Introduction
Background
Most acetabular fractures occur in the setting of significant trauma secondary to either a motor vehicle accident or a high-velocity fall. Blunt force is exerted on the femur, passes through the femoral head, and is transferred to the acetabulum. The direction and magnitude of the force, as well as the position of the femoral head, determine the pattern of acetabular injury. The determination of the pattern of injury is key to the classification of an acetabular fracture. Once the acetabular fracture is classified, appropriate therapy may be planned and implemented.1,2,3,4,5

Acetabular fracture orientation with a computed
tomography (CT) scan. A CT scan of the left acetabulum obtained
at the level of the dome shows that transverse-type acetabular
fractures have a vertical (sagittal) orientation. Column-type
fractures have a horizontal (coronal)
orientation.

Acetabular fracture orientation with a computed
tomography (CT) scan. A CT scan of the left midacetabulum shows
that wall fractures have an oblique
orientation.
Related eMedicine topics:
Acetabulum Fractures (from Orthopedic Surgery)
Pelvic Fractures
Pathophysiology
One function of the acetabulum is to provide a means of transferring weight-bearing forces from the appendicular skeleton to the axial skeleton via the acetabulum's articulation with the femoral head. The femoral head also transfers high-energy forces to the acetabulum in the setting of trauma. The pattern of acetabular injury is determined by the position of the femoral head at the time of the traumatic event. When the femoral head is rotated internally, the force is transferred to the posterior column. When the femoral head is rotated externally, the force is directed toward the anterior column. If the femoral head is adducted, the force is transmitted to the acetabular roof; if it is abducted, the force is directed inferiorly.
The direction of the force also determines which part of the acetabulum is injured. An anterior force applied to the femoral head is transmitted to the posterior wall and column. Conversely, a posterior force affects the anterior wall and column. A force to the lateral aspect of the femoral head is directed toward the medial wall of the acetabulum, often resulting in transverse acetabular fractures.
Frequency
United States
Table 1. Relative Frequency of Acetabular Fracture Types
| Fracture Type | Letournel 6 * (%) | Matta 7 ** (%) | Dakin et al 8 † (%) |
|---|
| Both-column | 27.9 | 33.3 | 14.1 |
| Transverse with posterior wall | 20.6 | 23.5 | 35.3 |
| Posterior wall | 22.4 | 8.6 | 12.9 |
| T-shaped | 5.3 | 12.2 | 3.5 |
| Transverse | 3.7 | 3.5 | 8.2 |
| Anterior column | 3.9 | 4.7 | 1.2 |
| Anterior column with posterior hemitransverse | 8.8 | 5.9 | 3.5 |
| Posterior column with posterior wall | 3.5 | 3.9 | 18.8 |
| Posterior column | 2.3 | 3.1 | 1.2 |
| Anterior wall | 1.6 | 1.2 | 1.2 |
* n = 567.
** n = 255.
† n = 85.
Mortality/Morbidity
- Associated injuries
- Significant trauma is required to cause a fracture of the acetabulum. Therefore, acetabular fractures are most often observed in the setting of major trauma, in which injuries elsewhere in the body are common.
- Intracranial, spinal, intrathoracic, and intra-abdominal injuries often are observed in conjunction with acetabular fractures.
- Pelvic ring and extremity fractures also are common in patients with acetabular fractures.
- Bladder injury and clinically significant pelvic hemorrhage are not routinely observed in the setting of acetabular fracture unless a concomitant pelvic ring injury also is present.
- Complications of acetabular fracture include the following:
- Immediate posttraumatic complications include injuries to the sciatic,9 femoral, or superior gluteal nerves.
- Immediate postsurgical complications include nerve injuries, such as sciatic,9 femoral, and superior gluteal nerve injuries; wound infection; and thromboembolic disease.
- Late complications include heterotopic ossification,10 osteonecrosis (avascular necrosis) of the femoral head or acetabular fracture fragment, chondrolysis, posttraumatic osteoarthritis, and acetabular implant failure.
Age
Elderly patients and persons with osteoporosis may occasionally have an acetabular fracture as a result of low-energy trauma, such as a fall from a standing height.
Anatomy

Lateral view of the left acetabulum. The left
femur has been removed. The articular surface of the acetabulum
is in the shape of an inverted horseshoe (outlined in red). The
anterior column of the acetabulum includes most of the iliac
wing, the anterior acetabulum, and the superior pubic ramus.
The posterior column begins at the sciatic notch and includes
the posterior portion of the acetabulum and the
ischium.

