wound healing and suture materials

1. WOUND HEALING AND
SUTURE MATERIAL
1. Classification of wound healing
2. Normal sequence of wound healing
3. Factors affecting healing
4. Complication of wound healing
5. Suture material

2. Classification of wound healing
Primary intention
• Clean, close edges. Edges can be
bridged directly.
• Small scar tissues involved.
• United in 2 weeks. Dense scar
tissue formed 1 month
Secondary intention
• Edges separated; cannot be
bridged directly.
• Larger amount of scar tissue
involved.
• Heal slow, from bottom towards
surface by granulation.
• Complication: shrinkage 
contracture.

3. Normal sequence of wound healing
HEMOSTASIS
• Epinephrine is released to
minimize bleeding into soft tisses
• When: initial injury to 3 hours post
injury
• cells involved: platelet cells (clot
formation + releasing cytokines)
INFLAMMATORY
• Leukocytes + macrophages destroy
bacteria, cleaning wound of
cellular debris
• When: immediately following
hemostasis phase (0-3 days post
injury)
• Cells: host of cells infiltrate wound
site, such as leukocytes and
macrophages. Leukocytes destroy
bacteria.
• Macrophages (1) cleanse the
wound of cellular debris (2)
replace leukocytes (3) produce
cytokines and other growth
factors (chemoattractant to other
PROLIFERATION
• Angiogenesis + granulation tissue
formation
• When: 3 – 21 days post injury
• Cells: macrophages; fibroblasts;
immature collagen; blood vessels;
ground substance make up
granulation tissue, which fills the
wound’s cavity.
• 3 stages:
• Granulation: fibroblast stimulate
collagen production  tensile
strength + structure
• Contraction
• Epithilialization
MATURATION
• Collagen fibers in the scars are
reorganized to improve tensile
strength
• When: 21 days post injury and up
to 1.5 years later
• Cells: fibroblasts secret
procollagen (under affect of GF –
platelet + macrophages) then
mature into collagen fibril, which
then connect to one another to
create collagen fibers. MMPs

4. Factors affecting healing
Local
• Wound sepsis
• Poor blood supply
• Wound tension
• Foreign bodies
• Previous irradiation
• Poor technique
systemic
• Nutritional deficiencies
• Systemic diseases
• Therapeutic agents
• Age

5. Factors affecting healing: Local
Wound
sepsis
Hair removal: performed at necessary area, just prior to surgery
Antiseptic wash skin with Chlorhexidine and povidone-iodine; double scrub needed area
Hand wash with antiseptic
Poor blood
supply
Areas with good blood supply heal wellwhereas those with poor blood supply (pretibial skin) heal poorly.
Surgical technique also have a significant effect on the blood supply to the area.
Wound
tension
Foreign
bodies
Traumatic wound: Extraneous material  infection; excess scar formation
Surgical wounds: endogenous material (devascularised pieces of fat, necrotic tissue resulting from excess use of
the diathermy, or the patient's hair)  Thorough wound cleaning before closure

6. Factors affecting healing: Local
Previous
radiation
Cause patchy vasculitis  impair blood supply  reduce healing potential.
Damages skin stem cells  poor reepithelialisation
Poor technique The incision should be made vertically through the skin.
Gentle handling of tissues. Rough handling, damaging of tissues  tissue edge necrosis, predisposing to poor
healing and infection
Careful haemostasis: (1) good visualization during surgery; (2) reduces tissue bruising and
haematoma formation.
Skin closure: (1) should include the strength-supplying dermis within the bite; (2) Sutures removal at the correct
time (variable between sites) helps prevent scarring.
Foreign
bodies
Traumatic wound: Extraneous material  infection; excess scar formation
Surgical wounds: endogenous material (devascularised pieces of fat, necrotic tissue resulting from excess use of
the diathermy, or the patient's hair)  Thorough wound cleaning before closure

7. Factors affecting healing: systemic
Nutritional deficiencies
• Vitamin A: epithialisation + collagen production
• Vitamin C: production and modification of collagen
• Zinc: (1) acts as an enzyme cofactor (2) has a role in cell proliferation (accelerates wound healing). Deficiency may be
encountered in patients on long-term total parenteral nutrition.
• Protein: (1)main building block in wound healing; (2) essential for collagen production
Systemic diseases
• diabetes, uraemia and jaundice
Therapeutic agents
• Immunosuppressive drugs: chemotherapeutic agents for malignancy and immunosuppressive and antiprostaglandin
drugs used for inflammatory conditions. (e.g. corticosteroid therapy: increase the fragility of small blood vessels)
Age: wound healing increase prior to puberty, decrease postpuberty

8. complications
Infection
Dehiscence Cause by
Conditions impair wound healing
Suture breakage, knott slipping, cutting out of sutures,
excess tension on sutureline
Incision hernia
Dehiscence of the deeper layers of a wound in which the skin layer
remains intact will result in incisional hernia
Hypertrophic scarring
scarring is essentially excess collagen
scarmtissue formation - almost an
overhealing of a wound
Characteristics
Non progressive after 6 months
Does not extend beyond the edges of the wound
Occurs most frequently around joints, where langers’ lines of tension are
crossed by the incision
Cause Overlapping skin edges
Treatment:
Difficult: injection of corticosteroids directly into the scars several times
Avoid surgery at least 6 months
Keloid scarring
due to abnormal
collagen metabolism.
Characteristic:
scar tissue extends out beyond the wound edges
might continue to enlarge after 6 months.
Prevalence
higher in patients with dark skin, in younger patients
and in those with burn wounds.
the face, dorsal surfaces of the body, sternum and
deltopectoral region.
Treatment:
Excision: excision followed by compression bandaging
can have slightly better results
Corticoids injections have some improvement.
Contractures
Charateristics: Occurs in any wound but more commonly
associated with wounds that experience delayed
healing, burns, cut across the Langers’ lines
Treatment: Surgical treatment; (skin grafting,
local flaps or wound Z-plasty)

9. SUTURE MATERIALS
• Classification
• Selection of materials
• Needles
• Quality of a good incision

11. 1. Different materials has different handling properties. Prolene has memory  difficult to knot
2. Absorbable/ Non-absorbable: absorbable for deep layers; non absorbable for vascular anastomoses.
For absorbable sutures, time to dissolve aka lose strength should be considered.
3. Strength: braided sutures > monofilament
4. Tissue reactivity: the higher, the more likely to cause inflammation and produce scarring.

12. Needles
Round bodied needles:
• Used for suturing delicate
structures (bowel anastomosis)
• Designed to push tissues to
either side rather than cutting
through them
Blunt needlts:
• Used for closing the muscle of
an abdominal wound or
suturing liver
Cutting/ reverse cutting:
• Used for closing the tough
tissues (skin, fascia)
• Skin clips as replacement

13. Quality of a good incision
• Good access to structures being explored
• Can be extended to give greater access if needed
• Easy to perform
• Avoid tissue, skin damage (avoid excess use of diathermy, esp. at skin
edges; meticulous haemostasis, avoid haematoma formation)
• Consider cosmetic results
• Wound closure:
• Higher tissue tension on deeper layer of wound  strong suture (avoid excess
tension to prevent wound edges necrosis and wound dehiscence)
• Skin tension (+)  interrupted sutures or clips
• Skin tension (-)  subticular suturing with braided absorbable sutures (Vicryl) or
non-absorbable monofilament (Prolene)