1 Introduction

“Exposure is the key to surgery”—this age-old adage has been revised in modern surgery. No longer are large skin incisions and wide subcutaneous exposures considered acceptable practice in trauma surgery. The health of the soft tissues, which surround a fracture, is now recognized as a key to successful fracture healing. The extent and the degree of soft-tissue injury at the time of fracture play an important role in healing and are one of the important factors that determine the personality of the injury. Patient factors, including advanced age, smoking, and systemic diseases, such as diabetes mellitus and vasculitis, may also affect soft-tissue healing and careful identification of comorbidities is essential when dealing with fractures. Correct interpretation of the soft-tissue damage, profound knowledge of the anatomy and the blood supply to the soft tissues, careful planning of incisions as well as accurate handling of the soft tissues can help avoid further damage and reduce complications.

2 Anatomy and blood supply of soft-tissue layers

Bone, endosteum, periosteum, muscles with their surrounding fascial layer, subcutaneous tissue, including its superficial fascial layer (tela subcutanea) [1], and finally skin can be regarded as an anatomical unit.

The blood supply to all these structures is closely related and interdependent, so it is important to understand the complex network of blood vessels and the flow of blood to successfully plan a safe and correct exposure of a fracture.

The blood supply to the skin is provided by two main sources: a fasciocutaneous vascular system and a musculocutaneous vascular network [2]. The fasciocutaneous vascular system runs through structures, such as fascia or septa of muscles. The musculocutaneous vascular system consists of three kinds of vessels:

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  Segmental arteries, which are in continuity with the aorta with regard to perfusion pressure, generally course underneath the muscles and are accompanied by a single large vein, and often by a peripheral nerve [3]. The radial artery is a good example.

  
  
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  Perforating vessels, also known as true muscle perforators, pass through the muscle or septa and serve as connections from segmental vessels to the cutaneous circulation. These conduits or perforators have connections to supply the muscles with blood.

  
  
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  Cutaneous vessels, which consist of:

  
  
  
  
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    – Musculocutaneous arteries coursing perpendicular to the skin surface

    
    
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    – Direct cutaneous vessels coursing parallel to the skin

The latter can be divided into fascial, subcutaneous, and cutaneous plexuses ( Fig 3.1.2-1 ) [4].

The fascia of the muscle, which consists of a dominant prefascial and a subfascial plexus, is well vascularized. In contrast, subcutaneous tissue is a poorly vascularized adipose tissue, which is separated by a well vascularized and mechanically resistant superficial fascial layer [1] that includes the subcutaneous plexus. This fascia is well developed in the trunk and in the thigh. The skin is vascularized by a complex system of various horizontal plexuses on different levels, including the subepidermal, the dermal, and the subdermal levels ( Fig 3.1.2-1 ).

The different horizontal vascular plexuses are interconnected by vertically oriented vessels that perforate the muscle, septa, and subcutaneous tissues. These vertically oriented vessels originate from the cutaneous and musculocutaneous vascular system.

In a horizontal extension, these plexuses form vascular territories, also known as angiosomes, which are composite units of skin and the underlying deep tissue supplied by their source arteries [5]. They are defined by the extent of connections of the source vessel before they anastomose with branches of adjacent source vessels.

To guarantee perfusion to the adjacent soft tissue, the surgeon has to be aware of two major facts before exposing a fracture site:

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  Mechanism of injury and the energy involved

  
  
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  Local angiosomes including anatomical relations of the perforator vessels

If these facts are not taken into account, there is a risk of underestimating the extent of the injury to the soft tissue. Direct injury and edema may reduce or completely interrupt collateral blood supply to the skin and so further surgical injury to perforating vessels may result in skin necrosis that would not occur during elective surgery on uninjured skin. Degloving injuries are a particular risk.

The surgeon must take care to avoid undermining the skin and to protect (vertical) perforating vessels during fracture surgery.

A wound must never be closed under tension, as this will reduce cutaneous blood flow and put the surrounding soft tissue at jeopardy.

3 Planning the surgical approach

The surgical approach will vary depending on the anatomical location of the injury, the type of reduction required, and the planned fracture fixation. In areas, such as the subcutaneous border of the ulna, where the skin is loosely attached to the underlying tissue and easily mobilized to cover a plate, a direct subcutaneous approach may be used. In other areas, such as the medial border of the distal tibia, the skin adheres tightly to the underlying structures and cannot be mobilized easily. Therefore, a subcutaneous approach may be much riskier. If the skin breaks down, the implant will be exposed and attempts to cover it by mobilizing local tissue will not be successful. Where possible, skin incisions should be sited over muscle. If there is skin break down with underlying muscle exposed, this can be covered by a skin graft.

Consideration should also be given to the following:

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  Langer′s lines (The result of elastic fibers within the dermis that serve to maintain the skin in a state of constant tension. They are a useful guide for the planning and designing of skin incisions.)

  
  
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  Prevention of soft-tissue contracture (Curved or broken incisions should be used over skin creases overlying joints.)

