Fractures of the Face

Fractures of the mandible, maxilla, zygoma and zygomatic arch are produced predominantly by assaults and motor vehicle accidents. All can be fractured by a single blow. Maxillary fractures can be placed in five categories (Figure 4.13):

1. Dentoalveolar

2. LeFort I

3. LeFort II

4. LeFort III

5. Sagittal

In dentoalveolar fractures, direct force applied anteriorly or laterally causes separation of a fragment of the mandible. This fragment generally contains a number of teeth. The LeFort I fracture is a transverse fracture of the maxilla, above the apices of the teeth, through the nasal septum and maxillary sinuses, the palatine bone and the sphenoid bone. The LeFort II (the "pyramidal") fracture has the same path posteriorly. As it proceeds anteriorly, however, it curves upward near the zygomatic-maxillary suture, through the inferior orbit rim onto the orbital floor, through the medial orbital wall and across the nasal bones and septum. The LeFort III is a high transverse fracture of the maxilla that goes through the nasofrontal suture, through the medial orbital wall and fronto-zygomatic suture, across the arch and through the sphenoid. Sagittal fractures run in a sagittal plane through the maxilla.

LeFort III

Figure 4.13 Fractures of the face: LeFort I, LeFort II, LeFort III.

LeFort III

Figure 4.13 Fractures of the face: LeFort I, LeFort II, LeFort III.

Fractures of the the Extremities

Fractures of the bones of the extremities can be produced by either the direct or indirect application of force to the bone.6

Fractures from Direct Application of Force

When a blunt object impacts a long bone, it tends to bend the bone, producing disruption or cracking of the bone on the side opposite the impact i.e., the convex or tension side of the bone. With significant impact, however, there is crushing on the side of the bone to which the force is applied (the concave side), prior to the bone's cracking. In comminuted fractures, the bone is broken into more than two pieces.

Fractures caused by direct application of force to a bone site can be divided into penetrating, focal or crush fractures, depending on the amount of force applied to the bone and the size of the area to which it is applied. Penetrating fractures are caused by a large force acting on a small area. Because, for all practical purposes, this category is synonymous with gunshot wounds, penetrating fractures will not be discussed in this book.

In focal fractures, a small force is applied to a small area and the resultant fracture is usually transverse. Overlying soft tissue injury is relatively minor, for example, an abrasion, contusion, or small laceration. In areas where two bones are adjacent to each other, such as in the forearm or calf region, typically only one bone is fractured. Focal fractures, produced by weapons such as a bat or pipe, are seen in forearms when an individual has tried to ward off blows from such instruments (Figure 4.14A).

In crush fractures, a large force is applied over a large area, with resultant extensive soft tissue injuries and, often, comminuted fractures of the bone. In the forearm and lower legs, there is usually fracture of both bones at the same level. Most crush fractures of the extremities involve the legs, with motor vehicle-pedestrian accidents the most common etiology. The fractures produced are called bumper fractures (Figure 9.18).

In severe impact injuries of the legs, a number of possible fracture patterns can be produced (transverse; oblique; spiral; segmental; comminuted; longitudinal split; tension wedge; compression wedge).7 The two most common patterns are tension wedge and oblique (Figure 4.14B). Tension wedge

Figure 4.14 Direct fractures. (A) Focal (B) Crushing. Arrow indicates direction of force.

Figure 4.14 Direct fractures. (A) Focal (B) Crushing. Arrow indicates direction of force.

fractures can be used as an indicator of the direction of impact. In tension wedge fractures, the fractures begin opposite to the point of impact and radiate back through the bone at a 90° angle, giving rise to a wedge of bone whose point is directed in the direction of the force and whose base is at the point of impact. What appears to be an oblique fracture on X-ray may turn out to be a tensile wedge fracture on dissection. On occasion, one will see compressive wedge-type fractures. These are extremely rare and may be confused with the common tension wedge fracture.

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