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Pelvic & Acetabular Trauma MCQs

Practice Set 32 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 621

Topic: Pelvic & Acetabular Trauma
A 25-year-old male sustains a pelvic ring injury after being crushed between two vehicles. Radiographs show widening of the pubic symphysis (>2.5 cm) and disruption of the anterior sacroiliac ligaments with partial tearing of the posterior sacroiliac ligaments. His posterior structures remain intact. This injury pattern is classified as which Young-Burgess type?
. Lateral Compression Type I (LC-I).
. Lateral Compression Type II (LC-II).
. Anteroposterior Compression Type I (APC-I).
. Anteroposterior Compression Type II (APC-II).
. Vertical Shear (VS).

Correct Answer & Explanation

. Anteroposterior Compression Type II (APC-II).

Explanation

The Young-Burgess classification categorizes pelvic ring injuries by mechanism and pattern of instability. An Anteroposterior Compression (APC) mechanism results from forces applied from anterior to posterior. APC-II injuries are characterized by widening of the pubic symphysis (>2.5 cm) and disruption of the anterior sacroiliac ligaments, but with intact posterior sacroiliac ligaments, making them rotationally unstable but vertically stable. APC-I has only symphysis widening or pubic rami fractures without significant posterior disruption. APC-III involves complete disruption of both anterior and posterior sacroiliac ligaments, leading to both rotational and vertical instability. Lateral compression injuries involve forces from the side, and vertical shear involves superior/inferior forces.

Question 622

Topic: Pelvic & Acetabular Trauma

Which of the following describes the most appropriate method for reducing a posterior hip dislocation?

. Stimson maneuver (patient prone, hip flexed 90 degrees, downward force on knee).
. Allis maneuver (patient supine, hip flexed 90 degrees, axial traction, internal/external rotation).
. Bigelow maneuver (patient supine, hip flexed 90 degrees, abduction, external rotation).
. Captain Morgan technique (patient supine, hip flexed 90 degrees, foot on gurney, hip extension).
. Immediate open reduction without attempting closed reduction.

Correct Answer & Explanation

. Stimson maneuver (patient prone, hip flexed 90 degrees, downward force on knee).

Explanation

Several techniques exist for closed reduction of a posterior hip dislocation, but the Stimson maneuver is widely taught and effective. In this maneuver, the patient is prone with the affected hip and knee flexed to 90 degrees, and downward axial pressure is applied to the knee while an assistant stabilizes the pelvis. The Allis maneuver (axial traction with internal/external rotation while the patient is supine) is also common. The Bigelow maneuver involves circumduction. The Captain Morgan technique involves placing the operator's knee under the patient's knee for leverage. All these maneuvers aim to apply traction and then gently rotate the femoral head into the acetabulum. Immediate open reduction is reserved for failed closed reduction or irreducible dislocations.

Question 623

Topic: Pelvic & Acetabular Trauma
Which of the following types of pelvic ring fractures, according to the Young-Burgess classification, is most commonly associated with significant arterial hemorrhage requiring angiography and embolization?
. Lateral Compression (LC) Type I
. Anterior-Posterior Compression (APC) Type I
. Vertical Shear (VS)
. Lateral Compression (LC) Type II
. Anterior-Posterior Compression (APC) Type II

Correct Answer & Explanation

. Vertical Shear (VS)

Explanation

Vertical Shear (VS) injuries and APC Type III injuries are most commonly associated with severe hemorrhage, particularly arterial bleeding. Vertical shear injuries result from high-energy trauma causing vertical displacement of one hemipelvis, often leading to rupture of posterior sacroiliac ligaments, pelvic floor muscles, and tears of posterior vessels (e.g., internal pudendal, superior gluteal arteries). These injuries are inherently unstable and have a high propensity for severe bleeding. APC Type II and III can also have significant bleeding, but VS injuries represent the highest risk for arterial involvement.

Question 624

Topic: Pelvic & Acetabular Trauma

What is the most appropriate initial management for an unstable pelvic ring injury in a hemodynamically unstable patient?

. Immediate open reduction internal fixation (ORIF).
. Application of an external fixator as definitive fixation.
. Application of a pelvic binder or sheet wrap.
. Skeletal traction to the lower extremities.
. Immediate angioembolization.

Correct Answer & Explanation

. Application of a pelvic binder or sheet wrap.

