There are a handful of terms used to describe fractures that are important to know and understand. These terms and their definitions are reviewed in the material that follows. Until the recent increase in our ability to share x-ray images using social media-based devices, the terms used to accurately describe fractures were critical. These terms helped orthopedic providers conjure up a mental picture of the fracture that was being described to them as they received consults over the phone. These days, providers can quickly and easily share x-rays on smartphones (patient-identifying information excluded, of course). As a result, the ability to accurately describe a fracture is becoming a lost art. When ordering x-rays, always order an anteroposterior (AP) and a lateral view (or two other orthogonal views). Figure 8-1 demonstrates how a broken bone can look perfectly aligned on one view (as the tibia looks on the AP view in Figure 8-1A) and be poorly aligned on the second view (see how angulated the tibia fracture is on the lateral view in Figure 8-1B). The fracture of the distal tip of the fibula also appears to be reasonably well aligned on the AP view, but we can appreciate that it is 100% displaced on the lateral view. If a long bone (like the tibia, femur, or humerus) is being studied, AP and lateral x-rays should include the joints above and below the fracture. This may not be practical in all cases, but strictly speaking, that is the protocol.
In orthopedics, we use the term fracture to describe any injury that disrupts the structure of a bone. For instance, we would consider a tiny “hairline” crack a fracture, and an injury that breaks a bone into two unconnected pieces is also a fracture. Also, we don’t use the term compound fracture. To some, a compound fracture is any severely displaced fracture. To others, the term indicates that the bone has penetrated through the skin. In orthopedics, we have other terms we use to describe these injuries, and we avoid using the term compound fracture because of the confusion it creates. The basic terms used in describing fractures are provided next.
An AP (A), and lateral (B) x-ray of a tibia and fibula (tib-fib) fracture demonstrating how the fracture can appear well aligned on one view and displaced on the other. When getting x-rays to evaluate an injured extremity, it is important to obtain at least two views at 90 degrees (orthogonal) to each other.
The terms intra-articular and extra-articular are used to indicate whether the fracture we are describing enters into an adjacent joint. Figure 8-2 shows an intra-articular fracture of the proximal tibia. The fracture enters the knee joint. The fracture in Figure 8-3 is an extra-articular fracture of the same bone. The fracture shown in Figure 8-3 does not enter the joint.
An intra-articular fracture of the proximal tibia (Licensed from Shutterstock).
An extra-articular fracture of the proximal tibia (Licensed from Shutterstock).
The terms displaced and nondisplaced help convey how far apart the broken pieces of bone (fracture fragments) are separated from each other or from their normal anatomic position. Technically speaking, all fractures are displaced some amount if we can see the fracture on an x-ray. The tiny radiolucent line that we see when we examine the x-ray of a bone with a hairline fracture is only there because the fracture fragments have separated (displaced) from one and other far enough to create a void, or gap. In living bone, that void is initially filled with blood. Because the density of blood is much less than the density of bone, blood does not block the x-ray beam as well as bone does, so the blood-filled gap appears on the x-ray as a radiolucent line. We generally consider fractures that are displaced a millimeter or two “nondisplaced,” even though they are displaced a small amount. Fractures in which the fragments are separated by a centimeter or more in smaller bones, or several centimeters in larger bones, are described as “widely displaced.” Other terms you will encounter that aim to describe fracture fragment displacement are “moderately displaced” and “minimally displaced.” Obviously, all of this is rather subjective. If you are uncertain how to describe the displacement of a particular fracture, you can always quantitate the displacement in millimeters.
Figure 8-4 shows a fracture of the proximal ulna at the elbow joint. I would estimate that the fracture fragments in Figure 8-4 are displaced about 1 mm. We could either describe this fracture as “an extra-articular fracture of the proximal ulna that is minimally displaced” or “an extra-articular fracture of the proximal ulna that is 1 mm displaced.” If you want to be precise, you can measure the displacement on the x-ray with a ruler, but an estimate will suffice. All that is really important is that we differentiate displaced fractures from those that are non-minimally displaced. Figure 8-5 shows a fracture that is widely displaced, and the femur fracture in Figure 8-6 is extremely displaced.
A minimally displaced (1 mm) fracture of the proximal ulna (see arrow) (Licensed from Shutterstock).
A widely displaced fracture of the distal tibia and fibula (tib-fib) (Licensed from Shutterstock).
A fracture of the femur demonstrating extreme displacement (Licensed from Shutterstock).
