Mastering Complications In External Fixation

Author(s): 
By David Kanuck, DPM, and Gary Jolly, DPM

   Any surgical procedure carries a risk of complications. Whether one opts to utilize internal or external fixation, there is both a common and yet unique set of problems based on hardware design and usage. Therefore, it is imperative to obtain an intimate working knowledge of the equipment and its capabilities in order to maximize the true potential of each method and hopefully minimize the risk of complications.    The ability to control an internal surgical environment by external manipulation is a powerful tool that is unique to external fixation. This “third dimension” empowers the surgeon to perform functions such as distraction, compression and neutralization in order to address suboptimal positioning postoperatively. It also enables one to extend the surgical procedure intentionally into the postoperative phase to facilitate gradual correction of deformities. Specifically, surgeons can accomplish this through frame morphing and adjustments via wire and ring modification. This distinction allows surgeons to address many problems in a “bloodless” fashion.    Therefore, it is not unreasonable for the initial frame setup to vary in construction prior to its final removal. This article focuses on the wire, the single most important component of external fixation. After all, it is the interface of wire and human tissue where most common complications occur.    The wire serves as an interface between an internal biological environment and an external mechanical one. This marriage between two subsystems results in the creation of a new entity that exists in a delicate balance. One should view the wire as the foundation to frame construction. A poor foundation will ultimately result in an unstable structure and lead to complications. Pin tract infection, nonunion, malunion, delayed union, hardware failure and neurovascular embarrassment are all complications that can be traced to this frame component.    The wire’s anatomic location serves as a passageway for organisms to colonize and possibly infect soft tissue and bone. This unique feature is why pin tract infections (PTI) are considered the most common complication associated with external fixation.    The key to treating and reducing the number of PTIs is understanding the etiology. A loose wire has a tendency to toggle, which irritates the bone and surrounding soft tissue. This action may provoke an inflammatory response and increases the susceptibility and passage of opportunistic pathogens. Therefore, one should strive to prevent wire loosening. One can reduce the incidence of PTIs through the judicious application of wires in terms of location, attachment to the ring, crossing angle and having a sufficient number of wires to produce a stable construct.

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