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Pelvic & Acetabular Trauma MCQs

Practice Set 30 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 581

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 35-year-old male is brought to the ED after a motorcycle collision. Radiographs show an APC-III pelvic ring injury. Despite a pelvic binder and 2 units of uncrossmatched blood, the patient's BP remains 75/40. FAST is negative. What is the most rapid and definitive surgical intervention to control the primary source of pelvic bleeding?
. Immediate REBOA placement
. Immediate anterior open reduction and internal fixation
. Preperitoneal pelvic packing
. Retrograde urethrogram
. Sacroiliac screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing

Explanation

In a hemodynamically unstable patient with an unstable pelvic fracture and negative FAST, the source of bleeding is likely the venous presacral plexus or cancellous bone (80% of cases). If instability persists despite binder and resuscitation, preperitoneal pelvic packing or angiography with embolization is indicated. Preperitoneal packing is favored for rapid control of venous bleeding in the emergent setting.

Question 582

Topic: Pelvic & Acetabular Trauma
In patients with Crowe types III and IV developmental dysplasia of the hip with high hip centers, acetabular reconstruction often requires lowering the acetabular component into the native acetabulum. In doing so, considerable risk for limb lengthening beyond 4 cm exists, making the hip difficult to reduce and raising the risk for nerve injury. Which technique is used to overcome this problem?
. Subtrochanteric osteotomy with femoral shortening
. An offset femoral component
. A lateralized liner
. Extended trochanteric osteotomy

Correct Answer & Explanation

. Subtrochanteric osteotomy with femoral shortening

Explanation

When substantial lengthening of a dysplastic hip will occur because a high dislocation is relocated into a considerably lower acetabulum, a femoral shortening may be necessary to reduce the hip and avoid a stretch injury to the sciatic nerve. No other choice specifically addresses the need for femoral shortening, and high offset stems and lateralized liners may exacerbate the problem if used alone and without femoral shortening.

Question 583

Topic: Pelvic & Acetabular Trauma
In patients with Crowe types III and IV developmental dysplasia of the hip with high hip centers, acetabular reconstruction often requires lowering the acetabular component into the native acetabulum. In doing so, considerable risk for limb lengthening beyond 4 cm exists, making the hip difficult to reduce and raising the risk for nerve injury. Which technique is used to overcome this problem?
. Subtrochanteric osteotomy with femoral shortening
. An offset femoral component
. A lateralized liner
. Extended trochanteric osteotomy

Correct Answer & Explanation

. Subtrochanteric osteotomy with femoral shortening

Explanation

When substantial lengthening of a dysplastic hip will occur because a high dislocation is relocated into a considerably lower acetabulum, a femoral shortening may be necessary to reduce the hip and avoid a stretch injury to the sciatic nerve. No other choice specifically addresses the need for femoral shortening, and high offset stems and lateralized liners may exacerbate the problem if used alone and without femoral shortening.

Question 584

Topic: Pelvic & Acetabular Trauma
A 42-year-old male sustains a severe pelvic ring injury from a crush mechanism. Radiographs show complete disruption of the pubic symphysis, bilateral rami fractures, and significant widening of the left sacroiliac joint. Despite the application of a pelvic binder and massive transfusion protocol, he remains hemodynamically unstable. An urgent angiogram is performed. In the context of major posterior pelvic ring disruptions, which branch of the internal iliac artery is statistically the most frequently injured, leading to life-threatening retroperitoneal hemorrhage?
. Superior gluteal artery
. Inferior gluteal artery
. Obturator artery
. Internal pudendal artery
. Iliolumbar artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

Pelvic ring fractures are associated with massive, life-threatening hemorrhage. The source is venous (presacral plexus) in approximately 80-90% of cases, and arterial in 10-20%. When arterial bleeding is present and requires embolization, the superior gluteal artery is historically the most frequently injured artery overall, specifically owing to its intimate anatomic relationship with the posterior pelvic ring and greater sciatic notch, which are often severely disrupted in high-energy trauma (such as APC-III or vertical shear injuries). The obturator and internal pudendal arteries are more commonly injured in isolated anterior ring fractures.

