Surgical Wound Healing

1. Surgical Wound Healing
Dr. Gilani
8/18/2022

2. Stages of Wound Healing

3. Stages
• Hemostasis/Inflammation
• Proliferation
• Maturation

4. Cells of Wound Healing
• Platelets
• Neutrophils
• Macrophages
• Monocytes
• Fibroblasts
• Keratinocytes
• Endothelial Cells
• Lymphocytes

5. Inflammation (Days 0-5)
Stage 1 – Hemostasis (clotting cascade) and Inflammation
• Cells:
• Platelets (fibrin clot)
• Release growth factors and cytokines
• Activate coagulation cascade
• Neutrophils
• Function:
• To concentrate cytokines and growth factors
• to sterilize
• Timing: 48hours (most abundant)

6. Inflammation (Days 0-5)
Stage 2
• Cells: Macrophages – major secretor of growth factors and cytokines
• orchestrates repair process by secretion of multiple growth factors
• Angiogenesis: FGF, PDGF, TGF –a/b, TNF-a
• Fibroplasia: IL,EGF, TNF
• Essential to progress to next step
• Function:
• phagocytosis (debris and bacteria)
• Signal migration of fibroblasts
• Involve in matrix synthesis
Stage 3  T lymphocytes

7. Proliferative (Days 5-21)
• Cells: fibroblasts and myofibroblasts
• Function: collagen (type III) synthesis and deposition
• Other important factors:
• cross-link: hydroxylysine and hydroxyproline
• Vitamin C: hydroxylation
• Deficiency  impairs collagen strength
*AFTER epithelium formed

8. Remodeling (Days 21-1 year)
• Function: remodeling (organized = tensile strength)
• Type III  type I
• 6-8 weeks (80% of normal strength)
• Up to 2 years
• Disorganization  Excessive collagen deposition
• Keloids: grow beyond boundary of wound (surgical excision)
• Disorganized type I/III collagen bundles
• Genetic component recurrence high
• Hypertrophic: within borders of wound (can spontaneously regress or
AgNitrate)
• Well-organized type III collagen
• Prolonged inflammation (high tension areas)

11. Wound Repair/Management

12. • Epidermis:
• Avascular
• Keratinized stratified squamous
epithelium
• “Come Let’s Get Sun Burned”
• Dermis:
• Blood vessels, lymphatics, nerves, hair
follicles, sweat glands
• Papillary
• Reticular  collagen/elastin (strength)
• Hypodermis/subcutaneous tissue
• Blood vessels, lymphatics, glandular
component

13. • Scalp laceration  galea
(aponeurosis) should be
approximated first
• For cosmesis

14. Wound Closure Goal: decrease inflammation
• Sterile technique and hemostasis
• decrease inflammation which decreases scar formation and risk of infection
• Fine forceps and skin hooks
• Avoids crush injury
• Types of suture/closure
• Nonabsorbable sutures for skin  nylon and polypropylene
• Absorbable for dermal or buried sutures  vicryl
• Staples for scalp wounds or incisions >5cm
• Fascial sutures need to have tensile strength at 6 weeks until max tensile
strength of wound is reached
• Steri-strips, fibrin glue, other sealants

15. Tissue layers for repair
• Deep sutures are placed in collagen-rich areas
– fascia and dermis
• Fatty layers are not closed
• Skin edges should be everted
Review
• Epithelization occurs within 24-48 hours
• Tensile strength is at 20% at 3 weeks, and 70-
80% in 6 weeks.

