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Pelvic & Acetabular Trauma MCQs

Practice Set 18 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 341

Topic: Pelvic & Acetabular Trauma
A 28-year-old male sustains a severe closed pelvic ring injury in a motorcycle collision. Radiographs demonstrate a lateral compression (LC) type III fracture pattern. He is hemodynamically unstable despite a pelvic binder and massive transfusion protocol. Angiography is performed. Which vessel is statistically most likely to be the source of major arterial hemorrhage in this specific fracture pattern?
. Superior gluteal artery
. Obturator artery
. Internal pudendal artery
. External iliac artery
. Inferior epigastric artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

In lateral compression (LC) pelvic ring injuries, the posterior pelvic ring is disrupted (e.g., sacral fracture or SI joint disruption), placing the posterior branches of the internal iliac artery at high risk. The superior gluteal artery is the most commonly injured artery in LC patterns. In contrast, anterior posterior compression (APC) injuries typically injure the anterior branches (obturator and internal pudendal arteries).

Question 342

Topic: Pelvic & Acetabular Trauma

A 28-year-old motorcyclist is brought to the trauma bay after a high-speed collision. Radiographs demonstrate widening of the pubic symphysis of 3.5 cm and widening of the anterior sacroiliac joints bilaterally. The posterior sacroiliac ligaments appear intact on CT scan. According to the Young-Burgess classification, which of the following is the most likely associated systemic injury or complication?

. Bowel perforation
. Arterial hemorrhage from the superior gluteal artery
. Urethral tear
. Lumbosacral plexus avulsion
. Aortic transection

Correct Answer & Explanation

. Urethral tear

Explanation

The injury described is an Anteroposterior Compression (APC) Type II pelvic ring injury (diastasis of the pubic symphysis > 2.5 cm, disruption of anterior SI ligaments, intact posterior SI ligaments). APC injuries, colloquially known as 'open book' pelvis fractures, are highly associated with genitourinary injuries (e.g., posterior urethral tears, bladder ruptures) due to the diastasis of the anterior ring tearing the surrounding ligaments and structures. Superior gluteal artery injury is more common in posterior ring disruptions such as Lateral Compression or Vertical Shear injuries.

Question 343

Topic: Pelvic & Acetabular Trauma
A 28-year-old woman is brought to the trauma bay following a high-speed motor vehicle collision. Pelvic radiographs demonstrate a symphysis pubis diastasis of 3.5 cm and widening of the anterior sacroiliac joints bilaterally. The posterior sacroiliac complex appears intact, and there is no vertical displacement of the hemipelvis. According to the Young-Burgess classification system, this injury pattern is best categorized as:
. Anterior Posterior Compression (APC) I
. Lateral Compression (LC) I
. Anterior Posterior Compression (APC) III
. Lateral Compression (LC) II
. Anterior Posterior Compression (APC) II

Correct Answer & Explanation

. Anterior Posterior Compression (APC) II

Explanation

An APC II injury is defined by disruption of the pubic symphysis (typically >2.5 cm), the anterior sacroiliac ligaments, and the sacrospinous and sacrotuberous ligaments, resulting in an 'open-book' pelvis. Because the strong posterior sacroiliac ligaments remain intact, the pelvis is rotationally unstable but vertically stable. APC I involves symphyseal widening <2.5 cm. APC III involves complete disruption of both anterior and posterior sacroiliac ligaments, rendering the hemipelvis both rotationally and vertically unstable.

Question 344

Topic: Pelvic & Acetabular Trauma

Figure 33a shows a line drawing of a normal hemipelvis. The anterior acetabular rim is bold. Figure 33b illustrates a hemipelvis with a crossover sign, which is indicative of what acetabular pathology?

