Surgical Management of Maxillofacial Fractures

Yoh Sawatari

• Publisher: Quintessence Publishing Co, Inc
• Year: 2019
• ISBN:
  9780867158427
• Topic: Medicine
• Subtopic: Dentistry

The facial skeleton is comprised of vertical and horizontal buttresses and the intersections they create; maxillofacial fractures occur when these buttresses sustain more force than they can withstand. The objective when managing these fractures is to reverse the damage that these buttresses sustained and restore appropriate facial dimensions. Not all fractures propagate in the same pattern, so surgeons must compartmentalize the face and define the character of the individual bones. This book approaches the face one bone at a time, outlining how to evaluate each type of fracture, the indications for surgery, the surgical management, and any complications. Specific protocols for clinical, radiographic, and CT assessment are included, as well as step-by-step approaches for surgical access and internal reduction and fixation. Isolated fractures are rare with maxillofacial trauma, and the author discusses how to sequence treatment for concomitant fractures to ensure the most successful outcome. This book is a must-have for any surgeon managing maxillofacial fractures.

Introduction to Facial Architecture

The face is defined by the contours and projection of the facial skeleton. All soft tissue structures including muscle, skin, ligaments, and tendons are supported by the facial skeleton and provide animation to the face. Critical structures including the optic nerve and sensory nerves are encased within deep architecture of the facial skeleton, and the facial nerves are intimately associated with these bones. In addition, the facial skeleton provides direct functional support, including the movement of the mandible, and fractures of the periorbital area can have a significant effect on vision and the ability to direct vision.

Besides the projection and contours of the face, the primary defining feature that affects both the appearance and functionality of the face is symmetry. Facial symmetry is based on the reflection of the bilateral face along the midsagittal plane. Although subtle facial asymmetry is a norm regarding facial features, displaced facial bone fractures and resultant deformities along with functional deficits associated with nonreduced malpositioned facial bones are the primary indications necessitating surgical management of the facial skeleton.

When attempting to understand facial fractures and the effect on appearance and function, the surgeon must begin by compartmentalizing the face and defining the character of the bones. The facial skeleton may be divided into three different regions: the frontal region, the midface, and the mandible. The projection and contours of these three regions have the greatest effect to define facial features. From the most superior aspect of the face, the frontal region defines the forehead extending from the trichion to the supraorbital bar. This region is responsible for brow projection and forehead contour. The frontal bone is not considered one of the facial bones but is part of the skull base. The second region is the midface area. The midface is what encompasses and defines the facial skeleton, as it is comprised of six pairs of facial bones—the zygomatic, maxilla, nasal, lacrimal, palatine, and inferior nasal concha—and the vomer. This midface area is the most critical region of the face in regard to facial projection, symmetry, and function. The periorbital area draws the majority of attention, and its projection is defined by the periorbital rims, nasal projection, intercanthal distance, zygomatic projection, zygomatic width, maxillary projection, and maxillary dental position. In addition, the midface bony structures define globe position (both depth and vertical level) and affect globe motility and occlusion as well as masticatory function. The last region that defines the face is the mandible. The mandible is critical for occlusion, masticatory function, chin projection, and transverse lower third width. In addition to facial projection and function as described above for each individual region, each region also has its own sensory branch of the trigeminal nerve. Thus, any fractures in these regions can compromise sensation on top of defects of form and function.

The facial bones can now be further conceptualized and defined into two different types of structures: dense rigid buttresses and laminar sheets. The buttresses are traditionally dense cortical pillars that provide stability and structure to the face. They are responsible for the contours and dimensions of the face as well as the support for the laminar bone and the entire soft tissue component of the face enveloping the facial skeleton. The buttresses are further divided into horizontal and vertical buttresses (Fig 1-1). Horizontal buttresses are characterized by dense bone and have an arcuate shape. The first horizontal buttress is the supraorbital bar. This section is comprised of the frontal bone and extends from the zygomaticofrontal (ZF) suture across the midline to the contralateral ZF suture. This bar provides supraorbital projection and shape to the brows and is the major prominence of the forehead. Progressing inferiorly, the next horizontal bar is at the infraorbital rims and zygomatic arches. This bar extends from the zygomatic arch on one side, across the infraorbital rims to the contralateral arch. The third horizontal buttress is the arc comprising the cortex from the pterygoid plate extending to the floor of the nose through the anterior nasal spine across to the contralateral pterygoid plate. The fourth horizontal buttress is the inferior aspect of the mandible (Fig 1-2). The vertical buttresses are also dense cortical pillars, but they exist in more of an upright columnar orientation. The first vertical buttress of the face includes the bilateral paired nasofrontal section extending along the piriform rim. The second vertical buttress is the ZF junction. The third paired buttress is at the pterygoid plates, and the last is the ramus of the mandible (see Fig 1-2). Finally, there are areas of the face where the vertical and horizontal buttresses intersect with each other. This is at the maxillary buttress, the base of the piriform aperture, the nasofrontal junction, and the angle of the mandible.

Fig 1-1 (a to c) Facial buttresses (red, vertical; blue, horizontal).

