Mechanism of wound healing ppt

WOUND HEALING

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2. Mechanism of WOUND HEALING DEPARTMENT OF PUBLIC HEALTH DENTISTRY GUIDED BY DR.(PROF) VEERANNA RAMESH PRESENTED BY DR.ANANT KUMAR PG FIRST YEAR B.I.D.S.H 2

3. contents Introduction History of wounds Definition Classification of wounds Process of healing Phases of healing Healing of oral wounds Complication of wound healing Factors affecting wound healing Management of wound Laser in wound healing Conclusion References 3

4. INTRODUCTION WOUND , is a breach in the surface of the body, can be caused by accident, assault, warfare & surgical operations. Heal i ng i s a n a r t o f na t ur e . it i s a c o m pl e x a nd a dyna m ic p r ocess whi c h involves various cells, tissues and the other components of the body. The healing of wounds has always been central consideration in surgical practice. So, for understanding of the various mechanism of healing and factors affecting , it is of the prime importance for successful practice. 4

5. 5 Ebe Papyrus , 1500 BC detailed the use of lint, animal grease and honey as topical treatments for wounds. Egyptians believed that closing a wound preserved the soul. Greeks were the first to differentiate between acute and chronic wounds. Galen , a Greek surgeon 120-201 A.D., made many contributions to the field of wound care, in 1980s represented the dawn of modern wound care treatment. The roles of various growth factors in wound healing was extensively studied in 1980’s . HISTORY OF WOUNDS

6. DEFINITION A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function. A Wound is simply a disruption of any tissues i.e soft tissue or bone or internal organs. H ealing is complex method t o achieve anatomical and functional integrity of disrupted tissue by various components like ( neutrophils , macrophages, lymphocytes, fibroblasts, collagen ). WOUND HEALING 6

7. various CLASSIFICATION of wounds Rank and Wakefield classification Classification based on the type of the wound Classification based on thickness of the wound Classification based on involvement of structures Classification based on the time elapsed Classification of surgical wounds 7

8. I. Rank and Wakefield classification A) TIDY WOUNDS :- They are wounds like surgical incisions and wounds caused by sharp objects . B) UNTIDY WOUNDS :- They are due to: – Crushing. – Tearing. – Avulsion. – Devitalised injury . – Vascular injury. – Multiple irregular wounds. – Burns. 8

9. II . Classification based on the type of the wound A) CLEAN INCISED WOUND :- It is a tidy, simple, clean cut wound with linear cut edges, usually due to a sharp object like blade, glace piece or knife. It is treated by primary suturing . B) LACERATED WOUND :- It has ragged edges with some part of the tissues getting devitalized, viability of the tissues may be impaired, depth of the injury and tissue damage should be carefully assessed. 9

10. C) BRUISE OR CONTUSION :- It is due to blow or blunt force to the skin and tissues underneath wherein blood vessels or capillaries are damaged underneath. There is skin discolouration without breaking of the skin. D) HAEMATOMA :- It is a localized collection of blood after blunt trauma or after surgery. Collected fluid blood in few minutes to hours gets clotted, later eventually it gets liquefied and shows discoloured fluid. 10

11. Complications of haematoma 11 Pressure effect and A bscess formation. A B C Fig. (C) SUBUNGUAL HAEMATOMA. In this type of Haematoma nail may need to be removed to evacuate the blood clot .

12. E) ABRASION :- It is superficial injury like (scratch/graze/pressure/contact) and is due to shearing of the skin where the surface is rubbed off. This tangential force causes loss of epidermis exposing dermal vessels and nerves leading into profuse painful Oozing . F) PUNCTURE WOUNDS :- It is usually a stab wound with a pointed object. Deeper vital structures or organs may be injured. so should be assessed, foreign body or object may be present in the depth of the wound. 12 F E

13. G) PENETRATING WOUNDS :- They are similar like puncture wounds, due to stab. Abdomen and chest are common sites. Ultrasound and CT scan should be done to evaluate deeper organ injuries . H) TRACTION AND AVULSION INJURIES :- These are complex injuries with tissues getting displaced from its normal anatomical position and alignment. It can occur in single plane like in subcutaneous tissue or in multiple planes like in machinery injuries and major injuries. Penetrating wound of the abdomen 13

14. I) CRUSH INJURY :- It is due to major wounds, war wounds, natural disaster like earth quake injuries, tourniquet injury. It leads into- compartment syndrome, muscle ischaemia , gangrene, sepsis . J) GUNSHOT INJURIES :- These injuries may be superficial or deep. Usually entry wound and exit wound will be present. It causes explosive and destructive injuries along with burn injuries in the deeper planes and organs . 14