Anteroposterior view of the pelvis. The left
femur has been removed for illustration purposes. The
iliopectineal, or iliopubic, line is an important landmark for
examining the anterior column of the acetabulum. The
ilioischial line demarcates the medial border of the posterior
column. The posterior wall of the acetabulum is larger and
projects more laterally than does the anterior
wall.

Left obturator oblique view of the pelvis. The
left obturator ring is seen en face. The anterior column and
posterior wall of the left acetabulum are profiled in this
position.

Left iliac oblique view of the pelvis. The left
iliac wing is demonstrated en face. The left posterior column
and the anterior wall are seen in profile.

Acetabular fracture classification system. Judet
and colleagues (1964) described the classification scheme that
is most commonly used today. Of the 10 types, 5 are elementary
fractures (top row), and 5 are associated fractures (bottom
row). Elementary types involve 1 primary fracture
plane. Associated types involve more than 1 fracture
plane.
Gross anatomy
The acetabulum is formed from 3 ossification centers; the ilium, ischium, and pubis each contribute to its development at the triradiate cartilage. The important anatomic components of the acetabulum are the columns, walls, dome, and quadrilateral plate. The acetabulum is divided into 2 columns: anterior and posterior. The 2 columns are described as having the shape of an inverted Y, or of the Greek letter lambda (l).
The anterior column is the larger of the 2 columns. It begins at the iliac wing and extends down the anterior portion of the acetabulum to incorporate the superior pubic ramus. The posterior column begins at the sciatic notch and extends down the posterior acetabulum into the ischium. Both columns are attached to the axial skeleton by the sciatic buttress, which connects the acetabulum to the sacroiliac joint. The column concept is appreciated more easily on the lateral view (see Image 1).
The posterior wall is larger than the anterior wall. The lateral portion of either wall is termed the acetabular rim. The walls help to stabilize the hip joint. The quadrilateral plate is the medial wall of the acetabulum. The dome of the acetabulum is the superior aspect that carries most of the weight-bearing forces. The obturator ring is an important landmark because some acetabular fractures spare the ring, whereas others disrupt it. The iliac wing is considered part of the anterior column.
Radiographic anatomy
The anteroposterior (AP) view of the pelvis is the primary tool for radiographic evaluation of the acetabulum (see Images 2-3). The iliopectineal, or iliopubic, line is the radiographic landmark for the anterior column. It begins at the sciatic notch and travels along the superior pubic ramus to the symphysis pubis. The ilioischial line demarcates the posterior column. It also begins at the sciatic notch, coursing inferiorly to the medial border of the ischium. The ilioischial line should pass through the acetabular teardrop. If it does not overlap the teardrop, the ilioischial line and, thus, the posterior column are disrupted.
The iliac wing is considered to be part of the anterior column. An iliac wing fracture in the setting of an acetabular injury indicates anterior column involvement. An iliac oblique radiograph provides a better view of the iliac wing. The posterior wall of the acetabulum is more visible than the anterior wall on the AP view because of its more lateral position. The anterior wall may be difficult to appreciate on the AP view. The obturator oblique view better depicts the posterior wall, and the iliac oblique view better depicts the anterior wall. The integrity of the obturator ring is an important feature to recognize. Certain fracture patterns (such as those of column and T-shaped fractures) characteristically include fractures through the obturator ring.
The oblique, or Judet, views of the pelvis are named relative to the side of interest (see Images 4-5). For example, if the acetabular fracture is on the left side, the views are named with reference to the left side. The left posterior oblique radiograph displays the iliac wing en face; therefore, this view is termed the left iliac oblique view. The right posterior oblique radiograph shows the obturator ring en face; therefore, this view is the left obturator oblique view. The iliac oblique view clearly demonstrates the iliac wing, sciatic notch, and ischial spine. In addition, the posterior column and anterior wall of the acetabulum are seen in profile. The obturator oblique radiograph provides the best depiction of the obturator ring and shows the anterior column and posterior wall in profile.
Presentation
Fractures of the acetabulum are most commonly classified according to the system described by Judet and colleagues.11 The system is based on the orientation of the fractures and the structures involved. In this system, the orientation of the fracture is based on its depiction on a lateral view of the acetabulum. In order to arrive at the correct classification, AP and oblique (Judet) radiographs of the pelvis are obtained and analyzed. Some authors have questioned the necessity of oblique views of the pelvis in the age of multidetector CT scanning.12 Harris and colleagues have proposed a new classification system based on the multidetector CT scan appearance.13,14 Other authors have defended the utility of the standard radiographic series in the evaluation of acetabular fractures.15 The Judet system will be presented in the remainder of this article.16

