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Pelvic & Acetabular Trauma MCQs

Practice Set 17 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 321

Topic: Pelvic & Acetabular Trauma
According to the Young-Burgess classification of pelvic ring injuries, which of the following ligamentous disruptions distinguishes an Anteroposterior Compression III (APC III) injury from an APC II injury?
. Symphysis pubis
. Sacrospinous ligament
. Sacrotuberous ligament
. Anterior sacroiliac ligament
. Posterior sacroiliac ligament

Correct Answer & Explanation

. Sacrospinous ligament

Explanation

In the Young-Burgess classification, an APC II injury involves disruption of the pubic symphysis, anterior sacroiliac (SI) ligaments, and the sacrotuberous/sacrospinous ligaments, but the posterior SI ligaments remain intact. An APC III injury involves complete disruption of both the anterior and posterior SI ligaments, resulting in complete spinopelvic dissociation.

Question 322

Topic: Pelvic & Acetabular Trauma

A 4-year-old girl is diagnosed with neglected left developmental dysplasia of the hip. She is scheduled for an open reduction, femoral shortening osteotomy, and a Dega pelvic osteotomy. Which of the following correctly describes the anatomical cuts of a Dega osteotomy?

. Complete trans-iliac osteotomy extending into the greater sciatic notch
. Incomplete trans-iliac osteotomy leaving the inner cortex and sciatic notch intact
. Osteotomies through the ilium, ischium, and pubis to allow free rotation
. Complete osteotomy of the ilium immediately above the acetabulum
. Dome-shaped osteotomy extending just superior to the joint capsule

Correct Answer & Explanation

. Incomplete trans-iliac osteotomy leaving the inner cortex and sciatic notch intact

Explanation

The Dega osteotomy is an incomplete trans-iliac pelvic osteotomy. The outer table is cut, but the inner table and the greater sciatic notch are left intact to act as a posterior hinge. This allows the acetabulum to be hinged downward, providing anterior, lateral, and posterior coverage.

Question 323

Topic: Pelvic & Acetabular Trauma
A 30-year-old male sustains an APC-III pelvic ring injury in a motorcycle accident. He is hemodynamically unstable despite initial fluid resuscitation. A pelvic binder is applied, but he remains hypotensive. FAST exam is negative. What is the most appropriate next step in management?
. Immediate exploratory laparotomy
. Pre-peritoneal pelvic packing and/or angioembolization
. Application of a REBOA in Zone 1
. Application of an external fixator and transfer to the ICU
. Immediate open reduction and internal fixation of the symphysis pubis

Correct Answer & Explanation

. Pre-peritoneal pelvic packing and/or angioembolization

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, the source of bleeding is presumed retroperitoneal (venous or arterial). Pre-peritoneal pelvic packing (PPP) and/or pelvic angiography with embolization are the mainstays of controlling retroperitoneal pelvic hemorrhage. Laparotomy releases the tamponade effect and is contraindicated for isolated retroperitoneal bleeding.

Question 324

Topic: Pelvic & Acetabular Trauma

In the acute management of a hemodynamically unstable patient with an anterior-posterior compression (APC) pelvic ring injury, what is the correct anatomic landmark for the placement of a circumferential pelvic sheet or binder?

. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Pubic symphysis
. Femoral shafts

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder or sheet must be placed at the level of the greater trochanters to effectively reduce the pelvic volume and close an 'open book' pelvis. Placement over the iliac crests is less mechanically effective and may paradoxically open the pelvis further or cause dangerous abdominal compression.

Question 325

Topic: Pelvic & Acetabular Trauma
Anterior posterior compression type III (APC-III) pelvic ring injuries involve complete disruption of the symphysis pubis. Which posterior ligamentous structures are disrupted in an APC-III injury?
. Sacrospinous ligament only
. Sacrotuberous ligament only
. Anterior sacroiliac ligaments only
. Anterior sacroiliac, posterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Iliolumbar ligaments only

Correct Answer & Explanation

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

Explanation

According to the Young-Burgess classification, an APC-III pelvic ring injury is a highly unstable 'open book' injury characterized by disruption of the symphysis pubis anteriorly and complete disruption of the posterior arch globally. This includes tearing of the anterior sacroiliac, interosseous sacroiliac, and posterior sacroiliac ligaments, as well as the sacrotuberous and sacrospinous ligaments, leading to complete spinopelvic dissociation on the affected side.