15. K) CLOSED BLUNT INJURY :- It may be due to fall, blunt injury wherein no obvious external injury may be seen but deeper injury occurs. it may be often severe enough to cause major injury like in blunt abdominal injury causing bowel/liver/spleen/renal injuries. WOUND CAN BE ALSO CLOSED, OPEN AND COMPLEX :- closed :- (bruise , haematoma , blunt injury). open :- (abrasion, incised, lacerated, penetrating). complex :- (traction/avulsion & gunshot injuries). 15

16. III. Classification based on thickness of the wound :- a) Superficial wound - involving only epidermis and dermal papillae. b) Partial thickness wound - with skin loss up to deep dermis with only deepest part of the dermis, hair follicle shafts and sweat glands are left behind. c) Full thickness wound - with loss of entire skin and subcutaneous tissue causing spacing out of the skin edges. d ) Deep wounds - are the one extending deeper, across deep fascia into muscles or deeper structures. e) Complicated wounds - are one associated with injury to vessels or nerves . f) Penetrating wound - is one which penetrates into either natural cavities or organs . 16

17. IV. CLASSIFICATION BASED ON INVOLVEMENT OF STRUCTURES :- A) SIMPLE WOUNDS are one involving only one organ or tissue . A   simple wound  is a break in the continuity of the skin limited in depth that does not affect the underlying structures (muscle, bone, joints, major arteries, nerves, tendons) and without significant loss of tissue. B) COMBINED/COMPLEX WOUNDS are one involving mixed tissues . Complex wound is the term used more recently to group those well-known difficult wounds, either chronic or acute, that challenge medical and nursing team. 17

18. V . Classification based on the time elapsed :- a) Acute wounds are generally defined as those that progress through the normal phases of healing and typically show signs of healing in less than 4 weeks. Examples – surgical wounds, traumatic wounds or burn wounds . b) Chronic wounds are defined as those that do not follow the normal healing process and show no signs of healing in 4 weeks. Causes are- Diabetes , venous/arterial disease and nutritional deficiency. 18

19. vi . Classification of surgical wounds a) CLEAN WOUND :- Herniorrhaphy . Excisions. Surgeries of the brain, joints, heart transplant. Infective rate is < 2% b) CLEAN CONTAMINATED WOUND :- Appendicectomy . Bowel surgeries, Gastrojejunostomy . Gallbladder, biliary and pancreatic surgeries. Infective rate is 10 %. 19 C) CONTAMINATED WOUND :- Acute abdominal conditions. Open fresh accidental wounds. Infective rate is 15–30%. d) DIRTY INFECTED WOUND :- Abscess drainage. Pyocele . Empyema gallbladder. Faecal peritonitis. Infective rate is 40–70%.

20. It involves two processes . REGENERATION REPAIR At times, both the processes takes place simultaneously. Process of HEALING 20 Healing is the body’s response to injury in an attempt to restore normal structure and function.

21. REGENERATION IT INVOLVES TWO PROCESS :- Proliferation of original cells. Proliferation of migrated cells . To maintain proper structure of tissues, cells are under the constant regulatory control of their cell cycle . THESE INCLUDE GROWTH FACTORS SUCH AS - Epidermal growth factor. Fibroblast growth factor. Platelet-derived growth factor. Endothelial growth factor . Transforming growth factor- β 21

22. cell cycle 22 Cell cycle is defind as the period between two successive cell divisions and is divided into 4 unequal phases. M (Mitosis ) phase: p hase of mitosis . G1 (Gap 1) phase: t he daughter cell enters G1 phase after mitosis. S (Synthesis ) phase: d uring this phase, the synthesis of nuclear DNA takes place . G2 (Gap 2) phase: a fter completion of nuclear DNA duplication , the cell enters G2 phase . G0 (Gap 0) phase: This is the quiescent or resting phase of the cell after an M phase . The cell cycle completes in 16-24 hours .

23. MITOSIS :- It is a process where a single cell divides into two identical daughter cells. Five phases of mitosis – 1. Interphase Prophase Metaphase Anaphase Telophase 23

24. Repair is the replacement of injured tissue by fibrous tissue. Two processes are involved in repair: Granulation tissue formation Contraction of wounds Repair response takes place by participation of mesenchymal cells (consisting of connective tissue stem cells , fibrocytes and histiocytes ), endothelial cells, macrophages, platelets , and the parenchymal cells of the injured organ. 24 REPAIR

