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Pelvic & Acetabular Trauma MCQs

Practice Set 23 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 441

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the ED after a motorcycle collision. He is hypotensive (BP 75/40 mmHg) and tachycardic (HR 130). AP pelvis radiograph shows a widened pubic symphysis of 4 cm and widened bilateral sacroiliac joints. A pelvic binder has been applied appropriately but he remains hemodynamically unstable after 2 liters of crystalloid and 2 units of packed red blood cells. What is the most appropriate next step in management?
. Emergent CT abdomen and pelvis
. External fixation of the pelvis in the emergency department
. Preperitoneal pelvic packing and/or angioembolization
. Exploratory laparotomy with internal fixation of the pelvis
. Re-application of the pelvic binder and observation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angioembolization

Explanation

In a hemodynamically unstable patient with an unstable pelvic ring injury (such as an APC-III), if the patient remains unstable despite initial resuscitation and pelvic binder application, emergent hemorrhage control is indicated. This is typically achieved via preperitoneal pelvic packing, pelvic angiography with embolization, or a combination of both. Exploratory laparotomy is generally reserved for intraperitoneal bleeding (e.g., positive FAST). External fixation takes time and does not stop venous bleeding as effectively as packing, nor arterial bleeding as well as embolization.

Question 442

Topic: Pelvic & Acetabular Trauma

A 42-year-old hemodynamically unstable male presents after a high-speed motor vehicle collision. A pelvic AP radiograph reveals a symphyseal diastasis of 4 cm and disruption of the anterior sacroiliac ligaments bilaterally. He is tachycardic (130 bpm) and hypotensive (80/50 mmHg). FAST exam is negative. What is the most appropriate initial step in management?

. Angiography with embolization
. Application of a pelvic binder centered over the greater trochanters
. Exploratory laparotomy
. External fixation of the pelvis
. Retrograde urethrogram

Correct Answer & Explanation

. Application of a pelvic binder centered over the greater trochanters

Explanation

In a hemodynamically unstable patient with an anteroposterior compression (APC) type pelvic ring injury (often presenting as an 'open book' pelvis), the immediate priority is mechanical stabilization to reduce pelvic volume. A pelvic binder, properly centered over the greater trochanters (not the iliac crests), is the most rapid and effective initial non-invasive step. If instability persists despite adequate volume reduction and fluid resuscitation, angiography with embolization or pre-peritoneal packing is indicated.

Question 443

Topic: Pelvic & Acetabular Trauma
A 28-year-old male is brought to the trauma bay after a high-speed motorcycle collision. His blood pressure is 80/50 mmHg, and his heart rate is 130 bpm. FAST examination is negative. Pelvic radiographs demonstrate an anteroposterior compression type III (APC-III) pelvic ring injury. A pelvic binder is applied appropriately, and he receives 2 units of uncrossmatched packed RBCs, but his blood pressure remains 85/55 mmHg. What is the most appropriate next step in management?
. Diagnostic peritoneal lavage
. Computed tomography of the abdomen and pelvis
. Pre-peritoneal pelvic packing and/or pelvic angiography with embolization
. Immediate open reduction and internal fixation of the anterior and posterior pelvic ring
. Application of a hip spica cast

Correct Answer & Explanation

. Pre-peritoneal pelvic packing and/or pelvic angiography with embolization

Explanation

This patient is hemodynamically unstable due to a major pelvic ring disruption (likely venous plexus bleeding or arterial injury), with no evidence of intra-abdominal hemorrhage (negative FAST). Mechanical stabilization with a pelvic binder is the first step. If the patient remains hemodynamically unstable despite a binder and initial volume resuscitation, emergent hemorrhage control is required. According to advanced trauma protocols, this should be achieved via pre-peritoneal pelvic packing (PPP) and/or pelvic angiography with embolization. CT is contraindicated in a persistently hemodynamically unstable patient.

Question 444

Topic: Pelvic & Acetabular Trauma
A 42-year-old male is brought to the emergency department after a high-speed motor vehicle collision. He is hemodynamically unstable with a blood pressure of 75/40 mmHg. Pelvic radiographs reveal an anteroposterior compression (APC) type III pelvic ring injury. A pelvic binder is applied, and he receives massive transfusion protocol. His FAST exam is negative. What is the most common anatomical source of massive hemorrhage in this specific clinical presentation?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. Cancellous bone bleeding
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

In pelvic ring injuries, particularly those involving widening of the sacroiliac joints and disruption of the posterior ligamentous complex (like APC III and vertical shear injuries), the most common source of massive pelvic hemorrhage (up to 80-90% of cases) is the presacral and prevesical venous plexuses, followed by cancellous bone bleeding. Arterial bleeding accounts for only 10-20% of cases. The superior gluteal artery is the most commonly injured artery, but overall venous bleeding remains the predominant source of hemodynamic instability.