Acetabular fracture classification system. Judet
and colleagues (1964) described the classification scheme that
is most commonly used today. Of the 10 types, 5 are elementary
fractures (top row), and 5 are associated fractures (bottom
row). Elementary types involve 1 primary fracture
plane. Associated types involve more than 1 fracture
plane.
In the system described by Judet and colleagues, 10 patterns of acetabular fracture are defined. The 10 patterns are divided into 5 elementary and 5 associated patterns (see Image 6). Elementary patterns include fractures with a single fracture orientation, whereas associated patterns usually involve combinations of the elementary fractures. Elementary patterns include anterior wall, posterior wall, anterior column, posterior column, and transverse fractures. Associated patterns include both-column fractures, posterior column fractures with posterior wall fractures, transverse fractures with posterior wall fractures, T-shaped fractures, and anterior column fractures with posterior hemitransverse fractures. For simplicity, the 10 patterns can be grouped into 3 categories: wall, column, and transverse fractures. Some fractures fit into 2 categories. The following fractures are indicated by pattern type:
- Wall fractures
- Anterior wall
- Posterior wall
- Posterior column with posterior wall (also a column fracture)
- Transverse with posterior wall (also a transverse fracture)
- Column fractures
- Anterior column
- Posterior column
- Both-column
- Posterior column with posterior wall (also a wall fracture)
- Anterior column with posterior hemitransverse (also a transverse fracture)
- Transverse fractures
- Transverse
- T-shaped
- Transverse with posterior wall (also a wall fracture)
- Anterior column with posterior hemitransverse (also a column fracture)
Fracture patterns
Isolated acetabular wall fractures typically do not involve the weight-bearing articular portion of the acetabulum (see Image 6). Fractures of the posterior wall are more common than are those of the anterior wall because of the preponderance of posteriorly directed forces responsible for acetabular fractures. Posterior wall fractures may occur in isolation (see Images 10-12) or in combination with posterior column or transverse fractures. Anterior wall fractures are rare (see Image 9).

Posterior wall acetabular fracture.
Anteroposterior radiograph of the pelvis. The posterior wall of
the left acetabulum is disrupted (arrow).

Posterior wall acetabular fracture. A left
obturator oblique radiograph of the pelvis. The posterior wall
fracture (arrow) is better depicted on this view than on the
anteroposterior view.
Both-column fractures are the most common acetabular injury. As the name implies, the anterior and posterior columns are involved (see Image 6). On AP radiographs, a disruption of the iliopectineal and ilioischial lines, as well as the obturator ring, may be seen (see Image 24). An iliac wing fracture may be seen on the AP view, but often, it is appreciated only on the iliac oblique radiograph (see Image 25). The pathognomonic spur sign (see Radiograph Findings) is present on the obturator oblique view (see Image 26) and confirmed on a computed tomography (CT) scan (see Images 27-29).

Both-column acetabular fracture. An
anteroposterior radiograph of the pelvis shows that the right
ilioischial and iliopectineal lines are completely disrupted. A
right iliac wing fracture is noted above the level of the
acetabulum (arrow). A nondisplaced fracture of the right
inferior pubic ramus is subtle.

Both-column acetabular fracture. A right iliac
oblique radiograph of the pelvis. The posterior column
(arrowhead) and iliac wing disruptions are
shown.

Both-column acetabular fracture. A right
obturator oblique radiograph of the pelvis best depicts
nondisplaced fractures of the obturator ring (arrowheads). The
iliopectineal line disruption (short arrow) signifies anterior
column involvement. The pathognomonic spur sign (long arrow) of
the both-column fracture is best appreciated on this view. The
spur represents a strut of bone extending from the sacroiliac
joint. The fracture of both columns disconnects this piece of
bone from the acetabulum and causes its spurlike
appearance.
Isolated anterior and posterior column fractures are uncommon. Anterior column fractures disrupt the iliopectineal line while preserving the ilioischial line. Conversely, posterior column fractures disrupt the ilioischial line but not the iliopectineal line (see Images 18-23). Column fractures divide the acetabulum into front and back halves (see Image 7). The posterior column fracture with a posterior wall fracture has the features of each of its components (see Image 6). The slightly more common anterior column fracture with a posterior hemitransverse fracture is the most complex acetabular fracture to classify.
The combination of column fractures and transverse fractures may be difficult to appreciate radiographically (see Image 30). The iliopectineal and ilioischial lines are broken, and an iliac wing fracture should be evident. Unlike the both-column fracture, which shares these features, the obturator ring is intact and the spur sign is not present. On CT scans, the anterior column and the posterior transverse fracture planes may be appreciated (see Image 31).

