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Pelvic & Acetabular Trauma MCQs

Practice Set 29 of 35

This practice set contains high-yield board review questions covering key concepts in Pelvic & Acetabular Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 561

Topic: Pelvic & Acetabular Trauma

A 19-year-old rugby player sustains a lateral compression injury to his shoulder. He presents to the ER with shortness of breath, a hoarse voice, and severe pain at the medial end of the clavicle. A CT scan confirms a posterior sternoclavicular joint dislocation. What is the most appropriate next step in management?

. Immediate open reduction through a standard anterior approach by an orthopedic surgeon alone
. Closed reduction under procedural sedation in the emergency department with posterior traction
. Closed reduction in the operating room under general anesthesia with a cardiothoracic surgeon on standby
. Sling immobilization and delayed reconstruction after 6 weeks to allow for tissue healing
. CT angiogram followed by discharge if vascular injury is excluded

Correct Answer & Explanation

. Immediate open reduction through a standard anterior approach by an orthopedic surgeon alone

Explanation

Posterior sternoclavicular (SC) joint dislocations are true orthopedic emergencies due to the proximity of mediastinal structures (trachea, esophagus, great vessels). Symptoms like dyspnea or dysphagia indicate compression. Management consists of urgent closed reduction (often using a towel clip on the clavicle with posterior/lateral traction) in the operating room under general anesthesia, with a cardiothoracic surgeon readily available in case of catastrophic vascular injury upon reduction.

Question 562

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 35-year-old male presents after a crush injury. An AP radiograph of the pelvis demonstrates a symphyseal diastasis of 4 cm and disruption of the anterior sacroiliac ligaments. You decide to apply a circumferential pelvic binder to aid in resuscitation. To maximize its biomechanical efficacy in reducing pelvic volume, the binder should be centered precisely over which of the following anatomic landmarks?
. Anterior superior iliac spines (ASIS)
. Iliac crests
. Greater trochanters
. Pubic symphysis
. Ischial tuberosities

Correct Answer & Explanation

. Greater trochanters

Explanation

Circumferential pelvic binders are critical in the acute resuscitation of patients with unstable pelvic ring injuries (e.g., APC II or III). To effectively close the pelvic ring and reduce the intrapelvic volume, the binder must be centered over the greater trochanters. Placing the binder too proximally (over the iliac crests or ASIS) is a common error that can paradoxically widen the pelvic outlet or fail to reduce the diastasis.

Question 563

Topic: Pelvic & Acetabular Trauma

A 60-year-old male sustains an isolated transverse acetabular fracture involving the posterior wall. According to the Judet-Letournel classification, an isolated anterior column fracture would classically demonstrate a disruption of which primary radiographic line on the anteroposterior (AP) pelvis view?

. Ilioischial line
. Iliopectineal line
. Radiographic teardrop
. Anterior border of the obturator foramen
. Posterior wall line

Correct Answer & Explanation

. Ilioischial line

Explanation

In the Judet-Letournel classification, the fundamental radiographic landmark for the anterior column is the iliopectineal line. The fundamental landmark for the posterior column is the ilioischial line. Disruption of the iliopectineal line with an intact ilioischial line suggests an isolated anterior column (or anterior wall) fracture.

Question 564

Topic: Pelvic & Acetabular Trauma

A 30-year-old male is involved in a high-speed MVC. A Judet obturator oblique radiograph of the pelvis is obtained.

Which of the following acetabular structures are best profiled on this specific radiographic view?

. Anterior column and posterior wall
. Posterior column and anterior wall
. Ilioischial line and anterior column
. Pelvic brim and posterior column
. Ischial spine and anterior wall

Correct Answer & Explanation

. Anterior column and posterior wall

Explanation

The obturator oblique view best profiles the anterior column and the posterior wall of the acetabulum. Conversely, the iliac oblique view highlights the posterior column and the anterior wall.

Question 565

Topic: Pelvic & Acetabular Trauma
A 45-year-old male sustains a closed pelvic ring injury. Clinical examination reveals a massive, fluctuant swelling over the greater trochanter with intact, but ecchymotic overlying skin. What is the primary pathophysiologic mechanism of this specific soft tissue injury?
. Rupture of the gluteus medius insertion
. Arterial hemorrhage from the superior gluteal artery
. Shearing of subcutaneous tissue from the underlying fascia
. Focal fat necrosis secondary to direct contusion
. Lymphatic obstruction from pelvic ring disruption

Correct Answer & Explanation

. Shearing of subcutaneous tissue from the underlying fascia

Explanation

A Morel-Lavallée lesion is a closed degloving injury caused by traumatic shearing of the subcutaneous tissue away from the underlying deep fascia. This creates a potential space that fills with hematoma and liquefied fat, significantly increasing the risk of deep infection if surgical incisions are placed directly through it.

