Key points

Skin

Soft tissue injuries, by their nature, involve the overlying skin and/or mucosa of the head and neck. The skin is the largest organ of the body and is also the most abused. The skin is, however, remarkably resilient and has a high capacity to heal. It provides protection from the environment, regulates body temperature, prevents fluid loss, and prevents entry of pathogens. It is made up of 3 general layers: the epidermis, dermis, and subcutaneous connective tissue ( Fig. 4 ). The epidermis is stratified squamous epithelium. It contains no blood vessels, minimal extracellular matrix, and few nerves. It does contain Langerhans cells, which are antigen-presenting cells of the immune system. It ranges in thickness from 0.05 mm over the eyelids to 1.5 mm over the soles of the feet. The epidermis is a waterproof, semipermeable membrane that turns over in about 40 days. Epidermal cells migrate through the 5 layers of the epidermis. They start at the basement membrane, which separates the epidermis from the dermis, and ultimately are desquamated at the skin’s surface. The 5 cell layers are the basal cells (the only dividing cell layer), stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

The 3 layers of the skin and dermal appendages.

( From Yildirimer L, Thanh NT, Seifalian AM. Skin regeneration scaffolds: a multimodal bottom-up approach. Trends Biotechnol 2012;30(12):638–48; with permission.)

Skin

Soft tissue injuries, by their nature, involve the overlying skin and/or mucosa of the head and neck. The skin is the largest organ of the body and is also the most abused. The skin is, however, remarkably resilient and has a high capacity to heal. It provides protection from the environment, regulates body temperature, prevents fluid loss, and prevents entry of pathogens. It is made up of 3 general layers: the epidermis, dermis, and subcutaneous connective tissue ( Fig. 4 ). The epidermis is stratified squamous epithelium. It contains no blood vessels, minimal extracellular matrix, and few nerves. It does contain Langerhans cells, which are antigen-presenting cells of the immune system. It ranges in thickness from 0.05 mm over the eyelids to 1.5 mm over the soles of the feet. The epidermis is a waterproof, semipermeable membrane that turns over in about 40 days. Epidermal cells migrate through the 5 layers of the epidermis. They start at the basement membrane, which separates the epidermis from the dermis, and ultimately are desquamated at the skin’s surface. The 5 cell layers are the basal cells (the only dividing cell layer), stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

The 3 layers of the skin and dermal appendages.

( From Yildirimer L, Thanh NT, Seifalian AM. Skin regeneration scaffolds: a multimodal bottom-up approach. Trends Biotechnol 2012;30(12):638–48; with permission.)

Dermis

The dermis makes up about 90% of the thickness of skin. It supports the epidermis with its collagen matrix and contains the dermal appendages, such as hair follicles, sweat glands, and sensory organs. The dermis provides nutritional support to the epidermis with a robust vascular plexus. Local and regional flaps owe their viability to this vascular plexus. It is thinnest over the eyelids (0.3 mm) and thickest over the back (3 mm). Closure of soft tissue wounds occurs primarily at the level of the dermis because it has the necessary tensile strength to support suture/staple closure. Accurate reapproximation of the dermis with eversion of the wound edges provides the greatest chance for a cosmetic closure. The dermis is 70% collagen by dry weight and 2% elastin, with glycosaminoglycans taking up the intervening space. A 1-mm collagen strand has a static load capacity of 20 kg. The subcutaneous tissue is a variable layer of adipose and connective tissue that intervenes between the skin and underlying musculature/fascia or skeleton. This subcutaneous fat allows the skin to move somewhat independently of the underlying tissue.

Healing

Skin and soft tissue heal in a regular pattern: an inflammatory phase, proliferative phase, and remodeling phase. The inflammatory phase is characterized by fibrin deposition and the start of epithelial cell migration under fibrin and over collagen. This phase lasts from 48 to 96 hours. The proliferative phase is characterized by fibroblast migration with production of extracellular matrix. It starts around the third to fourth day. Myofibroblasts contract the wound and macrophages clear debris. The remodeling phase begins with the decrement in fibroblast and macrophage number at around 3 weeks. At 6 weeks, the collagen synthesis and degradation is equalized. The final strength of the repaired tissue reaches 70% to 80% of the preinjury level ( Boxes 1 and 2 ).

Wound types

Facial wounds can be one of several types but are frequently a combination. A simple laceration is similar to a surgical incision. These lacerations should be irrigated and closed with minimal undermining. Complex lacerations require a more detailed study of their pattern to return tissue to its original position and should be closed in a layered fashion, suspending tissue as required to remove tension from wound edges.

Abrasions are the removal of the epidermis and outer portion of the dermis. Carefully debride and clean abrasions and cover with antibiotic ointment. These wounds should not be allowed to dry out during their re-epithelialization. Re-epithelialization will occur from keratinocytes migrating from the wound edges and from adnexal structures.

Avulsive injuries involve the loss of soft tissue, including complete loss of the epidermis and dermis. These wounds may be treated with the use of wound vacuums to prepare the wound bed for grafting procedures and/or reduce the size of the wound. Wet to dry dressings may also be used to debride the wound and allow the formation of granulation issue. Avulsive injuries may be closed by secondary intention, local flaps, regional flaps, or grafts ( Figs. 6–8 ).

Avulsion of left ala of nose, including skin and cartilage.

Same patient as Fig. 6 showing composite graft from helix of ear.

Same patient as Figs. 6 and 7 showing the inset composite graft from the ear to the left ala of the nose.

Puncture wounds have a small epidermal defect in comparison with their depth. The greatest challenge with puncture wounds is achieving adequate irrigation, which may require the use of catheters to reach the depth of the wound or may require opening the wound.

Contusions and blast injuries may produce extensive soft tissue damage, which is not readily apparent on initial presentation. These injuries compromise the microvasculature and, thus, the healing capacity of the soft tissue. Minimal manipulation is warranted with monitoring of the tissue to determine vitality and signs of infection ( Figs. 9–11 ). Burns require specialized treatment and should be referred to a burn unit for treatment except for those limited in surface area and depth. Small, superficial burns can be treated like an abrasion with topical antibiotic ointments.

M16 round to midface, a low-energy gunshot/blast type injury.

Same patient seen in Fig. 9 after primary calvarial bone grafting to replace missing midface skeleton.

Same patient seen in Figs. 9 and 10 after primary closure and microvascular free flap to close avulsion injury to left cheek.

Approach

The approach to the treatment of soft tissue trauma is an iterative process. The examination of the wound begins the moment patients are first visualized. Further evaluation of the facial wounds is then deferred to manage patients’ general medical condition following advanced trauma life-support protocol. Other than soft tissue trauma compromising the airway or resulting in life-threatening hemorrhage, treatment of facial trauma is delayed until patients are stabilized.

History and physical

The history and physical was already begun during the Advanced Trauma Life Support Change (ATLS) surveys but continues after the patient’s initial stabilization. Persistent facial hemorrhage should be controlled. Focused questions related to the facial soft tissue trauma should be pursued. Knowing the events surrounding the trauma will provide information on the mechanism, possible contamination, time since injury, and time since last oral intake. The patients’ general medical condition will have an impact on the patients’ wound-healing capacity.