Acetabular fracture

Acetabular fractures are a type of pelvic fracture, which may also involve the ilium, ischium or pubis depending on fracture configuration.

Epidemiology

Acetabular fractures are uncommon. The reported incidence is approximately 3 per 100,000 per year. This study reported a 63% to 37% male to female ratio ¹.

Pathology

Mechanism

• high-energy trauma: axial loading of the femur
  • fall from height
  • motor vehicle collision
  • crush injury
• low-energy trauma with abnormal bone: insufficiency fracture

Classification

The Judet and Letournel system for acetabular fractures is the most widely used classification system in clinical practice. It classifies fracture based on oblique pelvic view on plain radiographs.

Additional classification systems include:

• Orthopedic Trauma Association classification (primarily for research) ³ 
• Harris system (CT imaging based) ^4,5

Radiographic features

Plain radiograph

Initial assessment is often with a portable AP radiograph of the pelvis in the emergency department.

Assess the following lines:

1. anterior acetabular wall
2. posterior acetabular wall
3. acetabular roof
4. iliopectineal line: disrupted in fractures involving the anterior column
5. ilioischial line: disrupted in fractures involving the posterior column
6. radiographic U (teardrop)

After diagnosis, oblique pelvic views (Judet views) may be used for follow up. These include:

1. iliac oblique view for the posterior pelvic column and anterior acetabular wall
2. obturator oblique view for the anterior pelvic column and posterior acetabular wall

CT

CT has revolutionised the diagnosis, enabling precise delineation of the fracture configuration and assessment of any articular surface disruption.

Many patients with high-energy trauma will have a whole body CT, allowing initial assessment of the femoroacetabular joint as well as any other injuries that are likely to be present, given the typically high energy mechanism of injury ².

For those patients with pelvic insufficiency fractures involving the acetabulum, a standard CT with a bony algorithm may be useful, especially if operative management is under consideration.

A repeat CT after traction is sometimes used to assess response to treatment.

Treatment and prognosis

Treatment

• analgesia
• venous thromboembolism prophylaxis
• traction
  • skin traction
  • skeletal traction
• non-operative management ⁶
  • may be indicated in the setting of minimally displaced fracture
  • more common in developing countries
• open reduction and internal fixation (ORIF) ⁷
  • articular incongruence/displaced fracture
  • significantly distorted acetabular roof arc
  • entrapped intra-articular fragment
  • subluxation of the femoral head

Complications

• deep vein thrombosis
• post-traumatic osteoarthritis

Related articles

• acetabulum
• femoroacetabular joint
• pelvic fracture
• oblique pelvic views