Question 566

Topic: Pelvic & Acetabular Trauma
A 38-year-old male sustains a severe pelvic crush injury. He develops a large, fluctuant swelling over the greater trochanter. Aspiration yields serosanguinous fluid. What is the most appropriate definitive management of this Morel-Lavallée lesion to minimize infection prior to pelvic fixation?
. Observation and compression wrap alone
. Percutaneous aspiration and steroid injection
. Open debridement and delayed closure
. Immediate coverage with a split-thickness skin graft

Correct Answer & Explanation

. Open debridement and delayed closure

Explanation

A Morel-Lavallée lesion is a closed degloving injury that traps necrotic fat and hematoma, posing a high risk for subsequent surgical site infection. Formal open debridement (or extensive percutaneous debridement) with delayed closure is the safest approach before internal fixation.

Question 567

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the Emergency Department after a crush injury. He has an anteroposterior compression (APC-III) pelvic ring injury and is hemodynamically unstable. A pelvic binder is applied. Where must the pelvic binder be centered for maximal biomechanical effectiveness?
. Over the iliac crests
. Over the anterior superior iliac spines
. Over the greater trochanters
. Over the mid-femur
. Over the lower abdomen

Correct Answer & Explanation

. Over the greater trochanters

Explanation

A pelvic binder must be applied centered over the greater trochanters to effectively close the pelvic volume and stabilize the pelvic ring in open book (APC) injuries. Application over the iliac crests or abdomen does not provide the appropriate vectors to close the ring, can paradoxically widen the pelvis, and can limit abdominal access.

Question 568

Topic: Pelvic & Acetabular Trauma
A 38-year-old male sustains a severe APC-III pelvic fracture and arrives in hemorrhagic shock. Despite immediate pelvic binder application and massive transfusion protocol, he remains hypotensive and tachycardic. In the majority of pelvic ring injuries, what is the most common anatomic source of massive internal hemorrhage?
. Superior gluteal artery
. Internal pudendal artery
. External iliac artery
. Corona mortis
. Presacral venous plexus and cancellous bone

Correct Answer & Explanation

. Presacral venous plexus and cancellous bone

Explanation

While arterial bleeding (especially from the superior gluteal artery or internal pudendal) can be life-threatening and may require angioembolization, bleeding from the presacral venous plexus and the fractured cancellous bone surfaces accounts for approximately 80-90% of all pelvic bleeding. A pelvic binder works by closing the pelvic volume, facilitating a tamponade effect primarily on these low-pressure venous and osseous bleeding sources.

Question 569

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is struck by a motor vehicle and sustains a closed pelvic ring injury. Examination reveals a large, fluctuant area over the greater trochanter with overlying skin hypermobility and bruising. An MRI confirms a hemolymphatic fluid collection between the subcutaneous fat and the underlying fascia. What is the most appropriate initial management of this soft tissue injury to prevent deep infection prior to definitive internal fixation?
. Immediate large-bore needle aspiration followed by compressive wrapping
. Administration of prophylactic intravenous antibiotics without intervention
. Sclerotherapy using doxycycline
. Early open surgical debridement and delayed closure or negative pressure wound therapy
. Immediate percutaneous drainage catheter placement left in situ indefinitely

Correct Answer & Explanation

. Early open surgical debridement and delayed closure or negative pressure wound therapy

Explanation

The clinical presentation is classic for a Morel-Lavallée lesion (a closed degloving injury). Because a surgical approach for fracture fixation often must pass through or near the lesion, the standard of care to minimize infection is early open debridement of necrotic tissue and evacuation of the hematoma, frequently utilizing negative pressure wound therapy prior to or concurrently with definitive fixation.

Question 570

Topic: Pelvic & Acetabular Trauma

A 45-year-old male sustains a pelvic injury after being struck by a vehicle from the side. Pelvic radiographs and CT demonstrate an internal rotation deformity of the hemipelvis with a fracture extending from the sacroiliac joint through the posterior iliac wing. How is this injury classified according to the Young-Burgess system?

. Anteroposterior Compression I (APC-I)
. Anteroposterior Compression II (APC-II)
. Lateral Compression I (LC-I)
. Lateral Compression II (LC-II)
. Vertical Shear (VS)

Correct Answer & Explanation

. Anteroposterior Compression I (APC-I)

Explanation

A fracture extending from the sacroiliac joint through the posterior iliac wing is known as a "crescent fracture." In the Young-Burgess classification, this defines a Lateral Compression Type II (LC-II) injury.

