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Pelvic & Acetabular Trauma MCQs

Practice Set 11 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 201

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay after a high-speed motorcycle crash. His blood pressure is 70/40 mmHg and heart rate is 130 bpm. An AP pelvis radiograph demonstrates an APC-III pelvic ring injury. A FAST scan is negative. A pelvic binder is appropriately applied, but he remains hemodynamically unstable despite receiving 2 units of packed RBCs and plasma. What is the most appropriate next step in management?
. CT scan of the abdomen and pelvis with IV contrast
. Emergent exploratory laparotomy
. Preperitoneal pelvic packing and/or pelvic angiography
. Application of an external fixator in the Emergency Department
. Bilateral internal iliac artery ligation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angiography

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST scan (ruling out massive intra-abdominal hemorrhage), the bleeding is primarily venous or from pelvic arterial sources. Preperitoneal pelvic packing (PPP) and/or pelvic angiography with embolization are the treatments of choice after initial resuscitation and mechanical stabilization (binder).

Question 202

Topic: Pelvic & Acetabular Trauma
A 50-year-old pedestrian is struck from the side by a car. Pelvic radiographs show a transverse fracture of the pubic rami and a posterior iliac wing fracture that extends into the sacroiliac joint. What is the Young-Burgess classification of this injury, and what is the primary deforming force?
. Lateral Compression Type I; internal rotation
. Lateral Compression Type II; internal rotation
. Lateral Compression Type III; external rotation
. Anteroposterior Compression Type II; external rotation
. Vertical Shear; superior translation

Correct Answer & Explanation

. Lateral Compression Type II; internal rotation

Explanation

This is a Lateral Compression Type II (LC-II) pelvic ring injury. It is characterized by an anterior ring injury (e.g., transverse pubic rami fractures) combined with a crescent fracture of the posterior ilium extending into the SI joint. The primary deforming force in lateral compression injuries is internal rotation of the hemipelvis.

Question 203

Topic: Pelvic & Acetabular Trauma
A 40-year-old male is brought into the trauma bay with an APC-III (anteroposterior compression) pelvic ring injury and severe hemodynamic instability. A non-invasive pelvic binder is applied to reduce pelvic volume. To achieve maximal reduction of the symphyseal diastasis and control hemorrhage, over which anatomic landmark should the binder be centered?
. The iliac crests
. The anterior superior iliac spines (ASIS)
. The greater trochanters
. The level of the umbilicus
. The mid-thighs

Correct Answer & Explanation

. The greater trochanters

Explanation

Pelvic binders are a critical first step in managing hemodynamically unstable pelvic ring injuries, particularly open book (APC) patterns. To correctly apply vector force that effectively closes the pelvic ring and reduces the symphyseal diastasis, the binder must be centered directly over the greater trochanters. Placement too high (e.g., over the iliac crests or ASIS) is a common error and is ineffective at reducing pelvic volume.

Question 204

Topic: Pelvic & Acetabular Trauma

A 45-year-old male sustains a posterior dislocation of the right hip. Closed reduction is performed urgently in the emergency department. Post-reduction CT scan reveals a concentrically reduced hip, but shows a 4 mm intra-articular osteochondral fragment lodged within the weight-bearing dome of the acetabulum. What is the most appropriate next step in management?

. Skeletal traction for 6 weeks
. Operative intervention for fragment removal and joint debridement
. Immediate weight-bearing as tolerated
. MRI of the hip to assess the labrum before deciding on surgery
. Repeat closed reduction in the operating room

Correct Answer & Explanation

. Operative intervention for fragment removal and joint debridement

Explanation

A retained intra-articular fragment within the joint space, especially in the weight-bearing zone, will rapidly lead to third-body wear, cartilage destruction, and post-traumatic arthritis. It is an absolute indication for operative intervention (via arthroscopy, arthrotomy, or surgical dislocation) for removal.

Question 205

Topic: Pelvic & Acetabular Trauma
A 40-year-old male is brought to the trauma bay with hemodynamic instability following a crush injury to the pelvis. Radiographs demonstrate an anteroposterior compression (APC) III pelvic ring injury. A non-invasive pelvic binder is ordered. To optimally reduce pelvic volume and stabilize the ring, over which anatomic landmarks should the binder be centered?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines (ASIS)
. Pubic symphysis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

To effectively reduce an open-book pelvic injury (APC mechanism) and decrease pelvic volume, the pelvic binder must be centered over the greater trochanters. Placing the binder too high (e.g., over the iliac crests or ASIS) is a common error that fails to close the posterior ring and can paradoxically widen the pelvis.

