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Pelvic & Acetabular Trauma MCQs

Practice Set 3 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 41

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is crushed by a heavy machine and sustains a pelvic ring injury. Initial radiographs show widening of the pubic symphysis of 3.5 cm with disruption of the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments, but the posterior sacroiliac complex remains intact. Which of the following Young-Burgess classifications best describes this injury?
. 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

An APC Type II injury is characterized by symphyseal diastasis > 2.5 cm and disruption of the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments, causing rotational instability. The intact posterior sacroiliac ligaments maintain the vertical stability of the hemipelvis.

Question 42

Topic: Pelvic & Acetabular Trauma

The primary purpose of osteotomy in the closure of classic exstrophy of the bladder is to:

. Decrease the tension on the closure of the abdominal wall and bladder
. Decrease the strain on the sacroiliac joints
. Prevent degenerative disease of the hip
. Normalize the gait
. Allow reconstruction of a normal symphysis pubis

Correct Answer & Explanation

. Decrease the tension on the closure of the abdominal wall and bladder

Explanation

The primary purpose of osteotomy is to improve the chance of a successful urologic reconstruction. This is achieved by decreasing the tension on the closure of the abdominal wall and bladder. The strain on the sacroiliac joints has not been measured with or without closure; this is not a primary purpose of the osteotomy. There is no conclusive evidence that the hips are at increased risk of degenerative disease in patients with exstrophy, or that osteotomy will alter the condition. In patients with exstrophy, the gait progressively normalizes over time. It is not possible to reconstruct a normal symphysis pubis in exstrophy.

Question 43

Topic: Pelvic & Acetabular Trauma

Which of the following is not a common finding in cloacal exstrophy:

. Omphalocele
. Spinal dysrhaphism
. Hydrocephalus
. Dysplasia of the sacroiliac joints
. Dislocation of the hip(s)

Correct Answer & Explanation

. Hydrocephalus

Explanation

Hydrocephalus is rare because most patients have lipomeningocele, not myelomeningocele. Omphalocele is common in cloacal exstrophy. Most patients with cloacal exstrophy have a lipomeningocele that is a form of spinal dysrhaphism. Many patients have malformations of the sacroiliac joints. Approximately 25% of patients have dislocations of at least one hip.

Question 44

Topic: Pelvic & Acetabular Trauma

A 25-year-old man is brought to the emergency department after a motorcycle collision. Radiographs demonstrate symphyseal widening of 3.5 cm and widening of the anterior sacroiliac joints bilaterally. The posterior sacroiliac ligaments are intact. According to the Young-Burgess classification, which of the following ligaments is ruptured?

. Anterior sacroiliac, sacrospinous, and sacrotuberous ligaments
. Posterior sacroiliac and sacrotuberous ligaments
. Iliolumbar and posterior sacroiliac ligaments
. Anterior sacroiliac ligament only
. Sacrotuberous and sacrospinous ligaments only

Correct Answer & Explanation

. Anterior sacroiliac, sacrospinous, and sacrotuberous ligaments

Explanation

This is an APC-II pelvic ring injury (symphyseal widening greater than 2.5 cm with anterior SI joint widening). It is characterized by rupture of the symphyseal, anterior sacroiliac, sacrospinous, and sacrotuberous ligaments, while the strong posterior sacroiliac ligaments remain intact.

Question 45

Topic: Pelvic & Acetabular Trauma

Which of the following ligaments is the strongest in the body and provides the primary stability to the posterior pelvic ring against vertical shear forces?

. Anterior sacroiliac ligament
. Sacrotuberous ligament
. Sacrospinous ligament
. Interosseous sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Interosseous sacroiliac ligament

Explanation

The interosseous sacroiliac ligament is the strongest ligament in the body. It plays the primary role in stabilizing the posterior pelvic ring, particularly against vertical shear stresses.

Question 46

Topic: Pelvic & Acetabular Trauma

Where is the anatomically correct position to apply a pelvic binder to effectively reduce a suspected 'open book' pelvic ring injury?

. At the level of the iliac crests
. At the level of the anterior superior iliac spines
. Centered over the greater trochanters
. Below the level of the lesser trochanters
. Around the mid-thighs

Correct Answer & Explanation

. Centered over the greater trochanters

Explanation

A pelvic binder must be centered over the greater trochanters to directly close the pelvic ring through the pubic symphysis. Placement over the iliac crests is incorrect and can paradoxically open the pelvis further.