  
  
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  Anticipation of further surgery

For example, in periarticular knee fractures, delayed ligament repair or arthroplasty may be required, suggesting that straight incisions be used rather than curved ones. Likewise, an incision for plating of the fibula should be made more posteriorly to create a wide skin bridge if a second anterior approach is used to repair the distal tibial fracture at a later stage ( Fig 3.1.2-2 ).

4 Timing of surgery

There are several factors affecting the optimal timing of fracture fixation, the most important are:

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  General condition of the patient, eg, polytrauma, acute comorbidities

  
  
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  Soft-tissue injury

  
  
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  Fracture reduction

  
  
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  Planned rehabilitation

For each of these factors there may be a different optimal time for surgery and sometimes they are in conflict. Early fracture fixation allows earlier mobility of the limb and the patient, and reduces complications that are associated with prolonged immobilization, such as deep vein thrombosis and joint stiffness. Early surgery facilitates fracture reduction before the fracture becomes “sticky” due to callus formation and soft-tissue fibrosis. On the other hand, early fracture fixation may lead to increased wound complications if performed while the soft tissues are still traumatized and swollen. The amount of energy imparted on the tissues determines the zone of injury. This zone is characterized by disturbed microcirculation, which potentially endangers the viability of the soft tissues [6]. At the time of injury, it is often not possible to predict the extent of damage. Accordingly, the real area of traumatized soft tissue might be more extensive than initially appreciated, especially after high-energy trauma in the lower extremities.

The return of skin wrinkles shows that dermal edema has settled and is a favorable sign that soft-tissue swelling has decreased to the point where surgery can be undertaken safely. Gently pinching the skin or moving a neighboring joint (if possible) will demonstrate the presence or absence of skin wrinkles.

Fracture blisters are a problem for surgeons because they represent an injury to the dermis. There is little histological difference between blood-filled and clear blisters. Both are characterized by necrosis of the epidermis, although most surgeons are more concerned about blood-filled blisters [7]. There are many ways of treating fracture blisters while waiting for surgery. Removing the roof of the blister, followed by the application of various antibiotic ointments or Benzoin-tincture is advocated by some. Others leave the blister intact until surgery. No method is proven to be more beneficial than the other [7]. There is a consensus to delay surgery for 7–10 days for these types of injuries. If possible, incisions should avoid running through a blister and excessive retraction must be avoided.

As a rule, open reduction and internal fixation of the calcaneus, proximal and distal tibia can safely be postponed until 10–14 days after injury. In the upper limb, distal humeral fractures should ideally be repaired within 10 days. Elderly patients often benefit from early surgery and this has been established for hip fractures and may also be true for fractures in other sites, such as the proximal humerus [8]. The timing of fixation for fractures with associated compartment syndrome is difficult but early internal fixation in the upper limb is probably safe [9]. Most other fractures can be treated within 3 weeks from injury, if the soft tissues do not improve earlier. The patient should be counseled about smoking [10] and nutrition during this period when soft tissues are setting.

While waiting for surgery the fracture must be immobilized by a splint, by traction, or a temporary external fixator. This reduces not only pain but also significantly contributes to the recovery of the soft tissues. Moderate elevation of the extremity as well as foot compression devices—if applicable—help to resolve the swelling. Special attention must be given to the development of compartment syndrome (see chapter 1.5), especially if a circular splint or plaster cast has been applied.

A special and severe soft-tissue injury is the Morel-Lavallée lesion. It was originally described as an injury pattern associated with pelvic fractures where there is detachment of the skin and subcutaneous layers from deeper fascia. This type of lesion is caused by compression and shear stress at the transition zones of subcutaneous tissue and muscle fascia or the periosteum of bone as seen in run-over injuries. It leads to shearing of skin and subcutaneous tissue from the underlying muscle and/or bone, followed by the development of a blood-filled hollow space and fat liquefaction ( Fig 3.1.2-3 ). If the skin remains intact, this closed degloving injury can persist for weeks or even months, and carries a risk of infection generally thought to be caused by hematogenous seeding. Up to 46% of closed degloving lesions may have culture positive aspirates before incision and debridement. The usual clinical appearance is a fluctuant mass with mobile skin and bruising but it may also present as a solid tumor that could be confused with neoplasm. Once opened, these cases carry a similar prognosis as full-thickness burns with risk of severe infection and skin necrosis.

Occasionally, the soft-tissue envelope does not return to a state that permits surgery. For example, some open fractures need flap reconstructions and the interval between first debridement and definitive fixation is lengthy. This will result in delayed rehabilitation and poor functional outcomes. Recently, a two-stage protocol has been designed for open tibial injury consisting of a first stage that used low-profile, locking plates for temporary fixation after debridement and reduction, followed by soft-tissue reconstruction [12–14]. The second stage then consisted of locking plates for definitive internal fixation, using minimally invasive percutaneous osteosynthesis. This protocol allows patients to start rehabilitation before definitive internal fixation. Decision making is key in these complex situations and the surgeon must weigh the risks of surgery against the complications of nonoperative treatment. There are times when nonoperative treatment is the best option because the patient′s physiology, comorbidities, or soft tissues may never allow safe surgery. This course of treatment may be appropriate in older patients with poor nutrition or peripheral vascular disease or patients with severe multiple injuries who remain critically ill for a number of weeks.