2.2.1 Age

The structural integrity of bone deteriorates with increasing age. Osteopenia and osteoporosis are recognized public health issues. After approximately age 40 years, the strength of the pelvis gradually decreases because of loss of cancellous bone. As a result, less force is required to disrupt the bone elements of the pelvis in elderly patients. Elderly patients also are more prone to injury caused by plastic deformation of their characteristically softer bone.

In a younger person with good bone quality, injury to the pelvic ring requires great force. Thus, a specific fracture pattern in a young person may be associated with a greater degree of soft-tissue damage than a comparable fracture pattern in an elderly person. Even minor degrees of pelvic ring displacement may result in great instability from damage to ligamentous structures and pelvic viscera. Associated injuries to the pelvic nerves and blood vessels must be suspected in high-energy injury patterns.

2.2.2 Gender

Male patients are at risk for urological trauma. The anatomical course of the male urethra makes it prone to injury, especially in high-energy displaced pelvic ring fractures. Erectile dysfunction is also a concern for these patients at follow-up.

Urethral injuries in female patients are uncommon but an open pelvic fracture communicating with the vagina is a risk, and patients must be examined for this injury to minimize potentially severe complications.

2.2.3 Medical history

As in all areas of clinical medicine, details of a patient′s history supply important information to facilitate proper decision making about treatment. Therefore, the history of illnesses, medication use, allergies, current or past drug and alcohol use, and previous surgeries should be obtained.

2.2.4 Associated injuries

Other body systems are typically injured in patients who sustain a pelvic ring disruption in addition to other injuries. Knowledge of specific injuries and adherence to advanced trauma life support (ATLS) assessment and management protocols are essential for optimal management. Details regarding associated injuries are addressed in other chapters.

2.3.1 Magnitude of force

The amount of force that an injury imparts onto the pelvis is an important element of the patient history: the higher the level of energy, the higher the likelihood of pelvic ring instability. High-energy injuries, such as motor vehicle collisions and industrial incidents, are also more likely to be associated with internal injuries than low-energy falls.

2.3.2 Direction of force

In unconscious patients, general details of an injury usually can be obtained from collateral sources, such as bystanders or first responders. For example, the driver of a vehicle that is “T-boned” by another vehicle sustains a laterally directed force on the pelvis. A patient pinned against a wall in an industrial accident primarily experiences an anteroposterior directed force. This information is important when interpreting imaging studies because the classification schemes for pelvic fracture are partially based on direction of force [1–4].

Anteroposterior directed forces on the pelvis cause anterior structures to fail first, followed by posterior ligamentous structures. The integrity of the posterior structures directs the options for surgical treatment. Lateral compression mechanisms may cause several injury patterns but may not be associated with pelvic ring instability because of impaction. In fact, instability might be introduced only after a reduction maneuver exposes a disimpacted fracture gap. Violent shearing mechanisms are associated with the most grossly unstable injury patterns. Combination forces often tear apart pelvic ring supports, yielding displaced injuries with severe neurovascular injuries.

2.4.1 Look

The patient must be exposed appropriately to allow complete examination of the pelvis, genitalia, and lower extremities. Carefully logrolling a supine patient is necessary to examine the posterior structures. Important signs of open injuries and deformity can be missed without a thorough inspection.

2.4.2 Wounds and contusions

All wounds need to be examined. Lacerations in the pelvic area must be considered open pelvic fractures until proven otherwise. Open pelvic fractures can and often communicate through the rectum, vagina, or perineum. Thus, these areas require inspection with manual palpation and speculum examination.

Contusions suggest that force has been applied to a specific area and can help identify the direction of that force and with interpretation of radiographic studies. The skin should also be assessed for internal degloving (Morel-Lavallée) lesions, which occur when the skin and subcutaneous tissue separate from the underlying fascia. Subcutaneous fluid collection with associated fluid waves and fluctuance may be detected. Incisions through this type of tissue injury are associated with a high rate of complications.

The genitalia must be inspected for bleeding. Blood at the urethral meatus in men suggests a possible urethral injury. Rectal examination is necessary to identify potential displacement of the prostate. Bleeding of the genitalia in women suggests an open fracture communicating with the vagina ( Fig 1.5-1 ).

2.4.3 Displacement of the pelvis and lower extremities

Noting the position of the lower extremities is important during assessment for pelvic ring displacement. Concomitant injuries to the lower extremities must also be noted. However, in the absence of other trauma injuries to the lower extremities, shortening and/or rotation of the leg(s) can indicate the type of pelvic fracture sustained and whether surgical treatment may be advisable.

If the extremity is shortened, internally rotated, and displaced at the posteroinferior iliac spine, the pelvic injury is most likely a lateral compression injury with posterior impaction ( Fig 1.5-2 ). If the extremities are similar in length but both externally rotated, a displaced open book injury is expected ( Fig 1.5-3 ). Similarly, in the absence of ipsilateral trauma, a patient with a significantly shortened, externally rotated lower extremity is expected to have a vertically unstable shear injury.

Careful inspection of the level and rotation of the anteroposterior iliac spine also helps to confirm the presence of displacement and fracture pattern. Rotation of the posterior spine can be striking, giving the appearance of a bone mass.

