Author: Vanessa Ngan, Staff Writer, 2005.

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 a period of 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, e.g. 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, e.g. diabetic ulcers, pressure ulcers, venous ulcers
Other Bullet wound, bite wound, poisoned wound

Wound healing

The process of wound healing involves three overlapping phases:

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

Wounds heal fastest if they are attended to as quickly as possible after 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. This 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. This is the method of choice to cover large surface wounds, e.g. large burns.

Temporary coverings
Temporary coverings include allografts (e.g. de-epidermised cadaver skin and in-vitro cultured epidermal sheets), xenografts (e.g. pig skin grafting), and synthetic dressings. These coverings are temporary because of their synthetic 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 (e.g. gauze-based products) and paste bandages (e.g. 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 detailed description of wound dressings see synthetic wound dressings.

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