Bruising most often associated with tendinous avulsion, less commonly with musculotendinous junction or intramuscular tear Pec tears are not always associated with ecchymosis They are often missed in the ER…
- 1 Judet and Letournel Classification of Acetabular Fractures
- 2 Most Common Acetabular Fracture Patterns
- 3 References
Judet and Letournel Classification of Acetabular Fractures
The Judet and Letournel classification is the most common and consistently used method to classify acetabular fractures. The acetabulum is made up of anterior and posterior columns of bone, which join together just above the acetabulum (supra-acetabular region). If you are looking at the face of the acetabulum, the columns resemble the Greek letter lamda (λ), with the anterior column represented by the long stem. The anterior column is the largest of the columns, and extends from the superior pubic ramus to the iliac wing. The posterior column contains the ischium, the posterior wall and acetabular dome, and the posterior ilium.
The anterior and posterior walls extend out from their columns and extend the acetabular socket anterior and posterior, respectively. These anatomical landmarks can be visualized on plain x-rays and on CT scans.
Acetabular fractures are classified as either elementary (simple) or associated (complex) fracture types. The simple fracture types are posterior wall, posterior column, anterior wall, anterior column, and transverse. The associated fracture types are posterior wall & posterior column, transvers posterior wall, T-shaped, anterior with posterior hemi-transverse, and both column.
Most Common Acetabular Fracture Patterns
90% of acetabular fractures are represented by 5 of the fracture types. These 5 types can further be subdivided based on the involvement of the obturator ring. Two associated fracture patterns involve the obturator ring:
- T-type (may need combined approach)
- Associated both column (dissociation of the articular surface from the inominate bone, may see “spur sign” on obturator oblique)
Three of these fracture types (two simple, one associated) spare the obturator ring.
- Transverse (axial CT scan shows anterior to posterior fracture line; only simple/elementary fracture to involve both columns)
- Transverse with posterior wall (most common associated fracture)
- Posterior wall (most common acetabular fracture, “gull sign” on obturator oblique view)
Associated Both Column Acetabular Fracture
Both column acetabulum fractures involve both the anterior and posterior columns, as the name implies. There is extension into the obturator ring and iliac wing. On radiographs, a both column fracture is characterized by disruption of the iliopectineal line and ilioschial line (note: disruption of these lines can also be seen with a transverse fracture pattern and a T-shaped fracture pattern). The key is that the fracture must extend into the iliac wing and involve the obturator ring to be a both-column (note: this extension may only be obvious on a Judet view or CT scan).
The spur sign is pathognomonic of a both column fracture pattern. The spur sign represents posterior displacement of the sciatric buttress, disconnecting the weight bearing surface of the acetabulum from the axial skeleton. Disruption of the obturator ring can be variable, involving the superior pubic ramus at the pubo-acetabular junction or the inferior pubic ramus, which may be minimally displaced and difficulty to visualize.
T-Type Acetabular Fracture
A T-shaped fracture also involves both columns, disrupts the iliopectineal and ilioischial lines on x-ray, and disrupts the obturator ring, similar to the associated both column fracture. However, it does not extend into or involve the iliac wing, which is what distinguishes it from a true associate both column fracture.
Transverse Acetabular Fracture
A transverse acetabular fracture also involves both columns, although it is limited to the acetabulum and does not involve the obturator ring. This distinguishes it from the both column and t-shaped fractures. The iliopectineal and ilioschial lines are disrupted on AP radiographs. Notably, the transverse fractures appear to course superiorly and medially on AP radiographs due to the inclination of the acetabulum. The fracture line is in oriented transversely relative to the acetabulum and not the floor.
Transverse with Posterior Wall Acetabular Fracture
A transverse-posterior wall acetabular fracture is a result of a transverse fracture combined with a posterior wall fracture, which may be comminuted and is usually displaced. The key to distinguish this from T-type and both column fractures is to recognize that the fracture does not involve the obturator ring, and does not involve the iliac wing, opposite of the both column fracture.
On radiographs, the iliopectineal and ilioischial lines are disrupted. However, comminute of the posterior wall will be seen (CT scan or Judet views may be needed if the posterior wall fragment is non-displaced.
Isolated Posterior Wall Acetabular Fracture
A posterior wall acetabular fracture is the most common type of acetabular fracture. In fact, it probably makes up 25-30% of acetabular fractures. In the case of posterior wall fractures, the iliopectineal line is not disrupted because there is no involvement of the anterior column and no transverse component. There may however be disruption of the ilioischial line depending on the extension of the fracture. The “gull sign” was first described in 1965 and occurs when the posterior wall fragment forms a double-curved shadow that is visible on the obturator oblique view.
- Durkee NJ, Jacobson J, Jamadar D, Karunakar MA, Morag Y, Hayes C. Classification of common acetabular fractures: radiographic and CT appearances. AJR Am J Roentgenol. 2006 Oct;187(4):915-25. PubMed PMID: 16985135.
- Browner’s Skeletal Trauma: Basic Science, Management, and Reconstruction (5th Edition)
- Pagenkopf E, Grose A, Partal G, Helfet DL. Acetabular Fractures in the Elderly: Treatment Recommendations. HSS Journal. 2006;2(2):161-171. doi:10.1007/s11420-006-9010-7.