ACETABULUM FRACTURE
A 25yearold man has been involved in a highspeed road traffic accident.
What do these radiographs show and how would you manage this?
These radiographs show a grossly displaced acetabular fracture on the right side. There is disruption of the iliopectineal line as well as the ilioischial line and dome of the acetabulum. This is a highenergy injury, and the possibility of other life threatening injuries must be actively searched for using an ATLS approach to sys tematic diagnosis and concurrent management in the emergency department.
With regard to the acetabular fracture itself, an assessment should be made of the skin to rule out an open fracture, a Morel–Lavallée lesion, or any wounds which may interfere with planned surgical incisions. I would also perform a full neurovascular assessment of the affected limb and wish to exclude urogenital injuries. Unlike pel vic fractures, there is unlikely to be a lifethreatening haemorrhage with an isolated acetabular fracture, and pelvic binders would not be indicated.
- What additional radiographs might give you a better appreciation of the bony injury, and what is the importance of these?
Two additional radiographs may be utilised to improve the preoperative understand ing of the acetabular fracture. These are Judet views, which are composed of two pro jections: First, the iliac oblique for assessment of the posterior column and anterior wall; second, the obturator oblique view for the anterior column and posterior wall.
Although centres where patients are treated for these injuries will have access to modern CT scanning, these views have that advantage that can be achieved with the image intensifier in the operating theatre and are therefore a useful pre and periop erative adjunct to fixation.
Can you name the labelled areas of the plain AP radiograph of the pelvis?
A – Acetabular dome/roof B – Anterior wall
C – Posterior wall
D – Iliopectineal line (represents the anterior column) E – Tear drop
F – Ilioischial line (represents the posterior column)
What is the ‘tear drop’?
The pelvic tear drop results from the endon projection of a bony ridge running along the floor of the acetabulum.
It is formed laterally by the confluence of subchondral bone at the floor of the acetabular fossa (also known as the cotyloid fossa) and medially by the anterior flat portion of quadrilateral plate.
It represents the true floor of the acetabulum and is frequently used for preopera tive planning in hip arthroplasty.
What anatomical structures make up the anterior and posterior columns of the acetabulum?
Anterior column:
-
- Anterior iliac wing
- Anterior wall and dome
- Iliopectineal eminence
- Superior pubic ramus Posterior column:
- Quadrilateral plate
- Posterior wall and dome
- Ischial tuberosity
- Greater/lesser sciatic notches
Acetabulum Fracture 
How are acetabular fractures classified and what are the most common fracture patterns?
The most commonly referred to classification systems is the Judet and Letournel classification. This divides acetabular fractures into five ‘elementary’ types and five ‘associated’ fracture patterns. The elementary fractures are named as such owing to the involvement of only one element of pelvic anatomy. The most common acetabu lar fracture is an elementary fracture of the posterior wall. Others include the ante rior column, anterior wall, posterior column and transverse fracture pattern.
Associated fractures imply the presence of two or more of the elementary frac ture patterns. The most common of these are the (1) transverse/posterior wall frac ture and (2) the both column fracture, where there is complete dissociation of the articular surface from the inonimate bone. The both column fracture can be diag nosed in the presence of a ‘spur sign’, which is produced by a triangular fragment of iliac bone that remains attached to the sacroiliac joint but is separated from the fractured acetabulum. This spur is exposed when the fractured acetabular columns are displaced medially in a both column fracture. It is best seen on the obturator oblique view or on a CT scanning of the pelvis, although it can occasionally be seen on a plain AP radiograph.
What are the complications of operative treatment of acetabular fractures?
I would divide these into local or systemic and early or late complications.
Early local complications would include sciatic nerve injury (may be injured pre operatively), bleeding and infection – particularly in the context of a Morel–Lavallée lesion.
Early systemic complications would include venous thromboembolism, chest infection, urinary infection and other medical complications related to highenergy injuries, for example, ARDS, SIRS, MODS.
Late local complications would include malunion, nonunion, posttraumatic arthritis and AVN, in addition to ongoing pain and stiffness. Heterotopic ossifica tion is also a wellrecognised complication of acetabular surgery.