Judet and Letournel classification for acetabular fractures

The Judet and Letournel classification is the most widely used classification system for acetabular fractures. It classifies acetabular fractures into ten major fracture patterns, which consist of five simple patterns and five complex patterns ^1,2.

Classification

The morphology of fracture patterns is described from the point of view of looking at the acetabulum en face from the lateral side. Structures that are key to the classification are the anterior and posterior walls (rims) of the acetabulum and the anterior (iliopubic) and posterior (ilioischial) columns of the innominate bones, including their confluence at the sciatic buttress and the quadrilateral plate.

Elementary (simple) patterns

The elementary (or elemental) patterns fracture the innominate bone through the acetabulum into two major fragments. There are five types:

1. anterior wall
   • segmental fracture of the middle third of the anterior column, detaching a trapezoidal fragment that contains the anterior acetabular wall from the rest of the innominate bone
   • superiorly, fracture line begins below the anterior inferior iliac spine ⁹
   • medially, fracture line involves the anterior quadrilateral plate, so this pattern excludes isolated fractures of the anterior acetabular rim ⁵
   • inferiorly, fracture line exits at the superior pubic ramus, distinguishing this pattern from anterior column fracture ^5,8,9
2. anterior column
   • segmental fracture of the anterior column that crosses the obturator foramen, detaching a fragment that contains the anterior acetabular wall and most of the pubis from the rest of the innominate bone ¹¹
   • superiorly, fracture line begins variably in the anterior ilium ^5,10:
     • high: iliac crest
     • intermediate: between anterior iliac spines (anterior interspinous notch)
     • low: below the anterior inferior iliac spine (psoas gutter)
     • very low: anterior horn of the acetabular articular surface to the junction of ilium and pubis (iliopectineal eminence)
   • medially, fracture line involves the quadrilateral plate in a coronal orientation ⁵
   • inferiorly, fracture line exits at the ischiopubic ramus, distinguishing this pattern from anterior wall fracture ¹⁰
3. transverse
   • fracture across both columns of the acetabulum, separating the inferior (ischiopubic) and superior (iliac) portions of the innominate bone ^5,8,9
     • superiorly, superior portions of both columns remain connected to the sciatic buttress (fracture line does not extend superiorly to anterior or posterior iliac surfaces), unlike column fractures ^4,5
     • inferiorly, obturator ring remains intact, unlike T-shaped or column fractures ³
   • subclassified by level relative to acetabular roof ^5,8,9:
     • transtectal: traverses weightbearing dome
     • juxtatectal: traverses the junction of the acetabular (cotyloid) fossa and articular surface of the acetabular roof
     • infratectal: traverses the acetabular fossa and anterior and posterior horns of the acetabular articular surface
4. posterior column
   • segmental fracture of the posterior column that crosses the obturator foramen, detaching a fragment that contains the posterior acetabular wall and most of the ischium from the rest of the innominate bone
   • superiorly, fracture line enters at greater sciatic notch, sparing iliac wing ^5,11
   • medially, fracture line passes through the acetabular roof and involves the quadrilateral plate in a coronal orientation ^5,8,9,11
   • inferiorly, fracture line exits through ischiopubic ramus or, alternatively, splits the ischial tuberosity ^5,8
5. posterior wall
   • fracture detaching fragment(s) consisting of the posterior articular surface and/or the weight-bearing dome from most of the posterior column, but sparing the quadrilateral plate ^5,9
     • N.B. this is an asymmetric definition compared to anterior wall fractures, which do involve the medial acetabular surface ⁵

Associated (complex) patterns

The five complex patterns break the acetabulum into three major fragments and may be described as combinations of elementary fracture components:

1. both-column fracture
   • fractures detaching two fragments, respectively composed of most of the anterior and posterior columns, from the posterior iliac wing ⁸
     • entire weight-bearing portion of the acetabulum is disconnected from the sciatic buttress ^4,5
     • acetabular roof mostly remains with the anterior column fragment(s) ⁹
   • superiorly, two fracture lines enter in perpendicular fashion, one posteriorly (usually at the greater sciatic notch) and one anteriorly or superiorly (anterior ilium or iliac crest) ^5,8,9
   • above the acetabulum, descending fracture lines merge in coronal orientation ⁸
   • inferiorly, fracture line exits at the ischiopubic ramus
2. anterior column (or wall) + posterior hemitransverse fracture
   • fractures detaching two fragments, respectively composed of a segment of the anterior column and the inferior part of the posterior column, from the posterior iliac wing
     • part of the acetabular dome remains connected to the sciatic buttress, unlike in both-column fracture
   • superiorly, two fracture lines enter in perpendicular fashion, one posteriorly and one anteriorly or superiorly ¹⁰
     • ^​anteriorly, fracture line rises variably superiorly to the anterior inferior iliac spine up to iliac crest, unlike in T-shaped fracture where the fracture line is a straight continuation of the posterior transverse component ⁵​^,10
     • posteriorly, fracture line follows an oblique sagittal orientation and variably extends to level of ischial spine up to greater sciatic notch, unlike in T-shaped fracture ⁹
   • in the quadrilateral plate, fracture lines meet at a right angle
   • inferiorly, fracture line exits superior pubic ramus (anterior wall fracture) or ischiopubic ramus (anterior column fracture)
3. T-shaped fracture
   • fractures detaching two inferior (ischiopubic) fragments, one anterior and one posterior, from the rest of the innominate bone
   • superiorly, transverse fracture line is similar to the elemental transverse fracture, although the anterior and posterior components may not have a common orientation ⁹
   • inferiorly, stem of the fracture line crosses the acetabular fossa and then either across the obturator foramen or, uncommonly, through the ischium alone
   • includes posterior column with anterior hemitransverse fractures ^5,8
   • includes transverse with anterior wall fractures ⁵
4. transverse + posterior wall fractures    
5. posterior column + posterior wall fractures

Epidemiology

The most frequent types, accounting for more than 80% of fractures, are posterior wall, both column, and transverse + posterior wall, followed by T-shaped and transverse ^3,5,7. Thus, about one-half of acetabular fractures contain a posterior wall component ⁵.

Radiographic features

Plain radiograph

The classification was originally based on three radiographic views (anteroposterior view and two Judet views: obturator oblique view and iliac oblique view).

• fractures involving the anterior column (anterior wall, anterior column, transverse, and all associated patterns except posterior column + posterior wall fracture) disrupt the iliopectineal line
• fractures involving the posterior column (posterior column, transverse, and all associated patterns) disrupt the ilioischial line
• column and T-shaped fractures disrupt the obturator ring
• wall fractures disrupt the corresponding acetabular rim

CT

CT with multiplanar reformations or 3D volume rendering may improve accuracy ^5,6. As the acetabulum is oriented obliquely, such that the face points slightly anterior and inferior to the true lateral side of the patient, a rotatable 3D rendering with the femur virtually removed is needed to recapitulate the classic diagrams and terminology of the Judet-Letournel classification.

On axial CT images, at the level of the acetabular roof, various families of fractures have different orientations ⁴:

• transverse fracture lines appear sagittal
• column fracture lines appear coronal
• wall fractures appear oblique