Question 585

Topic: Pelvic & Acetabular Trauma
Review the clinical scenario. A patient involved in an MVC sustains a pelvic ring injury. AP Pelvis radiograph reveals widening of the pubic symphysis of 3.0 cm, alongside widening of the anterior sacroiliac joints bilaterally. CT scan confirms that the posterior sacroiliac ligaments remain intact. According to the Young-Burgess classification system, what specific type of injury is this?
. Anteroposterior Compression I (APC I)
. Anteroposterior Compression II (APC II)
. Anteroposterior Compression III (APC III)
. Lateral Compression I (LC I)
. Lateral Compression II (LC II)

Correct Answer & Explanation

. Anteroposterior Compression II (APC II)

Explanation

An Anteroposterior Compression Type II (APC II) injury is an 'open book' pelvis characterized by disruption of the pubic symphysis (>2.5 cm) and tearing of the anterior SI ligaments, sacrotuberous, and sacrospinous ligaments. The critical feature distinguishing it from an APC III is that the posterior SI ligaments remain intact, rendering the pelvis rotationally unstable but vertically stable.

Question 586

Topic: Pelvic & Acetabular Trauma



A 28-year-old male is brought to the trauma bay following a high-speed motor vehicle collision. He is hypotensive and tachycardic. An AP pelvic radiograph demonstrates a symphyseal diastasis of 3.5 cm with anterior sacroiliac joint widening. Which of the following is the most common anatomical source of massive hemorrhage in this type of injury?

. Superior gluteal artery
. Obturator artery
. Presacral venous plexus
. Internal pudendal artery
. Medial circumflex femoral artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

The presacral venous plexus and bleeding from fractured cancellous bone account for approximately 80% of hemorrhage in pelvic ring injuries. While arterial bleeding (e.g., internal pudendal or superior gluteal) can occur and is often more rapidly fatal, venous bleeding remains the most common overall source.

Question 587

Topic: Pelvic & Acetabular Trauma

A 22-year-old hockey player presents with anterior groin pain with flexion and internal rotation. Radiographs demonstrate an alpha angle of 65 degrees on the Dunn lateral view. Which of the following pathomechanical processes is most likely occurring in this patient?

. Impingement of the femoral neck on the labrum due to acetabular retroversion
. Shear forces on the anterosuperior articular cartilage leading to delamination
. Contrecoup lesion in the posteroinferior acetabulum
. Pincer impingement causing primarily posterior labral tearing
. Increased femoral anteversion leading to anterior subluxation

Correct Answer & Explanation

. Impingement of the femoral neck on the labrum due to acetabular retroversion

Explanation

An alpha angle > 55 degrees indicates a Cam deformity. Cam impingement typically causes outside-in shear forces as the non-spherical femoral head enters the acetabulum during flexion and internal rotation. This leads to delamination of the anterosuperior acetabular cartilage from the subchondral bone, often leaving the labrum relatively intact in the early stages.

Question 588

Topic: Pelvic & Acetabular Trauma

A 21-year-old hockey player presents with groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate a pistol grip deformity and an alpha angle of 65 degrees.

In an isolated Cam impingement, where does cartilage delamination typically first occur?

. Posteroinferior acetabulum.
. Anterosuperior acetabulum.
. Central fovea.
. Ligamentum teres insertion.
. Posterior femoral head.

Correct Answer & Explanation

. Posteroinferior acetabulum.

Explanation

Cam morphology involves an aspherical femoral head (reduced head-neck offset) that creates shear forces on the anterosuperior acetabular cartilage during hip flexion and internal rotation. This leads to chondral delamination from the underlying subchondral bone and subsequent labral tears in the anterosuperior quadrant. Pincer impingement typically causes direct labral compression and 'contrecoup' cartilage lesions in the posteroinferior acetabulum.

