Menu

Pelvic & Acetabular Trauma MCQs

Practice Set 2 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 21

Topic: Pelvic & Acetabular Trauma
In the acute management of an unstable anteroposterior compression (APC III) pelvic ring injury, where should a pelvic binder be anatomically centered to optimally reduce the pelvic volume?
. Over the iliac crests
. Over the greater trochanters
. Over the anterior superior iliac spines
. Just proximal to the umbilicus
. At the level of the ischial tuberosities

Correct Answer & Explanation

. Over the greater trochanters

Explanation

A pelvic binder must be centered over the greater trochanters to effectively compress the pelvic ring and reduce pelvic volume. Placement over the iliac crests can cause paradoxical opening of the pelvic floor and exacerbate bleeding.

Question 22

Topic: Pelvic & Acetabular Trauma
A 45-year-old male presents with hemorrhagic shock following an anteroposterior compression type III (APC-III) pelvic ring injury. Despite application of a pelvic binder, he remains hypotensive. What is the most common anatomic source of major pelvic hemorrhage in this setting?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. Corona mortis
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

The presacral venous plexus and bleeding from fractured cancellous bone surfaces account for 80-90% of bleeding in pelvic ring injuries. Arterial bleeding accounts for only 10-20% of cases, despite being the target of angioembolization.

Question 23

Topic: Pelvic & Acetabular Trauma

According to the Young-Burgess classification, an anteroposterior compression type II (APC-II) pelvic ring injury is characterized by rupture of which of the following ligaments?

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments only
. Anterior and posterior sacroiliac ligaments
. Iliolumbar ligaments only
. Posterior sacroiliac and sacrotuberous ligaments only
. Sacrotuberous, sacrospinous, and posterior sacroiliac ligaments

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments only

Explanation

An APC-II injury involves symphyseal diastasis with tearing of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact, providing vertical stability.

Question 24

Topic: Pelvic & Acetabular Trauma

A 22-year-old male is brought to the trauma bay after an MVC with an open-book pelvic fracture and systolic blood pressure of 80 mmHg. A pelvic binder is applied. To be most effective in reducing pelvic volume, the binder should be centered over which of the following anatomic landmarks?

. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Pubic symphysis
. Sacroiliac joints

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders should be placed directly over the greater trochanters to maximize closure of the pelvic ring and reduce pelvic volume. Placement over the iliac crests is incorrect and can potentially worsen the deformity.

Question 25

Topic: Pelvic & Acetabular Trauma
In a hemodynamically unstable patient with an anterior-posterior compression (APC) type III pelvic ring injury, what is the primary biomechanical rationale for applying a circumferential pelvic binder?
. To anatomically reduce the fracture of the sacrum
. To decrease pelvic volume to promote tamponade of venous bleeding
. To directly compress the internal iliac artery against the pelvic brim
. To immobilize the hip joints to prevent sciatic nerve injury
. To align the pubic symphysis to prevent urethral injury

Correct Answer & Explanation

. To decrease pelvic volume to promote tamponade of venous bleeding

Explanation

A pelvic binder internally rotates the hemipelves, effectively reducing the intrapelvic volume. This promotes the tamponade effect on bleeding cancellous bone surfaces and the presacral venous plexus, which are the most common sources of hemorrhage.

Question 26

Topic: Pelvic & Acetabular Trauma
A 45-year-old man is brought to the trauma bay after a high-speed motorcycle collision. He is hypotensive with a blood pressure of 80/50 mmHg. An AP pelvis radiograph reveals an anteroposterior compression type III (APC III) pelvic ring injury. A pelvic binder is applied, and a FAST scan is negative. His blood pressure remains 75/40 mmHg after 2 liters of crystalloid. What is the most appropriate next step in management?
. Bilateral lower extremity traction
. Immediate exploratory laparotomy
. Preperitoneal pelvic packing and/or angiography
. Placement of an external fixator in the emergency department
. Administration of hypertonic saline

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST scan, the source of bleeding is likely pelvic. After applying a pelvic binder, the next most appropriate step is preperitoneal pelvic packing or pelvic angiography to control venous or arterial hemorrhage.

Question 27

Topic: Pelvic & Acetabular Trauma

A 35-year-old male is brought to the trauma bay following a high-speed motorcycle collision. He is hemodynamically unstable with a suspected pelvic ring disruption. Where is the most appropriate anatomical level to apply a pelvic circumferential compression device (pelvic binder)?

. At the level of the iliac crests
. At the level of the anterior superior iliac spines
. At the level of the greater trochanters
. Just proximal to the pubic symphysis
. At the level of the lower lumbar spine

Correct Answer & Explanation

. At the level of the greater trochanters

Explanation

Pelvic binders should be placed at the level of the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is incorrect and can exacerbate rotational deformities.

