Causes & Formation of Scars


It is estimated that, on average, an individual has three scars on their body. Most scars can be attributed to everyday cuts, grazes and minor burns (34%). The remaining causes of scars include hospital surgery (20%), trauma (15%), elective surgery (15%), cosmetic surgery (10%) and mole removal (6%).

Common scars appear inflamed and dark in the beginning, but become flat and less noticeable over time resulting in a fine line scar.

Atrophic scars cause depressions or indentations below the surface of the skin. Examples are scars from acne or chickenpox.

Hypertrophic scars are raised above the surface of the skin characterized by excessive amounts of collagen. They remain within the boundary of the wound.

Keloid scars are also raised scars. However, keloids are characterized by the fact that they spread beyond the boundaries of a wound. They may continue to grow over time and usually recur after excision.

Contracture scars occur when the skin tightens permanently. They often develop following burn injuries or when scars cross joints. The scar tissue is resistant to stretching and can inhibit normal movement.

Stretch marks (Striae) occur during periods of rapid changes in weight, when the body expands faster than the skin covering it, causing internal tears in the skin tissue which form dermal scars.

Scars can cause physical discomfort and, in some instances, distressing psychological effects, particularly on a person’s confidence and self-esteem. 

Four phases of scar formation

First response - Haemostatic phase

This phase marks the body’s immediate response to injury as the wounded area attempts to restore its normal state by constricting blood vessels to control bleeding. The injured cells simultaneously release certain proteins to activate clotting, thereby sealing the area and reducing blood loss.

Enhanced protection – Inflammatory phase

The inflammatory phase is characterized by redness and swelling that appears for a period of three to four days after the initial trauma. This is a visible indicator of the immune response during which white blood cells release chemicals that cleanse the wound of debris and bacteria.

The cover-up - Proliferative phase

This phase begins around day three and continues for about three weeks. During this time three different processes occur simultaneously to close and bind the wound. Granulation takes place as fibroblast cells over proliferate at the site of injury to quickly synthesize collagen to fill the wound. Epithelialization creates a new layer of skin to cover the wound. Wound contraction ensues to minimize the defect.

Remodeling - Maturation phase

This ‘remodeling’ phase begins after three weeks, and can continue for up to two years. Collagen continues to build as the fibers are rearranged according to stresses placed on the area. These developments determine the final nature of a scar. Scar tissue generally achieves 70-80% tensile strength of normal skin*.

*A. Hsu, MD and T.A. Mustoe, MD, FACS (2010) 'The Principles of Wound Healing', in J. Weinzweig, MD, FACS, 'Plastic Surgery Secrets Plus'.