Acetabular Fractures
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Direct answer
Acetabular fractures are breaks of the hip socket, classified by Letournel into five elementary patterns and five associated patterns built from the anterior and posterior columns and walls. Plain AP and Judet oblique views, supplemented by CT, define the pattern, and the classification then guides whether the hip is managed conservatively or needs open reduction and internal fixation.
What you must remember
- Columns and walls: the anterior column runs from the iliac crest to the pubis, the posterior column from the sciatic notch to the ischium, and the walls form the rim of the socket.
- Elementary patterns: posterior wall, posterior column, anterior wall, anterior column and transverse fractures make up the five basic groups.
- Associated patterns: T-type, both-column, transverse with posterior wall, and posterior column with posterior wall, together with anterior column or wall with posterior hemitransverse, make up the five associated groups.
- Judet views: the obturator oblique view profiles the anterior column and posterior wall, while the iliac oblique view profiles the posterior column and anterior wall.
- Iliopectineal line: on the AP pelvis it marks the anterior column, so a break or step in it points to anterior column involvement.
- Ilioischial line: on the AP pelvis it marks the posterior column, so a break or step in it points to posterior column involvement.
- Hip stability: a posterior wall fracture with a dislocated femoral head is an urgent problem that needs reduction and a check of the sciatic nerve.
A pathway from imaging to fixation
A 28-year-old man is brought in after a dashboard injury, with a painful hip and a suspected acetabular fracture on the first film. The steps below show the order in which the pattern is read and the plan is made, which is the sequence a viva examiner usually expects.
- Exclude the emergency. Check for a dislocated femoral head and sciatic nerve function, and reduce a dislocated hip promptly before further imaging.
- Take the standard views. Obtain an AP pelvis with both Judet oblique views, then add CT with 3D reconstruction for articular, displaced or comminuted patterns.
- Trace the lines. Follow the iliopectineal and ilioischial lines on the AP film, then check the anterior and posterior columns on the oblique views.
- Name the pattern. Assign the elementary or associated Letournel group, and note whether the femoral head remains congruent with the articular surface.
- Plan the approach. Choose the approach to the column or wall involved, such as the Kocher-Langenbeck approach for posterior lesions or the ilioinguinal approach for anterior column lesions.
- Check the result. Confirm the reduction on post-operative films and CT, since articular step-off predicts the risk of later arthritis.
Where the exam tries to catch you
Acetabular questions reward the candidate who reads the columns and walls rather than the fracture name.
- Trap: reading the AP film alone for an acetabular fracture. Correct: the Judet views and CT are needed, because the AP view misses many column and wall fractures.
- Trap: choosing the approach by the fracture's name rather than the column. Correct: the approach follows the column or wall involved, such as Kocher-Langenbeck for posterior lesions.
- Trap: treating a posterior wall fracture with a dislocated hip as a routine case. Correct: it is an urgent reduction problem with a risk to the sciatic nerve, and fixation follows once the joint is stable.
Frequently asked questions
What is the Letournel classification of acetabular fractures?
The Letournel classification groups acetabular fractures into five elementary patterns and five associated patterns. Elementary patterns include posterior wall, posterior column, anterior wall, anterior column and transverse fractures, while associated patterns combine these elements.
Which Judet view shows the posterior column of the acetabulum?
The iliac oblique Judet view shows the posterior column and the anterior wall of the acetabulum. The obturator oblique view shows the anterior column and the posterior wall, so reading both views together defines the full pattern.
What do the iliopectineal and ilioischial lines indicate?
The iliopectineal line marks the anterior column, and the ilioischial line marks the posterior column on the AP pelvis radiograph. A break or step in either line suggests fracture of that column.
Why is CT needed in acetabular fractures?
CT with 3D reconstruction shows articular step-off, comminution and the position of the femoral head that plain films can miss. It is therefore used to plan fixation for articular and complex acetabular patterns.