Question 47

Topic: Pelvic & Acetabular Trauma
A hypotensive trauma patient is diagnosed with an anteroposterior compression type III (APC-III) pelvic ring disruption. A pelvic binder is applied, and the patient undergoes immediate pre-peritoneal pelvic packing. This intervention primarily aims to tamponade bleeding from which of the following anatomic structures?
. 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, the vast majority (up to 80-90%) of bleeding is venous in origin, primarily from the presacral venous plexus and prevesical veins. Pre-peritoneal packing effectively tamponades this low-pressure venous bleeding.

Question 48

Topic: Pelvic & Acetabular Trauma

According to the Young-Burgess classification, an Anteroposterior Compression Type II (APC II) pelvic ring injury is characterized by an open-book symphysis disruption along with the rupture of which specific posterior ligaments?

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Posterior sacroiliac ligaments only
. Anterior and posterior sacroiliac ligaments
. Sacrotuberous ligament only
. Iliolumbar ligaments only

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC II pelvic injury is defined by the rupture of the symphysis pubis alongside the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The structurally critical posterior sacroiliac ligaments remain intact, providing vertical stability.

Question 49

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the ED after a crush injury. He is hemodynamically unstable with a blood pressure of 75/40 mmHg. Radiographs show an anteroposterior compression (APC) type III pelvic ring injury. A pelvic binder is applied. To maximize biomechanical efficacy, the binder should be centered over which anatomic landmark?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Subtrochanteric region

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders are most effective at reducing pelvic volume when centered directly over the greater trochanters. Placement over the iliac crests is less effective and can sometimes worsen the deformity by externally rotating the hemipelvis.

Question 50

Topic: Pelvic & Acetabular Trauma

In an APC-II (Anteroposterior Compression type II) pelvic ring injury, which of the following ligaments remains intact, thereby preventing complete vertical instability?

. Anterior sacroiliac ligament
. Sacrotuberous ligament
. Sacrospinous ligament
. Posterior sacroiliac ligament
. Symphyseal ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

In APC-II injuries, the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments tear, causing rotational instability. The posterior sacroiliac ligament remains intact, maintaining vertical stability of the pelvis.

Question 51

Topic: Pelvic & Acetabular Trauma
A patient sustains an anteroposterior compression type III (APC-III) pelvic ring injury. Which of the following ligamentous structures is completely disrupted in this injury pattern, distinguishing it from an APC-II injury?
. Anterior sacroiliac ligament
. Sacrospinous ligament
. Sacrotuberous ligament
. Posterior sacroiliac ligament
. Symphyseal ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

An APC-III injury involves complete disruption of both the anterior and posterior sacroiliac ligaments, leading to complete pelvic instability. An APC-II injury disrupts the anterior SI, sacrospinous, and sacrotuberous ligaments but spares the strong posterior SI ligaments.

Question 52

Topic: Pelvic & Acetabular Trauma
In the Young-Burgess classification, an anteroposterior compression type III (APC III) pelvic ring injury is characterized by the complete disruption of which of the following posterior structures?
. Anterior sacroiliac ligaments only
. Sacrotuberous and sacrospinous ligaments only
. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Posterior sacroiliac ligaments only
. Anterior and posterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Correct Answer & Explanation

. Anterior and posterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

APC III injuries involve complete disruption of the pubic symphysis anteriorly and all posterior stabilizing structures. This includes both the anterior and posterior sacroiliac ligaments, as well as the sacrotuberous and sacrospinous ligaments, leading to complete spinopelvic instability.

Question 53

Topic: Pelvic & Acetabular Trauma

In the initial resuscitation of a hemodynamically unstable patient with an anteroposterior compression (APC) pelvic ring injury, what is the correct anatomical landmark for the placement of a circumferential pelvic binder?

. Anterior superior iliac spines
. Iliac crests
. Greater trochanters
. Symphysis pubis
. Subtrochanteric femur

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders must be centered directly over the greater trochanters to effectively close the pelvic ring and reduce internal pelvic volume. Placement higher over the iliac crests is less effective and may paradoxically open the pelvic floor.

Question 54

Topic: Pelvic & Acetabular Trauma
An anteroposterior compression (APC) type III pelvic ring injury involves complete disruption of the anterior ring and posterior sacroiliac complex. Which specific posterior ligamentous structure disruption distinguishes an APC II from an APC III injury?
. Sacrotuberous ligament
. Sacrospinous ligament
. Anterior sacroiliac ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

An APC II injury involves disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but the strong posterior sacroiliac ligaments remain intact. An APC III injury involves disruption of these posterior sacroiliac ligaments, resulting in complete global instability.

Question 55

Topic: Pelvic & Acetabular Trauma

In a vertical shear pelvic ring injury, which muscle group is primarily responsible for the cephalad migration of the unstable hemipelvis?

