Disorders of Wound Healing

DISORDERS OF WOUND HEALING

Disorders of wound healing in the burn patient result from ex-cessive abnormal healing or inadequate new tissue formation. Hypertrophic scarring and keloid formation result from excessive abnormal healing.

Scars

One of the most devastating sequelae of a burn injury is the for-mation of hypertrophic scars. Clinicians cannot reliably predict or prevent the formation of hypertrophic scars. Hypertrophic scars are more common in children, in people with dark skin, and in areas of stretch or motion. The pathophysiology behind these scars is not completely understood, but they are characterized by an overabundant matrix formation, especially collagen.

Hypertrophic scars and wound contractures are more likely to occur if the initial burn injury extends below the level of the deep dermis. Healing of such deep wounds results in the replacement of normal integument with highly metabolically active tissues that lack the normal architecture of the skin. In the collagen layer beneath the epithelium, many fibroblasts proliferate gradually. Myofibroblasts, cells that have the ability to contract, are also present in immature wounds. As the myofibroblasts contract, the collagen fibers, which normally lie in flat bundles, tend to form a wavy pattern. Eventually the collagen bundles take on a super-coiled appearance and collagen nodules develop. The scar be-comes red (because of its hypervascular nature), raised, and hard.

Burn personnel must be proactive in the prevention and management of scar formation. Compression measures are in-stituted early in burn wound treatment. Ace wraps are used ini-tially to help promote adequate circulation, but they can also be used as the first form of compression. Scar management occurs mainly in the rehabilitative phase, after the wounds are closed. Hypertrophic scarring may cause severe contracture across in-volved joints. Therefore, prevention and management of this type of scarring is essential (see “Prevention of Hypertrophic Scarring” in the rehabilitation phase discussion). However, these scars are limited to the area of injury and gradually regress over time.

Keloids

A large, heaped-up mass of scar tissue, a keloid, may develop and extend beyond the wound surface. Keloids tend to be found in people with darkly pigmented skin, tend to grow outside of wound margins, and are likely to recur after surgical excision.

Failure to Heal

Failure of the wound to heal may result from many factors, in-cluding infection and inadequate nutrition. A serum albumin level of less than 2 g/dL is usually a factor in impaired healing in the burn patient.

Contractures

Contractures are another concern as wounds heal. The burn wound tissue shortens because of the force exerted by the fi-broblasts and the flexion of muscles in natural wound healing. An opposing force provided by splints, traction, and purposeful movement and positioning must be used to counteract defor-mity in burns affecting joints.