**3. Radiographic evaluation**

The classification and subsequent treatment of acetabular fractures are based on imaging studies that have been derived from a thorough understanding of the

**Figure 6.** *The greater sciatic notch is divided by the piriformis.*

#### *Essentials in Hip and Ankle*

anatomy of the innominate bone [17–19]. Two limbs of an inverted *"Y"* of bone support the articular surface of acetabulum. These columns are connected to the sacroiliac articulation by a thick strut of bone lying above the greater sciatic notch known as the sciatic buttress.

The radiographic anatomy of the acetabulum can be determined using AP pelvis and two 45-degree oblique radiographs as proposed by Judet and Letournel. Therefore, three radiographic projections of the pelvis that are used to evaluate the fractures of acetabulum are as follows:


These plain films are interpreted based on the understanding of normal radiographic landmarks of the acetabulum, and disruption of these landmarks represents a fracture involving that portion of the bone. These landmarks are referred to as "lines". They are generated by the tangency of the applied x-ray beam to a region of cortical bone.