Question 206

Topic: Pelvic & Acetabular Trauma

According to the Young-Burgess classification, an Anteroposterior Compression Type II (APC-II) pelvic ring injury opens the symphysis greater than 2.5 cm. Which ligaments remain intact in this injury, preventing complete vertical instability of the hemipelvis?

. Anterior sacroiliac ligaments
. Posterior sacroiliac ligaments
. Sacrotuberous ligaments
. Sacrospinous ligaments
. Iliolumbar ligaments

Correct Answer & Explanation

. Posterior sacroiliac ligaments

Explanation

An APC-II injury ('open book' pelvis) is characterized by disruption of the pubic symphysis, anterior sacroiliac (SI) ligaments, sacrospinous ligaments, and sacrotuberous ligaments. The posterior SI ligaments, which are the strongest ligaments in the body, remain intact. Thus, the pelvis is rotationally unstable but vertically stable.

Question 207

Topic: Pelvic & Acetabular Trauma

A 25-year-old male sustains a vertical shear pelvic ring injury. He is hypotensive in the ED. A pelvic binder is applied, but his blood pressure remains 70/40 mmHg despite 2 units of PRBCs. The FAST exam is negative. What is the most appropriate next step in management?

. Diagnostic peritoneal lavage
. Exploratory laparotomy
. Preperitoneal pelvic packing
. Bilateral internal iliac artery ligation
. Application of a halo-femoral traction pin

Correct Answer & Explanation

. Preperitoneal pelvic packing

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST (ruling out intra-abdominal hemorrhage), preperitoneal pelvic packing or emergent angiography is indicated. Packing is rapid, can be done immediately in the OR, and controls the venous bleeding that is the most common source of hemorrhage.

Question 208

Topic: Pelvic & Acetabular Trauma

A 35-year-old man is brought to the trauma bay after a motorcycle accident. He remains hemodynamically unstable despite aggressive initial fluid resuscitation. Radiographs show a 4 cm pubic symphysis diastasis with intact posterior sacroiliac ligaments. A pelvic binder is applied but he remains hypotensive. What is the next most appropriate step in management?

. Immediate open reduction and internal fixation of the symphysis
. Retrograde urethrogram
. Preperitoneal pelvic packing or angioembolization
. Application of an anterior external fixator
. CT scan of the abdomen and pelvis

Correct Answer & Explanation

. Preperitoneal pelvic packing or angioembolization

Explanation

The patient has an APC-II pelvic ring injury and is in hemorrhagic shock. Following mechanical stabilization with a pelvic binder, persistent hemodynamic instability dictates immediate intervention for hemorrhage control via preperitoneal pelvic packing or angiography with embolization.

Question 209

Topic: Pelvic & Acetabular Trauma

In a patient with an anteroposterior compression (APC) pelvic ring injury, at what threshold of pubic symphysis diastasis are the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments typically disrupted, signifying an APC II injury?

. > 1.0 cm
. > 1.5 cm
. > 2.5 cm
. > 3.5 cm
. > 5.0 cm

Correct Answer & Explanation

. > 2.5 cm

Explanation

A symphyseal diastasis greater than 2.5 cm is the classic threshold indicating rupture of the pelvic floor ligaments (sacrotuberous and sacrospinous) and the anterior sacroiliac ligaments. This injury pattern defines an APC II pelvic ring injury. A diastasis of less than 2.5 cm (APC I) usually indicates the posterior ligaments remain intact.

Question 210

Topic: Pelvic & Acetabular Trauma
A 30-year-old male arrives in the trauma bay in hemorrhagic shock following a motorcycle accident. Radiographs reveal an anteroposterior compression (APC) type III pelvic ring injury. What is the correct anatomical landmark for the application of a circumferential pelvic sheet or binder?
. Just proximal to the iliac crests
. Directly over the anterior superior iliac spines (ASIS)
. Centered over the greater trochanters
. Mid-thigh level to compress the femoral vessels
. Over the lower abdomen, just superior to the pubic symphysis

Correct Answer & Explanation

. Centered over the greater trochanters

Explanation

Pelvic binders should be centered directly over the greater trochanters. Placement higher over the iliac crests or abdomen is ineffective for reducing the pelvic volume and can paradoxically widen the pelvis in open-book injuries.

