Pelvic Ring Injuries

Etiology

Pelvic ring injuries in young individuals are usually associated with high-energy trauma, including falls from height and motor vehicle collisions. High-force impact implies an increased incidence of associated injuries to other body regions.[5][3] Conversely, pelvic ring injuries in older populations commonly occur due to low-energy falls. Anterior-posterior compression injuries are frequently observed following equestrian saddle horn injuries and motorcycle accidents. Lateral compression injuries often occur when the pelvis is impacted by a vehicle. Vertical pelvis injuries usually result from falls or injuries involving an axial load. While mortality rates range from 1% to 15% in closed fractures, they can escalate to 50% in open fractures, with hemorrhage being the primary cause of death. Closed head injuries are notably the most common cause of mortality in lateral compression injuries.

Epidemiology

Key epidemiological points regarding pelvic ring injuries include:

• These injuries are prevalent across all age groups, accounting for approximately 3% of all skeletal fractures.
• Individuals between the age groups of 18 and 44 are most commonly affected.
• Men experience these injuries more frequently than women.
• The incidence rate is approximately 0.82 per 100,000 individuals, associated with a high overall injury severity score ranging from 25 to 48.[6][7]

Pathophysiology

The pelvic ring suffers disruption due to direct trauma to the pelvis or indirect trauma through compression or distraction of the spine and/or femur. The pelvic ring fails in predictable patterns, as described in the classification section. Depending on the degree of injury, stabilizing ligaments of the pelvis may be disrupted, requiring stabilization (see Image. Pelvic Ring Injuries). 

History and Physical

Due to the high-energy nature of pelvic ring injuries, associated morbidities require a thorough assessment. Incidence of associated trauma includes:

• Chest trauma: 63%
• Long bone fractures: 50%
• Head injuries: 40%
• Visceral organ damage: 40%
• Spinal fractures: 25%
• Intestinal injuries: 14%
• Genitourinary injuries: 6% to 15%
• Open fractures: 5%
  • Mortality of open pelvis fractures is around 50%; urgent antibiotic administration is necessary.
  • Rectal and vaginal exams should be performed, and breaks in the skin around the perineum should be looked for.

A pelvic ring injury can pose a life-threatening risk or may be linked to life-threatening injuries, necessitating a comprehensive examination. This examination typically includes:

• Advanced trauma life support
• Motor and sensory exam
• Physical examination of the pelvis, incorporating the push/pull test and lateral compression test
• Examination for leg length inequality not accounted for by limb fractures
• Observation for a high-riding prostate or blood at the urethral meatus, which may indicate a genitourinary injury
• Rectal and/or vaginal examination
• Assessment of the perineum, which may reveal swollen and/or mobile genitalia

Destot sign: The Destot sign refers to a palpable hematoma in the perineum above the inguinal ligament or proximal thigh, which may indicate a pelvic fracture with active bleeding.

Grey Turner sign: The Grey Turner sign is characterized by flank bruising, which is indicative of retroperitoneal bleeding.

Morel-Lavallée lesion: Morel-Lavallée lesion is an internal degloving injury resulting from skin shear during trauma, which may necessitate intervention and influence surgical planning. Clinically, it manifests as significant soft tissue abrasions, ecchymosis, or subdermal hematoma. Additionally, it can be identified on a computed tomography (CT) scan by assessing soft tissues.[1][2]

Evaluation

Evaluation of pelvic ring injuries involves various imaging modalities to assess the extent of damage and guide treatment decisions accurately. These modalities include x-rays, CT scans, and occasionally magnetic resonance imaging (MRI), each serving specific purposes in delineating the injury and its associated complications.

Imaging                        

• X-rays: Standard x-rays of the chest (CXR) and anteroposterior (AP) pelvis provide initial evaluation, while additional views, such as the inlet and outlet views, are crucial for assessing anterior or posterior translation and coronal plane deformities. Flamingo views aid in chronic pelvic ring instability assessment.

• CT scan: This scanning technique is essential for all pelvic ring injuries. CT scans offer detailed visualization of bony structures and help evaluate the extent of sacral injury.

• MRI: Although rarely indicated in acute pelvic ring trauma, MRI may be utilized for specific cases to characterize soft tissue injuries further.[8]

Classification

Type A: Stable

• A1: Fractures not involving the pelvic ring
• A2: Stable minimally displaced fractures of the pelvic ring

Type B: Rotationally unstable, but vertically stable

• B1: Open book
• B2: Lateral compression ipsilateral
• B3: Lateral compression contralateral

Type C: Rotationally and vertically unstable

• C1: Unilateral
• C2: Bilateral
• C3: Associated with an acetabular fracture [1]

The Young and Burgess classification: This classification system categorizes pelvic ring injuries into 4 main mechanisms.

