DIAGNOSIS

Upon evaluation of a traumatic wound for reconstruction, many factors are considered. Assuming that the overall condition of the patient permits reconstructive surgery, the plastic surgeon must evaluate the nature and location of the wound. The wound bed needs to be clean and free of devitalized tissues. High-energy wounds and electrical burns produce extensive soft tissue damage, far beyond the zone of injury. All necrotic material needs to be aggressively debrided prior to embarking on reconstruction.

The concept of the “reconstructive ladder” recommends the use of the least invasive repair that will satisfactorily close a wound. The methods begin with secondary healing and progress through skin grafting to microvascular free-tissue transfer. This paradigm has been largely supplanted by the “reconstructive elevator” concept.¹ With this approach, the surgeon evaluates the wound and decides on the best option, not necessarily the least complicated one (Figure 1).

Figure 1 The “reconstructive elevator” evolved from the “reconstructive ladder” as the paradigm for approaching complex musculoskeletal reconstruction.

The ultimate goal for involvement of the plastic surgeon is to provide a reconstructive plan that gives special consideration to body symmetry and contouring and minimizes donor site defect and deformity.

ANATOMY

Split-thickness skin grafts (STSG) consist of the entire epidermis and a portion of the dermis, with an average thickness of 0.012–0.015 inches. STSGs require a vascularized wound bed, free of necrosis, with minimal bacterial burden. Healed grafts shrink considerably, bear abnormal pigmentation, and leave underlying tissues highly susceptible to trauma. Full-thickness grafts include the entire thickness of the skin, resist contraction, have potential for growth, and have texture and pigment more similar to normal skin. However, they require an even better vascularized wound bed.

The most important anatomical aspect of muscle flaps is their vascularity. Because blood supply is usually the limiting factor in flap success, flaps are most often categorized by the vascular system on which they are based. McGregor proposed the concept of “random” and “axial” pattern flaps based on the importance of the presence or absence of a major vessel running along the axis of the flaps.² Random pattern flaps do not incorporate a dominant vascular supply, relying on the networks of small-diameter vessels to sustain the transferred tissue. They are limited in size and may require delay for successful transfer. Axial pattern flaps incorporate an anatomically recognized arteriovenous system running along the long axis of the tissue which permits successful transfer of vascularized flaps with high length-to-breadth ratios. They obtain their vascular supply from the musculocutaneous and fasciocutaneous systems, both of which rely on multiple “perforator” arteries. Knowledge of muscle vascular anatomy is helpful in predicting the viability of overlying skin territories based on such perforating vessels.

The now classic schema of Nahai and Mathes has divided muscles into groups according to their principal means of blood supply.² A type I muscle, such as the gastrocnemius or tensor fascia lata (TFL), is supplied by a single pedicle. A type II muscle, such as the trapezius or gracilis, has a dominant pedicle, with one or more minor pedicles. A type III, the serratus anterior (SA) or gluteus maximus (GM), for example, has dual dominant pedicles. A type IV, such as the tibialis anterior (TA) or sartorius, has segmental pedicles. The type V, such as the internal oblique muscle or latissimus dorsi (LD), has a dominant pedicle, with secondary segmental pedicles. Most muscles fall into the type II group. Types I, III, and V are the most reliable because complete muscle viability can be sustained by a single vessel. Sometimes the muscle territory of a minor pedicle is poorly captured by the dominant pedicle in a type II muscle. Owing to their segmental means of perfusion, type IV muscles would potentially only allow small flaps that have limited application.

Certain muscle flaps can be raised on a simple pedicle. Due to musculocutaneous vascular perforators, an island of skin can be carried with the muscle (myocutaneous/musculocutaneous flaps). When the perforator is traced through the muscle to the pedicle, thereby preserving the muscle, a cutaneous perforator flap results. Blood vessels also travel from major arteries and veins through intermuscular septae to the skin. When the skin and fascia are raised on septal perforators, a fasciocutaneous flap is created. Any flap with a dominant pedicle can become a free flap by division and subsequent reanastomosis of the vascular pedicle artery and vein into the recipient bed. Free flaps may be muscle only, musculocutaneous, fasciocutaneous, or osteomyocutaneous.

SURGICAL MANAGEMENT: PRIMARY FLAPS

Musculoskeletal trauma will be grouped into five soft tissue coverage regions: head and neck, upper extremity, chest and trunk, abdomen, and the lower extremity (Table 1).