Anterior column fracture with a posterior
hemitransverse acetabular fracture, as depicted on computed
tomography (CT) scans obtained above and at the level
of the right acetabulum. Left: The image shows an iliac wing
fracture (arrow) that was not appreciated on the
anteroposterior radiograph. (The oblique radiographs were not
of good quality.) Middle: The image clearly depicts a
column-type fracture (arrow) that is oriented horizontally on
the CT scans. Right: The image again demonstrates the column
fracture (long arrow), but now a transverse (vertically
oriented) fracture can be seen posteriorly (short
arrow).
Transverse fractures are transverse because of their appearance when the acetabulum is examined from the lateral view (see Image 6). The iliopectineal and ilioischial lines are interrupted, but the obturator ring is spared. On CT scans, the fracture is oriented vertically (front to back).
Transverse fractures divide the acetabulum into top and bottom halves, as seen on the lateral view of the acetabulum (see Image 7). The transverse fracture with a posterior wall fracture is a common fracture that incorporates the features of transverse and posterior wall elementary fractures (see Images 13-15). The T-shaped fracture is a fairly common acetabular injury. This fracture has the characteristics of an elementary transverse fracture with the addition of a medial acetabular wall fracture extending through the obturator ring (see Images 16-17). The anterior column with posterior hemitransverse fracture is discussed earlier.
In a study by Brandser and colleagues, the following 3 most common types of acetabular fracture accounted for roughly two thirds of all fractures: both-column fractures, transverse fractures with posterior wall fractures, and posterior wall fractures.
7 This number increased to 90% when the next 2 most common fracture types were considered: T-shaped and transverse fractures. The frequency of the fractures types is as follows:
- Commonly occurring acetabular fractures (90%)
- Both-column
- Transverse with posterior wall
- Posterior wall
- T-shaped
- Transverse
- Uncommonly occurring acetabular fractures (10%)
- Anterior column
- Anterior column with posterior hemitransverse
- Posterior column with posterior wall
- Posterior column
- Anterior wall
Preferred Examination
AP radiography of the pelvis is used in the initial radiographic assessment of patients with major trauma that is suggestive of pelvic and/or acetabular injury (see Images 2-3).17,18 Images are obtained with the patient in the supine position and with the radiographic beam passing in an AP direction. Abnormalities depicted on the AP pelvis radiograph direct the need for the next set of radiographs. Acetabular fractures are imaged by using oblique (ie, Judet) views of the pelvis. Pelvic ring fractures are imaged by using inlet and outlet views of the pelvis (see Pelvic Ring Fractures).

Anteroposterior view of the pelvis. The left
femur has been removed for illustration purposes. The
iliopectineal, or iliopubic, line is an important landmark for
examining the anterior column of the acetabulum. The
ilioischial line demarcates the medial border of the posterior
column. The posterior wall of the acetabulum is larger and
projects more laterally than does the anterior
wall.

Anteroposterior (AP) radiograph of the pelvis
(compare with Image above). The iliopectineal (or iliopubic)
and ilioischial lines serve as landmarks for the anterior and
posterior columns, respectively. The larger and more lateral
posterior wall is visualized more easily than is the smaller,
more medial anterior wall. The acetabular tear figure is a
composite shadow of the inferomedial structures that compose
the acetabulum. The ilioischial line should pass through the
teardrop on a true AP view of the pelvis.
Oblique, or Judet, radiographs of the pelvis are obtained with the patient in the left posterior oblique and right posterior oblique positions (see Images 4-5). The patient should be at a 45º angle relative to the radiographic beam, which remains perpendicular to the cassette. This technique results in 2 orthogonal radiographs of the pelvis. The patient must be moved to the oblique position; the radiographic tube is not moved so as to be at a 45º angle relative to the patient and film cassette. Angling the tube results in unacceptable radiographic distortion. A common mistake in this radiographic technique is the positioning of the patient in an oblique position that is not steep enough, with a resultant angle of less than 45 º. On an oblique view obtained with good positioning, the coccyx should project over the femoral head.

Left obturator oblique view of the pelvis. The
left obturator ring is seen en face. The anterior column and
posterior wall of the left acetabulum are profiled in this
position.

