83 Pelvic Shear Fractures

CASE 83


Pelvic Shear Fractures


Hema N. Choudur, Anthony G. Ryan, and Peter L. Munk


Clinical Presentation


A young man who fell from a three-story building was brought to the radiology department on a stretcher, unable to move.



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Figure 83A



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Figure 83B


Radiologic Findings


An anteroposterior (AP) radiograph of the pelvis (Fig. 83A) shows the pubic symphysis to be widely diastased, with an accompanying disruption and displacement of the right sacroiliac (SI) joint. There is an additional vertical fracture through the left sacral ala parallel to the SI joint.


The fractures were successfully treated with internal fixation (Fig. 83B).


Diagnosis


Pelvic shear fracture type 3.


Differential Diagnosis


None.


Discussion


Background


Fractures of the pelvis account for 3% of all fractures. The classification of these fractures is based on the direction of the vector and the degree of disruption resulting from applied force. These fractures are classified as lateral compression, AP compression, vertical shear, and combined mechanical injury.


Etiology


These injuries occur as a result of road traffic accidents or falls from a height. A high-impact vector directs the type of injury.


Pathophysiology


The major types of fractures are due to the following:



  1. External rotation resulting in an open-book type of fracture: the pubic symphysis is diastased due to an externally rotating force acting on the femora and anterosuperior iliac spines. The anterior SI joint ligaments may be severed, but not the posterior. The force may also be applied to the posterosuperior iliac spines.
  2. Vertical shear force acting perpendicular to the posterior pelvis may cause anterior and posterior pelvic fractures in addition to soft-tissue injury (bladder, urethra, etc).
  3. A lateral compression force causes an internal rotation of the hemipelvis, resulting in fractures of the pubic rami and SI joint on the same side of the sacrum. Sometimes, an impaction can occur at the sites of the fracture and at the SI joints.
  4. Complex injury may result from a combination of all of the above.

Clinical Findings

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Feb 14, 2016 | Posted by in MUSCULOSKELETAL IMAGING | Comments Off on 83 Pelvic Shear Fractures

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