I. Mechanism of injury: high-energy blunt trauma ¹ , ² :

1. 
   

   Motorcycle collision.

   
   
2. 
   

   Auto-pedestrian collision.

   
   
3. 
   

   Fall.

   
   
4. 
   

   Motor vehicle collision.

   
   
5. 
   

   Crush injury.

II. Associated with other high-energy injuries:

1. 
   

   Chest/thoracic injury.

   
   
2. 
   

   Long bone fracture.

   
   
3. 
   

   Reproductive organ injury.

   
   
4. 
   

   Head injury.

   
   
5. 
   

   Abdominal injury.

   
   
6. 
   

   Spine fracture.

III. Mortality rate:

1. 
   

   10–50%. ³ – ⁸

   
   
2. 
   

   Hemorrhage is leading cause. ⁹ – ¹¹

   
   
3. 
   

   Associated with ¹² :

   
   
   
   
   1. 
      

      Systolic BP less than 90 on presentation.

      
      
   2. 
      

      Age older than 60 years.

      
      
   3. 
      

      Increased injury severity scale (ISS): an anatomical scoring system providing overall score for patients with multiple injuries, based on assignment of an Abbreviated Injury Scale (AIS) score to each of six body regions—score range 3 to 75.

      
      
      
      
      1. 
         

         Head and neck.

         
         
      2. 
         

         Face.

         
         
      3. 
         

         Chest.

         
         
      4. 
         

         Abdomen.

         
         
      5. 
         

         Extremity.

         
         
      6. 
         

         External.

      
      
   4. 
      

      Need for greater than 4 U of pure red blood cells.

I. Mechanism of injury: bimodal:

1. 
   

   High energy in young patients.

   
   
2. 
   

   Low energy in elderly patients. ¹³

   
   
3. 
   

   May be seen with concomitant hip dislocation ( Fig. 9.1 ).

II. Associated injuries (up to 50% of patients) ¹⁴ – ¹⁷ :

1. 
   

   Extremity injury: 35%.

   
   
2. 
   

   Head injury: 19%.

   
   
3. 
   

   Chest injury: 18%.

   
   
4. 
   

   Nerve palsy: 13%.

   
   
5. 
   

   Abdominal injury: 8%.

   
   
6. 
   

   Genitourinary injury: 6%.

   
   
7. 
   

   Spine injury: 4%.

III. Fracture pattern defined by ¹⁸ :

1. 
   

   Force vector.

   
   
2. 
   

   Position of the femoral head (hip position).

   
   
3. 
   

   Bone mineral density.

I. Osteology:

1. 
   

   Sacrum and two innominate bones.

   
   
2. 
   

   Stability dependent on strong surrounding ligamentous structures.

   
   
3. 
   

   Displacement with obligatory disruption of ring in minimum of two places.

   

   

II. Ligaments ( Fig. 9.3 ):

1. 
   

   Anterior symphyseal (resist external rotation):

   
   
2. 
   

   Pelvic floor:

   
   
   
   
   1. 
      

      Sacrospinous ligaments (resist external rotation).

      
      
   2. 
      

      Sacrotuberous ligaments (resist shear and flexion).

   
   
3. 
   

   Posterior sacroiliac (SI) complex: most important for stability:

   
   
   
   
   1. 
      

      Anterior SI ligaments (resist external rotation).

      
      
   2. 
      

      Interosseous SI (resist anteroposterior [AP] translation).

      
      
   3. 
      

      Posterior SI (resist cephalad–caudad translation).

      
      
   4. 
      

      Iliolumbar (resist external and internal rotation).

III. Neurovascular structures ( Fig. 9.4 ):

1. 
   

   Lumbosacral plexus.

   
   
2. 
   

   Internal iliac vessels.

   
   
3. 
   

   Numerous neurovascular structures intimately associated with posterior pelvic ligaments.

I. Osteology:

1. 
   

   Based on two-column theory ( Fig. 9.5 ):

   
   
   
   
   1. 
      

      Acetabulum supported by two columns of bone.

      
      
   2. 
      

      Inverted Y configuration.

      
      
   3. 
      

      Anterior column:

      
      
      
      
      1. 
         

         Anterior ilium.

         
         
      2. 
         

         Anterior wall and dome.

         
         
      3. 
         

         Iliopectineal eminence.

         
         
      4. 
         

         Lateral superior pubic ramus.

         

         

      
      
   4. 
      

      Posterior column:

      
      
      
      
      1. 
         

         Quadrilateral surface.

         
         
      2. 
         

         Posterior wall and dome.

         
         
      3. 
         

         Ischial tuberosity.

         
         
      4. 
         

         Greater and lesser sciatic notches.

II. Vascular structures:

1. 
   

   Obturator artery and vein.

   
   
2. 
   

   Corona mortis:

   
   
   
   
   1. 
      

      Anastomosis of the external iliac and internal iliac vessels.

      
      
   2. 
      

      At risk during injury and operative intervention.

I. Young–Burgess Classification ( Table 9.1; Fig. 9.6 ). ¹⁹

II. Tile classification ( Table 9.2 ). ²⁰

I. Letournel classification ( Table 9.3 ). ¹⁵ , ¹⁶ , ¹⁸ , ²¹ , ²²

I. Mechanism of injury.

II. Level of consciousness:

1. 
   

   Glasgow Coma Scale (score range 3–15; eye opening, verbal, and motor responses).

III. Initial physical examination.