Pennal et al. propose a mechanistic classification of pelvic ring injuries organized by the direction of causative force. The three categories are anteroposterior compression, lateral compression (four subtypes), and vertical shear. The paper also establishes the three-view radiographic protocol required to characterize displacement in all planes.
A pelvic fracture that looks like isolated pubic rami on the AP film has a second lesion somewhere in the ring — this is biomechanical fact, not incidence. The pelvis is a ring; it cannot fail at one point alone.
Get all three views (AP, inlet, tangential) on every significant pelvic injury. When you see gross posterior instability, treat it as a hemorrhagic emergency: these patients need 2.5× more blood and die 4× more often. A symphyseal gap greater than 2.5 cm means the posterior ring is injured. Do not be reassured by a posterior film that looks acceptable.
Never apply a pelvic sling to a lateral compression injury. It drives the already internally rotated hemipelvis further inward and worsens the deformity. The Pennal classification is the direct predecessor of the Tile and AO/OTA systems. Understanding force direction here makes every downstream pelvic fracture algorithm interpretable.
Pennal et al. propose a mechanistic classification of pelvic ring injuries organized by the direction of causative force. The three categories are anteroposterior compression, lateral compression (four subtypes), and vertical shear. The paper also establishes the three-view radiographic protocol required to characterize displacement in all planes.
A pelvic fracture that looks like isolated pubic rami on the AP film has a second lesion somewhere in the ring — this is biomechanical fact, not incidence. The pelvis is a ring; it cannot fail at one point alone.
Get all three views (AP, inlet, tangential) on every significant pelvic injury. When you see gross posterior instability, treat it as a hemorrhagic emergency: these patients need 2.5× more blood and die 4× more often. A symphyseal gap greater than 2.5 cm means the posterior ring is injured. Do not be reassured by a posterior film that looks acceptable.
Never apply a pelvic sling to a lateral compression injury. It drives the already internally rotated hemipelvis further inward and worsens the deformity. The Pennal classification is the direct predecessor of the Tile and AO/OTA systems. Understanding force direction here makes every downstream pelvic fracture algorithm interpretable.