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Author: Vanessa Ngan, Staff Writer, 2005.

Table of contents

What is a wound?

A wound is defined as a physical injury where the skin or mucous membrane is torn, pierced, cut, or otherwise broken. The process of wound healing is complex and involves inflammatory, vascular, connective tissue and epithelial cells working together over some time. To better understand wound healing, we need to learn more about the different types of wounds and factors involved in their healing.

Classification of wounds

There are many different ways in which wounds can be classified. In many cases, a wound may consist of a combination of the different classifications.

1. Wound thickness
Superficial Involves only the epidermis and the upper dermis
Partial thickness Involves skin loss up to the lower dermis
Full thickness Involves skin and subcutaneous tissue
Deep and complicated Involves penetration into natural cavities, an organ or tissue
2. Wound complexity
Simple Affecting only one organ or tissue
Combined Affecting multiple organs and/or tissue
3. Wound age
Fresh Up to 8 hours from the time of injury
Old After 8 hours from the time of injury
4. Wound origin
Superficial Breaking the skin’s surface from scratching, rubbing, picking, or a graze from falling
Incised Usually as a result of surgical intervention
Crush Made with a heavy blow of a cutting tool, such as a hatchet, sword
Lacerated Fragments of tissue torn away with a sharp-edged object
Stab Made with a pointed tool or weapon
Contused Injury to tissue under the skin's surface, most common type of wound seen in traffic accidents
Secondary Wounds originating from primary diseases, such as diabetic ulcers, pressure ulcers, venous ulcers
Other Bullet wound, bite wound, poisoned wound

Wound healing

The process of wound healing involves three overlapping phases:

  • Inflammation – involves scab formation and infiltration of damaged tissue by white blood cells. These are responsible for removing dead tissue and ingesting bacteria.
  • Proliferation – involves the development of granulation tissue, contraction of the wound and growth of epithelial cells under the dried scab
  • Maturation – wound becomes less vascular and is strengthened by the rearrangement of collagen fibres.

The rate at which a wound heals is dependent on several factors. These factors need to be considered before deciding on the method(s) used to treat a wound. Factors to consider include:

  • Position and size of the wound
  • Tissue type (eg, sloughy, necrotic, granulating)
  • Amount of exudate
  • Presence or absence of infection
  • Presence or absence of pain

Wounds heal fastest if they are attended to as quickly as possible after an injury. The aim should be to dress or close the wound using appropriate methods to keep it free from infection and to create an environment that promotes healing.

Methods of wound healing

In recent times there has been much development in the field of wound management. To minimise scar formation and to accelerate healing time, different wound coverings and different techniques of skin substitution have been introduced.

Wound covering can be broken down into two categories:

Permanent coverings – autografts

An autograft is when a layer of epidermis and dermis is taken from healthy skin areas of the patient and grafted onto the wounded area. An autograft is the optimum wound cover, but it has the drawback of creating a second wound (donor wound) on the patient, which now also needs to be managed. An autograft is the method of choice to cover large surface wounds, such as extensive burns.

Temporary coverings

Temporary coverings include allografts (eg, de-epidermised cadaver skin and in-vitro cultured epidermal sheets), xenografts (eg, pigskin grafting), and synthetic dressings. These coverings are temporary because of their artificial or chemical components, limited adhesion to the wound surface, and foreign body character.

Synthetic wound dressings have come a long way from the days of traditional dressings (eg, gauze-based products) and paste bandages (eg, zinc paste). In the mid-1980s, the use of polyurethane foams and hydrocolloids as wound dressings was the beginning of the discovery of a vast array of compounds and materials that are now available for dressing wounds. For a detailed description of wound dressings see synthetic wound dressings.



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