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Pelvic injuries
Essentials
- 1
Pelvic fractures account for 3% of skeletal fractures.
- 2
Fractures are either stable or unstable. Unstable fractures result from considerable mechanical force; they are associated with concomitant injuries and with a significant overall mortality.
- 3
Understanding the mechanism of injury and recognizing the pelvic fracture pattern on x-ray provides insight into the potential for complications, such as associated haemorrhage or urogenital injuries.
- 4
Isolated stable pelvic fractures are usually treated conservatively.
Anatomy
The pelvic ring is formed by two innominate bones and the sacrum. The innominate bones are made up of the ileum, ischium and pubis and are joined anteriorly at the symphysis pubis and posteriorly at the left and right sacroiliac joints. The lateral surface of the innominate bone forms a socket, the acetabulum, contributed to by the ileum, ischium and pubis.
Stability of the pelvic ring is dependent on the strong posterior sacroiliac, sacrotuberous and sacrospinous ligaments. Disruption of the ring can result in significant trauma to the neurovascular and soft tissue structures it protects. A break at one point in the ring merits consideration of breaks at other points on the ring.
Classification of pelvic fractures
Pelvic fractures can be open or closed, major or minor, stable or unstable depending on the degree of ring disruption; they may be associated with haemodynamic compromise and/or hollow viscus or neurological injury.
Young and Resnik classification
The Young and Resnik pelvic fracture classification (also outlined in Chapter 3.8 ) classifies pelvic fractures by the mechanism of injury and the direction of the causative force. It does not include isolated fractures outside the bony pelvic ring or acetabular fractures, which are discussed later.
Most pelvic fractures result from lateral compression, anteroposterior compression or vertical shear forces. These injuries may be suggested by mechanism of injury and are confirmed radiographically.
Lateral compression injuries
Lateral compression accounts for 50% of pelvic fractures and commonly occurs when a pedestrian or motor vehicle occupant is struck from the side. Most of these injuries are stable, but as a result of the considerable forces involved, there is a high potential for associated injury. This mechanism of injury can produce several fracture patterns involving anterior and posterior pathology.
Anteriorly, there is a transverse fracture of at least one set of pubic rami. These fractures may be unilateral or bilateral and can include disruption of the pubic symphysis. The posterior element of lateral compression fractures is important but may be overlooked when one is concentrating on the anterior findings. However, it is critical in determining the functional stability of the pelvic ring and defining associated injuries.
Type 1 fractures
Type 1 fractures are the most common and involve compression injury to the sacrum posteriorly and oblique pubic rami fractures anteriorly.
These injuries occur on the side of impact and are usually stable, involving impaction of the cancellous bone of the sacrum without ligamentous disruption. X-rays confirm discontinuity of the sacral foramina posteriorly.
Type 2 fractures
Type 2 fractures result from greater lateral compressive forces. The iliac wing is fractured posteriorly, with the fracture line often extending to involve part of the sacroiliac joint. This leaves part of the ileum firmly attached to the sacrum.
Anteriorly, there are associated fractures of the pubic rami. Stability is determined by the degree of sacroiliac joint disruption and mobility of the anterior hemi-pelvis involved. These fractures are usually stable to external rotation and vertical movement but are more mobile to internal rotation.
Type 3 fractures
Type 3 fractures usually occur when one hemi-pelvis is trapped against the ground and a lateral force rolls over the mobile hemi-pelvis. This produces a lateral compression injury to the side of primary impact and an unstable anteroposterior compressive injury to the contralateral sacroiliac joint.
Anteroposterior compression injuries
Anteroposterior compression injuries of the pelvis account for 25% of pelvic fractures. They result from anterior forces applied directly to the pelvis or indirectly via the lower extremities to produce an open-book type injury.
Type 1 injuries
Type 1 injuries result from low-energy forces that stretch the ligamentous constraints of the pelvic ring. The pubic symphysis is disrupted anteriorly but with less than 2.5 cm diastasis seen radiographically. These fractures are stable and there is usually no significant posterior pelvic injury.
Type 2 injuries
Type 2 injuries classically cause an open-book fracture. They involve rupture of the anterior sacroiliac, sacrospinous and sacrotuberous ligaments posteriorly and disruption of the pubic symphysis anteriorly. There is widening of the anterior sacroiliac joint with diastasis of the pubic symphysis by more than 2.5 cm on radiology; occasionally there is avulsion of the lateral border of the lower sacral segments.
Considerable force is needed to disrupt these ligaments; therefore neurovascular injuries and complications are common. The pelvis is unstable to external rotation and external compression will ‘spring’ the pelvis. This should be avoided.
Type 3 injuries
Type 3 injuries occur when an even greater force is applied and involves disruption of all the pelvic ligaments on the affected side. Rupture of the posterior sacroiliac ligaments leads to lateral displacement and disconnection of the affected hemi-pelvis from the sacrum. These injuries are grossly unstable and associated with the highest rate of haemorrhage and neurological injury ( Fig. 4.6.1 ).
Vertical shear injury (Malgaigne fracture)
These injuries account for only 5% of pelvic fractures. They usually occur following a fall from a height or during a motor vehicle accident, when the victim reflexly extends his or her leg against the brake pedal before impact. These mechanisms force the hemi-pelvis in a vertical direction and result in complete ligamentous or bony disruption, with cephalo-posterior hemi-pelvic displacement.
Anterior disruption occurs through the pubic symphysis or pubic rami. Posteriorly, dissociation usually occurs through the sacroiliac joint, but it may occur vertically through the sacrum. These fractures are usually unilateral but may be bilateral and are associated with significant bleeding and/or intra-abdominal injury.
Clinical assessment
A standard trauma management protocol is adhered to in managing the multi-trauma patient, with usual attention being paid initially to the airway, breathing and circulations (ABCs) in the primary survey and resuscitation phases of care (see Chapter 3.1 ).
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