16. Acute Wounds
• Assess for neurovascular and tendon compromise
• Tetanus prophylaxis
• Assess for the usual factors: DM, immunodeficiency, venous
insufficiency, radiation, PAD
• Usually causes chronic or nonhealing wounds i.e.:
• Pressure sores
• Lower extremity ulcers from arterial or venous insufficiency
• Radiation skin injury

17. Nutrition and Wound Healing
• Vitamin C: Deficiency leads to Decreased collagen deposition, angiogenesis,
hemorrhage, infection
• Vitamin A
• Enhances inflammatory response
• Vitamin E
• Stabilizes Cell membrane
• Antioxidant
• Anti-inflammatory

19. Primary Intention
• Wound edges approximated
• Epithelialization
• 24-48 hours
Secondary Intention
• Open wound edges (not
approximated)
• Tensile strength
• Epithelization across longer
distance - covers
• Proliferation is longer
• More granulation and contraction
• Moist environment speeds healing
• More sensitive to thermal and
mechanical injury

20. Surgical Management of Wounds
Indications
• Dirty wounds
• debridement, irrigation, wound
management
• Pressure ulcers
• Debride
• Long term: wound management
vs flap
Contra-Indications
• Venous wounds/ulcers
• 80% of leg ulcers 2/2 venous
insufficiency
• Leg compression and elevation
• Arterial insufficiency/ischemia
• Trauma  non-healing wound
• AVOID DEBRIDEMENT
• NEED REVASCULARIZATION
• Or amputation…

21. Infected Wounds
• Symptoms:
• Fevers, tenderness, erythema, edema, drainage
• Open (incision and drainage)  culture  drain/debride 
antibiotics for surrounding cellulitis
• Remove foreign bodies (sutures, etc)
• Abx if not draining or if there are no fluid pockets

23. Chronic/Non-healing/Open wound
• Pressure sores  decrease pressure
• Turn and prop/off load or Low-pressure beds
• Ischemic extremities with dry, chronic wounds  Revascularize 
debridement
• Irradiated areas  Hyperbaric oxygen or tissue flaps
Treat Underlying Cause
• Control of infection, DM, or malnutrition
• Debride necrotic tissue in open wounds

24. Chronic/Non-healing/Open wound
Wound Care
• Daily wet to dry dressing changes
• Wound VAC
Long Term
• Skin graft for wounds where healing will not be complete in 2-3 weeks
• Granulation tissue at wound bed needed
• Flap coverage
• Local, regional, distant free flap

25. Post-op care
• Closed wounds – sterile until 24-48 hours after epithelization occurs
• Shower after 24-48 hours
• Avoid heavy activity for 6 weeks for closure of deep structures (fascia)
• Keep area clean
• Other things to consider:
• Open wounds – keep moist, clean environment
• Hydrocolloid dressings over bony areas or extremities
• Collagenases for fine debridement
• Can apply growth factors (PDGF, TGF-beta, FGF) to improve healing rates

26. Long Term Considerations
(chronic/enlarging wounds)
• Negative Pressure therapy (VAC)
• Decrease edema
• Increase blood flow
• Acellular dermal matrices (collagen matrix w/ growth factors)
• Skin grafts (full vs partial)
• Flap closure

27. Skin grafts
• Primary contraction – immediate recoil in freshly harvested skin graft
• Secondary contraction – after the graft is on its bed
• The thinner, the more 2nd contraction
• 4 stages of wound healing
• Adherence
• Imbibition – in 24-48 hours, nutrition and oxygen via passive diffusion from
wound bed
• Inosculation – new capillaries form to begin neovascularization
• Remodeling

28. Skin grafts
• Partial/Split thickness
• Donor site: thigh or buttock, variable amount of dermis
• Has more secondary contraction – avoid over areas of high tension!
• High function, cometic areas, large surface areas (i.e.burns)
• Relies on recipient site for nutrient/oxygenation/
neovascularization/incorporation
• Imbibition and inosculation
• Full thickness – entire dermis from areas that’ll allow tension-free
closure of donor site
• For areas where less secondary contraction is desired
• Donor sites are closed primarily

29. Flaps
• Transferred with blood supply (immediate)
• Local, region, or distant (free flaps)
• Skin and fat (and muscle, bone, nerve, fasica)
• Classified by movement needed to relocate
• Free flaps require microsurgical techniques for anastomosis of artery
and veins
• Great for previously radiated wounds, extremity reconstruction,
salvage after trauma