• Lateral compression (LC)
  • LC1: Anterior sacral compression fracture +/- pubic rami fractures (typically stable)
  • LC2: Crescent fracture +/- pubic rami fracture (unstable)
  • LC3: LC 1 or LC2 with a contralateral AP compression injury

• Anterior-posterior compression (APC)
  • APC1: Minor symphysis widening or distracted ramus fracture
  • APC2: Opening of symphysis greater than 2.5 cm, with disruption of sacrospinous and anterior sacroiliac ligaments, assumes posterior sacroiliac ligaments remain intact
  • APC3: Complete disruption of the symphysis and sacroiliac joint

• Vertical shear (VS): Vertical displacement of the hemipelvis represents complete instability

• Combined Mechanism (CM): Any combination [9]

The Denis classification of sacral fractures: Sacral fractures are categorized into 3 zones according to the Denis classification, as mentioned below.

• Zone 1: Lateral to the sacral foramen
• Zone 2: Entering sacral foramen
• Zone 3: Medial to sacral foramen – Highest incidence of neurologic injury, including nerve root or cauda equina [2]

Lumbopelvic dissociation: Lumbopelvic dissociation refers to a fracture pattern that disrupts the continuity between the base of the spine and the pelvis, necessitating fixation. This topic is beyond the scope of this activity. Notably, bilateral sacral fractures often present with lumbopelvic dissociation, emphasizing the importance of carefully reviewing CT scans for coronal plane sacral disruptions.[10]

Treatment / Management

As recognizing a pelvic ring injury may represent a life-threatening emergency, healthcare professionals should collaborate as a team to resuscitate critically injured patients.

Advanced Trauma Life Support

Healthcare providers should avoid assuming that a patient with a pelvic ring injury does not have another source of hemorrhage. A pelvic ring injury should serve as a reminder to all clinicians of high-energy trauma and prompt them to conduct a comprehensive assessment of all body systems. Before attributing a patient's hemorrhage to a pelvic ring injury, it is essential to exclude thoracic and abdominal bleeding through thorough evaluation.

Hemorrhage Associated with High-Energy Trauma and Pelvic Ring Disruption

Pelvic ring injuries can cause significant blood loss from various sources, which include:[9] (A1)

• Pelvic venous plexus is a common source of hemorrhage in 80% of cases and can lead to a retroperitoneal hematoma, which can hold up to 4 L of blood.

• Osseous blood supply includes nutrient arteries and bleeding cancellous bone.

• Arterial injury, although less common (occurring in 10% to 20% of cases), may involve arteries such as the superior gluteal artery, which is most frequently affected in APC injuries, as well as the internal pudendal and obturator arteries in LC injuries.

Initial Management and Resuscitation

Resuscitation: In cases requiring massive transfusion, ideally, a transfusion ratio of packed red blood cells:fresh frozen plasma:platelets at 1:1:1 has been shown to improve mortality rates.

Pelvic binder/circumferential sheet placement: Temporary intervention to partially reduce the displacement of a pelvic ring injury should be placed at the level of the greater trochanters. Adding stability will help with clot formation within the pelvis and limit hemorrhage. The effect of added stability on pelvic volume is a matter of controversy.

• Indications:
  • Hemodynamically unstable pelvic ring injuries, including APC and VS injuries
  • LC injuries treated with a binder may risk over-compression, potentially causing harm to other pelvic structures.[11]

•  Contraindications:
  • Acetabular fractures

• The intervention may mask an injury from being identified:
  • When the patient is hemodynamically stable upon arrival without radiographic evidence of a pelvic ring injury, the binder should be removed, and repeat imaging should be obtained.[12]

 Angiography/embolization:

• Pelvic ring injuries that remain hemodynamically unstable after transfusion and binder placement should undergo further intervention. At most centers, the next step is angiography and embolization.[13] At some centers, external fixation and open pelvic packing are considered the subsequent steps; however, this approach remains controversial. Peritoneal pelvic packing in this scenario was reported to be associated with higher rates of inpatient venous thromboembolism events and sequelae compared with angioembolization.[14]

• CT angiography confirms the presence or absence of ongoing arterial hemorrhage with 98% to 100% negative predictive value.

• Ongoing bleeding after selective embolization indicates bilateral temporary internal iliac embolization, which can be effective. On the other hand, it can be complicated by gluteal necrosis and impotence.

 External fixation:

• Pelvic clamp or traditional frames.

• Indicated as a temporary or definitive fixation for unstable injuries with hemodynamic instability, injuries with external rotation component, and symphyseal widening with fecal or urinary contamination.[15]

• The external fixation facilitates improving ventilation, especially in patients with chest trauma.

• Pin positions for frames: Pin positions for frames include the gluteal pillar, anterosuperior (into the iliac crest), or anteroinferior (supraacetabular). Under fluoroscopic guidance, supraacetabular pin placement offers the advantage of significantly increased sacroiliac joint stability.[16] Conversely, the lateral femoral cutaneous nerve injury risk is higher with supraacetabular pin placement.[17]
(A1)

• The intervention is contraindicated in the ilium and acetabular fractures.