Question 571

Topic: Pelvic & Acetabular Trauma
A 40-year-old male is brought to the trauma bay after a severe motor vehicle crash. He is hemodynamically unstable with a blood pressure of 80/50 mmHg. Radiographs show an anteroposterior compression (APC-III) pelvic ring injury. A circumferential pelvic binder is indicated. What is the most appropriate anatomical landmark for the correct placement of the pelvic binder?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Subtrochanteric femur

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder should be centered over the greater trochanters. Placement at the level of the greater trochanters provides the most effective mechanical advantage to close the pelvic ring, decrease pelvic volume, and promote tamponade of venous bleeding. Placement higher (e.g., iliac crests) can paradoxically widen the symphysis in some fracture patterns.

Question 572

Topic: Pelvic & Acetabular Trauma
A 40-year-old male arrives in the trauma bay hypotensive and tachycardic. Radiographs confirm an anteroposterior compression type III (APC-III) pelvic ring injury. After application of a circumferential pelvic binder and transfusion of 2 units of packed red blood cells, his blood pressure remains 75/40 mmHg. A FAST examination is negative. What is the most appropriate next step in management?
. Exploratory laparotomy
. Application of a supracondylar femoral traction pin
. Preperitoneal pelvic packing and/or pelvic angioembolization
. Removal of the pelvic binder to re-examine the pelvis
. Immediate open reduction and internal fixation of the symphysis pubis

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angioembolization

Explanation

In a hemodynamically unstable patient with an unstable pelvic ring injury and a negative FAST scan, the source of bleeding is primarily presumed to be retroperitoneal/pelvic (venous plexus or arterial). The gold standard interventions are preperitoneal pelvic packing and/or angiography for embolization.

Question 573

Topic: Pelvic & Acetabular Trauma

A 38-year-old male sustains a pelvic ring injury and presents with a large, fluctuant swelling over the greater trochanter with ecchymosis. What is the underlying pathophysiology of this specific soft tissue lesion?

. Acute hematoma within the muscle fascia
. Shearing of the subcutaneous tissue from the underlying fascia
. Disruption of the deep venous system
. Arterial pseudoaneurysm formation
. Lymphatic fluid accumulation due to node injury

Correct Answer & Explanation

. Acute hematoma within the muscle fascia

Explanation

A Morel-Lavallee lesion is a closed degloving injury where subcutaneous tissue is sheared off the underlying deep fascia. This creates a potential space that fills with blood, lymph, and necrotic fat, carrying a high risk of infection.

Question 574

Topic: Pelvic & Acetabular Trauma

A 35-year-old male is brought in after a motorcycle accident with an unstable pelvis and hemodynamic shock. EMS placed a pelvic binder. Upon evaluation in the ED, the binder is noted to be centered at the level of the anterior superior iliac spines (ASIS). What is the appropriate next step regarding the binder?

. Leave it in place and proceed with fluid resuscitation
. Reposition the binder to be centered over the greater trochanters
. Remove the binder immediately to assess the skin
. Tighten the binder further to reduce the volume of the false pelvis
. Replace the binder with a C-clamp immediately before any imaging

Correct Answer & Explanation

. Leave it in place and proceed with fluid resuscitation

Explanation

A pelvic binder must be centered over the greater trochanters, not the iliac crests or ASIS, to effectively close an open book pelvic ring injury (APC) and reduce the volume of the true pelvis. Placement over the iliac wings can potentially act as a fulcrum, exacerbating the deformity in certain injury patterns, and is less biomechanically effective at closing the symphysis.

Question 575

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable trauma patient presents with an Anteroposterior Compression (APC) Type III pelvic ring injury. Following the placement of a pelvic binder, the patient's blood pressure remains 70/40 mmHg despite receiving 2 units of uncrossmatched packed RBCs. A FAST scan is negative. What is the most appropriate next step in management?
. Retrograde urethrogram
. Pre-peritoneal pelvic packing and/or angioembolization
. Exploratory laparotomy
. Open reduction and internal fixation of the symphysis pubis
. Immediate application of a C-clamp

Correct Answer & Explanation

. Pre-peritoneal pelvic packing and/or angioembolization

Explanation

In a hemodynamically unstable patient with an unstable pelvic ring injury and a negative FAST (ruling out massive intra-abdominal hemorrhage), the source of life-threatening hemorrhage is assumed to be the pelvis (most commonly the presacral venous plexus, but also arterial branches). If mechanical stabilization (binder) and initial resuscitation fail, emergent intervention with pre-peritoneal pelvic packing and/or pelvic angiography with embolization is required.