Left iliac oblique view of the pelvis. The left
iliac wing is demonstrated en face. The left posterior column
and the anterior wall are seen in profile.
Pelvic CT scans may be obtained alone or in combination with abdominal CT scans during the initial trauma evaluation. Axial CT scans may be obtained, but helical CT scanning yields better 2-dimensional and 3-dimensional reformatted images. Pelvic CT scans allow the detection of subtle fractures and displacements that are not appreciated on radiographs.
18 Limitations of Techniques
Virtually all acetabular fractures may be correctly classified after careful interpretation of AP and oblique radiographs of the pelvis. Intra-articular fracture fragments may be difficult to recognize on radiographs.
Compared with radiography, pelvic CT scanning allows a more precise determination of the degree of articular involvement, as well as of fragment displacement and orientation. Pelvic CT scanning also permits the identification of intra-articular fracture fragments. In complex acetabular fractures, 3-dimensional reformatted images may help conceptualize the fracture pattern and, thereby, aid in the planning of orthopedic surgery.
Differential Diagnoses
Pelvic Ring Fractures
Pelvis, Insufficiency Fractures
Other Problems to Be
Considered
Hip dislocation
Pelvic avulsion fracture
Radiography

Both-column acetabular fracture. A right
obturator oblique radiograph of the pelvis best depicts
nondisplaced fractures of the obturator ring (arrowheads). The
iliopectineal line disruption (short arrow) signifies anterior
column involvement. The pathognomonic spur sign (long arrow) of
the both-column fracture is best appreciated on this view. The
spur represents a strut of bone extending from the sacroiliac
joint. The fracture of both columns disconnects this piece of
bone from the acetabulum and causes its spurlike
appearance.

Posterior wall acetabular fracture.
Anteroposterior radiograph of the pelvis. The posterior wall of
the left acetabulum is disrupted (arrow).

Posterior wall acetabular fracture. A left
obturator oblique radiograph of the pelvis. The posterior wall
fracture (arrow) is better depicted on this view than on the
anteroposterior view.

T-shaped acetabular fracture. An anteroposterior
radiograph of the pelvis shows that a transverse fracture
(arrows) disrupts the left iliopectineal and ilioischial lines.
The obturator ring also is interrupted (arrowheads). No iliac
wing fracture is seen above the level of the
acetabulum.
Findings
Brandser and Marsh devised a system of observations leading to the correct classification of most acetabular fractures.
19 The answers to the following questions about the radiographic observations are used to determine the acetabular fracture pattern:
- Is a fracture of the obturator ring present? A fracture of the obturator ring indicates either a T-shaped or a column fracture (with the exception of the hemitransverse type of fracture). An intact obturator ring eliminates these fractures from consideration.
- Is the ilioischial line disrupted? Disruption of the ilioischial line occurs in fractures involving the posterior column or fractures in the transverse group.
- Is the iliopectineal line disrupted? Disruption of the iliopectineal line indicates anterior column involvement or 1 of the transverse-type fractures.
- Is the iliac wing above the acetabulum fractured? Iliac wing fractures are observed in fractures involving the anterior column.
- Is the posterior wall fractured? Posterior wall fractures may occur in isolation or in combination with posterior column or transverse fractures.
- Is the spur sign present? The spur sign is observed exclusively in the both-column fracture. The spur is a strut of bone extending from the sacroiliac joint. Usually, this strut of bone connects to the articular surface of the acetabulum. In the both-column fracture, this connection is disrupted; a fractured piece of bone that resembles a spur remains. The spur sign is best depicted on the obturator oblique view (see Image 26). In addition, the spur sign can be appreciated on CT scans (see Image 27).
Table 2 shows the combined set of radiographic and CT scan observations that are useful in acetabular fracture classification.
Table 2. Radiographic Features of Acetabular Fracture Types 19 | Fracture Type | Obturator Ring Fracture | Ilioischial Line Disrupted | Iliopectineal Line Disrupted | Iliac Wing Fracture | Posterior Wall Fracture | Pelvis Into Halves | Spur Sign | CT Scan Fracture Orientation |
|---|
| Both-column | Yes | Yes | Yes | Yes | No | Front/back | Yes | Horizontal |
| Anterior column | Yes | No | Yes | Yes | No | Front/back | No | Horizontal |
Posterior column | Yes | Yes | No | No | No | Front/back | No | Horizontal |
Posterior column with posterior wall | Yes | Yes | No | No | Yes | Front/back | No | Horizontal |
| T-shaped | Yes | Yes | Yes | No | No | Top/bottom | No | Vertical |
Transverse with posterior wall | No | Yes | Yes | No | Yes | Top/bottom | No | Vertical |
| Transverse | No | Yes | Yes | No | No | Top/bottom | No | Vertical |
| Posterior wall | No | No | No | No | Yes | No | No | Oblique |
| Anterior wall | No | No | Yes | No | No | No | No | Oblique |
Anterior column with posterior hemitransverse | No | Yes | Yes | Yes | No | N/A * | No | N/A |
* N/A indicates not applicable.
Degree of Confidence
By using Brandser and Marsh's system, the accurate classification of acetabular fractures is possible in almost every patient.
False Positives/Negatives
An accessory ossification center, the os acetabulum, may mimic an acetabular wall fracture. Its differentiating features include its characteristic superolateral location and well-corticated margins. Fractures of the anterior puboacetabular junction may be observed in pelvic ring fractures. These fractures may extend into the anterior column of the acetabulum, but they are not anterior column fractures per se. Such fractures are more correctly considered to be superior pubic ramus fractures.
Computed Tomography