Anterior subcutaneous pelvic fixator (INFIX): The INFIS is a new technique to avoid complications associated with pelvic external fixation, including pin site infection. Despite yielding comparable functional outcomes, the INFIX offers advantages, including shorter operative time and reduced blood loss, when compared to symphyseal plating.[18][19] (A1)

Diverting colostomy: A diverting colostomy may be necessary in cases of open pelvic ring injury accompanied by perineal trauma.

Definitive Management

Non-operative: Indicated for stable fractures such as APC1 and LC injuries. Pubic rami fractures are managed conservatively as surgical dissection necessary for fixation outweighs the benefits.[20]

Operative: Indicated in unstable fractures such as APC, LC types 2 and 3, and VS injuries. Operative intervention is relatively indicated in APC1 and LC injuries if significant displacement is indicated by lower limb rotational deformity resulting in complete loss of rotation or leg length discrepancy of 1.5 cm or more. Other relative indications include associated trauma necessitating laparotomy, tilt fracture protruding into the perineum, and refractory pain.[21]

Open reduction internal fixation (ORIF):

• ORIF results in improved quality of reduction and better biomechanical stability compared to external fixation.

• Plates and screws across the symphysis can support the anterior ring.[22]

• Parasymphyseal pubic ramus fracture is treatable with open plating or percutaneous screw fixation.

• Sacroilial dislocation or sacral fracture can be treated with sacroiliac, transiliac transacral, or transiliac screws percutaneously.[23] A thorough understanding of pelvic ring osseous fixation pathways is necessary to perform these techniques safely. Sacral dysmorphism is common and can complicate safe percutaneous fixation of the posterior pelvic ring.[24]
(B3)

• Open plating of sacroiliac joints or sacral fractures may be necessary if a closed reduction is unobtainable or the fracture pattern is not amenable to percutaneous fixation.

• ORIF approaches may include Pfannenstiel, Stoppa, or ilioinguinal approaches, which can be used to access anterior structures. In cases of inadequate reduction of the sacroiliac joint or associated sacral fractures, posterior approaches are indicated.

Percutaneous fixation: Iliosacral screw fixation is a popular technique for addressing instability of the posterior ring, particularly in cases with traumatized posterior skin that could deteriorate with ORIF.[25][26] The most common complications associated with this procedure include nerve root injury, incorrectly placed screws, and loss of reduction.[27]

Triangular osteosynthesis: Lumbosacral pedicle screw fixation combined with a sacroiliac fixation for management of lumbopelvic discontinuity. Absolute indications are still unclear.[10]

The timing for definitive fixation remains controversial. Early definitive fixation offers advantages such as pain relief, supportive care, improved reduction quality, bleeding control, and early mobility. However, it comes with the potential drawbacks of increased bleeding risk and a possible second hit in trauma patients who are not fully resuscitated.[28][29][26](B2)

Pertinent Studies and Ongoing Trials

In their 2011 study published in the Journal of Orthopaedic Trauma, Sagi et al assessed pelvic ring injuries using dynamic fluoroscopy in the operating room. They discovered that a subset of pelvic ring injuries exhibited greater instability than anticipated based on fracture pattern alone. Clarification regarding which patients necessitate examination under anesthesia (EUA) is still needed. EUA proves effective during the fixation of pelvic ring injuries, aiding in determining the extent of required fixation.[30][31]

Treatment Planning

Treatment Plans

• Advanced trauma life support:
  • Healthcare providers can administer 2 large-bore intravenous (IVs) for fluid resuscitation to patients.
  • Inserting a Foley catheter can be considered unless contraindicated by the presence of blood at the urethral meatus.
    • Indications for conducting a retrograde cystourethrogram in male patients include symphysis disruptions, hematuria, blood at meatus, inability to void, ecchymosis or hematoma of the perineum, or high-riding or boggy prostate.
  • A rectal and vaginal examinations are conducted as part of the assessment.
  • Hemodynamic instability can be managed by initiating fluid resuscitation initially, and transitioning to immediate blood products, as necessary, can be considered.

• CXR: In cases of high-energy trauma, a chest X-ray (CXR) may reveal findings such as a widened mediastinum or pneumothorax.

• AP pelvis:
  • Healthcare providers should aim to differentiate between APC and LC/VS/CM injury patterns.
    • In cases where the symphysis has significantly widened, it likely indicates an APC pattern.
      • If the symphysis is wide and the patient exhibits hemodynamic instability, applying a pelvic binder or circumferential sheet is recommended.
    • For pelvis fractures or disruptions not indicative of an APC pattern, healthcare providers should consider other interventions before applying a pelvic binder.
      • Traction may be considered for managing a VS injury.