Question 589

Topic: Pelvic & Acetabular Trauma

A hemodynamically unstable 40-year-old male is brought to the trauma bay after a high-speed motorcycle accident. An AP pelvis radiograph reveals an 'open book' anterior-posterior compression (APC) pelvic ring injury. Where is the correct anatomical level to place a non-invasive circumferential pelvic binder?

. Over the iliac crests
. Over the anterior superior iliac spines
. Over the greater trochanters
. Over the symphysis pubis
. Over the lower lumbar spine

Correct Answer & Explanation

. Over the greater trochanters

Explanation

To effectively reduce pelvic volume and control venous bleeding in an unstable pelvic ring injury, the pelvic binder or sheet must be centered directly over the greater trochanters. Placing it over the iliac crests is a common error and can paradoxical widen the pelvic outlet or fail to close the ring adequately.

Question 590

Topic: Pelvic & Acetabular Trauma
In a Young-Burgess Anteroposterior Compression (APC) Type III pelvic ring injury, the mechanism involves severe external rotation of the hemipelvis. Which of the following ligamentous complexes are completely disrupted, distinguishing it from an APC II injury and resulting in complete global (rotational and vertical) instability?
. Anterior sacroiliac, sacrospinous, and sacrotuberous ligaments only
. Posterior sacroiliac ligaments only
. Anterior sacroiliac, posterior sacroiliac, sacrospinous, and sacrotuberous ligaments
. Iliolumbar and posterior sacroiliac ligaments only
. Symphyseal ligaments only

Correct Answer & Explanation

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

Explanation

In the Young-Burgess classification, APC injuries occur in a sequential cascade. APC I involves symphyseal diastasis < 2.5 cm. APC II involves symphyseal widening > 2.5 cm with tearing of the anterior SI ligaments, sacrospinous, and sacrotuberous ligaments, causing rotational instability but maintaining vertical stability because the posterior SI ligaments remain intact. An APC III injury implies complete disruption of both the anterior AND posterior SI ligaments (along with the pelvic floor ligaments), leading to complete spinopelvic dissociation and both rotational and vertical instability.

Question 591

Topic: Pelvic & Acetabular Trauma

A 35-year-old male arrives after a severe crush injury with a blood pressure of 75 mmHg and a heart rate of 135 bpm. Pelvic radiographs show a displaced vertical shear pelvic fracture. A pelvic binder is applied, and uncrossmatched blood is transfused, but his hemodynamics do not improve. The FAST exam is negative. What is the most appropriate next step?

. Exploratory laparotomy
. Application of a supra-acetabular external fixator
. Computed tomography (CT) of the abdomen and pelvis
. Retroperitoneal pelvic packing or pelvic angiography
. Administration of intravenous tranexamic acid and observation

Correct Answer & Explanation

. Exploratory laparotomy

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST (ruling out major intra-abdominal hemorrhage), the pelvic retroperitoneum is the primary source of bleeding. Emergent retroperitoneal pelvic packing or angiography with embolization is indicated.

Question 592

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay after a motorcycle accident. His blood pressure is 80/40 mmHg and heart rate is 130 bpm. A radiograph of the pelvis is obtained as part of the primary survey. Assuming an Anteroposterior Compression Type III (APC III) pattern is confirmed with complete disruption of the anterior and posterior pelvic rings, what is the most likely anatomic source of life-threatening arterial hemorrhage in this specific injury pattern?
. Superior gluteal artery
. Internal pudendal artery
. Inferior gluteal artery
. Median sacral artery
. External iliac artery

Correct Answer & Explanation

. Internal pudendal artery

Explanation

In pelvic ring injuries, the vascular injury pattern closely correlates with the mechanism of injury. Anteroposterior compression (APC) injuries typically result in an increase in pelvic volume and stretch or tear anterior vascular structures, most commonly the internal pudendal or obturator arteries. Conversely, vertical shear or severe posterior ring disruptions are more closely associated with injuries to the superior gluteal artery.

