eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics

Fracture, Pelvic

Author: C Crawford Mechem, MD, MS, FACEP, Associate Professor, Department of Emergency Medicine, University of Pennsylvania School of Medicine; Emergency Medical Services Medical Director, Philadelphia Fire Department
Contributor Information and Disclosures

Updated: Aug 11, 2008

Introduction

Background

Pelvic fracture is a disruption of the bony structures of the pelvis. In elderly persons, the most common cause is a fall from a standing position. However, fractures associated with the greatest morbidity and mortality involve significant forces such as from a motor vehicle crash or fall from a height.

For related information, see Medscape’s Fracture Resource Center.

For a CME/CE activity, see CME/CE - Patients May Need Better Pain Interventions After Traumatic Injury.

Pathophysiology

The bony pelvis consists of the ilium (ie, iliac wings), ischium, and pubis, which form an anatomic ring with the sacrum. Disruption of this ring requires significant energy. Because of the forces involved, pelvic fractures frequently involve injury to organs contained within the bony pelvis. In addition, trauma to extra-pelvic organs is common. Pelvic fractures are often associated with severe hemorrhage due to the extensive blood supply to the region.

Pelvic fractures are most commonly described using one of two classification systems.

The Tile classification system is based on the integrity of the posterior sacroiliac complex.

• In type A injuries, the sacroiliac complex is intact. The pelvic ring has a stable fracture that can be managed nonoperatively.
• Type B injuries are caused by either external or internal rotational forces resulting in partial disruption of the posterior sacroiliac complex. These are often unstable. 
• Type C injuries are characterized by complete disruption of the posterior sacroiliac complex and are both rotationally and vertically unstable. These injuries are the result of great force, usually from a motor vehicle crash, fall from a height, or severe compression.  

The Young classification system is based on mechanism of injury: lateral compression, anteroposterior compression, vertical shear, or a combination of forces. Lateral compression (LC) fractures involve transverse fractures of the pubic rami, either ipsilateral or contralateral to a posterior injury.

• Grade I - Associated sacral compression on side of impact
• Grade II - Associated posterior iliac ("crescent") fracture on side of impact
• Grade III - Associated contralateral sacroiliac joint injury

Anterior-posterior compression (APC) fractures involve symphyseal diastasis or longitudinal rami fractures.

• Grade I - Associated widening (slight) of pubic symphysis or of the anterior sacroiliac (SI) joint, while sacrotuberous, sacrospinous, and posterior SI ligaments remain intact
• Grade II - Associated widening of the anterior SI joint caused by disruption of the anterior SI, sacrotuberous, and sacrospinous ligaments; posterior SI ligaments remain intact
• Grade III (open book) - Complete SI joint disruption with lateral displacement and disrupted anterior SI, sacrotuberous, sacrospinous, and posterior SI ligaments

Vertical shear (VS) involves symphyseal diastasis or vertical displacement anteriorly and posteriorly, which is usually through the SI joint, though occasionally through the iliac wing or sacrum. Combined mechanical (CM) fractures involve a combination of these injury patterns, with LC/VS being the most common.

Acetabular fractures most commonly involve disruption of the acetabular socket when the hip is driven backward in a motor vehicle accident. Occasionally, they occur in a pedestrian struck by a vehicle moving at a significant rate of speed. 

Falls in elderly persons may involve fractures (usually of the pubic rami) without disruption of the ring.

Frequency

United States

Pelvic fractures represent 3% of all skeletal fractures and 1-2% of fractures seen by orthopedists who care for children. Single pubic rami and avulsion fractures are most common.

Mortality/Morbidity

Over half of all pelvic fractures occur as a result of minimal-to-moderate trauma, such as a fall from a standing position. Of these, 95% are minor. On the other hand, the more severe pelvic fractures involve significant trauma. Most of this discussion relates to the more severe pelvic fractures.