Question 576

Topic: Pelvic & Acetabular Trauma

A 29-year-old male sustains an acetabular fracture in an MVC. Plain radiographs reveal a disruption of the iliopectineal line, a teardrop that is displaced medially, an intact ilioischial line, and an intact posterior wall. Based on the Judet-Letournel classification, which type of acetabular fracture is this?

. Posterior column
. Anterior column
. Transverse
. Both column
. T-shaped

Correct Answer & Explanation

. Posterior column

Explanation

In radiographic evaluation of the acetabulum, the iliopectineal line represents the anterior column, and the ilioischial line represents the posterior column. Disruption of the iliopectineal line with an intact ilioischial line firmly indicates an isolated anterior column fracture. The radiographic teardrop is often displaced or disrupted in anterior column or anterior wall injuries.

Question 577

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 42-year-old male is brought in after a motorcycle crash. Pelvic radiographs demonstrate an anteroposterior compression (APC-III) pelvic ring injury. Where is the anatomically correct position to place a pelvic circumferential compression device (binder) for optimal reduction and hemorrhage control?
. Level of the anterior superior iliac spines (ASIS)
. Level of the iliac crests
. Level of the greater trochanters
. Midway between the umbilicus and the pubic symphysis
. Proximal third of the femurs

Correct Answer & Explanation

. Level of the greater trochanters

Explanation

A pelvic binder must be placed at the level of the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement higher (e.g., at the iliac crests or ASIS) is a common error and fails to adequately close the symphysis pubis, and can sometimes paradoxically open the pelvic floor or impede abdominal access.

Question 578

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 45-year-old male arrives in the trauma bay following a high-speed motor vehicle collision. He has a mechanically unstable pelvic ring injury (APC Type III). Despite placement of a pelvic binder and aggressive fluid/blood resuscitation, he remains hypotensive. FAST exam is negative. What is the most common anatomical source of retroperitoneal hemorrhage in this specific injury pattern?
. Superior gluteal artery
. Presacral venous plexus and bleeding from cancellous bone surfaces
. Internal pudendal artery
. Corona mortis
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus and bleeding from cancellous bone surfaces

Explanation

The vast majority (80-90%) of bleeding in severe pelvic ring disruptions is of venous or osseous origin, most commonly from the presacral venous plexus and the raw cancellous bone ends of the fractured pelvis. While arterial bleeding (such as from the superior gluteal artery or internal pudendal artery) can occur and is often the target for angioembolization, it accounts for only 10-20% of cases. Venous and osseous bleeding is initially managed by reducing pelvic volume (pelvic binder) and may require preperitoneal pelvic packing if hemodynamic instability persists.

Question 579

Topic: Pelvic & Acetabular Trauma

A 65-year-old female with long-standing rheumatoid arthritis presents with progressive hip pain. Radiographs demonstrate severe protrusio acetabuli with the femoral head migrated medially past the Kohler line. During THA, which of the following is the most appropriate technique to reconstruct the acetabulum and restore biomechanics?

. Use of a jumbo uncemented cup to fill the entire uncontained defect
. Placement of the acetabular component at the current, medially migrated center of rotation
. Impaction of morselized cancellous bone graft medially followed by a standard hemispherical cup
. Resection of the anterior column to lateralize the acetabular cup
. Use of a constrained tripolar liner to prevent medial subluxation

Correct Answer & Explanation

. Use of a jumbo uncemented cup to fill the entire uncontained defect

Explanation

In protrusio acetabuli, the center of rotation is pathologically medialized. The goal of surgery is to restore the anatomic center of rotation laterally to its native position. This is best achieved by impacting morselized cancellous bone graft into the medial defect to lateralize the standard hemispherical cup, preventing further medial migration.

Question 580

Topic: Pelvic & Acetabular Trauma

What is the optimal anatomic location for the application of a circumferential pelvic binder in a hemodynamically unstable trauma patient with a suspected anteroposterior compression ('open book') pelvic ring injury?

. At the level of the iliac crests
. Centered over the greater trochanters
. Midway between the iliac crests and the umbilicus
. At the level of the anterior superior iliac spines (ASIS)
. Distal to the lesser trochanters

Correct Answer & Explanation

. At the level of the iliac crests

Explanation

A pelvic binder should be centered precisely over the greater trochanters (the level of the pubic symphysis) to effectively close the pelvic ring and reduce pelvic volume. Placement higher up, such as over the iliac crests or ASIS, is a common error and can be less effective or even paradoxically open the pelvis further.

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