Fig 1-2 (a and b) Facial architecture: Vertical buttresses are struts, and horizontal buttresses are arcs.

To understand fracture patterns, it is important to understand the concept of vertical and horizontal buttresses and the intersections they create. Based on the distribution of forces, the horizontal and vertical buttresses fracture in different ways. Because the majority of facial fractures develop from the application of force from an anterior-to-posterior vector, the way in which the facial bones fracture is somewhat predictable. When force is applied to the horizontal buttresses, due to the arcuate shape, the bone fractures with displacement of the anterior segment posteriorly (losing projection), and the posterior segments splay in a lateral dimension (Fig 1-3). On the other hand, when vertical buttresses fracture, the central section of the buttress also displaces in a posterior vector, and the vertical height is shortened (Fig 1-4). Understanding the differences between how these buttresses fracture allows the surgeon to understand the resultant deformities that are created from these facial fractures. The loss of projection of a naso-orbitoethmoidal (NOE), Le Fort, or zygomaticomaxillary complex (ZMC) fracture is due to fracture of a vertical buttress. On the other hand, the development of telecanthus, the widening of the zygomatic arch, and the widening of the posterior mandible from a symphysis fracture are due to fractures of a horizontal buttress.

Fig 1-3 (a) All horizontal buttresses are arcs. (b) Force application to a horizontal buttress leads to decreased anterior projection and increased posterior transverse width.

Fig 1-4 (a) All vertical buttresses are struts. (b) Force application to a vertical buttress leads to decreased anterior projection and decreased vertical height.

In order to effectively manage facial fractures, the objective is to reverse the damage that the buttresses sustained and restore appropriate facial dimensions. This translates to the uprighting of the vertical buttresses, the reduction of the posterior horizontal buttresses, and the restoration of anterior projection for both vertical and horizontal buttresses. Thus, generally all fractures of the face will require restoration of the anterior projection, restoration of the vertical height, and closure of the widened posterior dimensions of the face (Fig 1-5). The management of each fracture type is ultimately dependent on the location of the fracture (Fig 1-6), and the concept of fracture management is always the same: Use adjacent stable bone as a reference and bring unstable fractured segments to the stable references; this is reduction. Once the fractured segments are aligned and the preinjury position is established, fixation is used to (1) stabilize the fracture to prevent collapse of the segments and (2) allow for appropriate bony apposition for immobility and adequate healing. The stable references are invariably the vertical and horizontal buttresses of the face, and the fixation points for all facial fractures are traditionally the intersection of the vertical and horizontal buttresses.

Fig 1-5 (a) Force application from anterior to posterior. (b) Force application to horizontal and vertical buttresses. (c) Increase in transverse dimension of the zygomatic arches and mandible. (d) Increase in transverse dimension of the maxilla.

Fig 1-6 (a and b) Frontal and lateral views showing the delineation of facial fractures. (c and d) Frontal bone, (e and f) ZMC. (g and h) NOE. (i and j) Le Fort 1. (k and i) Le Fort 2. (m and n) Le Fort 3.

Once the concept of facial buttresses is understood, the next step is to understand the different patterns of facial fractures. Essentially all facial fractures are a combination of vertical and horizontal buttress fractures. However, there are multiple factors that influence the incidence of each type. The first factor that determines the incidence of fractures is the location on the face. Any area of the face that projects more tends to be more susceptible to fracture. The nose is first, followed by the ZMC, and then the mandible. The second factor that dictates the incidence of fractures is the mechanism. The most common cause of facial fractures is assault, followed by falling and motor vehicle crashes. The third factor that influences fracture type is the amount of force applied to the face. The classic physics laws are always at work when analyzing facial fractures:

F = ma [force equals mass times acceleration]

KE = ½mv² [kinetic energy is directly proportional to the mass of an object and the square of its velocity]

An assault by a fist is far different from an assault with a solid object, which is again very different from the force of a high-velocity motor vehicle crash to the face. The greater the force, the greater the damage inflicted, and the more fractures, the more comminution that the patient will likely develop from the injury.

Clinical Examination

The clinical examination should be thorough and systematic, efficient and effective. A routine should be established with sequencing and techniques so as not to miss any relevant findings. It is critical to utilize the clinical examination to gather as much information as possible regarding the visible injuries that were sustained and the deformities that provide clues to the fractures that lie within (Fig 1-7).

Fig 1-7 (a) Clinical view of a panfacial fracture. (b) Clinical view of a severely displaced ZMC. (c) Clinical view of a severely displaced NOE.

The clinical examination involves a sequence of steps. Beginning at the vertex of the skull and proceeding with the examination in a top-down fashion is generally the most logical and thorough method (Fig 1-8). The points of origin and end are not as important as being thorough to comprehensively cover all aspects of the facial skeleton. For an examination to be effective, the provider must visualize and palpate all facial components. With visualization, positive findings including deformities, edema, erythema, ecchymosis, lacerations, exposed bone, foreign bodies, malocclusion, bleeding, and asymmetry should be noted. In addition, with visualization, any reactive movement is also documented. This includes assessment of facial...