Question 211

Topic: Pelvic & Acetabular Trauma

A 32-year-old female presents with an anteroposterior compression (APC) type II pelvic ring injury following a crush accident. Which specific ligamentous structures are completely disrupted in an APC-II injury compared to an APC-I injury?

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

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

According to the Young-Burgess classification, an APC-II injury involves symphyseal diastasis with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. This results in rotational instability while maintaining vertical stability since the posterior SI ligaments remain intact.

Question 212

Topic: Pelvic & Acetabular Trauma

A 45-year-old pedestrian struck by a car presents with a hemodynamically stable APC-II (Anteroposterior Compression Type II) pelvic ring injury. Radiographs show a 3 cm pubic symphysis diastasis and widening of the anterior sacroiliac joints. According to the Young-Burgess classification, which of the following ligaments remains intact, preventing vertical instability?

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

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

In an APC-II injury, the pubic symphysis, anterior sacroiliac ligaments, sacrotuberous, and sacrospinous ligaments are disrupted. The posterior sacroiliac ligaments remain intact. This allows the hemipelvis to externally rotate (rotational instability or "open book") but prevents cranial migration (maintains vertical stability).

Question 213

Topic: Pelvic & Acetabular Trauma
A 40-year-old male sustains an APC-III pelvic ring injury. In the trauma bay, the decision is made to apply a non-invasive external pelvic binder to reduce pelvic volume. To maximize biomechanical efficacy, the binder should be centered over which of the following anatomic landmarks?
. Iliac crests
. Anterior superior iliac spines (ASIS)
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

For effective reduction of pelvic volume in anterior-posterior compression injuries, a pelvic binder must be applied directly over the greater trochanters. Placement higher over the iliac crests is incorrect and can paradoxically open the true pelvis further or be less effective in closing the symphyseal diastasis.

Question 214

Topic: Pelvic & Acetabular Trauma

On a standard anteroposterior (AP) radiograph of the pelvis in a patient with a suspected acetabular fracture, the iliopectineal line serves as the radiographic landmark for which structural component of the acetabulum?

. Anterior wall
. Posterior wall
. Anterior column
. Posterior column
. Quadrilateral plate

Correct Answer & Explanation

. Anterior column

Explanation

In the radiographic evaluation of acetabular fractures (Judet-Letournel principles), the iliopectineal line represents the anterior column. The ilioischial line represents the posterior column. The anterior rim of the acetabulum represents the anterior wall, and the posterior rim represents the posterior wall.

Question 215

Topic: Pelvic & Acetabular Trauma

A 28-year-old male is involved in a high-speed motorcycle accident and sustains a pelvic ring injury. Radiographs and CT demonstrate a symphysis pubis diastasis of 3.5 cm, with widening of the anterior sacroiliac joints. The posterior sacroiliac ligaments are intact. According to the Young and Burgess classification, what is the injury type and its primary plane of instability?

. Lateral Compression Type 1 (LC-1); internally rotationally unstable
. Lateral Compression Type 2 (LC-2); internally rotationally and vertically unstable
. Anteroposterior Compression Type 2 (APC-2); externally rotationally unstable but vertically stable
. Anteroposterior Compression Type 3 (APC-3); externally rotationally and vertically unstable
. Vertical Shear (VS); vertically and horizontally unstable

Correct Answer & Explanation

. Anteroposterior Compression Type 2 (APC-2); externally rotationally unstable but vertically stable

Explanation

An APC-2 injury is characterized by rupture of the symphysis pubis (>2.5 cm diastasis) and rupture of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact. This results in rotational instability (an 'open book' pelvis) but preserves vertical stability. APC-3 involves complete disruption of both anterior and posterior SI ligaments, resulting in both rotational and vertical instability.

