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Pelvic & Acetabular Trauma MCQs

Practice Set 24 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 461

Topic: Pelvic & Acetabular Trauma

A 24-year-old male hockey player presents with gradual onset of deep groin pain exacerbated by hip flexion and internal rotation. Radiographs reveal an alpha angle of 65 degrees and normal acetabular coverage. Which of the following pathologic mechanisms is most likely responsible for his symptoms?

. Shear forces causing anterosuperior labral detachment and chondral delamination
. Contrecoup cartilage injury in the posteroinferior acetabulum
. Pincer impingement causing circumferential labral ossification
. Dysplastic subluxation causing labral hypertrophy
. Ischiofemoral impingement causing quadratus femoris edema

Correct Answer & Explanation

. Shear forces causing anterosuperior labral detachment and chondral delamination

Explanation

Cam impingement is characterized by an abnormal femoral head-neck junction (high alpha angle) that forcefully enters the acetabulum during flexion. This creates tremendous shear forces that lead to anterosuperior chondral delamination and inside-out labral tears.

Question 462

Topic: Pelvic & Acetabular Trauma
A 40-year-old male sustains a pelvic ring injury. Radiographs show a widened pubic symphysis of 3.5 cm and disruption of the anterior sacroiliac ligaments with intact posterior sacroiliac ligaments. What type of injury is this according to the Young and Burgess classification?
. APC I
. APC II
. APC III
. LC I
. VS

Correct Answer & Explanation

. APC II

Explanation

An APC II injury involves symphyseal widening >2.5 cm and disruption of the anterior SI ligaments but with intact posterior SI ligaments, causing rotational instability while maintaining vertical stability.

Question 463

Topic: Pelvic & Acetabular Trauma



A 70-year-old man requires a revision THA. Preoperative evaluation of the pelvis reveals severe bone loss with a complete dissociation of the superior and inferior halves of the hemipelvis. Which of the following constructs is most appropriate to achieve durable fixation in this scenario?

. Jumbo multi-hole hemispherical cup alone
. Impaction bone grafting with a cemented polyethylene cup
. Cup-cage construct or custom triflange acetabular component
. Standard porous-coated cup with adjunctive anterior column plating
. Bipolar hemiarthroplasty articulating with the remaining native bone

Correct Answer & Explanation

. Cup-cage construct or custom triflange acetabular component

Explanation

The scenario describes a pelvic discontinuity. Achieving stability requires bridging the defect to unite the superior and inferior segments. This is best accomplished using highly porous metal augments with a cup-cage construct, a custom triflange, or a pelvic distraction technique.

Question 464

Topic: Pelvic & Acetabular Trauma

A 24-year-old male hockey player presents with anterior groin pain exacerbated by hip flexion and internal rotation. Radiographs reveal a pistol-grip deformity and an alpha angle of 70 degrees. Which of the following best describes the pathomechanics of his condition?

. Linear contact between the aspheric femoral head-neck junction and acetabular rim causing labral and cartilage shear
. Repetitive microtrauma to the ligamentum teres causing instability
. Increased femoral anteversion leading to posterior rim overload
. Global acetabular overcoverage causing a pincer impingement
. Dysplastic shallow acetabulum leading to edge loading

Correct Answer & Explanation

. Linear contact between the aspheric femoral head-neck junction and acetabular rim causing labral and cartilage shear

Explanation

Cam impingement features an aspherical femoral head that forcefully enters the acetabulum during flexion. This creates outside-in shear forces that cause labral separation and adjacent chondral delamination from the acetabular rim.

Question 465

Topic: Pelvic & Acetabular Trauma

A 35-year-old man presents with a hemodynamically unstable pelvic ring injury following a motorcycle collision. A pelvic binder is applied. To optimally reduce the pelvic volume in an anteroposterior compression (APC) injury, over which anatomic structure should the pelvic binder be centered?

. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Pubic symphysis
. Sacral ala

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders should be centered over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume in APC-type injuries. Placement over the iliac crests is less effective and may cause paradoxical opening of the pelvic floor.

Question 466

Topic: Pelvic & Acetabular Trauma
A 45-year-old woman is brought to the emergency department after a motor vehicle collision. Her blood pressure is 80/50 mm Hg. Pelvic radiographs show a widely displaced anteroposterior compression (APC) type III pelvic ring injury. After initial fluid resuscitation, a pelvic binder is applied. What is the optimal anatomic landmark for the proper placement of the pelvic binder?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Ischial tuberosities

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder should be placed at the level of the greater trochanters to effectively reduce pelvic volume and stabilize the fracture. Placement over the iliac crests is incorrect and can exacerbate the deformity or fail to reduce the volume.

Question 467

Topic: Pelvic & Acetabular Trauma

In the pre-hospital and emergency department management of a hemodynamically unstable patient with a suspected pelvic ring injury, what is the proper anatomical placement of a circumferential pelvic binder?