Question 593

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is involved in a motor vehicle collision. He is hemodynamically stable. An AP pelvis radiograph demonstrates symphysis pubis widening of 3.2 cm and widening of the anterior sacroiliac (SI) joints, but the posterior SI ligaments appear functionally intact. According to the Young-Burgess classification, what is the most likely injury pattern and best definitive treatment?
. APC I; non-operative management with weight-bearing as tolerated
. APC II; anterior stabilization (e.g., symphyseal plating)
. APC III; symphyseal plating and percutaneous SI screws
. LC I; non-operative management with protected weight-bearing
. LC II; open reduction and internal fixation of the ilium

Correct Answer & Explanation

. APC II; anterior stabilization (e.g., symphyseal plating)

Explanation

The clinical description of a symphysis pubis widening greater than 2.5 cm with disrupted anterior SI ligaments but intact posterior SI ligaments describes an Anteroposterior Compression (APC) Type II injury. In a hemodynamically stable patient, definitive treatment for an APC II injury typically requires anterior stabilization, most commonly via symphyseal plating, to restore the anterior tension band. APC III injuries involve complete posterior disruption and require both anterior and posterior fixation.

Question 594

Topic: Pelvic & Acetabular Trauma
In the emergency management of a hemodynamically unstable patient with an anteroposterior compression (APC-III) pelvic ring injury, over which exact anatomical landmarks should a pelvic binder be centered?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

To effectively reduce pelvic volume, close the pelvic ring, and provide tamponade effect, a pelvic binder must be centered directly over the greater trochanters. Misplacement over the iliac crests is common but incorrect, as it can worsen the deformity in certain fracture patterns.

Question 595

Topic: Pelvic & Acetabular Trauma
A 40-year-old male presents with an APC III pelvic ring injury and hemodynamic instability. Despite a correctly placed pelvic binder, he remains hypotensive. What is the most common anatomical source of the hemorrhage in this scenario?
. Superior gluteal artery
. Obturator artery
. Presacral venous plexus
. Internal pudendal artery
. Middle sacral artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

The presacral venous plexus and cancellous bone bleeding are the most common sources of hemorrhage in pelvic ring injuries. Arterial bleeding occurs in about 10-20% of cases, typically involving the superior gluteal or internal pudendal arteries.

Question 596

Topic: Pelvic & Acetabular Trauma

In the Young-Burgess classification of pelvic ring injuries, which of the following fracture patterns is most characteristic of an Anteroposterior Compression Type II (APC II) injury?

. Symphysis pubis widening < 2.5 cm with intact posterior ligaments
. Symphysis pubis widening > 2.5 cm with disruption of anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but intact posterior sacroiliac ligaments
. Complete disruption of the symphysis pubis and both anterior and posterior sacroiliac ligaments
. Vertical displacement of the hemipelvis through the sacroiliac joint
. Internal rotation of the hemipelvis with a sacral crush injury

Correct Answer & Explanation

. Symphysis pubis widening < 2.5 cm with intact posterior ligaments

Explanation

An APC II injury involves an 'open book' pelvic ring with symphysis diastasis >2.5 cm and disruption of the anterior SI ligaments, sacrotuberous, and sacrospinous ligaments. The strong posterior SI ligaments remain intact, maintaining vertical stability but resulting in rotational instability.

Question 597

Topic: Pelvic & Acetabular Trauma
A 40-year-old male presents with a hemodynamically unstable APC-III pelvic ring injury following a motorcycle collision. Despite a properly applied pelvic binder and massive transfusion protocol, he remains profoundly hypotensive. What is the most common anatomical source of massive hemorrhage in this fracture pattern?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. External iliac artery
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

Up to 80% of massive hemorrhage in pelvic ring injuries is venous in origin, most frequently arising from the presacral venous plexus. While arterial bleeding (such as from the superior gluteal artery) can be catastrophic, it is more commonly associated with posterior ring disruptions and represents a smaller percentage of overall pelvic bleeding.