Question 326

Topic: Pelvic & Acetabular Trauma
A 45-year-old male sustained a closed pelvic ring injury in a high-speed motor vehicle collision. Examination reveals a massive, fluctuant mass over the greater trochanter with areas of overlying skin necrosis. Aspiration yields serosanguinous fluid. What is the best initial management for this lesion?
. Observation and compression wrapping
. Percutaneous aspiration and injection of a sclerosing agent
. Open debridement with excision of necrotic tissue
. Immediate internal fixation of the pelvis directly through the lesion
. Application of a negative pressure wound therapy dressing over the intact necrotic skin

Correct Answer & Explanation

. Open debridement with excision of necrotic tissue

Explanation

This is a Morel-Lavallée lesion (a closed degloving injury). When overlying skin necrosis is present, conservative measures or percutaneous drainage are inadequate and carry a high risk of deep infection. Open debridement with excision of all non-viable tissue is required, particularly before proceeding with any definitive osteosynthesis.

Question 327

Topic: Pelvic & Acetabular Trauma
In the emergency management of a hemodynamically unstable patient with an open-book pelvic ring injury (APC-II or III), a circumferential pelvic sheet or binder must be applied. For optimal biomechanical reduction of the symphysis, the binder should be centered precisely over which anatomical landmark?
. Iliac crests
. Anterior superior iliac spines (ASIS)
. Greater trochanters
. Pubic symphysis
. Subtrochanteric femur

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders must be centered over the greater trochanters to effectively close the pelvic ring and reduce the pubic symphysis. Placing the binder too high (over the iliac crests) can paradoxically widen the true pelvis by pushing the iliac wings inward at the top, acting as a fulcrum.

Question 328

Topic: Pelvic & Acetabular Trauma
According to the Resnick criteria for diagnosing Diffuse Idiopathic Skeletal Hyperostosis (DISH), all of the following are required except:
. Flowing ossification along the anterolateral aspect of at least four contiguous vertebral bodies
. Relative preservation of intervertebral disc height in the involved segments
. Absence of facet joint ankylosis
. Absence of sacroiliac joint erosion or fusion
. Presence of HLA-B27 antigen

Correct Answer & Explanation

. Presence of HLA-B27 antigen

Explanation

DISH is diagnosed radiographically using the Resnick criteria: 1) Flowing ossification over at least 4 contiguous vertebral bodies, 2) Preservation of disc space height without signs of degenerative disc disease, and 3) Absence of apophyseal joint ankylosis and sacroiliac joint erosion/sclerosis. Unlike Ankylosing Spondylitis, DISH is not strongly associated with the HLA-B27 antigen.

Question 329

Topic: Pelvic & Acetabular Trauma
A 40-year-old male is brought to the trauma bay in hemorrhagic shock following a motorcycle accident. Radiographs reveal an Anteroposterior Compression Type III (APC-III) pelvic ring injury. According to the Young and Burgess classification, which of the following ligamentous structures are completely disrupted in this specific injury pattern?
. Symphyseal ligaments and anterior sacroiliac ligaments only
. Symphyseal, sacrospinous, and sacrotuberous ligaments only
. Symphyseal, sacrospinous, sacrotuberous, and anterior sacroiliac ligaments
. Symphyseal, sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments
. Symphyseal and iliolumbar ligaments only

Correct Answer & Explanation

. Symphyseal, sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments

Explanation

An APC-III pelvic fracture represents complete global instability (a 'completely open book' pelvis). It involves disruption of the anterior structures (symphyseal ligaments) and a complete disruption of the posterior pelvic floor and arch, including the sacrospinous, sacrotuberous, anterior sacroiliac, and posterior sacroiliac ligaments. This allows the hemipelvis to separate completely from the sacrum.

Question 330

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay hypotensive after a motorcycle crash. A pelvic binder is applied. Radiographs show a widened pubic symphysis (3.5 cm) and disrupted anterior and posterior sacroiliac ligaments (APC III). Hemodynamic instability in this injury is primarily caused by bleeding from which of the following sources?
. Presacral venous plexus
. Internal pudendal artery
. Superior gluteal artery
. Corona mortis
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus

Explanation

In pelvic ring injuries (especially Anteroposterior Compression III types), 80-90% of significant hemorrhage is venous in origin, most commonly from the presacral venous plexus and prevesical veins. While arterial bleeding (e.g., superior gluteal artery in lateral compression, pudendal in APC) can occur and is life-threatening, massive venous bleeding secondary to pelvic volume expansion is the most frequent cause of hemodynamic instability.