. Over the iliac crests
. Over the greater trochanters
. Over the anterior superior iliac spines
. Over the mid-abdomen
. Over the symphysis pubis and lower lumbar spine

Correct Answer & Explanation

. Over the greater trochanters

Explanation

A pelvic binder should be centered directly over the greater trochanters. Placement over the iliac crests is a common error that can paradoxically widen the true pelvis and fail to adequately reduce pelvic volume.

Question 468

Topic: Pelvic & Acetabular Trauma
A 50-year-old patient presents with a massive, fluctuant Morel-Lavallée lesion over the greater trochanter that has been present for 4 weeks following a blunt trauma. What is the most definitive management?
. Observation and compression dressings
. A single percutaneous aspiration
. A short course of oral antibiotics
. Open excision of the pseudocapsule or percutaneous debridement with sclerodesis
. Primary closure with deep tension sutures

Correct Answer & Explanation

. Open excision of the pseudocapsule or percutaneous debridement with sclerodesis

Explanation

Chronic Morel-Lavallée lesions form an epithelialized pseudocapsule that prevents resorption. Simple aspiration has a very high recurrence rate; therefore, definitive treatment requires open excision or aggressive debridement with sclerodesis.

Question 469

Topic: Pelvic & Acetabular Trauma
A 33-year-old male sustains an anteroposterior compression (APC) pelvic ring injury. Which of the following anatomic disruptions defines an APC III injury and differentiates it from an APC II injury?
. Disruption of the anterior sacroiliac ligaments only
. Symphysis pubis diastasis greater than 2.5 cm
. Complete disruption of both the anterior and posterior sacroiliac ligaments
. Fracture of the superior and inferior pubic rami
. Avulsion of the sacrotuberous ligament

Correct Answer & Explanation

. Complete disruption of both the anterior and posterior sacroiliac ligaments

Explanation

According to the Young-Burgess classification, an APC II injury involves disruption of the anterior sacroiliac ligaments with an intact posterior hinge. An APC III injury involves complete disruption of both the anterior and posterior sacroiliac ligaments, leading to complete global instability.

Question 470

Topic: Pelvic & Acetabular Trauma
A 25-year-old male is brought to the trauma bay after a motorcycle crash with an anteroposterior compression type III (APC-III) pelvic ring injury. He remains hypotensive despite 2 liters of crystalloid and application of a pelvic binder. A FAST exam is negative. What is the next best step in management?
. Exploratory laparotomy
. Pelvic angiography with embolization or preperitoneal packing
. Immediate open reduction and internal fixation of the pelvis
. Retrograde urethrogram
. Placement of a Greenfield filter

Correct Answer & Explanation

. Pelvic angiography with embolization or preperitoneal packing

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST (which rules out major intra-abdominal hemorrhage), the bleeding is primarily retroperitoneal. Pelvic angiography with embolization or preperitoneal pelvic packing is the preferred intervention.

Question 471

Topic: Pelvic & Acetabular Trauma
A 40-year-old male presents after a high-speed motorcycle crash. His blood pressure is 70/40 mmHg. Pelvic radiographs show an APC-III injury. A pelvic binder is applied, and 2 units of PRBCs are given. Repeat blood pressure is 75/40 mmHg. FAST exam is negative. What is the most appropriate next step in management?
. Diagnostic peritoneal lavage
. Application of an anterior pelvic external fixator
. Retroperitoneal pelvic packing or angiography
. CT abdomen and pelvis
. Exploratory laparotomy

Correct Answer & Explanation

. Retroperitoneal pelvic packing or angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and negative FAST, the source of bleeding is likely retroperitoneal. Pelvic packing or angiography with embolization is the appropriate next step to control hemorrhage.

Question 472

Topic: Pelvic & Acetabular Trauma

A 45-year-old male is involved in a high-speed motorcycle crash. Pelvic radiographs demonstrate a widened symphysis pubis of 3.5 cm and widened anterior sacroiliac joints bilaterally, but the posterior sacroiliac ligaments remain intact. What is the most appropriate definitive management for this specific injury pattern?

. Application of a pelvic binder followed by spica casting
. Anterior symphyseal plate fixation
. Posterior percutaneous iliosacral screws alone
. Non-weight bearing and bed rest for 6 weeks
. Bilateral total hip arthroplasty

Correct Answer & Explanation

. Anterior symphyseal plate fixation

Explanation

This is an Anteroposterior Compression Type II (APC-II) pelvic ring injury, characterized by symphyseal diastasis and disruption of the anterior SI ligaments with intact posterior SI ligaments. Anterior symphyseal plate fixation is the standard definitive treatment to restore stability.

Question 473

Topic: Pelvic & Acetabular Trauma

A 35-year-old male presents with a hemodynamically unstable pelvic ring injury after a motorcycle collision. To be most effective at reducing pelvic volume, at what anatomic level should a pelvic circumferential compression device (binder) be placed?

