What is the anatomy of the pelvis relevant to acetabulum fractures?

Updated: Jun 25, 2019
  • Author: David S Levey, MD; Chief Editor: Felix S Chew, MD, MBA, MEd  more...
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Answer

Answer

The anteroposterior (AP) view of the pelvis is the primary tool for radiographic evaluation of the acetabulum (see the images below). 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. [14]

Anteroposterior view of the pelvis. The left femur 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. The Anteroposterior (AP) radiograph of the pelvis. 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.

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 the images below). [15, 16] 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 (see the image below). 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.

Left obturator oblique view of the pelvis. The lef 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 il 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.

The obturator oblique radiograph provides the best depiction of the obturator ring and shows the anterior column and posterior wall in profile.


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