Wound Healing Concepts and Classification

Wound Healing Goals

• Primary goal: Achieve anatomical integrity and full function of the injured part.
• Secondary goal: Achieve the best possible cosmetic result.

Wound Healing Classification

• Primary Intention:*

• Wound edges are clean and well-approximated.

• Healing is rapid, with minimal scar tissue formation.

• Usually united within 2 weeks, with dense scar formation within 1 month.

• Secondary Intention:*

• Wound edges are separated.

• Healing occurs from the wound base upward.

• Results in more extensive scar tissue formation.

• Healing is slower and may lead to wound contracture.

Normal Wound Healing Sequence

• Similar process for both primary and secondary intention.
• Steps are not detailed in the text.

Factors Affecting Wound Healing

• Local Factors:*
• Wound Sepsis:
  • Shaving skin before surgery increases bacterial counts and worsens infection rates.
  • Hair removal should be performed immediately before surgery.
  • Thorough antiseptic skin preparation with chlorhexidine or povidone-iodine is crucial.
  • Double skin scrubbing is standard procedure in most surgeries.
  • Surgeon's hand hygiene with the same antiseptics is important to reduce wound sepsis.
• Poor Blood Supply:
  • Areas with good vascularity heal faster.
  • Surgical technique affects blood supply to the area.
  • Maintenance of the vascular supply is critical.
  • Appropriate incision planning minimizes vascular disruption.
• Wound Tension:
  • High tension separates edges, impairs blood supply, and leads to complications.
  • Incision planning should minimize tension.
  • Skin grafting or flaps may be used to bridge large gaps.
  • Incisions along Langer's lines (natural skin creases) improve cosmetic results.
• Foreign Bodies:
  • Foreign material in the wound increases infection risk and scar formation.
  • Traumatic wounds should be thoroughly debrided.
  • Surgical wounds should be cleaned to remove devascularized fat, necrotic tissue, or hair.
• Previous Irradiation:
  • Preoperative radiotherapy damages blood vessels and skin stem cells, impacting healing.
• Systemic Factors:*
• Nutritional Deficiencies:
  • Vitamins A and C are essential for epithelialization and collagen production.
  • Zinc is an enzyme cofactor for cell proliferation.
  • Protein is needed for collagen production, impaired healing occurs with deficient intake.
• Systemic Diseases:
  • Diabetes, uremia, and jaundice impair wound healing.
• Therapeutic Agents:
  • Immunosuppressants (chemotherapy, corticosteroids) inhibit inflammatory response, slowing healing.
  • Corticosteroids specifically weaken small blood vessels.
• Age:
  • Healing rates are higher before puberty.

Complications of Wound Healing

• Infection: (Further discussion is needed in the next lecture).
• Dehiscence:
  • Total separation of the surgical wound layers.
  • High mortality rate in abdominal wounds.
  • Causes can include suture breakage, knot slippage, suture cutting, excessive tension.
• Incisional Hernia:
  • Dehiscence of deeper layers, skin intact.
  • Visceral (e.g., intestine) protrusion through defect.
  • More common in abdominal wounds.
• Hypertrophic Scarring:
  • Excess collagen scar tissue (non-progressive after 6 months).
  • Does not extend beyond edges of the wound.
  • Occurs in specific areas (joints, incisions across Langer's lines).
  • Poor suturing techniques, overlapping edges can cause hypertrophic scars.
  • Difficult to treat.
• Keloid Scarring:
  • Abnormal collagen metabolism leading to excess scar tissue extending beyond wound edges.
  • Continue to enlarge after 6 months.
  • Higher frequency in dark-skinned individuals and burn wounds.
  • Difficult to treat, recurrence is common.
• Contractures:
  • Scar tissue shortening, limiting movement, especially at joints.
  • More common in wounds with delayed healing, burns.
  • Avoid vertical incisions across joints.
  • Surgical treatments are required.