. Low acetabular index
. Excessive acetabular retroversion
. Deficient anterior column bone
. Labral detachment
. Pelvic discontinuity

Correct Answer & Explanation

. Excessive acetabular retroversion

Explanation

In a normal AP pelvis radiograph, the anterior rim of the acetabulum runs medially and distally, diverging from the posterior rim which runs much more vertically. In excessive acetabular retroversion, the anterior rim (bold line in Figure 33b) and posterior rim start laterally, and as these lines progress medially and distally, the anterior line crosses the posterior line. This predisposes to femoral acetabular impingement. Reynolds D, Lucas J, Klaue K: Retroversion of the acetabulum: A cause of hip pain. J Bone Joint Surg Br 1999;81:281-288.

Question 345

Topic: Pelvic & Acetabular Trauma

A 45-year-old male presents in hemorrhagic shock following a crush injury. A pelvic binder is applied. Secondary survey reveals blood at the urethral meatus and a high-riding prostate on digital rectal examination. Pelvic radiographs show a displaced pubic symphysis diastasis. Which of the following is the most appropriate next step in the urologic management of this patient?

. Immediate blind placement of a 16-French Foley catheter
. Immediate suprapubic catheter placement in the trauma bay
. Retrograde urethrogram
. CT cystogram
. Flexible cystoscopy

Correct Answer & Explanation

. Retrograde urethrogram

Explanation

Blood at the urethral meatus, scrotal/perineal ecchymosis, and a high-riding prostate are classic signs of a posterior urethral injury, which is highly associated with anterior pelvic ring injuries (e.g., APC patterns). Blind insertion of a Foley catheter is contraindicated as it may convert a partial urethral tear into a complete tear. A retrograde urethrogram (RUG) is the gold standard diagnostic study and must be performed prior to any attempt at transurethral catheterization.

Question 346

Topic: Pelvic & Acetabular Trauma

A 42-year-old man is brought to the emergency department after a high-speed motorcycle collision. His blood pressure is 80/50 mm Hg and heart rate is 120 bpm. Primary survey reveals an unstable pelvis. The trauma team decides to apply a pelvic binder. To be maximally 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
. Symphysis pubis
. Ischial tuberosities

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders are most effective in reducing pelvic volume and controlling hemorrhage in anterior-posterior compression pelvic ring injuries when they are centered over the greater trochanters. Placement over the iliac crests or anterior superior iliac spines can paradoxically open the pelvis further or be less effective in creating the necessary compression.

Question 347

Topic: Pelvic & Acetabular Trauma
A 42-year-old man arrives in the emergency department hypotensive and tachycardic following a high-speed motor vehicle collision. A pelvic radiograph reveals an anteroposterior compression (APC) type III pelvic ring injury. A pelvic binder is applied, and a FAST scan is negative for intra-abdominal fluid. Despite fluid resuscitation, he remains hypotensive. What is the most common anatomic source of hemorrhage in this clinical scenario?
. Superior gluteal artery
. Presacral venous plexus and cancellous bone
. Internal pudendal artery
. Obturator artery
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus and cancellous bone

Explanation

The most common source of bleeding in pelvic ring injuries is the presacral venous plexus and bleeding from the cancellous bone edges, accounting for up to 80% of cases. Arterial bleeding (e.g., from the superior gluteal or internal pudendal arteries) occurs in only 10% to 20% of cases but is more likely to be the culprit in a patient who remains hemodynamically unstable despite mechanical stabilization with a binder. However, standard board teaching dictates that overall, the venous plexus and cancellous bone are the most frequent sources of hemorrhage in pelvic fractures.

Question 348

Topic: Pelvic & Acetabular Trauma
A 45-year-old man is brought to the emergency department after falling from a 20-foot scaffold. He is hemodynamically unstable with a blood pressure of 80/40 mm Hg. Radiographs reveal an APC-III pelvic ring injury. A pelvic binder is to be applied. What is the most appropriate anatomical landmark for the optimal placement of the pelvic binder to effectively reduce pelvic volume?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

The optimal placement of a pelvic binder or sheet is centered over the greater trochanters. Biomechanical and clinical studies have shown that placing the binder at the level of the greater trochanters most effectively closes the pelvic ring and reduces pelvic volume. Placement higher, such as over the iliac crests or ASIS, is less effective and may paradoxically widen the pelvis in certain fracture patterns.