. Hamstrings
. Gluteus maximus
. Quadratus lumborum
. Iliopsoas
. Rectus abdominis

Correct Answer & Explanation

. Quadratus lumborum

Explanation

The quadratus lumborum and the lateral abdominal wall musculature attach to the iliac crest. In a vertically unstable pelvic fracture, these muscles contract and draw the hemipelvis cranially.

Question 56

Topic: Pelvic & Acetabular Trauma
In an anteroposterior compression type III (APC-III) pelvic ring injury, which of the following ligamentous structures is completely disrupted, distinguishing it from an APC-II injury?
. Symphyseal ligaments
. Sacrospinous ligament
. Anterior sacroiliac ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

An APC-II injury involves disruption of the symphysis, anterior SI, sacrospinous, and sacrotuberous ligaments but leaves the posterior SI ligaments intact. An APC-III injury includes complete disruption of the posterior SI ligaments, causing complete global pelvic instability.

Question 57

Topic: Pelvic & Acetabular Trauma
A 40-year-old male sustains an anteroposterior compression (APC) type III pelvic ring injury after a motorcycle crash. Anteroposterior pelvic radiographs reveal a pubic symphysis diastasis of 3.5 cm and widening of the sacroiliac joints bilaterally. Which of the following ligamentous structures is completely disrupted in this specific injury pattern?
. Sacrospinous ligament only
. Sacrotuberous ligament only
. Anterior sacroiliac, sacrotuberous, sacrospinous, and posterior sacroiliac ligaments
. Anterior sacroiliac ligament only
. Posterior sacroiliac ligament only with intact anterior structures

Correct Answer & Explanation

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

Explanation

APC Type III injuries involve complete symphyseal diastasis with complete disruption of both the anterior and posterior sacroiliac ligaments, as well as the sacrotuberous and sacrospinous ligaments. This extensive ligamentous failure results in complete global instability of the hemipelvis.

Question 58

Topic: Pelvic & Acetabular Trauma

According to the Young-Burgess classification, an Anteroposterior Compression Type II (APC-II) pelvic ring injury is characterized by which of the following ligamentous disruptions?

. Symphysis disruption with intact anterior and posterior sacroiliac ligaments
. Symphysis disruption with torn anterior sacroiliac ligaments but intact posterior sacroiliac ligaments
. Symphysis disruption with completely torn anterior and posterior sacroiliac ligaments
. Complete disruption of the sacrotuberous, sacrospinous, and posterior sacroiliac ligaments only
. Vertical shear through the ilium with completely intact sacroiliac ligaments

Correct Answer & Explanation

. Symphysis disruption with torn anterior sacroiliac ligaments but intact posterior sacroiliac ligaments

Explanation

An APC-II injury is an "open book" pelvic fracture where the pubic symphysis is widened, the sacrotuberous/sacrospinous and anterior sacroiliac ligaments are disrupted, but the stout posterior sacroiliac ligaments remain intact.

Question 59

Topic: Pelvic & Acetabular Trauma

A 28-year-old motorcyclist is brought to the ED after a collision. Pelvic radiographs show a symphyseal diastasis of 3.5 cm and widening of the anterior sacroiliac joints bilaterally.

Which ligamentous structures are completely ruptured in this injury?

. Sacrotuberous, sacrospinous, and anterior sacroiliac ligaments
. Sacrotuberous and posterior sacroiliac ligaments
. Anterior and posterior sacroiliac ligaments
. Iliolumbar and anterior sacroiliac ligaments
. Sacrotuberous, sacrospinous, anterior, and posterior sacroiliac ligaments

Correct Answer & Explanation

. Sacrotuberous, sacrospinous, and anterior sacroiliac ligaments

Explanation

In an Anteroposterior Compression (APC) Type II injury, pubic symphysis diastasis exceeds 2.5 cm. There is rupture of the anterior SI, sacrotuberous, and sacrospinous ligaments, while the posterior SI ligaments remain intact providing vertical stability.

Question 60

Topic: Pelvic & Acetabular Trauma

A 42-year-old man presents in hemorrhagic shock following a severe crush injury to his pelvis. Pelvic radiograph shows a 4 cm pubic symphysis diastasis with disruption of the sacroiliac joints. Following 1L of crystalloid fluid, his blood pressure remains 75/40 mmHg. The most appropriate immediate next step in management is:

. Immediate operative open reduction and internal fixation
. Angiography for embolization
. Application of a circumferential pelvic binder
. Retrograde urethrogram
. Intravenous administration of high-dose vasopressors

Correct Answer & Explanation

. Application of a circumferential pelvic binder

Explanation

The initial management of a mechanically unstable pelvic ring injury in a hemodynamically unstable patient is closing the pelvic volume with a binder or sheet. This facilitates tamponade of venous bleeding and bony stabilization prior to potential angiography or surgery.

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