Explanation

For hemodynamically unstable patients with unstable pelvic ring injuries, the most critical immediate intervention after primary survey and resuscitation is to stabilize the pelvic ring to reduce the pelvic volume and tamponade venous bleeding. This is achieved quickly and effectively with a pelvic binder, sheet wrap, or C-clamp. While angioembolization may be needed for arterial bleeding, and external fixation or ORIF for definitive stabilization, these are subsequent steps after initial hemorrhage control. Traction is not for pelvic ring stabilization.

Question 625

Topic: Pelvic & Acetabular Trauma

What is the primary biomechanical advantage of an interbody fusion cage (e.g., TLIF or ALIF cage) in treating spondylolisthesis?

. It prevents hardware failure of pedicle screws.
. It provides immediate pain relief by distracting the vertebral bodies.
. It restores anterior column support and disc height, promoting indirect decompression and better sagittal balance.
. It replaces the need for posterior instrumentation.
. It allows for dynamic stabilization.

Correct Answer & Explanation

. It restores anterior column support and disc height, promoting indirect decompression and better sagittal balance.

Explanation

Interbody cages are critical for restoring anterior column support, which in turn helps restore disc height, opens the neuroforamina (indirect decompression), and contributes to the restoration of optimal sagittal balance (lordosis). This robust anterior column support shares load, promoting solid arthrodesis. It complements, rather than replaces, posterior instrumentation for stability, and it doesn't directly prevent hardware failure or provide immediate pain relief (fusion is a slower process).

Question 626

Topic: Pelvic & Acetabular Trauma

You are asked about the non-operative management of a stable pelvic ring injury (e.g., lateral compression type I). To achieve optimal marks, you should emphasize:

. Immediate weight-bearing as tolerated.
. Only bed rest for several weeks.
. Analgesia, early mobilization within pain limits (often with protected weight-bearing), and close clinical and radiological follow-up to monitor stability and healing, along with VTE prophylaxis.
. Aggressive physical therapy immediately.
. Ignoring pain management.

Correct Answer & Explanation

. Analgesia, early mobilization within pain limits (often with protected weight-bearing), and close clinical and radiological follow-up to monitor stability and healing, along with VTE prophylaxis.

Explanation

For stable pelvic ring injuries managed non-operatively, the key elements for a high-scoring answer are: adequate pain control to facilitate mobilization, early protected weight-bearing (not full weight-bearing initially) to prevent stiffness and reduce complications, VTE prophylaxis, and regular clinical and radiological follow-up to ensure stability and monitor healing. Prolonged bed rest or aggressive, unprotected mobilization would be inappropriate.

Question 627

Topic: Pelvic & Acetabular Trauma
In the Young-Burgess classification of pelvic ring injuries, an Anterior Posterior Compression Type II (APC II) injury is defined by the widening of the symphysis pubis and the disruption of which of the following posterior pelvic structures?
. Sacrospinous, sacrotuberous, and posterior sacroiliac ligaments
. Sacrospinous, sacrotuberous, and anterior sacroiliac ligaments
. Complete disruption of both anterior and posterior sacroiliac ligaments
. Fracture of the iliac wing with intact sacroiliac ligaments
. Sacral fracture with intact sacroiliac ligaments

Correct Answer & Explanation

. Sacrospinous, sacrotuberous, and anterior sacroiliac ligaments

Explanation

An APC II pelvic ring injury (an 'open book' pelvis) is rotationally unstable but vertically stable. It involves disruption of the symphysis pubis anteriorly, along with tearing of the sacrospinous, sacrotuberous, and the anterior sacroiliac ligaments. The strong posterior sacroiliac ligaments remain intact, which preserves the vertical stability of the hemipelvis. If the posterior SI ligaments fail, the injury becomes an APC III.

Question 628

Topic: Pelvic & Acetabular Trauma
In a hemodynamically unstable patient with an anteroposterior compression (APC) Type III pelvic ring injury, what is the anatomically correct landmark for the placement of a circumferential pelvic binder?
. Iliac crests
. Anterior superior iliac spines (ASIS)
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder must be placed over the greater trochanters to effectively reduce pelvic volume and create a tamponade effect. Placement over the iliac crests is incorrect and can exacerbate an 'open book' deformity by pushing the iliac wings medially and hinging the pubic symphysis wider.

Question 629

Topic: Pelvic & Acetabular Trauma

In the acute management of a hemodynamically unstable patient with an 'open-book' anteroposterior compression pelvic ring injury, where is the optimal anatomic location to apply a circumferential pelvic binder?