Question 331

Topic: Pelvic & Acetabular Trauma

A 45-year-old male sustains an LC-II pelvic ring injury (crescent fracture) after a motor vehicle accident. Which of the following best describes the pathomechanics and optimal fixation of this specific injury?

. External rotation force causing SI joint disruption; anterior symphyseal plating
. Internal rotation force fracturing the posterior ilium leaving the SI ligaments attached to the fragment; ORIF of the ilium
. Vertical shear force causing complete pelvic floor disruption; spinopelvic fixation
. Internal rotation force avulsing the sacrotuberous ligament; percutaneous SI screws
. External rotation force causing pubic symphysis diastasis >2.5cm; anterior and posterior plating

Correct Answer & Explanation

. Internal rotation force fracturing the posterior ilium leaving the SI ligaments attached to the fragment; ORIF of the ilium

Explanation

An LC-II (crescent fracture) is caused by a lateral compression (internal rotation) force. It results in a fracture of the posterior ilium. The strong posterior sacroiliac (SI) ligaments remain attached to the crescent-shaped posterior iliac fragment, leaving the SI joint intact. Treatment typically involves Open Reduction and Internal Fixation (ORIF) of the ilium rather than an SI screw, because the SI joint itself is not dislocated.

Question 332

Topic: Pelvic & Acetabular Trauma
A 35-year-old male arrives at the trauma bay with hemodynamic instability following a crush injury to the pelvis. AP pelvis radiograph demonstrates an anteroposterior compression (APC III) injury with an "open book" pelvic ring disruption. A pelvic binder is ordered. To most effectively reduce the pelvic volume and provide a tamponade effect, the binder should be centered precisely over which of the following anatomic landmarks?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders and sheets are most effective at reducing pelvic volume and closing an "open book" pelvic ring disruption when they are centered over the greater trochanters. A common error is placing the binder too high over the iliac crests, which is mechanically inferior and can inadvertently force the inferior aspect of the pelvis wider.

Question 333

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay following a high-speed motorcycle collision. Pelvic radiographs reveal symphyseal diastasis of 3.5 cm and widening of both the anterior and posterior aspects of the sacroiliac joint. Based on the Young-Burgess classification, what injury pattern is present and what is the primary source of life-threatening hemorrhage typically associated with this specific pattern?
. Anteroposterior Compression (APC) Type I; Superior gluteal artery
. Anteroposterior Compression (APC) Type II; Obturator artery
. Anteroposterior Compression (APC) Type III; Venous plexus and internal iliac arterial branches
. Lateral Compression (LC) Type II; Corona mortis
. Vertical Shear; External iliac artery

Correct Answer & Explanation

. Anteroposterior Compression (APC) Type III; Venous plexus and internal iliac arterial branches

Explanation

This is an APC Type III injury, characterized by complete disruption of the pubic symphysis, anterior SI ligaments, interosseous SI ligaments, and posterior SI ligaments (causing complete hemipelvis instability). APC injuries significantly increase pelvic volume and disrupt the pre-sacral venous plexus and anterior branches of the internal iliac artery (e.g., pudendal, obturator), which are the primary sources of massive hemorrhage in these open-book fractures.

Question 334

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay after a motorcycle crash. His blood pressure is 70/40 mmHg, HR 135 bpm. FAST exam is negative. Pelvic radiograph shows an AP Compression Type III (APC-III) pelvic ring injury. A pelvic binder is applied, but the patient remains hemodynamically unstable despite massive transfusion protocol initiation. What is the most appropriate next step in management?
. Immediate open reduction and internal fixation of the symphysis pubis
. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) or Preperitoneal Pelvic Packing/Angiography
. Exploratory laparotomy and bowel resection
. Application of an external fixator and immediate transfer to the ICU
. Immediate bilateral lower extremity amputations

Correct Answer & Explanation

. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) or Preperitoneal Pelvic Packing/Angiography

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST, bleeding is predominantly retroperitoneal (venous plexus or arterial). If a pelvic binder does not restore hemodynamic stability, immediate intervention to control hemorrhage is required. This is optimally achieved via Preperitoneal Pelvic Packing, Angioembolization, or REBOA as an adjunct.

Question 335

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay in hemorrhagic shock following a motorcycle collision. Radiographs demonstrate an anteroposterior compression (APC) type III pelvic ring injury. A circumferential pelvic binder is applied. To achieve the most effective reduction and mechanical stabilization, over which anatomic structure should the binder be centered?
. Anterior superior iliac spines
. Iliac crests
. Greater trochanters
. Pubic symphysis
. Subtrochanteric femur

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder or sheet must be centered over the greater trochanters to effectively close an open-book pelvic injury. Placement over the iliac crests or ASIS is less effective and can inadvertently cause paradoxical widening of the pelvic inlet or fail to close the posterior ring disruption adequately.