25. Granulation tissue formation The term granulation tissue derives its name from slightly granular and pink appearance of the tissue. Each granule corresponds histologically to proliferation of new small blood vessels which are slightly lifted on the surface by thin covering of fibroblasts and young collagen . 3 PHASES ARE INVOLVED IN THE FORMATION OF GRANULATION TISSUE . PHASE OF INFLAMMATION PHASE OF CLEARANCE PHASE OF INGROWTH OF GRANULATION TISSUE 25

26. a. PHASE OF INFLAMMATION Following trauma, blood clots at the site of injury. There is acute inflammatory response with exudation of plasma, neutrophils and some monocytes within 24 hours . b. PHASE OF CLEARANCE Combination of proteolytic enzymes liberated from neutrophils, autolytic enzymes from dead tissues cells, and phagocytic activity of macrophages clear off the necrotic tissue, debris and red blood cells. c. PHASE OF INGROWTH OF GRANULATION TISSUE This phase consists of 2 main processes: Angiogenesis Fibrogenesis 26

27. Angiogenesis Fibrogenesis For m a t ion o f new blo o d ve s se l s a t the si t e o f i n j u r y t a kes place by proliferation of endothelial cells from the margins of severed blood vessels. The process of angiogenesis is stimulated with proteolytic destruction of basement membrane and takes place under the influence of the following factors: a) Angiogenesis takes place under the influence of vascular endothelial growth factor (VEGF) elaborated by mesenchymal cells but its receptors are present in endothelial cell only. b) Platelet-derived growth factor (PDGF) , transforming growth factor-β (TGF- β ), other cytokines and surface integrins are the factors which are associated with cellular proliferation . The new l y f or m ed b l ood v e sse l s are pr e sent i n a n a m o r phous gr o und substance or matrix. The new fibroblasts originate from fibrocytes as well as by mitotic division of fibroblasts. As maturation proceeds, more and more of collagen is formed while the number of active fibroblasts and new blood decreases. This results in formation of inactive looking scar known as cicatrisation . 27

28. Contraction of wounds Wound starts contracting after 2-3 days and the process is completed by the 14 th day. Factors - 1. Dehydration as a result of removal of fluid by drying of wound was first suggested being substantiated. 2. Contraction of collagen was thought to be responsible for contraction but wound contraction proceeds at a stage when the collagen content of granulation tissue is very small. 3. Discovery of myofibroblasts appearing in active granulation tissue has resolved the controversy surrounding the mechanism of wound contraction. 28

29. HEMOSTASIS INFLAMMATORY PROLIFERATIVE REMODELING 29 STAGE OF WOUND HEALING

30. Phases of WOUND healing (Figure ) Primary union of skin wounds . A , The incised wound as well as suture track on either side are filled with blood clot and there is inflammatory response from the margins . B, Spurs of epidermal cells migrate along the incised margin on either side as well as around the suture track. Formation of granulation tissue also begins from below. C , Removal of suture at around 7th day results in scar tissue at the sites of incision and suture track. Wound healing occurs by two ways – Healing by first intention ( primary union ) Healing by second intention (secondary union) 30

31. HEALING BY FIRST INTENTION (PRIMARY UNION) This is defined as healing of a wound which has the following characteristics :- clean and uninfected. surgically incised. without much loss of cells and tissue. edges of wound are approximated by surgical sutures . 31

32. sequence of events in primary intension Initial haemorrhage Immediately after injury, the space between the approximated surfaces of incised wound is filled with blood which then clots and seals the wound against dehydration and infection . Acute inflammatory response This occurs within 24 hours with appearance of polymorphs from the margins of incision . By 3rd day, polymorphs are replaced by macrophages. Epithelial changes The basal cells of epidermis from both the cut margins start proliferating and migrating towards incisional space in the form of epithelial spurs. A well approximated wound is covered by a layer of epithelium in 48 hours. The migrated epidermal cells separate the underlying viable dermis from the overlying necrotic material and clot, forming scab which is cast off. By 5th day, a multilayered new epidermis is formed which is differentiated into superficial and deeper layers. 32

33. 4. Organisation By 3rd day, fibroblasts also invade the wound area. By 5th day, new collagen fibrils start forming which dominate till healing is completed. In 4 weeks, the scar tissue, vascular elements, a few inflammatory cells and epithelialised surface is formed . 5. Suture tracks Each suture track is a separate wound and incites the same phenomena as in healing of the primary wound i.e . filling the space with haemorrhage , some inflammatory cell reaction , epithelial cell proliferation along the suture track from both margins, fibroblastic proliferation and formation of young collagen. When sutures are removed around 7th day, much of epithelialized suture track is avulsed and the remaining epithelial tissue in the track is absorbed. 33

