to thalamus by two fibers • C-fibers – smaller and slower (Unmyelinated) • A –delta – larger and faster (myelinated) • Stimulation of nociceptors • When stimulated – release of neuropeptide, substance P. • This initiates an electrical impulse toward the spinal cord

36. Transmission and stimulation cont… • A delta • Moves up the spinal cord at moderate rapid speed • It goes to the thalamus • It will give the exact location of pain • The pain will be sharp, bright and/or stabbing

37. Transmission and Stimulation cont… • C- fibers • Also terminates in the Thalamus, but moves slower. • But has projections to the limbic cortex • this provides an emotional aspect to the pain • Pain by the c-fibers is dull, aching , and unpleasant

38. Endogenous analgesics • Nervous system is powered electrochemically • Neurotransmitter - is a chemical released at a pre-synaptic cell across a synapse and stimulating or inhibiting a postsynaptic cell

39. Endogenous analgesic cont.. • Two neurotransmitters help with pain • Endorphins and serotonin • They are generated usually by a noxious stimuli • This stimulates the periaquaductal gray area and other areas. • Where a morphine like substance , i.e. Endorphins and enkephalins, are produced • This helps cause analgesia

40. Pain categories • Pain sources • cutaneous • skin • sharp, bright, and burning – fast or slow onset • deep somatic • pain that stems from structures as tendons, muscles, joints, periosteum and blood vessels. • visceral • pain from organs • pain is diffuse at first then becomes localized. • Psychogenic • pain is caused from emotion no physical

41. Pain categories cont… • Fast vs. slow pain • fast – transmitted by A delta fiber – localized • slow – transmitted by C-fibers – aching, throbbing, burning • Acute vs. Chronic pain • acute – last less than six months • chronic – lasts more than six months

42. Pain categories cont… • Projected (referred) pain • Defined as pain away from the actual site of injury • signs and symptoms will vary • Three types of referred pain • Myofascial • Sclerotomic • Dermatomic

43. Myofascial • Musculoskeletal pain triggered by trigger points • trigger points – specific sensitive area that has been referred to soft tissue. • nerve impulses within this area bombard the CNS. • Two types – active and latent • active – one that causes pain and latent is dormant • latent may cause ROM decrease

44. Sclerotomic • Deep pain originating from bone or fascia • Transmitted along C-fibers • Pain is deep, aching and poorly localized • May be projected to limbic system, hypothalamus, reticular formation • this may cause depression, fear, and anxiety. • autonomic changes – blood pressure changes, sweating, vasomotor changes – (shock)

45. Dermatomic • An irritation to the A-delta fibers may cause this nerve irritation • Pain is sharp and well localized • Does not cause autonomic and affective response like sclerotomic

46. Pain Sensitivity • Vocabulary • Hyperesthesia – hyper-excitablity of sensory nerves • Paresthesia – unpleasant sensation from severe nerve irritation. Tingling • Analgesia – absence of pain • Pain assessment • May use number scale, visual analog, verbal descriptor

47. Pain sensitivity cont… • Pain treatment • Breaking of the pain-spasm-hypoxia-pain cycle a musculoskeletal injury cycle • Heat – increases blood circulation • Reduces nociception and ischemia caused my muscle spasm • May induce endogenous opoids • Cold – decreases blood circulation • Pain is reduced by reduction of swelling and muscle spams • Numbs the nerve endings

48. Pain sensitivity cont… • Induced analgesia • Use of TENS and acupuncture • Gate theory • All senses go to an area located in the dorsal horn. • Located here is T-cells and the substantia gelatinosa (SG) • T-Cells organize stimulus and transmit to them to the brain • The SG is the gate keeper. Determines what is sent to the T-cells • Three fibers send impulses – A-beta, A-delta and C-fibers. • A-beta is faster than all sends non pain senses to the gate.

49. Acupuncture/acupressure • stimulation of specific points along meridians located on the body that connect the whole body • when there is pain or illness the meridian point associated with that area is stimulated.

50. Pharmacological • Analgesic • Examples acetaminophen –a.k.a Tylenol • Blocks pain • Anti-inflammatory • Examples ibuprofen (Advil) and naprosyn (Alleve) • Decrease swelling which help reduce pain