• Cited mortality rates for pelvic fractures range from 3-20%. One study of pelvic fractures in children aged 16 years or younger cited a mortality rate of 5%, with death most commonly due to hemorrhage or multiple injuries.¹  
• Ultimately, the patient's Injury Severity Score, not the nature of the pelvic fracture, is the best predictor of mortality. Hemorrhage, either pelvic or extrapelvic, or associated severe head injury are the most common causes of early death, whereas multisystem organ failure and secondary infection are the main causes of delayed death.
• The complication rate associated with pelvic fractures is significant and is related to injury of underlying organs and bleeding. Because of the tremendous force necessary to cause most unstable pelvic fractures, concomitant severe injuries are common and are associated with high morbidity and mortality.
• Pelvic fractures increase the incidence of pulmonary emboli.

Sex

• In a 2007 study of a trauma registry in the United Kingdom, 58% of patients sustaining a pelvic ring fracture were male.²  A trauma registry review that same year from New South Wales, Australia, revealed that most patients sustaining high-energy pelvic ring fractures, such as from an motor vehicle crash (MVC), were male, whereas females predominated in low-energy injuries.³
• Associated genitourinary (GU) injuries vary greatly between men and women and are discussed in other articles. For many years, it was believed that women did not suffer urethral injuries. It is now known that, while women suffer urethral injuries at a much lower incidence than men, injuries do occur. Women suffer partial lacerations and partial disruption. Complete urethral disruption is rare.

Age

• Age distribution largely matches that of motor vehicle crashes, with car-car injuries more prevalent in adults, especially younger adults, and car-pedestrian injuries more likely to cause injury in children. The other group is the elderly, who tend to suffer pubic rami fractures without internal injuries as a result of falls from a standing position.
• In a 2007 study of a trauma registry in the United Kingdom, the median age of patients sustaining a pelvic ring fracture was 39 years.²  
• Urethral injuries vary widely by age with injuries to the prostatic urethra and bladder neck limited to children. Direct lacerations to the urethra occur only in boys (small prostate) and women.
• The incidence of urethral injuries also varies by the type of pelvic fracture. Straddle fractures associated with sacroiliac diastasis have the highest incidence (odds ratio of 24). Without diastasis, the odd ratio dropped to 3.85. Urethral injuries were essentially nonexistent for fractures not involving the ischiopubic rami.

Clinical

History

• Basic mechanism of significant blunt trauma should prompt consideration of a pelvic fracture.

Physical

• Tenderness, laxity, or instability on palpation of the bony pelvis suggests fracture. 
• Extensive manipulation of a fractured pelvis can increase patient discomfort and potentially increase bleeding, elaborate diagnostic maneuvers should be avoided. 
• Remember that, in the later stages of pregnancy, the pelvic ligaments become stretched, mimicking bony instability.
• Instability on hip adduction and pain on hip motion suggests an acetabular fracture, with or without an associated hip fracture.
• Signs of urethral injury in males include a high-riding or boggy prostate on rectal examination, scrotal hematoma, or blood at the urethral meatus.
• Vaginal bleeding or palpable fracture line on careful bimanual examination suggests pelvic fracture in females.
• Other signs that may suggest a pelvic fracture include hematuria; a hematoma over the ipsilateral flank, inguinal ligament, proximal thigh, or in the perineum; neurovascular deficits in the lower extremities; or rectal bleeding.
• Note that digital rectal examination has a very low sensitivity for diagnosing pelvic fractures. In fact, in a 2007 study assessing the utility of routine digital rectal examinations to diagnose injury in 1401 trauma patients, the rectal examination missed 100% of the 67 pelvic fractures.⁴

Causes

• Adults with significant pelvic fracture
  • Motor vehicle crash (50-60%)
  • Motorcycle crash (10-20%)
  • Pedestrian versus car (10-20%)
  • Falls (8-10%)
  • Crush (3-6%)
• Children
  • Pedestrian versus car (60-80%)
  • Motor vehicle crash (20-30%)

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