Acetabular fracture orientation with a computed
tomography (CT) scan. A CT scan of the left acetabulum obtained
at the level of the dome shows that transverse-type acetabular
fractures have a vertical (sagittal) orientation. Column-type
fractures have a horizontal (coronal)
orientation.

Acetabular fracture orientation with a computed
tomography (CT) scan. A CT scan of the left midacetabulum shows
that wall fractures have an oblique
orientation.

Computed tomography (CT) scan of a transverse
fracture with a posterior wall acetabular fracture. The
vertically oriented transverse fracture (arrow) of the left
acetabulum is well depicted on CT scans. Note the oblique
posterior wall fracture (arrowhead). Posterior wall fractures
often are associated with femoral head
dislocation.

Posterior column acetabular fracture. A computed
tomography (CT) scan obtained at the level of the midacetabulum
shows the horizontally oriented column fracture. The femoral
head is relocated, but the recent posterior dislocation is
evident in the anterior impaction fracture
(arrow).

Both-column acetabular fracture. A computed
tomography (CT) scan obtained just above the level of the
acetabular dome shows that the CT scan spur sign is present
(arrow).
Findings
Brandser and Marsh described several CT scan–based observations in the classification of acetabular fractures.20 The answers to the following questions may help in the classification of these fractures:
- Does the fracture divide the acetabulum into top and bottom halves or into front and back halves? Transverse-type fractures divide the acetabulum into top and bottom halves, as seen from the lateral perspective of the acetabulum. Column fractures divide the acetabulum into front and back halves. Isolated wall fractures do not divide the acetabulum.
- Can an intact strut of bone be followed from the sacroiliac joint to the acetabular articular surface? In other words, is the CT scan spur sign present? Only the both-column fracture causes the spur sign.
- What is the orientation of the major fracture line on CT scans? Transverse-type fractures have a vertical (sagittal) CT scan orientation. Column fractures have a horizontal (coronal) orientation. Wall fractures are oriented obliquely.
Table 2 shows the combined set of radiographic and CT scan observations that are useful in acetabular fracture classification.
Durkee and colleagues presented an algorithm for classification of the 5 most common types of acetabular fracture based on several observations.3 The observations are similar to those presented in Table 2.21,22,4
Degree of Confidence
Interpreted in conjunction with the pelvic radiographs, CT scans allow accurate fracture classification and appropriate surgical planning.
False Positives/Negatives
False findings can occur (see Radiograph Findings).
Magnetic Resonance Imaging
Findings
Magnetic resonance imaging (MRI) is not routinely used in the primary evaluation of acetabular fractures. Potter and colleagues described the use of MRI in the evaluation of occult femoral head injuries and in the detection of subclinical sciatic nerve injury.23 Intra-articular fracture fragments may be missed on magnetic resonance images.
Currently, the use of MRI in imaging deep venous thrombosis in patients with pelvic or lower extremity injuries is being evaluated. Magnetic resonance venography may be useful in depicting lower extremity and pelvic venous thrombosis.24,25,26
Ultrasonography
Findings
Ultrasonography is not used to evaluate acetabular fractures. Lower extremity Doppler ultrasonography is used to assess lower extremity deep venous thrombosis.
Multimedia

Media file 1:
Lateral view of the left acetabulum. The left
femur has been removed. The articular surface of the acetabulum
is in the shape of an inverted horseshoe (outlined in red). The
anterior column of the acetabulum includes most of the iliac
wing, the anterior acetabulum, and the superior pubic ramus.
The posterior column begins at the sciatic notch and includes
the posterior portion of the acetabulum and the
ischium.

Media file 2:
Anteroposterior view of the pelvis. The left
femur has been removed for illustration purposes. The
iliopectineal, or iliopubic, line is an important landmark for
examining the anterior column of the acetabulum. The
ilioischial line demarcates the medial border of the posterior
column. The posterior wall of the acetabulum is larger and
projects more laterally than does the anterior
wall.