Question 28

Topic: Pelvic & Acetabular Trauma
A 35-year-old man is brought in after a severe motorcycle crash. Pelvic radiographs demonstrate an anteroposterior compression (APC) type III pelvic ring injury. Which of the following ligamentous complexes is disrupted in this injury pattern but remains intact in an APC type II injury?
. Anterior sacroiliac ligament
. Sacrospinous ligament
. Sacrotuberous ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

APC III injuries involve complete disruption of the pelvic ring, including both anterior and posterior sacroiliac ligaments. APC II injuries spare the strong posterior SI ligaments.

Question 29

Topic: Pelvic & Acetabular Trauma
A 35-year-old male sustains an anteroposterior compression (APC) pelvic ring injury. Radiographs demonstrate a 3.5 cm diastasis of the pubic symphysis. Which of the following ligamentous complexes remains intact in an APC-II injury but is disrupted in an APC-III injury?
. Anterior sacroiliac ligaments
. Sacrotuberous ligaments
. Posterior sacroiliac ligaments
. Sacrospinous ligaments
. Iliolumbar ligaments

Correct Answer & Explanation

. Posterior sacroiliac ligaments

Explanation

In an APC-II pelvic injury, the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments are disrupted, but the posterior sacroiliac ligaments remain intact. Disruption of the thick posterior sacroiliac ligaments defines an APC-III injury, leading to complete spinopelvic instability.

Question 30

Topic: Pelvic & Acetabular Trauma

A 35-year-old male presents with a pelvic ring injury after a motorcycle accident. Radiographs show symphyseal diastasis of 3.5 cm and widening of the anterior sacroiliac joints. He remains hypotensive despite 2 liters of crystalloid and pelvic binder placement. FAST scan is negative. What is the next best step in management?

. CT angiography of the abdomen and pelvis
. Retrograde urethrogram
. Application of an external fixator
. Pelvic angiography and embolization
. Immediate open reduction and internal fixation

Correct Answer & Explanation

. Pelvic angiography and embolization

Explanation

Hemodynamically unstable pelvic fractures with a negative FAST scan are highly suspicious for arterial bleeding. Pelvic angiography with embolization is the standard of care for identifying and stopping retroperitoneal arterial hemorrhage.

Question 31

Topic: Pelvic & Acetabular Trauma
A 35-year-old hemodynamically unstable male is brought to the trauma bay after a high-speed motor vehicle collision. Radiographs demonstrate an anteroposterior compression type III (APC-III) pelvic ring injury. Following application of a pelvic binder and initiation of a massive transfusion protocol, the patient remains hypotensive. A FAST exam is negative. What is the most appropriate next step in management?
. Immediate exploratory laparotomy
. Preperitoneal pelvic packing or pelvic angiography
. Application of a lower extremity traction pin
. Transfer to the CT scanner for a contrast-enhanced scan
. Administration of intravenous mannitol

Correct Answer & Explanation

. Preperitoneal pelvic packing or pelvic angiography

Explanation

In hemodynamically unstable patients with pelvic ring injuries and a negative FAST, the source of bleeding is presumed to be the pelvis. Immediate mechanical stabilization followed by preperitoneal packing or angiography is critical to control venous and arterial hemorrhage.

Question 32

Topic: Pelvic & Acetabular Trauma
A 24-year-old motorcyclist sustains an Anteroposterior Compression (APC) III pelvic ring injury. Disruption of which of the following ligamentous structures distinguishes an APC III injury from an APC II injury?
. Anterior sacroiliac ligament
. Sacrotuberous ligament
. Sacrospinous ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

An APC II injury involves disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. An APC III injury is characterized by the additional complete disruption of the posterior sacroiliac ligaments, leading to complete hemipelvic instability.

Question 33

Topic: Pelvic & Acetabular Trauma

A 45-year-old male presents following a high-speed motorcycle accident. Radiographs reveal an Antero-Posterior Compression (APC) Type II pelvic ring injury. In this specific injury pattern, which of the following structures remains intact, thereby preserving vertical stability?

. Symphysis pubis
. Sacrotuberous ligament
. Sacrospinous ligament
. Posterior sacroiliac ligament
. Anterior sacroiliac ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

In an APC II injury, the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments are ruptured alongside a symphyseal diastasis. The strong posterior sacroiliac ligaments remain intact, which preserves vertical stability despite the rotational instability.