. Over the iliac crests
. At the level of the greater trochanters
. Midway between the anterior superior iliac spine and the umbilicus
. Directly over the lower lumbar spine
. Proximal to the anterior inferior iliac spine

Correct Answer & Explanation

. At the level of the greater trochanters

Explanation

Pelvic binders are most effective at reducing pelvic volume and closing the symphysis when placed at the level of the greater trochanters. Placement higher over the iliac crests is less effective and may cause paradoxical widening of the pelvic brim.

Question 474

Topic: Pelvic & Acetabular Trauma
A 35-year-old male presents with a hemodynamically unstable APC-III pelvic ring injury following a motorcycle collision. What is the correct anatomical landmark to center a pelvic circumferential compression device?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders must be centered over the greater trochanters to effectively reduce pelvic volume and stabilize the fracture, minimizing internal hemorrhage. Placement over the iliac crests can paradoxically worsen the deformity.

Question 475

Topic: Pelvic & Acetabular Trauma
A 30-year-old female presents in hemorrhagic shock after a crush injury. Pelvic radiograph shows an APC-III injury with pubic symphysis diastasis of 4 cm and complete disruption of the sacroiliac joints bilaterally. After applying a pelvic binder, her hemodynamics remain unstable. What is the next most appropriate step?
. Immediate open reduction internal fixation
. Retrograde urethrogram
. Preperitoneal pelvic packing and/or angioembolization
. Bilateral lower extremity traction
. Immediate sacral screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angioembolization

Explanation

In an unstable pelvic ring injury with ongoing hemorrhagic shock despite mechanical stabilization, immediate hemorrhage control is mandatory. Preperitoneal pelvic packing or angioembolization are the standard interventions for refractory hemodynamic instability.

Question 476

Topic: Pelvic & Acetabular Trauma
A 42-year-old trauma patient has an unstable pelvic ring injury with a widened pubic symphysis (APC-III). A pelvic binder is applied in the trauma bay. For maximal mechanical effectiveness in reducing the pelvic volume, at what anatomical landmark should the binder be centered?
. The iliac crests
. The greater trochanters
. The anterior superior iliac spines
. The level of the umbilicus
. The pubic tubercle

Correct Answer & Explanation

. The greater trochanters

Explanation

To effectively reduce pelvic volume and stabilize the bony ring, a pelvic binder must be centered directly over the greater trochanters. Placement higher over the iliac crests is less mechanically effective and can limit abdominal access.

Question 477

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the trauma bay in hemorrhagic shock following a motorcycle collision. An anteroposterior pelvic radiograph demonstrates an anteroposterior compression (APC) type III pelvic ring injury. A pelvic binder is to be applied. What is the correct anatomical landmark for the optimal placement of the pelvic binder?
. Anterior superior iliac spines
. Iliac crests
. Greater trochanters
. Symphysis pubis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders must be centered over the greater trochanters to effectively reduce pelvic volume and control hemorrhage. Placement over the iliac crests is a common error and can paradoxically widen the true pelvis in APC injuries.

Question 478

Topic: Pelvic & Acetabular Trauma

In the Young-Burgess classification of pelvic ring injuries, which of the following ligamentous structures remains completely intact in an anteroposterior compression type II (APC II) injury?

. Anterior sacroiliac ligaments
. Sacrotuberous ligaments
. Sacrospinous ligaments
. Posterior sacroiliac ligaments
. Symphyseal ligaments

Correct Answer & Explanation

. Posterior sacroiliac ligaments

Explanation

An APC II pelvic ring injury is characterized by rupture of the symphyseal, anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The strong posterior sacroiliac ligaments remain intact, providing continued vertical stability to the hemipelvis.

Question 479

Topic: Pelvic & Acetabular Trauma
In a patient with an anterior-posterior compression (APC) type III pelvic ring injury, what is the most common source of major retroperitoneal hemorrhage?
. Anterior division of the internal iliac artery
. Posterior division of the internal iliac artery
. Venous plexus and cancellous bone
. Superior gluteal artery
. External iliac artery

Correct Answer & Explanation

. Venous plexus and cancellous bone

Explanation

Despite the life-threatening nature of arterial bleeding, the most common source of hemorrhage in pelvic ring injuries is venous, originating from the presacral and prevesical plexuses, as well as bleeding from fractured cancellous bone.

Question 480

Topic: Pelvic & Acetabular Trauma

On an anteroposterior (AP) radiograph of the pelvis, disruption of the iliopectineal line indicates a fracture involving which structural component of the acetabulum?

. Posterior column
. Anterior column
. Posterior wall
. Anterior wall
. Ischial spine

Correct Answer & Explanation

. Anterior column

Explanation

The iliopectineal line is the primary radiographic landmark for the anterior column of the acetabulum. Disruption of this line on an AP pelvis radiograph is indicative of an anterior column fracture.

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