Introduction

Acetabular fractures are complex injuries that require a thorough understanding of pelvic anatomy, underlying fracture pattern, and host factors. Radiographic classification aids in determining the optimal surgical approach, reduction tactics, and sequence of fixation. Percutaneous treatment methods and acute total hip arthroplasty (THA) are evolving as treatment options for specific types of acetabular fractures (▶Video 31.1).

I. Preoperative

1. 
   

   History

   
   
   
   
   1. 
      

      Typically results from a high-energy mechanism of injury in young patients (motor vehicle accident, motorcycle accident, bicycle accident, pedestrian struck, fall from height).

      
      
   2. 
      

      Can result from low-energy mechanism in elderly patients (fall from standing).

      
      
   3. 
      

      Frequently occur in multiply-injured patients (head, neck, chest, abdomen, retroperitoneum, and associated extremity injuries).

   
   
2. 
   

   Physical examination

   
   
   
   
   1. 
      

      Pain with rotation of the affected hip.

      
      
   2. 
      

      Hip and flank ecchymosis: Morel–Lavallée lesion.

      
      
      
      
      1. 
         

         Closed, internal degloving injury due to severe trauma.

         
         
      2. 
         

         Commonly associated with pelvis, acetabulum, and femur fractures.

         
         
      3. 
         

         A potential space is created by separation of the skin and subcutaneous tissue from the underlying fascia. This space fills with blood and/or serous fluid.

         
         
      4. 
         

         Typically debrided when treating the associated fracture operatively.

         
         
      5. 
         

         In the setting of nonoperative fracture management, observation of the Morel–Lavallée lesion is warranted with consideration of surgical debridement if signs of infection develop.

      
      
   3. 
      

      Flexed, adducted, and internally rotated leg in the presence of an associated posterior hip dislocation.

      
      
   4. 
      

      Abducted, externally rotated leg in the presence of an associated anterior hip dislocation.

      
      
   5. 
      

      Nerve palsy:

      
      
      
      
      1. 
         

         Sciatic nerve involvement in 10 to 15% of posteriorly displaced acetabular fractures, usually in conjunction with posterior hip dislocations.

         
         
      2. 
         

         Absence of foot dorsiflexion and decreased dorsal foot sensation signifies injury to the peroneal division of the sciatic nerve.

         
         
      3. 
         

         Absence of foot dorsiflexion and plantar flexion with diminished sensation on the dorsal and plantar surfaces of the foot signifies injury to both the peroneal and tibial divisions of the sciatic nerve (medial foot sensation intact from the saphenous nerve contribution).

   
   
3. 
   

   Anatomy

   
   
   
   
   1. 
      

      Osteology (▶ Fig. 31.1a, b ):

      

      
      
      
      
      1. 
         

         Judet and Letournel described the acetabulum as consisting of two columns of bone in an inverted Y.

         
         
      2. 
         

         The anterior column consists of the superior pubic ramus, anterior wall, anterior pelvic brim, iliopectineal eminence, anterior iliac wing (including the anteroinferior iliac spine [AIIS] and anterosuperior iliac spine [ASIS]), and iliac crest.

         
         
      3. 
         

         The posterior column consists of the ischial tuberosity, ischial spine, majority of the quadrilateral plate, posterior wall, and inferior aspect of the sciatic buttress (adjacent to the greater sciatic notch).

      
      
   2. 
      

      Soft tissue: Labrum—ring of fibrocartilage around the acetabulum that contributes to stability of the hip by increasing the surface area and deepening the joint.

      
      
   3. 
      

      Vascular supply (▶ Fig. 31.2a, b ):

      

      
      
      
      
      1. 
         

         Anterior:

         
         
         
         
         • 
           

           i. External iliac artery and vein.

           
           
         • 
           

           ii. Obturator artery and vein.

           
           
         • 
           

           iii. Corona mortis–connection between the external iliac artery and obturator artery.

         
         
      2. 
         

         Posterior:

         
         
         
         
         • 
           

           i. Superior gluteal and inferior gluteal arteries and veins are branches of the internal iliac system and exit the sciatic notch above and below the piriformis, respectively.

           
           
         • 
           

           ii. Ascending branch of the medial femoral circumflex artery within the quadratus femoris muscle—main blood supply to the femoral head.

   
   
4. 
   

   Imaging

   
   
   
   
   1. 
      

      Radiographs—anteroposterior (AP) pelvis and Judet (45-degree oblique) radiographs:

      
      
      
      
      1. 
         

         Obturator oblique—visualization of the anterior column and posterior wall.

         
         
      2. 
         

         Iliac oblique—visualization of the posterior column and anterior wall.

      
      
   2. 
      

      Classic radiographic landmarks (▶ Fig. 31.3 ):

      

      
      
      
      
      1. 
         

         Iliopectineal line—anterior column.

         
         
      2. 
         

         Ilioischial line—posterior column.

         
         
      3. 
         

         Teardrop: bone between the cotyloid fossa and anterior quadrilateral plate (also considered the medial wall of the acetabulum).

         
         
      4. 
         

         Roof (sourcil)—acetabular dome.

         
         
      5. 
         

