**5. Classification**

iliac crest, iliac spine, anterior half of the acetabulum and pubis. The posterior column extends superiorly from the ischiopubic ramus and consists of ischim, ischial spine and the posterior half of the acetabulum and the dense bone forming the sciatic notch. The anterior and the posterior columns meet at the sciatic buttress. The sciatic buttress extends posteriorly from anterior and posterior column to become the articular surface of the sacroiliac joint thus connecting the columns with the axial skeleton. The roof (dome) of the acetabulum is the weight bearing area that supports the femoral head. The quadrilateral plate is flat thin bone which is forming the medial wall of acetabulum. The iliopectineal eminence is the prominent part in

The radiographic evaluation of the acetabulum includes an anterio-posterior (AP) view and Oblique (Judet) views [19]. Minimal individual variations of the normal articular area can be visualized by comparing the anatomical landmarks of both hips. For example, comparison of the medial clear space between the head and tear drop will give a clue regarding femoral head subluxation. The iliopectineal line represents the anterior column and ilioischial line represents the posterior column. A line joining the lateral edge of sourcil to lateral edge of the inferior tear drop represents the anterior wall and a line representing the lateral edge of superior acetabulum to the lateral sclerotic area in the inferior margin of acetabulum represents the posterior wall [20].

**3.** Tear drop (formed laterally by inner wall of acetabulum and medially by quadrilateral

The iliac oblique view will clearly show anterior wall and posterior column, quadrilateral surface and posterosuperior roof arc. The obturator oblique view will show posterior wall, anterior column and anteriosuperior roof arc. The obturator ring represents parts of both columns, and fracture of the obturator ring may be associated with other pelvic injuries like

Evaluation of the acetabular fracture is made easier by both 2D and 3D CT scan [21]. The entire pelvis is usually included in the tomogram to avoid missing a fracture and comparison of the opposite side. The newer spiral CT scan of 1.5 mm and continuous bone section through the pelvis and acetabulum can be obtained. The 3D reconstruction view will help the surgeon to understand the fracture pattern and its anatomical location inter-operatively. Fracture lines in sagittal and coronal planes, marginal impaction, intra-articular loose fragments, concentricity

In the AP radiograph, we have to look into certain radiological landmarks.

the anterior column that lies directly over the femoral head.

**4. Radiological evaluation**

**1.** Iliopectineal line.

**2.** Ilioischial line.

**5.** Anterior wall. **6.** Posterior wall.

lateral pelvic compression injury or sacral fracture.

plate).

**4.** Roof.

44 Trauma Surgery

The universally accepted classification of acetabular fracture was described by Judet and Letournel in 1964 and later modified by Letournel [12, 14]. This classification helps the surgeon to approach acetabular fracture in a more anatomical and fracture biomechanics. The Orthopaedic Trauma Association (OTA) modified Letournel classification and gave computerized coding according to AO comprehensive classification of fractures of long bones [23]. According to Judet and Letournel classification, acetabular fractures are divided into two basic groups: simple fracture type and complex fracture type. Each group consists of five types. The simple fracture pattern includes isolated anterior and posterior wall fractures, isolated anterior and posterior column fractures and transverse fracture (**Figure 2**). The Associated fracture pattern includes T-type fracture, combined fractures of posterior column and wall, transverse fracture with posterior wall fracture, anterior column with posterior hemitransverse fracture and bicolumnar

**Figure 2.** Simple acetabular fractures. (A) Posterior wall fracture (B) Posterior column fracture (C) Anterior wall fracture (D) Anterior column fracture (E) Transverse fracture.

break in the ilioischial line and displaced articular cartilage along with posterior segment with an intact portion of roof, creating an image resembling a flying bird (Gull sign) [11]. In CT scan,

Clinical and Radiological Assessment of Acetabular Fracture

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47

It involves disruption of anterior wall. The radiograph demonstrate disruption in the iliopectineal line which is best seen in iliac oblique view. CT scan demonstrates fracture in sagittal

The fracture disrupts iliopectineal line. The fracture line extends from anterior iliac crest to superior pubic ramus disrupting the obturator formen. Obturator oblique view will show fracture line disrupting the anterior column. In high or intermediate anterior column fractures, the roof segment usually displaces medially. CT scan shows fracture in coronal plane in

This fracture separates acetabulum into two segments transversely. It involves both columns with intact obturator foramen. This fracture is subdivided into three types according to the level of fracture, namely infratectal, juxtatectal and supratectal [11] (**Figure 4**). Radiographically, both iliopectineal and ilioischial lines will be disrupted. In CT scan, it is

characterized by sagittal-oriented fracture line extending through both columns.

**Figure 4.** Types of transverse fractures. (A) Supratectal fracture (B) Transtectal fracture (C) Infratectal fracture.

fracture line will be seen in the posterior column in the coronal plane of axial section.

**6.3. Anterior wall fractures**

**6.4. Anterior column fracture**

the anterior column of axial section.

**6.5. Transverse fracture**

plane of axial cut.

**Figure 3.** Associated fractures. (A) Posterior wall with posterior column fracture (B) Transverse with posterior wall fracture (C) T shaped fracture.(D) Anterior column with posterior hemitransverse fracture.(E) Bicolumn fracture.

fracture (**Figure 3**). There is one exception in each group. The transverse fracture in the simple group involves both columns and the anterior column with posterior hemitransverse fracture involves only one column in complex group [24].