Question 34

Topic: Pelvic & Acetabular Trauma
In anteroposterior compression (APC) type III pelvic ring injuries, massive hemorrhage is most commonly associated with disruption of which of the following structures?
. Superior gluteal artery
. Inferior gluteal artery
. Pre-sacral venous plexus
. Femoral artery
. Internal pudendal artery

Correct Answer & Explanation

. Pre-sacral venous plexus

Explanation

While arterial bleeding (e.g., internal pudendal or obturator) can occur in APC injuries, the most common source of massive hemorrhage in pelvic ring disruptions is the presacral venous plexus and cancellous bone.

Question 35

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the emergency department after a high-speed motorcycle collision. His blood pressure is 70/40 mmHg and heart rate is 135 bpm. A pelvic radiograph shows an anteroposterior compression type III (APC-III) pelvic ring injury. A pelvic binder is applied correctly, but he remains hemodynamically unstable despite aggressive blood product resuscitation. A FAST scan is negative. What is the most appropriate next step in his management?
. Application of an external fixator
. Urgent exploratory laparotomy
. Retrograde urethrogram to rule out urethral injury
. Preperitoneal pelvic packing or pelvic angiography
. Immediate open reduction and internal fixation of the symphysis pubis

Correct Answer & Explanation

. Preperitoneal pelvic packing or pelvic angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST scan, the bleeding is typically retroperitoneal from the presacral venous plexus or internal iliac branches. Preperitoneal pelvic packing or angioembolization is the standard life-saving next step after binder application.

Question 36

Topic: Pelvic & Acetabular Trauma
The migration index of Reimers is best described as:
. The vertical migration of the center of the femoral head with respect to the lateral margin of the acetabulum.
. The distance between the medial wall of the acetabulum and the femoral head.
. The ratio of the uncovered portion of the femoral head to its total width.
. The difference in subluxation between neutral and abduction films.
. The angle between two lines through the center of the femoral head - one vertical and one through the lateral edge of the acetabulum.

Correct Answer & Explanation

. The ratio of the uncovered portion of the femoral head to its total width.

Explanation

The migration index of Reimers is used to quantitate hip subluxation in cerebral palsy. It is defined as the ratio of the uncovered portion of the femoral head (lateral to a vertical line through the outer edge of the acetabulum) to the total width of the head.

Question 37

Topic: Pelvic & Acetabular Trauma
A 45-year-old man sustains an APC-III (anteroposterior compression III) pelvic ring injury. Which of the following ligaments must be disrupted to classify this injury as an APC-III rather than an APC-II?
. Anterior sacroiliac ligament
. Sacrospinous ligament
. Sacrotuberous ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

In the Young-Burgess classification, an APC-II injury involves disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. An APC-III injury includes complete disruption of the posterior sacroiliac ligament, leading to complete spinopelvic instability.

Question 38

Topic: Pelvic & Acetabular Trauma
A 40-year-old male sustains an anteroposterior compression (APC) III pelvic ring injury. He remains hemodynamically unstable despite a pelvic binder and fluid resuscitation. FAST exam is negative. What is the most appropriate next step?
. Immediate open reduction and internal fixation of the symphysis pubis
. Preperitoneal pelvic packing and/or angiography
. Exploratory laparotomy
. Application of a halo-femoral traction
. Sacroiliac screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angiography

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic fracture and no evidence of intra-abdominal bleeding, the source of shock is likely pelvic vascular injury. Preperitoneal packing and/or angioembolization are critical to achieve hemostasis.

Question 39

Topic: Pelvic & Acetabular Trauma

In an anteroposterior compression type II (APC-II) pelvic ring injury, the pubic symphysis is widened by more than 2.5 cm. Which posterior ligamentous structures remain intact to provide rotational stability?

. Anterior sacroiliac ligaments
. Sacrotuberous ligaments
. Sacrospinous ligaments
. Posterior sacroiliac ligaments
. Iliolumbar ligaments

Correct Answer & Explanation

. Posterior sacroiliac ligaments

Explanation

An APC-II injury involves disruption of the pubic symphysis, anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact, preventing vertical translation.

Question 40

Topic: Pelvic & Acetabular Trauma

During the percutaneous placement of an iliosacral screw into the S1 vertebral body for a posterior pelvic ring injury, the guidewire inadvertently breaches the anterior cortex of the sacral ala. Which of the following neurological structures is most at risk of injury in this location?

. L4 nerve root
. L5 nerve root
. S1 nerve root
. S2 nerve root
. Sciatic nerve

Correct Answer & Explanation

. L5 nerve root

Explanation

The L5 nerve root courses anteriorly over the sacral ala and is highly vulnerable to injury if an S1 iliosacral screw is misdirected anteriorly. The S1 root is typically protected unless the screw enters the sacral foramen.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page