         Anterior lip—anterior wall.

         
         
      6. 
         

         Posterior lip—posterior wall.

      
      
   3. 
      

      Roof arc measurements provide information regarding fracture stability:

      
      
      
      
      1. 
         

         Vertical line drawn through the center of the acetabulum.

         
         
      2. 
         

         Second line drawn from the center of the acetabulum to the point of fracture extension into the acetabulum.

         
         
      3. 
         

         Roof arc angle measured at the intersection of the two lines.

         
         
      4. 
         

         Medial roof arc angle is measured on the AP pelvis for evaluation of transverse fracture patterns. An angle less than 45 degrees is concerning for instability.

         
         
      5. 
         

         Anterior roof arc angle is measured on the obturator oblique radiograph for evaluation of anterior column fractures. An angle less than 30 degrees potentially signifies instability.

         
         
      6. 
         

         Posterior roof arc angle is measured on the iliac oblique radiograph for evaluation of posterior column fractures. An angle less than 70 degrees potentially signifies instability.

         
         
      7. 
         

         CT scan subchondral arc as described by Olson and Matta—the superior 10 mm of the acetabular articular surface (dome) corresponds to the area encompassed by 45-degree roof arc measurements.

      
      
   4. 
      

      CT scan with coronal and sagittal reconstructions:

      
      
      
      
      1. 
         

         Improved identification of fracture fragments with respective translational and rotational displacement.

         
         
      2. 
         

         Accurate measure of articular displacement (millimeters).

         
         
      3. 
         

         Assessment of marginal impaction of the articular surface.

         
         
      4. 
         

         Evaluation of intra-articular fracture fragments.

         
         
      5. 
         

         Posterior wall involvement to predict hip stability measured on axial cuts: Moed et al.’s technique—at the level of the largest posterior wall fracture involvement, measure the mediolateral width of the fracture. Divide that number by the width of the intact wall/acetabulum (▶ Fig. 31.4 ).

         

      
      
   5. 
      

      Three-dimensional (3D) reconstructions provide an enhanced understanding of the complex anatomy of the pelvis and acetabulum. 3D imaging aids in delineation of fracture lines and preoperative planning.

   
   
5. 
   

   Classification of acetabular fractures according to letournel and judet

   
   
   
   
   1. 
      

      Elementary patterns: single fracture plane (▶ Fig. 31.5 ):

      

      
      
      
      
      1. 
         

         Posterior wall:

         
         
         
         
         • 
           

           i. Most common type of acetabular fracture (20–30%).

           
           
         • 
           

           ii. Marginal impaction is common and best identified on CT.

           
           
         • 
           

           iii. “Gull sign” signifies dome impaction.

         
         
      2. 
         

         Posterior column—fracture disrupts the ilioischial line.

         
         
      3. 
         

         Anterior wall:

         
         
         
         
         • 
           

           i. Rare.

           
           
         • 
           

           ii. Does not involve the iliopectineal line (pelvic brim).

         
         
      4. 
         

         Anterior column:

         
         
         
         
         • 
           

           i. Fracture disrupts the iliopectineal line.

           
           
         • 
           

           ii. The superior point at which the fracture line exits the ilium influences treatment and may be described as exiting:

           
           
           
           
           • 
             

             Low: AIIS or below.

             
             
           • 
             

             Intermediate: between the AIIS and ASIS.

             
             
           • 
             

             High: above the ASIS along the iliac crest.

         
         
      5. 
         

         Transverse:

         
         
         
         
         • 
           

           i. The only elementary pattern that involves both columns.

           
           
         • 
           

           ii. Transtectal—fracture through the roof or dome of the acetabulum.

           
           
         • 
           

           iii. Juxtatectal—fracture through the superior extent of the cotyloid fossa with the majority of the dome intact.

           
           
         • 
           

           iv. Infratectal: fracture through the cotyloid fossa and involving the anterior and posterior walls without dome involvement.

      
      
   2. 
      

      Associated patterns (▶ Fig. 31.6 ):

      

      
      
      
      
      1. 
         

         Posterior column/posterior wall.

         
         
      2. 
         

         Transverse/posterior wall.

         
         
      3. 
         

         T-shaped—transverse fracture with a vertical stem that travels inferiorly into the obturator foramen (most common), posteroinferior to divide the ischium, or anteroinferior to divide the pubis.

         
         
      4. 
         

         Anterior column or wall/posterior hemitransverse:

         
         
         
         
         • 
           

           i. Anterior column fracture combined with a transverse fracture line exiting posterior from the primary anterior fracture, effectively dividing the posterior column into superior and inferior components.

           
           
         • 
           

           ii. Most common fracture pattern in elderly patients.

         
         
      5. 
         

         Associated both columns:

         
         
         
         
         • 
           

           i. No portion of the articular surface is in continuity with the intact ilium.

           
           
         • 
           

           ii. “Spur sign” seen on the obturator oblique radiograph corresponds to the intact ilium and is pathognomonic for this fracture type.

           
           
         • 
           

           iii. “Secondary congruence” refers to the maintenance of femoral head congruity with the fractured acetabulum although dissociated from the innominate bone.