30. Factors that affect wound healing
• Infection
• Chronic wounds colonized by bacteria (>105 organisms/gram)
• Nutrition
• Vitamin C – hydroxylation (cross linking of collagen)
• Vitamin A – reverse chronic steroid treatment on wound healing
• Vitamin E – too much inhibits healing
• Zinc – poor epithelization
• Low protein (albumin <3)
• Perfusion – hypoxia/edema
• Diabetes – microvascular occlusive disease  glucose control
• Glycosylated hemoglobin  affinity for O2  low O2 delivery
• Smoking – increased CO  affinity for O2  low O2 delivery
• Steroids  vitamin A (our hospital does not have this…)
• Immunologic imbalances/inflammation
• Radiation  hyperbaric oxygen

31. MISCELLANEOUS

32. Marjolin ulcer
• Squamous cell carcinoma
• Cutaneous malignancy
• Setting of wound/long standing scars

34. Cytokine Quick Cheat Sheet
• TNF-a: wasting/Cachexia in cancer patients
• IL-1: fever (alveolar macrophages – atelectasis)
• IL-2: melanoma treatment (activats natural killer cells)
• IL-6: activate acute phase proteins (C-reactive protein, fibrinogen)
• IL-8: chemotaxis and angiogenesis
• TGF b: fibroplasia (keloid player)
• IFN gamma: inhibit viral replication
• Anti-inflammatory cytokines: IL-4, IL-10, IL-13

35. Bites Quick Sheet
• Human – polymicrobial (only 10-15% become infected)  AUGMENTIN (amoxicillin-clavulante)
• Eikenella, GAS, fusobacterium, other oral flora
• HIV, HBV, HCV, HSV – consider
• Look for foreign bodies and wash out extensively
• Dog – polymicrobial
• Rabies, Pasteurella, Eikenella corrodens, staphylococcus, streptococcus
• Cat – polymicrobial
• Cat scratch  bartonella henselae
• Toxoplasmosis, Pasteurella, staphylococcus, streptococci, moraxella
• Snakes (~25% are dry – no envenomation)
• Viperidae (rattlesnakes/copperheads/cottonmouths) – 95% in USA
• Hematologic effects  thrombocytopenia, coagulopathy, DIC, rhabdomyolysis
• Elapidae (coral snakes)
• Toxic neurologic effects (acetycholine)  weakness, fasciculations, respiratory paralysis, death (Myasthenia Gravis/Lamber Eaton)
• Spiders
• Black widow – benzodiazepine, resuscitation, pain control, ANTIVENIN available
• Brown recluse – NO ANTIVENIN, 10% progress to necrotic ulcer

36. Surgical Site Infections
SSI categories
• Superficial
• Deep
• Organ/space infections
• Fever, tenderness, erythema,
edema, drainage
Examples
• Clean – inguinal hernia
• Clean-contaminated –
appendectomy
• Contaminated – bile spillage
• Dirty – perforated appendix
Delayed primary or secondary intention for incisions with high risk for SSI

37. Common Absite Questions
What are the optimal nutrition parameters?

38. • Albumin >3 g/dL and prealbumin >16 mg/dL

39. • Most important factor in healing closed wounds by
primary intention:

40. Tensile strength

41. • What is the most important layer to close for strength in
skin lacerations?

42. • Dermis

43. • Rate of regeneration of a peripheral nerve:

44. • 1 mm/d or 1 in./mo

45. • The strongest layer of the bowel:

46. • Submucosa

47. • This cell is responsible for the movement and contraction
of wound edges:

48. • Myofibroblast

49. • What is the maximal tensile strength that a wound can
reach?

50. • 80% of original tissue strength

51. • Time period for maximum collagen accumulation in a
wound:

52. • 2 to 3 weeks (mostly type III, then gets converted to type I
with maturation)