This document discusses the process of wound healing through first and second intention. It begins by outlining the steps of healing by first intention for clean surgical incisions, including clot formation, re-epithelialization across the wound by day 3, and collagen deposition and scar maturation over subsequent weeks. Healing by second intention for wounds with separated edges involves more granulation tissue formation and wound contraction to reduce the gap between tissue edges. Complications can arise from deficient or excessive scar formation, including dehiscence, ulceration, hypertrophic scarring, and contractures.

2. REPAIR AND WOUND
HEALING
BY DR. ABDUL AZIZ SHAIKH

3. HEALING BY 1ST INTENTION
INCISION (CUT) & LACERATION (TEAR):
THE LEAST COMPLICATED WOUND REPAIR IS THE HEALING OF
CLEAN, UNINFECTED SURGICAL INCISION APPROXIMATED BY
SURGICAL SUTURES. THIS IS REFERRED AS PRIMARY UNION
OR HEALING BY 1ST INTENTION.

5. HEALING BY 1ST INTENTION
THE INCISION CAUSES DEATH OF LIMITED NUMBER OF
EPITHELIAL AND CONNECTIVE TISSUE CELLS AS WELL
AS DISRUPTION OF EPITHELIAL BASEMENT MEMBRANE
CONTINUITY.
THE NARROW INCISIONAL SPACE IMMEDIATELY FILLS
WITH CLOTTED BLOOD CONTAINING FIBRIN AND BLOOD
CELLS.
DEHYDRATION OF THE SURFACE CLOTS FORM THE
WELL KNOWN SCAB THAT COVERS THE WOUND.

6. STEPS IN WOUND HEALING BY 1ST
INTENTION
• WITHIN 24 HRS, NEUTROPHILS APPEARS AT THE MARGINS OF
THE INCISION MOVING TOWARDS THE FIBRIN CLOT.
• IN 24 TO 48 HRS SPURS OF EPITHELIAL CELLS MOVE FROM
THE WOUND EDGES WITH LITTLE CELL PROLIFERATION
ALONG THE CUT MARGINS OF THE DERMIS, DEPOSITING
BASEMENT MEMBRANE COMPONENT AS THEY MOVE.
• THEY FUSE IN THE MIDLINE BENEATH THE SURFACE SCAB
PRODUCING A CONTINUOUS BUT THIN EPITHELIAL LAYER
THAT CLOSES THE WOUND.

7. • BY DAY 3 THE NEUTROPHILS HAVE BEEN LARGELY
REPLACED BY THE MACROPHAGES.
• GRANULATION TISSUE PROGRESSIVELY INVADES
THE INCISION SPACE.
• COLLAGEN FIBERS ARE NOW PRESENT IN THE
MARGINS OF THE INCISION, BUT AT 1ST THESE ARE
VERTICALLY ORIENTED AND DO NOT BRIDGE THE
INCISION
• EPITHELIAL CELL PROLIFERATION THICKEN THE
EPIDERMAL LAYER

8. • BY DAY 5, THE INCISIONAL SPACE IS FILLED WITH
GRANULATION TISSUE
• NEOVASCULARIZATION IS MAXIMUM
• COLLAGEN FIBRILS BECOME MORE ABUNDANT AND
BEGINS TO BRIDGE THE INCISION
• THE DERMIS RECOVER ITS NORMAL THICKNESS
AND DIFFERENTIATION OF SURFACE CELLS YIELD A
MATURE ARCHITECTURE WITH SURFACE
KERATINIZATION

9. • DURING 2ND WEEK, THERE IS CONTINUED
ACCUMULATION OF COLLAGEN AND
PROLIFERATION OF FIBROBLAST .
• THE LEUKOCYTIC INFILTRATE ,EDEMA AND
INCREASE VASCULARITY HAVE LARGELY
DISAPPEARED
• AT THIS TIME THE LONG PROCESS OF BLANCHING
BEGINS ACCOMPLISHED BY THE INCREASED
ACCUMULATION OF COLLAGEN WITHIN THE
INCISIONAL SCAR ACCOMPANIED BY REGRESSION
OF VASCULAR CHANNELS.

10. • BY THE END OF 1ST MONTH, SCAR IS MADE UP OF
CELLULAR CONNECTIVE TISSUE DEVOID OF
INFLAMMATORY INFILTRATE COVERED BY INTACT
EPIDERMIS.
• THE DERMAL APPENDAGES THAT HAVE BEEN
DESTROYED IN THE LINE OF INCISION ARE
PERMANENTLY LOST.
• TENSILE STRENGTH F THE WOUND INCREASES
THEREAFTER BUT IT MAY TAKE MONTHS FOR THE
WOUNDED AREA TO OBTAIN ITS MAXIMAL
STRENGTH

11. HEALING BY 2ND INTENTION (WOUND
WITH SEPARATED EDGES)
WHEN THERE IS LARGE INJURY REGENERATION OF
PARANCHYMAL CELLS CANNOT COMPLETELY
RESTORE ORIGINAL ARCHITECTURE SO THERE IS
ABUNDANT GRANULATION TISSUE GROWS IN FROM
THE MARGINS TO COMPLETE THE REPAIR, THIS FORM
OF HEALING IS REFERRED AS 2NDRY UNION OR
HEALING BY 2ND INTENTION