Question 349

Topic: Pelvic & Acetabular Trauma
A 42-year-old construction worker is crushed by a heavy machine. On arrival, his blood pressure is 70/40 mmHg. A FAST examination is positive for intra-abdominal fluid, and a portable pelvic radiograph shows a widened pubic symphysis with disruption of the posterior sacroiliac complex (APC III injury). A commercial pelvic binder is ordered. To optimally reduce the pelvic volume and stabilize the fracture, the binder should be centered over which of the following anatomic landmarks?
. The anterior superior iliac spines
. The iliac crests
. The greater trochanters
. The pubic symphysis directly
. The mid-lumbar spine

Correct Answer & Explanation

. The greater trochanters

Explanation

For emergent stabilization of an unstable pelvic ring injury, pelvic binders or sheets should be centered strictly over the greater trochanters. Placement higher over the iliac crests or anterior superior iliac spines is less effective at reducing pelvic volume, can paradoxically open the true pelvis further in some fracture patterns, and may restrict abdominal access for exploratory laparotomy.

Question 350

Topic: Pelvic & Acetabular Trauma

A 35-year-old man is brought to the emergency department after a motorcycle collision. He is hemodynamically unstable, and a pelvic binder is ordered. Which of the following landmarks is the most appropriate location to center the pelvic binder?

. Iliac crests
. Pubic symphysis
. Greater trochanters
. Anterior superior iliac spines
. Lumbar spine

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder should be centered over the greater trochanters to effectively reduce the pelvic volume and stabilize the pelvic ring, particularly in the setting of an anteroposterior compression (open-book) injury. Placement over the iliac crests is a common clinical error and can paradoxically widen the pelvic inlet, exacerbating the deformity and bleeding.

Question 351

Topic: Pelvic & Acetabular Trauma
A 25-year-old man arrives at the trauma center hemodynamically unstable with an anteroposterior compression type III (APC-III) pelvic ring injury. A pelvic binder is applied, and he receives massive transfusion protocol. His FAST exam is negative, but he remains hypotensive. What is the most likely anatomic source of his ongoing pelvic hemorrhage?
. Superior gluteal artery
. Internal pudendal artery
. Obturator artery
. Sacral venous plexus
. External iliac vein

Correct Answer & Explanation

. Sacral venous plexus

Explanation

While arterial bleeding (such as from the superior gluteal artery or internal pudendal artery) can cause rapid exsanguination, the presacral and perivesical venous plexuses, along with cancellous bone bleeding, account for 80-90% of all pelvic hemorrhage in major pelvic ring injuries.

Question 352

Topic: Pelvic & Acetabular Trauma

During the percutaneous placement of an S1 transiliac-transsacral screw for a posterior pelvic ring injury, the surgeon must be aware of sacral dysmorphism. Which of the following is a radiographic sign of sacral dysmorphism that indicates the S1 osseous corridor may be restricted or unsafe?

. Colinear upper sacral neural foramina on the outlet view
. Recessed upper sacrum within the pelvis
. An acute upward angulation of the sacral ala
. Absence of mammillary processes at the sacroiliac joint
. Symmetrical S1 neural foramina on the inlet view

Correct Answer & Explanation

. An acute upward angulation of the sacral ala

Explanation

Sacral dysmorphism refers to anatomic variations that make standard placement of S1 iliosacral screws difficult or unsafe. Radiographic signs include an acute upward angulation of the sacral ala (alar slope), a non-recessed (flush) upper sacrum, tongue-in-groove sacroiliac joints, non-circular (often teardrop-shaped) upper sacral neural foramina on the outlet view, and residual upper sacral disc spaces. These features result in a narrow, oblique osseous corridor.

Question 353

Topic: Pelvic & Acetabular Trauma

A 50-year-old male is involved in a high-speed collision and sustains an APC II (anteroposterior compression) pelvic ring injury with widening of the symphysis pubis. If isolated internal fixation is planned for the anterior ring, which of the following statements regarding the biomechanics of symphyseal plating is correct?