. Directly over the iliac crests
. Midway between the ASIS and the umbilicus
. Centered directly over the greater trochanters
. Just superior to the symphysis pubis
. At the level of the ischial tuberosities

Correct Answer & Explanation

. Centered directly over the greater trochanters

Explanation

A pelvic binder must be centered over the greater trochanters to generate the optimal mechanical advantage for closing the disrupted symphysis pubis. Placement over the iliac crests can paradoxically force the pelvis further open.

Question 630

Topic: Pelvic & Acetabular Trauma
A 32-year-old male is brought to the trauma bay following a motorcycle collision. He is hypotensive with an anteroposterior compression type III (APC-III) pelvic ring injury. A pelvic binder is applied, and he is resuscitated with blood products but remains hemodynamically unstable. A FAST exam is negative. What is the primary method to initially control the most common source of bleeding in this scenario?
. Immediate exploratory laparotomy
. Bilateral internal iliac artery embolization
. Pelvic ring closure and stabilization
. Administration of tranexamic acid only
. Open preperitoneal pelvic packing without stabilization

Correct Answer & Explanation

. Pelvic ring closure and stabilization

Explanation

The majority of hemorrhage in pelvic ring injuries is venous in origin, arising from the presacral plexus and bleeding cancellous bone. Mechanical volume reduction and stabilization of the ring with a binder or external fixator is the most effective initial method to tamponade this venous bleeding.

Question 631

Topic: Pelvic & Acetabular Trauma

A trauma patient presents with an anteroposterior compression type II (APC-II) pelvic ring injury. By definition, which of the following ligamentous complexes have been disrupted?

. Symphysis pubis and anterior sacroiliac ligaments only
. Symphysis pubis, anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Symphysis pubis, posterior sacroiliac, and iliolumbar ligaments
. Symphysis pubis and complete disruption of the posterior sacroiliac complex
. Sacrotuberous, sacrospinous, and posterior sacroiliac ligaments only

Correct Answer & Explanation

. Symphysis pubis, anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC-II injury (open book pelvis) is characterized by disruption of the symphysis pubis, anterior sacroiliac ligaments, and the pelvic floor (sacrotuberous and sacrospinous ligaments). The posterior sacroiliac ligaments remain intact, providing vertical stability.

Question 632

Topic: Pelvic & Acetabular Trauma
In a patient with an anteroposterior compression (APC) type II pelvic ring injury, which of the following ligaments remains primarily intact, preventing vertical instability?
. 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 symphysis pubis, as well as the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments, causing rotational instability ('open book'). However, the strong posterior sacroiliac ligaments remain intact, providing vertical stability to the hemipelvis. An APC III injury involves disruption of the posterior sacroiliac ligaments as well, leading to both rotational and vertical instability.

Question 633

Topic: Pelvic & Acetabular Trauma

In an APC-II (Anteroposterior Compression Type II) pelvic ring injury, the symphysis pubis is diastatic and there is opening of the anterior sacroiliac joints. Which of the following ligamentous structures remains intact, preventing vertical instability?

. Sacrotuberous ligament
. Sacrospinous ligament
. Anterior sacroiliac ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Sacrospinous ligament

Explanation

An APC-II injury (open book pelvis) involves disruption of the symphysis pubis, the sacrotuberous and sacrospinous ligaments, and the anterior sacroiliac ligaments. The strong posterior sacroiliac ligaments remain intact, acting as a hinge. This allows the pelvis to open anteriorly (rotational instability) but prevents vertical displacement (vertical stability).

Question 634

Topic: Pelvic & Acetabular Trauma
An adult male is brought to the trauma bay following a high-speed motorcycle collision. He is hemodynamically unstable with a mechanically unstable anteroposterior compression (APC-III) pelvic ring injury. A commercial pelvic binder is applied. To optimize mechanical closure of the pelvic volume and minimize the risk of iatrogenic complications, the binder should be centered strictly over which anatomic landmarks?
. Anterior superior iliac spines (ASIS)
. Iliac crests
. Greater trochanters
. Pubic symphysis and L5 vertebral body
. Inferior pubic rami

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders must be centered directly over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume, particularly in "open book" (APC) injuries. Placement over the iliac crests or ASIS is anatomically too high and can paradoxically widen the pelvic floor, exacerbating bleeding and instability.