Question 336

Topic: Pelvic & Acetabular Trauma

A 35-year-old male sustains a closed pelvic ring injury. Examination reveals a large, fluctuant swelling over the greater trochanteric region with overlying skin bruising. Aspiration yields serosanguinous fluid. What is the precise anatomic location of this fluid collection in a Morel-Lavallee lesion?

. Between the epidermis and the dermis
. Between the dermis and the subcutaneous fat
. Between the subcutaneous fat and the deep fascia
. Between the deep fascia and the underlying muscle
. Deep to the muscle, adjacent to the periosteum

Correct Answer & Explanation

. Between the subcutaneous fat and the deep fascia

Explanation

A Morel-Lavallee lesion is a post-traumatic closed degloving injury where the subcutaneous tissue is sheared off and separated from the underlying deep (muscular) fascia. This creates a potential space that rapidly fills with blood, lymph, and necrotic fat.

Question 337

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the trauma bay after an MVA. He is hypotensive (BP 70/40 mmHg) and tachycardic (HR 130 bpm). Primary survey reveals an unstable pelvis (APC III pattern). A pelvic binder is applied, and he receives 2 units of packed RBCs. His BP improves transiently but drops again to 75/45 mmHg. A FAST scan is negative. What is the most appropriate next step in management?
. CT angiogram of the pelvis
. Preperitoneal pelvic packing and/or pelvic angiography
. Exploratory laparotomy
. Application of an anterior external fixator in the ER
. Bilateral internal iliac artery ligation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury who remains hypotensive despite initial resuscitation and mechanical stabilization (pelvic binder), and who has a negative FAST (ruling out massive intra-abdominal hemorrhage), the next step is addressing pelvic bleeding. This is achieved via preperitoneal pelvic packing or pelvic angiography/embolization, depending on institutional protocols and available resources.

Question 338

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay following a high-speed motor vehicle collision. He has an anteroposterior compression (APC III) pelvic ring injury and is hemodynamically unstable. A pelvic binder is applied, but he remains hypotensive. FAST exam is negative. What is the most common anatomical source of massive hemorrhage in this clinical scenario?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. Obturator artery
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus

Explanation

In severe pelvic ring disruptions, 80-90% of massive hemorrhage is venous in origin, primarily from the presacral venous plexus and bleeding from the cancellous bone surfaces. Arterial bleeding (e.g., superior gluteal, internal pudendal) accounts for only 10-20% of cases, though it may require specific interventions such as angioembolization if venous bleeding is controlled via pelvic packing/binder.

Question 339

Topic: Pelvic & Acetabular Trauma
In a Young-Burgess Anterior Posterior Compression Type III (APC III) pelvic ring injury, which of the following ligamentous complexes is definitively disrupted compared to an APC II injury?
. Anterior sacroiliac ligaments
. Sacrospinous ligaments
. Sacrotuberous ligaments
. Posterior sacroiliac ligaments
. Iliolumbar ligaments

Correct Answer & Explanation

. Posterior sacroiliac ligaments

Explanation

APC II involves disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, while the posterior sacroiliac ligaments remain intact, maintaining some vertical stability. APC III involves complete disruption of both anterior and posterior sacroiliac ligaments, causing complete multidirectional pelvic instability.

Question 340

Topic: Pelvic & Acetabular Trauma

A 40-year-old hemodynamically unstable male presents after a motorcycle accident. Pelvic radiographs show a symphysis pubis diastasis of 4 cm and widening of the anterior sacroiliac joints bilaterally, with intact posterior SI ligaments (APC Type II). What is the primary source of life-threatening hemorrhage in this specific injury pattern?

. Superior gluteal artery
. Internal pudendal artery
. Venous presacral plexus
. Obturator artery
. External iliac artery

Correct Answer & Explanation

. Venous presacral plexus

Explanation

In anteroposterior compression (APC) pelvic ring injuries (open book), the most common source of massive hemorrhage is the presacral venous plexus and bleeding from raw cancellous bone. Venous bleeding accounts for up to 80-90% of pelvic hemorrhage. Arterial bleeding (e.g., superior gluteal) is more common in posterior ring injuries (e.g., vertical shear).

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