. A multi-hole plate with locking screws provides significantly more stability than standard cortical screws in the symphysis
. Two-hole plates provide equivalent biomechanical stability to multi-hole plates for APC II injuries
. Symphyseal plating alone predictably restores the stability of the posterior sacroiliac complex in vertically unstable patterns
. Placement of a plate on the superior surface of the symphysis is biomechanically superior to anterior placement
. Symphyseal plates should be routinely removed at 6 months to prevent hardware failure

Correct Answer & Explanation

. Placement of a plate on the superior surface of the symphysis is biomechanically superior to anterior placement

Explanation

Biomechanical studies have consistently demonstrated that a plate placed on the superior surface of the symphysis pubis provides superior mechanical stability compared to an anteriorly placed plate. This is due to the thicker and denser bone available for screw purchase on the superior pubic rami, as well as an improved mechanical advantage against the deforming forces of the pelvic ring. Routine removal is not indicated unless symptomatic.

Question 354

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay after a motorcycle collision. He is hypotensive (BP 75/40 mmHg) and tachycardic (HR 130 bpm). A FAST exam is negative. A pelvic radiograph shows an anteroposterior compression type III (APC-III) pelvic ring injury. A pelvic binder is applied, and he receives 2 units of uncrossmatched blood, but his hemodynamics remain unstable. What is the most appropriate next step in management?
. CT scan of the abdomen and pelvis
. Retrograde urethrogram
. Pelvic angiography and embolization
. Exploratory laparotomy
. Application of a supra-acetabular external fixator

Correct Answer & Explanation

. Pelvic angiography and embolization

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST exam (excluding intra-abdominal hemorrhage), the source of bleeding is presumed to be the pelvis. After application of a pelvic binder and initial fluid/blood resuscitation, pelvic angiography with embolization (or preperitoneal pelvic packing, depending on institutional protocol) is the most appropriate next step to address life-threatening arterial bleeding.

Question 355

Topic: Pelvic & Acetabular Trauma
A 40-year-old man is brought to the trauma bay after a motorcycle crash. His blood pressure is 80/40 mmHg and heart rate is 130 bpm. Pelvic radiographs demonstrate an anteroposterior compression type III (APC-III) pelvic ring injury with marked symphyseal diastasis. A FAST exam is negative. What is the most appropriate initial step to acutely reduce pelvic volume and aid hemodynamic stability?
. Immediate open reduction and internal fixation of the pubic symphysis
. Application of a pelvic binder centered over the iliac crests
. Application of a pelvic binder centered over the greater trochanters
. Emergent pelvic angiography and embolization
. Exploratory laparotomy and preperitoneal packing

Correct Answer & Explanation

. Application of a pelvic binder centered over the greater trochanters

Explanation

In an unstable patient with an open-book pelvic fracture (APC injury), the initial mechanical intervention is to reduce pelvic volume. A pelvic binder or sheet must be applied centered directly over the greater trochanters. Placing it over the iliac crests is incorrect and can paradoxically open the pelvis further or fail to provide adequate mechanical advantage to close the posterior ring.

Question 356

Topic: Pelvic & Acetabular Trauma

A 35-year-old man is brought to the emergency department after a motorcycle collision. He is hypotensive with a blood pressure of 80/50 mm Hg. A pelvic radiograph shows a widened pubic symphysis consistent with an anteroposterior compression (APC) injury. You decide to apply a pelvic binder to provide temporary stability. To most effectively reduce the pelvic volume, at what anatomical level should the binder be centered?

. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Mid-thighs
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

The most effective placement of a pelvic binder or sheet to reduce pelvic volume in anteroposterior compression (APC) and open-book pelvic fractures is at the level of the greater trochanters. Placing the binder higher, at the level of the iliac crests, is a common error that is less effective and may inadvertently worsen the pelvic deformity by everting the lower pelvis.