The term comminution refers to the number of bone fragments that result from a fracture. In general, we describe fractures with three or more fracture fragments as “comminuted,” and those with more than four or five fracture fragments as “highly comminuted.” Figure 8-6 shows a fracture in which the distal femur is broken into two, separate, widely displaced pieces (fragments). The fragments are widely displaced, but this is not a comminuted fracture. Figure 8-7 shows a highly comminuted fracture of the tibia with many different fracture lines and fragments.
A comminuted fracture of the proximal tibia (Licensed from Shutterstock).
If there is communication between the fracture and the outside environment through a laceration or other defect in the skin, we consider the fracture to be an “open fracture.” Open fractures are associated with a high risk of infection and require immediate evaluation by an orthopedist, emergency room physician, or other qualified provider.
A fracture-dislocation is a fracture adjacent to a joint dislocation. Figure 8-8 shows a fracture-dislocation of the elbow. In this example, the ulna is broken, and the joint between the radius and the humerus is dislocated. Figure 8-9A shows a fracture dislocation of the ankle. When you compare it to the x-ray of a normal ankle (Figure 8-9B), you’ll see that the posterior part of the distal tibia has broken (yellow arrow), allowing the talus bone to dislocate posteriorly (white arrow). The wrist injury in Figure 8-10 may appear at first glance to be a fracture-dislocation, but the wrist joint is not dislocated. The carpal bones are articulating properly with the end of the radius, but there is a widely displaced, extra-articular fracture of the radius.
A fracture dislocation of the elbow. The radius is dislocated; the ulna is fractured (Licensed from Shutterstock).
A fracture dislocation of the ankle. The distal tibia is fractured, and the ankle (tibio-talar) joint is dislocated (Images licensed from Shutterstock).
A widely displaced fracture of the distal radius. You might initially think that the wrist is dislocated, but it is not. The distal radius fragment and the carpal bones are articulating normally, but the hand, wrist, and distal radius fracture fragment are all displaced from the shaft of the radius (Licensed from Shutterstock).
When describing fractures, it is helpful not only to identify which bone is broken, but also to make some attempt to identify where on the bone the fracture has occurred. Figure 8-11 shows the names given to the different parts of a typical bone. The long, tubular, center section is called the shaft, or the diaphysis. The parts of the bone toward the ends of the bone where the bone starts to flare out and widen are called the metaphysis, and the very ends of the bone are called the epiphysis. In the skeletally immature bones of children who have not yet finished growing, there is an uncalcified section in the bone between the metaphysis and the epiphysis that is the growth plate, or the physis. In very young bones, the entire epiphysis and parts of the metaphysis and diaphysis are not yet calcified and appear radiolucent on x-ray. Figure 8-12 shows an x-ray of the hand and wrist of an infant. Only the diaphysis of the ulna bone is calcified and is visible on the x-ray. The diaphysis and the center of the distal metaphysis of the radius are calcified and appear on the film. The epiphysis of the ulna and six of the eight carpal bones are there, but they are composed of cartilage, not bone, so we can’t see them. As the child grows, the cartilage will calcify and become visible on x-ray. One of the challenges faced when caring for children with bony injuries is that fractures through the cartilaginous portions of the bone cannot be seen on x-ray.
The names given to the individual parts of a typical long bone.
An x-ray of the hand of a child demonstrating that many of the bones in the skeleton at this age are made of uncalcified cartilage. These yet-to-be-calcified bones are not visible on an x-ray (Licensed from Shutterstock).
The freshly calcified bone of a young skeleton is more flexible and softer than brittle adult bone, and it can deform in ways that adult bones cannot. Examples of fractures that are unique to pediatric bone include greenstick fractures (fractures in which the bone cracks or bends, but the two pieces of bone stay connected to one another, like a green stick does when you try to snap it in half) and torus, or buckle, fractures (fractures in which the bone collapses like an accordion, but doesn’t actually break). Figure 8-13 shows a typical greenstick fracture.
A greenstick fracture of the radius and ulna. In a greenstick fracture, part of the bone breaks and part of it bends (like a green stick) (Licensed from Shutterstock).
We will often try to describe the geometry of the fracture (oblique or transverse) and the type of deformity (angulated, shortened, and translated). Figure 8-5 shows a transverse, widely displaced fracture of the diaphysis of the distal third of the tibia that is translated laterally with minimal shortening. Figure 8-14 shows a long oblique fracture of the mid diaphysis of the femur with shortening and an angular deformity.
A long, oblique fracture of the shaft (diaphysis) of the femur that is displaced and angulated (Licensed from Shutterstock).