12. STEPS INVOLVED IN
HEALING BY 2ND INTENTION
• LARGE TISSUE DEFECTS GENERATE A LARGER FIBRIN CLOT
THAT FILLS THE DEFECTS AND MORE NECROTIC DEBRIS AND
EXUDATE THAT MUST BE REMOVED .
• THE INFLAMMATORY REACTION IS MORE INTENSE.
• MUCH LARGER AMOUNT OF GRANULATION TISSUE ARE
FORMED
• WOUND CONTRACTION, THAT DECREASES THE GAP BETWEEN
THE DERMAL EDGES OF THE WOUND
• SCAR FORMATION AND THINNING OF THE EPIDERMIS

14. 24 hrs: proliferation of fibroblasts & endothelial cells
Within 3-5 days:
Sequence of events in repair

15. Angiogenesis: 2 mechanisms

16. Summary: phases of wound healing
Wound tensile strength: 10% of normal at 7 days;
70-80% of normal at 3 months

17. Rabbit Ear Chamber: Direct observation of fibrous repair.
1) Exudate clots 2) Neutrophils
infiltrate
and digest clot
3) Macrophages
and
lymphocytes are
recruited

18. Rabbit Ear Chamber: Direct observation of fibrous repair
4) Vessels sprout,
myofibroblasts make
glycoproteins
5) Vascular network;
collagen
synthesised;
macrophages reduced
6) Maturity. Cells
much reduced; collagen
matures, contracts,
remodels

19. Angiogenesis

23. Regeneration and repair combined:
A chronic peptic ulcer

26. FACTORS AFFECTING WOUND HEALING
• SYSTEMIC FACTORS:
- DRUGS (STEROIDS, CYTOTOXIC DRUGS, INTENSIVE ANTIBIOTIC THERAPY)
- GENETIC DISORDERS (OSTEOGENESIS IMPERFECTA, EHLER-DANLOS
SYNDROME)
- HYPOVOLUMIA, HYPOXIA
- AGE - ANEMIA
- HORMONES - DM
- MALIGNANT DISEASES - MALNUTRITION
- INFECTIONS
- VITAMIN DEFICIENCY (VIT. C)

27. LOCAL FACTORS:
- BLOOD SUPPLY - DENERVATION
- INFECTIONS - FOREIGN BODY
- HEMATOMA - MECHANICAL STRESS
- NECROTIC TISSUE - PROTECTION
(DRESSINGS)
- SURGICAL TECHNIQUES - TYPE OF TISSUE

28. COMPLICATIONS OF WOUND HEALING
• THERE ARE THREE GENERAL CATEGORIES
1. DEFICIENT SCAR FORMATION: INADEQUATE
FORMATION OF GRANULATION TISSUE OR
ASSEMBLY OF A SCAR CAN LEAD TO 2 TYPES OF
COMPLICATIONS:
- WOUND DEHISCENCE
- ULCERATION

29. COMPLICATIONS OF WOUND
HEALING
WOUND DEHISCENCE: OR RUPTURE OF WOUND IS MOST
COMMON AFTER ABDOMINAL SURGERY DUE TO INCREASE
ABDOMINAL PRESSURE
ULCERATION: WOUND CAN ULCERATE BECAUSE OF
INADEQUATE VASCULARIZATION DURING HEALING E.G.
LOWER EXTREMITY WOUNDS IN PTS WITH ATHEROSCLEROTIC
PERIPHERAL VASCULAR DISEASES AND PTS WITH DIABETIC
NEUROPATHY.

30. TISSUE ULCERATIONTISSUE ULCERATION
skin ulcer
ulcer
healing by second intention

31. 2. EXCESSIVE FORMATION OF SCAR
COMPONENTS:
• HYPERTROPHIC SCAR:
THE ACCUMULATION OF EXCESSIVE AMOUNT OF
COLLAGEN GIVE RISE TO A RAISED SCAR KNOWN AS
HYPERTROPHIC SCAR.
• KELOID: IF THE SCAR TISSUE GROWS BEYOND THE
BOUNDARIES OF THE ORIGINAL WOUND AND DOESN’T
REGRESS IS CALLED KELOID.

32. TISSUE REPAIRTISSUE REPAIR
abnormal tissue reaction with excessive fibroplasia
collagen deposition
keloid
dense collagen

33. PROUD FLESH: (EXUBERANT GRANULATION)
FORMATION OF EXCESSIVE AMOUNT OF GRANULATION
TISSUE WHICH PROTRUDES ABOVE THE LEVEL OF THE
SURROUNDING SKIN AND BLOCKS RE-EPITHELIALIZATION
• DESMOIDS OR AGGRESSIVE FIBROMATOSIS:
INCISIONAL SCARS OR TRAUMATIC INJURIES MAY BE
FOLLOWED BY EXUBERANT PROLIFERATION OF
FIBROBLAST AND OTHER CONNECTIVE TISSUE
ELEMENTS AND IN FACT REOCCUR AFTER EXCISION
CALLED DESMOIDS

34. 3.FORMATION OF CONTRACTURES :
AN EXAGGERATION OF CONTRACTION
IS CALLED CONTRACTURE AND RESULTS
IN DEFORMITIES OF THE WOUNDS AND
SURROUNDING TISSUE
PALM, SOLE AND ANTERIOR ASPECT OF
THORAX

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41. TISSUE REPAIRTISSUE REPAIR
first intention second intentionscab
neutrophils
mitoses
new capillaries
fibrous union
wound
contraction
Granulation tissue
macrophage
fibroblast
24 hours
3 to 7 days
weeks
clot