Question 598

Topic: Pelvic & Acetabular Trauma
A 35-year-old male presents to the trauma bay following a motorcycle collision. Pelvic radiographs demonstrate a 3.5 cm symphyseal diastasis. A CT scan confirms an anteroposterior compression type II (APC-II) pelvic ring injury with disruption of the anterior sacroiliac ligaments but intact posterior sacroiliac ligaments. He is hemodynamically stable. What is the most appropriate definitive management for this patient's pelvic injury?
. Pelvic binder application and strict bed rest for 6 weeks
. Open reduction and internal fixation of the pubic symphysis alone
. Open reduction and internal fixation of the pubic symphysis combined with percutaneous posterior iliosacral screws
. External fixation of the anterior pelvis without internal fixation
. Percutaneous iliosacral screws bilaterally without anterior fixation

Correct Answer & Explanation

. Open reduction and internal fixation of the pubic symphysis alone

Explanation

An APC-II pelvic ring injury represents a rotationally unstable but vertically stable injury characterized by disruption of the symphysis pubis and the anterior sacroiliac ligaments, while the strong posterior sacroiliac ligaments remain intact. Because vertical stability is maintained, anterior ring stabilization alone (most commonly via open reduction and internal fixation of the pubic symphysis with a plate) is sufficient definitive treatment to restore rotational stability. Adding posterior fixation (iliosacral screws) is indicated for APC-III injuries, which involve disruption of both anterior and posterior SI ligaments, rendering the pelvis both rotationally and vertically unstable.

Question 599

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is evaluated in the trauma bay following a motorcycle collision. Pelvic radiographs demonstrate a 3.5 cm widening of the pubic symphysis. CT scan confirms widening of the anterior sacroiliac joints bilaterally, but the posterior sacroiliac ligaments remain intact. According to the Young and Burgess classification, what is the specific injury pattern?
. Anteroposterior Compression (APC) Type I
. Anteroposterior Compression (APC) Type II
. Anteroposterior Compression (APC) Type III
. Lateral Compression (LC) Type II
. Vertical Shear (VS)

Correct Answer & Explanation

. Anteroposterior Compression (APC) Type II

Explanation

This is an Anteroposterior Compression (APC) Type II injury. APC II is characterized by disruption of the symphysis pubis (typically > 2.5 cm) and tearing of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. Crucially, the posterior sacroiliac ligaments remain intact, providing vertical stability but leaving the pelvis rotationally unstable. APC III would involve disruption of the posterior sacroiliac ligaments as well, causing both rotational and vertical instability.

Question 600

Topic: Pelvic & Acetabular Trauma
In the evaluation of adults with early-onset hip osteoarthritis secondary to childhood Legg-Calvรฉ-Perthes disease, the Stulberg classification is utilized to describe the residual head shape and its congruency with the acetabulum, which dictates the long-term prognosis. Which of the following best describes the radiographic appearance of a Stulberg Class III hip?
. A perfectly spherical femoral head with coxa magna and a short neck
. An aspherical (ovoid or mushroom-shaped) femoral head that is congruent with the acetabulum
. An aspherical (flattened) femoral head that is highly incongruent with the acetabulum
. A spherical femoral head with normal neck length and normal acetabulum
. Complete collapse of the femoral head with joint space obliteration before skeletal maturity

Correct Answer & Explanation

. An aspherical (ovoid or mushroom-shaped) femoral head that is congruent with the acetabulum

Explanation

The Stulberg classification predicts osteoarthritis risk. Class I is normal. Class II is a spherical head with a short, wide neck (coxa magna/breva). Class III is an aspherical (often ovoid or mushroom-shaped) femoral head that remains congruent with the shape of the acetabulum (they adapt to each other). Class IV is an aspherical head that is incongruent with the acetabulum (flat head, round cup). Class V is a completely flat, severely incongruent joint. Class III hips typically develop mild-to-moderate arthritis in late adulthood, whereas Class IV/V hips develop severe arthritis much earlier.

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