Question 216

Topic: Pelvic & Acetabular Trauma
A 30-year-old male is brought to the trauma bay following a motorcycle crash. His pelvis is mechanically unstable (APC III pattern), his blood pressure is 70/40 mmHg, and his heart rate is 130 bpm. A pelvic binder is applied, and he remains hypotensive despite 2 liters of crystalloid and 2 units of PRBCs. FAST exam is negative. What is the most appropriate next step?
. Bilateral retrograde intramedullary femoral nailing
. Pelvic angiography with embolization or pre-peritoneal packing
. Immediate open reduction and internal fixation of the symphysis pubis
. Laparotomy for bowel exploration
. Application of an external fixator followed by CT scan

Correct Answer & Explanation

. Pelvic angiography with embolization or pre-peritoneal packing

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST scan, the source of bleeding is retroperitoneal. Pre-peritoneal pelvic packing or angiography with embolization is the critical next step to achieve hemostasis.

Question 217

Topic: Pelvic & Acetabular Trauma
A 42-year-old male arrives in the trauma bay with an APC-III pelvic ring injury and a systolic blood pressure of 75 mmHg. A pelvic binder is applied. What is the correct anatomical placement for the pelvic binder to effectively reduce pelvic volume?
. Over the iliac crests
. At the level of the greater trochanters
. Over the umbilicus
. Just proximal to the anterior superior iliac spines (ASIS)
. Around the mid-thighs

Correct Answer & Explanation

. At the level of the greater trochanters

Explanation

To effectively reduce pelvic volume and stabilize the pelvic ring in an anteroposterior compression (APC) injury, a pelvic binder or sheet must be centered at the level of the greater trochanters. Placing it over the iliac crests is ineffective and can exacerbate the deformity.

Question 218

Topic: Pelvic & Acetabular Trauma
A 28-year-old male construction worker is crushed by heavy equipment, sustaining an anteroposterior compression (APC) type III pelvic ring injury. Examination reveals blood at the urethral meatus and a high-riding prostate on digital rectal exam. What is the most appropriate next step in his urologic evaluation?
. CT cystogram
. Suprapubic catheterization
. Retrograde urethrogram
. Pelvic angiography
. Transrectal ultrasound

Correct Answer & Explanation

. Retrograde urethrogram

Explanation

Blood at the meatus and a high-riding prostate strongly suggest a urethral disruption, which is highly associated with pelvic ring disruptions. A retrograde urethrogram (RUG) must be performed prior to the insertion of a Foley catheter to prevent converting a partial tear into a complete transection.

Question 219

Topic: Pelvic & Acetabular Trauma

A 38-year-old male sustains an anteroposterior compression type II (APC-II) pelvic ring injury. Based on the Young-Burgess classification, which of the following ligaments must be disrupted to define this specific injury pattern?

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Posterior sacroiliac and sacrotuberous ligaments
. Iliolumbar and posterior sacroiliac ligaments
. Anterior sacroiliac and iliolumbar ligaments
. Sacrospinous and posterior sacroiliac ligaments

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC-II injury is characterized by symphyseal diastasis and widening of the anterior SI joint. This requires rupture of the anterior sacroiliac ligaments as well as the pelvic floor ligaments (sacrotuberous and sacrospinous). The posterior sacroiliac ligaments remain intact, conferring vertical stability but leaving the pelvis rotationally unstable.

Question 220

Topic: Pelvic & Acetabular Trauma

A 24-year-old male sustains an anteroposterior compression type II (APC-II) pelvic ring injury. According to the Young-Burgess classification, which posterior pelvic ligaments are disrupted and which remain intact in an APC-II injury?

. Anterior sacroiliac ligaments are disrupted; posterior sacroiliac ligaments are intact
. Both anterior and posterior sacroiliac ligaments are disrupted; sacrotuberous ligament is intact
. Anterior sacroiliac ligaments are intact; posterior sacroiliac ligaments are disrupted
. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments are disrupted; posterior sacroiliac ligaments are intact
. All anterior, posterior, sacrotuberous, and sacrospinous ligaments are disrupted

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments are disrupted; posterior sacroiliac ligaments are intact

Explanation

In an APC-II pelvic ring injury ('open book' pelvis), the symphysis pubis is diastatic (>2.5 cm). Posteriorly, the anterior sacroiliac ligaments, as well as the sacrotuberous and sacrospinous ligaments, are disrupted, causing rotational instability. The robust posterior sacroiliac ligaments remain intact, maintaining vertical stability.

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