Question 357

Topic: Pelvic & Acetabular Trauma
A 30-year-old male sustains a mechanically and hemodynamically unstable anteroposterior compression (APC-III) pelvic ring injury. A circumferential pelvic binder is applied in the trauma bay. To achieve optimal mechanical stability and maximal reduction in pelvic volume, over which anatomical landmark should the center of the binder be positioned?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

In hemodynamically unstable patients with open-book pelvic ring injuries, rapid application of a pelvic binder is crucial to reduce pelvic volume and promote the tamponade of venous and cancellous bone bleeding. Biomechanical and clinical studies have definitively shown that positioning the binder directly over the greater trochanters provides the most effective mechanical advantage for closing the symphysis pubis. Placement over the iliac crests is less effective and can paradoxically widen the true pelvis.

Question 358

Topic: Pelvic & Acetabular Trauma

A 42-year-old man sustains an anteroposterior compression type II (APC II) pelvic ring injury. He is hemodynamically stable. Imaging shows a 3.5 cm symphyseal diastasis and bilateral anterior sacroiliac joint widening. The posterior sacroiliac ligaments are intact. What is the optimal surgical treatment to restore pelvic ring stability?

. Anterior external fixation alone
. Open reduction and internal fixation of the pubic symphysis alone
. Percutaneous iliosacral screw fixation alone
. ORIF of the pubic symphysis combined with bilateral percutaneous iliosacral screws
. Nonoperative management with a pelvic binder for 6 weeks

Correct Answer & Explanation

. Open reduction and internal fixation of the pubic symphysis alone

Explanation

An APC II injury involves disruption of the symphysis pubis (or anterior ring) and the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, while the robust posterior sacroiliac ligaments remain intact. Because the posterior tension band is intact, restoring the anterior ring with open reduction and internal fixation of the pubic symphysis alone is sufficient to stabilize the entire pelvic ring.

Question 359

Topic: Pelvic & Acetabular Trauma

A 40-year-old man presents with a pelvic ring injury after a high-speed motorcycle crash. An AP pelvis radiograph demonstrates widening of the pubic symphysis of 3.5 cm and widening of the left sacroiliac joint. He remains hemodynamically unstable (BP 70/40) despite receiving 2 liters of crystalloid and 2 units of PRBCs. What is the most appropriate next step in orthopedic management?

. Application of a pelvic binder centered over the iliac crests
. Application of a pelvic binder centered over the greater trochanters
. Immediate CT scan of the abdomen and pelvis to identify the bleeder
. Transfer to the operating room for an immediate exploratory laparotomy
. Placement of a supra-acetabular external fixator in the emergency department

Correct Answer & Explanation

. Application of a pelvic binder centered over the greater trochanters

Explanation

In a hemodynamically unstable patient with an anteroposterior compression (APC) pelvic ring injury, immediate mechanical stabilization must be achieved to reduce pelvic volume and promote venous tamponade. This is best accomplished emergently with a pelvic binder or sheet placed correctly and centered over the greater trochanters. Placement over the iliac crests is incorrect and can act as a fulcrum, paradoxically exacerbating the pubic symphysis diastasis.

Question 360

Topic: Pelvic & Acetabular Trauma
A 40-year-old man sustains an anteroposterior compression type III (APC III) pelvic ring injury in a high-speed motorcycle collision. In the trauma bay, a pelvic binder is applied, and he receives massive transfusion protocol. His systolic blood pressure remains 70 mm Hg. The Focused Assessment with Sonography for Trauma (FAST) examination is negative, and a chest radiograph shows no abnormalities. What is the most appropriate next step in the management of this patient?
. Computed tomography (CT) scan of the abdomen and pelvis
. Retrograde urethrogram
. Pelvic angiography with potential embolization
. Exploratory laparotomy
. Application of an external fixator

Correct Answer & Explanation

. Pelvic angiography with potential embolization

Explanation

The patient remains hemodynamically unstable despite a pelvic binder and fluid resuscitation, with a negative FAST exam indicating the absence of massive intra-abdominal hemorrhage. The bleeding is most likely retroperitoneal from the highly unstable APC III pelvic injury. Pelvic angiography is the most appropriate next step to identify and embolize actively bleeding arterial vessels (most commonly branches of the internal iliac artery, such as the superior gluteal or pudendal arteries). CT scanning is contraindicated in hemodynamically unstable patients.

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