Question 635

Topic: Pelvic & Acetabular Trauma
In an anterior-posterior compression (APC) type III pelvic ring injury, which of the following ligaments is disrupted, causing severe rotational and vertical instability?
. Anterior sacroiliac ligament only
. Sacrotuberous ligament only
. Sacrospinous ligament only
. Anterior and posterior sacroiliac ligaments, sacrotuberous, and sacrospinous ligaments
. Iliolumbar ligament only

Correct Answer & Explanation

. Anterior and posterior sacroiliac ligaments, sacrotuberous, and sacrospinous ligaments

Explanation

An APC III injury involves complete disruption of the symphysis pubis along with the anterior and posterior sacroiliac, sacrotuberous, and sacrospinous ligaments. This leads to complete pelvic dissociation and profound hemodynamic instability.

Question 636

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the trauma bay following a motorcycle collision. He is hemodynamically unstable with an anteroposterior compression (APC) type III pelvic ring injury. Following the application of a pelvic binder, what is the primary pathophysiological source of pelvic bleeding in this specific injury pattern?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus and cancellous bone
. External iliac artery
. Corona mortis

Correct Answer & Explanation

. Presacral venous plexus and cancellous bone

Explanation

Despite the potential for catastrophic arterial bleeding, approximately 80-90% of hemorrhage in severe pelvic ring injuries originates from the presacral venous plexus and bleeding cancellous bone surfaces. A pelvic binder helps reduce pelvic volume to tamponade this venous and osseous bleeding.

Question 637

Topic: Pelvic & Acetabular Trauma
According to the Young-Burgess classification for pelvic ring injuries, what specific anatomical disruption differentiates an Anteroposterior Compression Type III (APC III) injury from an APC II injury?
. Symphyseal diastasis greater than 2.5 cm
. Disruption of the anterior sacroiliac ligaments
. Disruption of the posterior sacroiliac ligaments
. Disruption of the sacrotuberous ligaments
. Disruption of the sacrospinous ligaments

Correct Answer & Explanation

. Disruption of the posterior sacroiliac ligaments

Explanation

In the Young-Burgess classification, APC II injuries involve symphyseal diastasis with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but the strong posterior sacroiliac ligaments remain intact (opening book). APC III injuries involve complete disruption of the anterior AND posterior sacroiliac ligaments, leading to complete hemipelvic instability.

Question 638

Topic: Pelvic & Acetabular Trauma
A 25-year-old male is brought to the ED after a motorcycle collision. Pelvic radiographs show a symphysis pubis diastasis of 3.5 cm and widening of the anterior sacroiliac joints bilaterally. The posterior sacroiliac ligaments are intact. According to the Young-Burgess classification, what is this injury?
. Anterior-Posterior Compression (APC) I
. Anterior-Posterior Compression (APC) II
. Anterior-Posterior Compression (APC) III
. Lateral Compression (LC) I
. Lateral Compression (LC) II

Correct Answer & Explanation

. Anterior-Posterior Compression (APC) II

Explanation

APC II injuries are characterized by symphysis diastasis > 2.5 cm and widening of the anterior SI joints, indicating disruption of the anterior SI ligaments, as well as the sacrotuberous and sacrospinous ligaments. The posterior SI ligaments remain intact, maintaining vertical stability. APC III involves disruption of both anterior and posterior SI ligaments, causing complete spinopelvic instability.

Question 639

Topic: Pelvic & Acetabular Trauma
In the management of pelvic ring injuries, the volume of the true pelvis plays a critical role in hemodynamics. Which of the following injury patterns is associated with the greatest increase in pelvic volume, thereby accommodating the largest amount of retroperitoneal hemorrhage?
. Lateral Compression Type I (LC-I)
. Anteroposterior Compression Type III (APC-III)
. Lateral Compression Type III (LC-III)
. Isolated pubic rami fractures
. Vertical Shear (VS) with superior migration

Correct Answer & Explanation

. Anteroposterior Compression Type III (APC-III)

Explanation

Anteroposterior Compression Type III (APC-III) injuries involve complete disruption of the symphysis pubis and both the anterior and posterior sacroiliac ligaments. This 'open book' deformity significantly increases the internal volume of the pelvis, negating the tamponade effect and allowing for massive, life-threatening retroperitoneal venous and arterial hemorrhage. Lateral compression injuries generally decrease pelvic volume.

Question 640

Topic: Pelvic & Acetabular Trauma

In a hemodynamically unstable trauma patient with an anteroposterior compression (APC) pelvic ring injury, at what anatomical landmark should a pelvic binder be centered to effectively reduce pelvic volume?

. Anterior superior iliac spines (ASIS)
. Iliac crests
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders must be centered directly over the greater trochanters to generate the appropriate force vector to close the pubic diastasis. Placement over the iliac crests is ineffective and can paradoxically open the pelvis further.

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