Media file 3:
Anteroposterior (AP) radiograph of the pelvis
(compare with Image above). The iliopectineal (or iliopubic)
and ilioischial lines serve as landmarks for the anterior and
posterior columns, respectively. The larger and more lateral
posterior wall is visualized more easily than is the smaller,
more medial anterior wall. The acetabular tear figure is a
composite shadow of the inferomedial structures that compose
the acetabulum. The ilioischial line should pass through the
teardrop on a true AP view of the pelvis.

Media file 4:
Left obturator oblique view of the pelvis. The
left obturator ring is seen en face. The anterior column and
posterior wall of the left acetabulum are profiled in this
position.

Media file 5:
Left iliac oblique view of the pelvis. The left
iliac wing is demonstrated en face. The left posterior column
and the anterior wall are seen in profile.

Media file 6:
Acetabular fracture classification system. Judet
and colleagues (1964) described the classification scheme that
is most commonly used today. Of the 10 types, 5 are elementary
fractures (top row), and 5 are associated fractures (bottom
row). Elementary types involve 1 primary fracture
plane. Associated types involve more than 1 fracture
plane.

Media file 7:
Acetabular fracture orientation with a computed
tomography (CT) scan. A CT scan of the left acetabulum obtained
at the level of the dome shows that transverse-type acetabular
fractures have a vertical (sagittal) orientation. Column-type
fractures have a horizontal (coronal)
orientation.

Media file 8:
Acetabular fracture orientation with a computed
tomography (CT) scan. A CT scan of the left midacetabulum shows
that wall fractures have an oblique
orientation.

Media file 9:
Anterior wall acetabular fracture. A computed
tomography (CT) scan demonstrates an oblique fracture through
the anterior wall of the left acetabulum (arrow). Such
fractures are uncommon in isolation. The patient had other
pelvic injuries.

Media file 10:
Posterior wall acetabular fracture.
Anteroposterior radiograph of the pelvis. The posterior wall of
the left acetabulum is disrupted (arrow).

Media file 11:
Posterior wall acetabular fracture. A left
obturator oblique radiograph of the pelvis. The posterior wall
fracture (arrow) is better depicted on this view than on the
anteroposterior view.

Media file 12:
Computed tomography (CT) scan of a posterior
wall acetabular fracture. The oblique fracture of the left
acetabulum is clearly depicted. The degree of displacement and
marginal impaction can be determined more accurately with CT
scanning than with radiography.

Media file 13:
Transverse with posterior wall acetabular
fracture. An anteroposterior radiograph of the pelvis shows
that the central dislocation of the left femoral head results
in the disruption of the iliopectineal and ilioischial lines.
In addition, the left posterior acetabular wall is
disrupted.

Media file 14:
Transverse fracture with a posterior wall
acetabular fracture. Compared with the anteroposterior view,
this left obturator oblique view of the pelvis view better
demonstrates the anterior column and posterior wall disruption.
The obturator ring is intact.

Media file 15:
Computed tomography (CT) scan of a transverse
fracture with a posterior wall acetabular fracture. The
vertically oriented transverse fracture (arrow) of the left
acetabulum is well depicted on CT scans. Note the oblique
posterior wall fracture (arrowhead). Posterior wall fractures
often are associated with femoral head
dislocation.

Media file 16:
T-shaped acetabular fracture. An anteroposterior
radiograph of the pelvis shows that a transverse fracture
(arrows) disrupts the left iliopectineal and ilioischial lines.
The obturator ring also is interrupted (arrowheads). No iliac
wing fracture is seen above the level of the
acetabulum.

Media file 17:
Computed tomography (CT) scan of T-shaped
acetabular fracture. The transverse portion of the fracture has
a vertical (sagittal) orientation (arrow). The extension of the
fracture through the medial wall represents the stem of the T
(arrowhead). More inferior CT scans demonstrated the
obturator ring fractures.

Media file 18:
Posterior column acetabular fracture. An
anteroposterior radiograph of the pelvis shows that the left
femoral head is dislocated posteriorly. The ilioischial line is
broken, but the iliopectineal line remains
intact.

Media file 19:
Posterior column acetabular fracture. Compared
with the anteroposterior view, the left obturator oblique
radiograph of the pelvis better depicts the posteriorly
displaced posterior column, posterior wall, and femoral
head.

Media file 20:
Posterior column acetabular fracture. A left
iliac oblique radiograph of the pelvis shows that the posterior
column is markedly displaced.

Media file 21:
Computed tomography (CT) scan of a posterior
column acetabular fracture at the level of the acetabular dome.
The characteristic horizontal (coronal) orientation of the
column fracture is appreciated easily by using CT
scanning.