34. HEALING BY SECOND INTENTION ( SECONDARY intension) This is defined as healing of a wound having the following characteristics : i ) Open with a large tissue defect ii) Having extensive loss of cells and tissues iii ) The wound is not approximated by surgical sutures but is left open. The basic events in secondary union are similar to primary union but differ in having a larger tissue defect which has to be bridged . Hence, healing takes place from the base upward and also from the margins inwards. Healing by secondary intention is slow and results in a large, at times ugly, scar. 34

35. sequence of events in secondary union INITIAL HAEMORRHAGE :- The wound space is filled with blood and fibrin clot which gets dries . INFLAMMATORY PHASE :- There is an initial acute inflammatory response followed by appearance of macrophages which clear off the debris as in primary union . EPITHELIAL CHANGES :- As in primary healing, the epidermal cells from both the margins of wound proliferate and migrate into the wound in the form of epithelial spurs till they meet in the middle and re-epithelialize the gap completely. GRANULATION TISSUE :- Main bulk of secondary healing is by granulations . Granulation tissue is formed by proliferation of fibroblasts and neovascularization from the adjoining viable elements . The newly-formed granulation tissue is deep red, granular and very fragile . 35

36. 5. WOUND CONTRACTION :- Contraction of wound is an important feature of secondary healing . Due to the action of myofibroblasts present in granulation tissue, the wound contracts to 1/3 rd to 1/4 th of its original size . 36

37. 37 Hypertropic scar keloid COMPLICATIONS OF WOUND HEALING Epidermal cyst

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39. To be continued ………. 39 Introduction History of wounds Definition Classification of wounds Process of healing Phases of healing Healing of oral wounds

40. 40 Complication of healing of extraction wound Factors affecting wound healing Management of wound Laser in wound healing Conclusion References

41. COMPLICATION OF HEALING OF EXTRACTON WOUND 41 DRY SOCKET FIBROUS UNION

42. Causes treatment 42 Smoking Surgical extraction of wisdom teeth Traumatic extraction Poor oral hygiene Drinking through a straw Radiotherapy

43. FIBROUS HEALING OF EXTRACTION WOUND Uncommon complication. Followed by difficult, complicated extraction. Loss of both the lingual and labial buccal plate of bones with loss of periosteum. 43 CLINICAL FEATURE :- Asymptomatic . TREATMENT :- Excision of the lesion. RADIOGRAPHIC FEATURE :- Well circumscribed radiolucent area in the site of a previous extraction wound.

44. FACTOR AFFECTING WOUND HEALING 44 NUTRITION OBESITY AGE MEDICATION SKIN MOISTURE CHRONIC CONDITION REPEATED TRAUMA

45. wound management Wound cleaning is needed to optimize the healing environment. It is achieved by removing visible devitalized tissues or dressing materials or excess exudates. Absolute aseptic technique should be used while cleaning the wound, warm sterile isotonic normal saline is ideal, normal exudates in the wound should be remove, gentle cleaning of the wound is important to minimize the interference of the wound-healing process. Gentle irrigation of warm saline using a sterile syringe on the wound surface is ideal, rubbing with undue force using cotton or gauze may cause mechanical damage on the process of wound healing . 45

46. Wound is measured either in two dimensions (length and width) or in three dimensions (length, width and depth ). Wound is inspected and classified as per the type of wounds . If it is in the vital area, then: The airway should be maintained. if bleeding is present, it should be controlled. Intravenous fluids are started. Oxygen , if required, may be given in Deeper communicating injuries. Antibiotics , fluid and electrolyte balance, blood transfusion, tetanus toxoid (0.5 ml intramuscular to deltoid muscle), or antitetanus globulin (ATG) injection . Later definitive management is done with: (Wound debridement or wound excision) 46

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48. LASERS IN WOUND HEALING Lasers employing low-level radiant energy have been claimed to produce a positive effect on the biological and bio-chemical processes of wound re-constitution. It has been reported that low level radiant energy of lasers has accelerated wound healing, reduced pain and enhanced neural regeneration. Dermatologic investigations have demonstrated more rapid epithelialization, enhanced neovascularization, and increased production of collagen by fibroblasts in vivo by the application of radiation from Argon or Helium neon l asers . 48

49. Wound care is becoming more complex as the range of wounds increases. Correction of underlying causative factor is essential and multidisciplinary. Overall patient benefit with the different wound healing strategies remains to be determined. 49

50. REFERENCES Mohan Harsh, Essential Pathology for Dental Students. 3 rd ed. M Bhatt Sriram , SRB’S Manual of Surgery 5 th Edition. Cotran and Robbins, Pathologic Basis of Disease 9 th Edition. 50

51. 51 Thank you