The timing of the wound closure using microsurgical techniques is important. In severe injuries of the lower extremity with associated soft tissue defects, early aggressive wound debridement and soft tissue coverage with a free flap within five days was found to reduce postoperative infection, decrease flap failure, nonunion and chronic osteomyelitis.4,5 Godina emphasized the pathophysiology of the high-energy trauma and the emergency (during the first operation) or the importance of radical debridment and early tissue coverage within the first 72 hours.6
Lister and Scheker reported the first case of an emergency free flap transfer to the upper extremity in 1988, and they defined the emergency free flap as a "flap transfer performed either at the end of primary debridment or within 24 hours after the injury".7 Yaremchuk recommended that flaps should be transferred between 7-14 days after injury and several debridements. The argument in favor of this approach
is that the zone of injury, which often may not be apparent at presentation, can be determined by serial debridements performed in the operating room over several days.8
When deciding to perform a primary closure with a free flap two keys factors should be considered; the presence of an exposed vital structure and the risk of infection. A vital structure is defined as "one that will rapidly necrose if not covered by adequate soft tissue."9 The decision of what constitutes a vital structure depends on circumstances. Tissues such as vessels, nerves, joint surfaces, tendons and bone denuded of periosteum, may lose function and may create an environment resulting in infection when left exposed for long periods of time. In the decision-making process, the surgeon must consider the risk of leaving the vital structure exposed, its functional importance, and the probability of differential recovery of function considering primary or delayed primary coverage.
The risk of infection is the second important factor that should be considered, because it may jeopardize the quality of the functional recovery or the free flap. As the risk of infection increases, the wisdom of primary closure with a free flap is reduced. Debridement of the wound is the most powerful surgical tool to reduce the risk of infection of the wound. If radical debridement is not possible, it is not considered safe to perform a primary free flap transfer. Another perspective is that the capability to perform free tissue transfer allows the surgeon increased freedom to proceed with radical debridement and may actually reduce the risk of infection.10 Factors such as the mechanism of injury, the elapsed time and the degree of contamination of the wound should be considered in order to better evaluate the degree of wound infection. In an acute, sharp noncontaminated injury, when closure would be routinely performed if there were no skin loss, there seems to be little reason not to consider an emergency free flap.
There is more than one classification of flaps. The flap may be named after the first describing author, or it may be named according to several anatomical features, including the type or name of the tissue(s) (skin, muscle, musculocutaneous, fasciocutaneous), the location from where it is harvested (anterior lateral thigh), the type of vascularization (number of pedicles, septocutaneous, anterograde and retrograde flow) the name of the main feeding artery (dorsalis pedis flap), the shape of the flap (island flap), the origin of the flap (local versus distant flap) and way that are transplanted (free, microvascular flaps).
For practical use it seems best to divide muscle from fasciocutaneous flaps. We use classic flap terminology. Attention is focused on the few most useful free flaps with which most problems can be adequately solved.
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