• CT head, neck, chest, abdomen, and pelvis: Healthcare providers should order CT scans of the head, neck, chest, abdomen, and pelvis of the patient. Fine cuts with a thickness of 2 mm should be obtained specifically for the pelvis. Importantly, they should also consider the possibility of other injuries, including hemorrhage in the head, neck, chest, abdomen, and pelvis, when evaluating a patient.

• In cases where the patient remains hemodynamically unstable:
  • If an identifiable source of bleeding outside the pelvis is identified, healthcare providers should control the bleeding by other means according to general surgery recommendations.
  • If no other source of bleeding is identified apart from the pelvic ring injury, interventional radiology embolization is typically the preferred course of action in most centers. However, this approach remains controversial when it comes to emergent pelvic external fixation and pelvic packing.

• After the patient is hemodynamically stable:
  • Once the patient achieves hemodynamic stability, healthcare providers should obtain inlet and outlet X-rays of the pelvis, primarily for surgical planning purposes.
  • If the patient presents with polytrauma, it may necessitate delaying definitive surgical intervention. In such cases, temporary external fixation following damage control orthopedic principles is recommended.
  • Once the patient is deemed stable, with corrected lactate levels, definitive fixation should be pursued.

Prognosis

Mortality rates associated with pelvic ring injuries, particularly in cases of hemodynamic instability, remain high due to factors such as rapid exsanguination, challenging hemostasis, and the severity of associated injuries.[32][9][33][34] Recent advancements have shown a notable improvement in mortality rates related to pelvic ring injuries compared to earlier years, with a reduction from 9.1% to 4.9%.[35] This improvement is even more significant when considering factors such as the patient's age and Abbreviated Injury Severity (AIS) score for the brain, chest, and abdomen.

The Young and Burgess classification has predictive value for mortality in pelvic ring injuries. When combining the classification into stable (LC1 and APC1) versus unstable (LC2, LC3, APC 2, and APC 3) categories, stable injuries exhibit a mortality rate of 7.9%, whereas unstable injuries have a mortality rate of 11.5%.[36] Furthermore, reducing the posterior ring within 1 cm has been associated with improved long-term outcomes.

Additionally, the return-to-work rate following pelvic ring injuries is highly variable, with the majority of patients reporting some degree of persistent impairment, as discussed below.[37]

• 24% of patients lose their jobs
• 34% of patients return to work but with modified duties
• 46% of patients are unable to perform their pre-injury duties

Male gender and older populations are associated with higher mortality rates in pelvic ring injuries. However, females who undergo symphysis fixation can still have safe vaginal deliveries, provided that both the front and back of the pelvis are not restrained by fixation.[38][39]

Complications

The complications associated with pelvic ring injuries are discussed below.

Malunion

• Controversy exists surrounding the definition or measurement of displacement and malunion in pelvic ring injuries.
• Patients who achieve anatomic reductions tend to have better outcomes, although displacements less than 1 cm are often considered tolerable.
• Distinguishing stable patterns from unstable patterns can sometimes be challenging.
• In select cases or to guide treatment during surgery, manipulation under anesthesia may be considered to determine stability.
• Nonoperative treatment of complete sacral fractures with ipsilateral rami fractures may lead to displacement over time in 39% of cases, while the rate increases to 68% for those with bilateral rami fractures.[40][41]

Hardware Failure

• Micromotion is present in a well-aligned and healed pelvic ring. Therefore, hardware failure rates tend to be high over time. However, if the pelvic ring has fully healed, no displacement will occur in the event of hardware failure, and this alone does not necessitate hardware removal.
• Plating across the symphysis exhibits a hardware failure rate of 43% at 1 year, with 97% of these failures being asymptomatic.[42]

Neurological Dysfunction

Denis 3 fractures of the sacrum have approximately a 50% rate of neurologic dysfunction of lumbosacral nerve roots.

 Sexual Dysfunction

• Erectile dysfunction occurs in 46% of males after pelvic ring injury.
• Dyspareunia occurs in 56% of females after pelvic ring injury, 91% with APC injuries, and 79% of patients treated with symphysial plating.[43][44]

Chronic Pain and Disability

Refer to the Prognosis section for more information.

Infections

• Infections can occur in up to 16% of cases when utilizing a posterior approach to the sacrum.
• Obesity has been identified as a factor that increases the risk of complications and the likelihood of requiring reoperation.[45]

Deep Vein Thrombosis/Pulmonary Embolism

In cases of pelvic ring injury, the need for an inferior vena cava (IVC) filter may arise to prevent deep vein thrombosis (DVT) or pulmonary embolism.[46]

Combined Injuries

Combined injuries involving both the acetabulum and pelvic ring are often associated with high rates of complications. Specifically, hip dislocation has been linked to an increased rate of complications.[47]