2.5.1 Palpation

Careful palpation and manipulation of the pelvis may reveal deformity, crepitus, and instability. Abnormal motion of the hemipelves can indicate instability (rotational and/or horizontal).

Horizontal stability is assessed by carefully rotating the ilia with medial force directed on the iliac crests to identify abnormal internal rotation or reduction of a displaced open book type injury. Similarly, a posterolaterally directed force at the iliac crests will reveal potentially abnormal external rotation instability of the pelvis ( Fig 1.5-4 ). In the absence of lower extremity injury, internally and externally rotating the legs will reveal rotational instability of the pelvis. Static internal rotation deformity without instability may indicate a posteriorly impacted lateral compression injury. Palpation of the pubic symphysis may reveal a gap, suggesting a symphyseal disruption ( Fig 1.5-5 ).

2.5.2 Traction (vertical stability and/or posterior stability)

Applying traction to the extremity is important to assess for craniocaudal (vertical) instability and posterior and flexion-extension rotational instability of the hemipelvis. A shortened extremity reduces with traction, suggesting gross instability of the pelvic ring. The degree of vertical movement is best assessed with the examiner palpating the iliac crests while an assistant applies traction to the extremity ( Fig 1.5-6 ). A variation of this maneuver is the push-pull test, which is done with the patient under anesthesia [6]. With this test, an assistant pushes on the well leg while the examiner pulls on the potentially unstable extremity and/or pelvis. Abnormal vertical or pelvic flexion of the iliac crests indicates pelvic instability.

2.5.3 Rectal and vaginal examination

Examination of the perineum, rectum, and vaginal areas is essential. Otherwise occult open fractures may be palpable or visible with careful examination. A digital rectal examination is important to identify prostate displacement and possible communicating open fractures. Anal sensation and motor power of the sphincters must be assessed as part of the rectal examination to identify lower sacral root or pelvic splanchnic nerve injuries. Vaginal bleeding warrants a speculum examination to inspect for injury to the genitalia and possible fracture communication.

2.5.4 Neurological examination

Injuries to the lumbosacral plexus are common with pelvic trauma; therefore, assessment of these structures is mandatory. Specifically, the functional status of the L5 and S1 nerve roots bilaterally must be documented. Injuries to other nerve roots and the pudendal nerves should be documented when possible, although assessment of these structures may be difficult. A large trauma force is required to injure the nerve roots; thus, the presence of these lesions signals a high likelihood of pelvic instability.

3.1.1 AP view

With the patient supine on the x-ray table, the pelvic brim lies oblique to the axis of the trunk, subtending an angle of 45–60° ( Fig 1.5-8 ). The standard AP view is obtained by directing the x-ray beam perpendicular to the x-ray table and obtains the oblique view of the pelvis ( Fig 1.5-9 ).

This view can provide a wealth of information with careful analysis. Symmetry between each hemipelvis should be assessed. Gross displacement of the pelvic ring implies significant instability. On occasion, the pelvis may be displaced and stable because of severe impaction of the sacroiliac complex. Height of the iliac wings and/or femoral heads yields information on craniocaudal (vertical) displacement or internal rotation displacement, although displacement is best assessed with outlet views. Anterior injury to the pelvic ring can be examined for symphysis diastasis, pubic rami fractures, or both. Posterior injury may disrupt the sacrum and ilium via fractures or disrupt the sacroiliac joint and many potential combinations. A sacroiliac joint disruption often involves a segment of attached posterior ilium (crescent fracture). The weakest areas of the sacrum are the sacral foramen and often are involved in posterior pelvic trauma.

Avulsions of the pelvis and adjacent structures are important to examine when assessing the AP view. The transverse processes of the L5 vertebra serve as the origin for important stabilizing ligaments of the posterior pelvis. When one or both of these ligaments are disrupted by an avulsion fracture, suspicion for posterior ring instability should be high. The sacrospinous ligament is a supporting structure that extends from the ischial spine to the inferior sacrum (Fig 1.1-2b and Fig 1.1-8). Avulsion fragments from the ischial spine or sacrum suggest instability of the hemipelvis. Avulsions from other prominences, such as the anterior superior iliac spine, anterior inferior iliac spine, and ischial tuberosity, also should be examined even though they rarely contribute to pelvic ring instability (see Chapter 1.8.3). Fractures of the acetabulum in combination with pelvic ring injuries can be identified but require further radiographic assessment (Chapters 2.4 and 2.6).

3.1.2 Inlet view

Fig 1.5-10 was obtained at Sunnybrook Health Sciences Centre with the x-ray beam centered on the pelvis and directed 30° from the vertical toward the head of the patient. Ricci et al [8] correlated computed tomographic (CT) scans with optimal profiles of the S1 and S2 sacral bodies. They suggested that the screening inlet view should be done at 25° to best assess these structures rather than the often described 45° orientation. The goal of the inlet view is to obtain an image of the true pelvic inlet. This view best shows anterior and posterior displacement of the anterior and posterior pelvic ring, including the sacroiliac joints. Relative internal and external rotation of the hemipelvis also is best assessed with this projection. These displacements are not well visualized on other x-rays and can be missed without a full radiographic examination.