Media file 22:
Posterior column acetabular fracture. A computed
tomography (CT) scan obtained at the level of the midacetabulum
shows the horizontally oriented column fracture. The femoral
head is relocated, but the recent posterior dislocation is
evident in the anterior impaction fracture
(arrow).

Media file 23:
Posterior column acetabular fracture. A computed
tomography (CT) scan obtained at the level of the ischial
tuberosities shows that posterior column fractures sometimes
can exit through the ischial tuberosity (arrow) rather than
through the obturator ring.

Media file 24:
Both-column acetabular fracture. An
anteroposterior radiograph of the pelvis shows that the right
ilioischial and iliopectineal lines are completely disrupted. A
right iliac wing fracture is noted above the level of the
acetabulum (arrow). A nondisplaced fracture of the right
inferior pubic ramus is subtle.

Media file 25:
Both-column acetabular fracture. A right iliac
oblique radiograph of the pelvis. The posterior column
(arrowhead) and iliac wing disruptions are
shown.

Media file 26:
Both-column acetabular fracture. A right
obturator oblique radiograph of the pelvis best depicts
nondisplaced fractures of the obturator ring (arrowheads). The
iliopectineal line disruption (short arrow) signifies anterior
column involvement. The pathognomonic spur sign (long arrow) of
the both-column fracture is best appreciated on this view. The
spur represents a strut of bone extending from the sacroiliac
joint. The fracture of both columns disconnects this piece of
bone from the acetabulum and causes its spurlike
appearance.

Media file 27:
Both-column acetabular fracture. A computed
tomography (CT) scan obtained at the level of the sacroiliac
joints shows that the horizontal (coronal) column fracture
begins superiorly at the iliac wing in the both-column
fracture. The CT scan equivalent of the spur sign can be seen
(arrow).

Media file 28:
Both-column acetabular fracture. A computed
tomography (CT) scan obtained just above the level of the
acetabular dome shows that the CT scan spur sign is present
(arrow).

Media file 29:
Both-column acetabular fracture. A computed
tomography (CT) scan obtained at the level of the acetabular
dome shows the CT scan spur sign (arrow). Note how this spur
does not connect to the articular portion of the acetabulum. In
a both-column fracture, the articular surface of the acetabulum
is completely disconnected from the axial
skeleton.

Media file 30:
Anterior column fracture with a posterior
hemitransverse acetabular fracture. An anteroposterior
radiograph of the pelvis shows disruption of the iliopectineal
(long arrow) and ilioischial (short arrows) lines. The
obturator ring is intact.

Media file 31:
Anterior column fracture with a posterior
hemitransverse acetabular fracture, as depicted on computed
tomography (CT) scans obtained above and at the level
of the right acetabulum. Left: The image shows an iliac wing
fracture (arrow) that was not appreciated on the
anteroposterior radiograph. (The oblique radiographs were not
of good quality.) Middle: The image clearly depicts a
column-type fracture (arrow) that is oriented horizontally on
the CT scans. Right: The image again demonstrates the column
fracture (long arrow), but now a transverse (vertically
oriented) fracture can be seen posteriorly (short
arrow).
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Keywords
acetabulum fracture, acetabulum trauma, acetabular trauma, femur trauma, femoral trauma
Contributor Information and Disclosures
Author
D Dean Thornton, MD, Clinical Associate Professor, Department of Radiology, University of Alabama at Birmingham; Musculoskeletal Radiologist, Radiology Associates of Birmingham, PC
D Dean Thornton, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Radiology, American Roentgen Ray Society, Medical Association of the State of Alabama, Radiological Society of North America, and Society of Skeletal Radiology
Disclosure: Nothing to disclose.
Medical Editor
Michael A Bruno, MD, Associate Professor, Departments of Radiology and Medicine, Pennsylvania State University College of Medicine; Director, Radiology Quality Management Services, Milton S Hershey Medical Center, Pennsylvania State University College of Medicine
Michael A Bruno, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America, Society of Nuclear Medicine, and Society of Skeletal Radiology
Disclosure: Nothing to disclose.
Pharmacy Editor
Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.
Managing Editor
William R Reinus, MD, MBA, FACR, Professor of Radiology, Temple University; Chief of Musculoskeletal and Trauma Radiology, Vice Chair, Department of Radiology, Temple University Hospital
William R Reinus, MD, MBA, FACR is a member of the following medical societies: Alpha Omega Alpha, American College of Radiology, American Roentgen Ray Society, Radiological Society of North America, and Sigma Xi
Disclosure: Nothing to disclose.
CME Editor
Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.
Chief Editor
Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington
Felix S Chew, MD, MBA, EdM is a member of the following medical societies: American Roentgen Ray Society, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.