Question 445

Topic: Pelvic & Acetabular Trauma
A 28-year-old male presents in hemorrhagic shock following a high-speed motorcycle crash. A pelvic radiograph reveals an anterior-posterior compression type III (APC-III) pelvic ring injury. A pelvic binder is immediately applied, and a massive transfusion protocol is initiated. A FAST (Focused Assessment with Sonography for Trauma) scan is negative. His blood pressure remains 70/40 mm Hg. What is the most appropriate next step in management?
. Exploratory laparotomy
. Computed tomography (CT) scan of the abdomen and pelvis
. Placement of a supra-acetabular external fixator
. Retroperitoneal pelvic packing and/or angioembolization
. Definitive open reduction and internal fixation of the symphysis pubis

Correct Answer & Explanation

. Retroperitoneal pelvic packing and/or angioembolization

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST scan, the primary source of hemorrhage is presumed to be the retroperitoneal venous plexus or pelvic arterial branches. Following initial volume reduction with a binder, the next most appropriate step in a patient who remains hypotensive is retroperitoneal pelvic packing (RPP) or pelvic angioembolization to achieve direct hemostasis. CT scanning is contraindicated in hemodynamically unstable patients. Laparotomy is indicated if the FAST scan is positive (intra-abdominal bleeding).

Question 446

Topic: Pelvic & Acetabular Trauma

A 28-year-old man is struck by a car and sustains an anteroposterior compression type II (APC-II) pelvic ring injury. He is hemodynamically stable. Fluoroscopic examination under anesthesia demonstrates 3 cm of symphyseal diastasis and widening of the anterior sacroiliac joints. Which of the following ligaments must be disrupted to produce this specific injury pattern?

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

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC-II pelvic ring injury ('open book' pelvis) involves disruption of the symphysis pubis (or anterior rami) along with the anterior sacroiliac ligaments, sacrotuberous ligaments, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact, which preserves vertical stability while allowing rotational instability.

Question 447

Topic: Pelvic & Acetabular Trauma
A 45-year-old male presents in hemorrhagic shock following a high-speed motor vehicle collision. Primary survey reveals an unstable pelvis. Anteroposterior pelvic radiograph demonstrates an anteroposterior compression type III (APC III) injury. A pelvic binder is to be applied. What is the anatomically correct landmark for the placement of the pelvic binder to optimally reduce pelvic volume?
. Centered over the iliac crests
. Centered over the greater trochanters
. Centered over the anterior superior iliac spines
. Transversely at the level of the umbilicus
. Circumferentially bridging the costal margin to the iliac wings

Correct Answer & Explanation

. Centered over the greater trochanters

Explanation

The optimal placement for a pelvic binder is centered over the greater trochanters. This allows the forces to be transmitted directly through the femurs to the pubic symphysis, effectively closing the pelvic ring and reducing pelvic volume in "open book" (APC) injuries. Placement over the iliac crests is a common error; it is less effective and can paradoxically open the true pelvis further or cause skin necrosis over bony prominences.

Question 448

Topic: Pelvic & Acetabular Trauma

A 42-year-old male presents hypotensive (BP 75/40 mmHg) after a severe crush injury. AP pelvis radiograph demonstrates a 4-cm pubic symphysis diastasis and disruption of the bilateral sacroiliac joints. A pelvic binder is applied in the trauma bay, but his blood pressure remains 80/40 mmHg despite balanced crystalloid and blood product resuscitation. A FAST exam is negative. What is the most appropriate next step in management?

. Retrograde urethrogram
. Pelvic angiography with possible embolization
. Immediate anterior plate fixation of the symphysis pubis
. Percutaneous sacroiliac joint screw fixation
. Exploratory laparotomy

Correct Answer & Explanation

. Pelvic angiography with possible embolization

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, retroperitoneal hemorrhage is the most likely source of bleeding. When mechanical stabilization (e.g., pelvic binder) fails to restore hemodynamics, pelvic angiography is indicated to identify and embolize arterial bleeders. The most commonly injured arteries are branches of the internal iliac artery, such as the superior gluteal or internal pudendal arteries.

Question 449

Topic: Pelvic & Acetabular Trauma

A 35-year-old male is brought to the trauma bay after a motorcycle crash. His blood pressure is 75/40 mmHg, and his heart rate is 135 bpm. A FAST scan is negative. Pelvic radiograph shows a widened pubic symphysis of 4 cm and bilateral sacroiliac joint disruptions. A pelvic binder is placed, and he receives 2 units of uncrossmatched blood, but his blood pressure remains 80/45 mmHg. What is the most appropriate next step in management?

. CT abdomen and pelvis
. Exploratory laparotomy
. Preperitoneal pelvic packing and/or angioembolization
. Application of an anterior external fixator
. Zone 3 REBOA placement

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angioembolization

Explanation

Hemodynamically unstable patients with pelvic ring injuries and a negative FAST scan require immediate intervention for pelvic hemorrhage. Preperitoneal pelvic packing or angioembolization are the treatments of choice for ongoing hemorrhage from the presacral venous plexus or internal iliac arterial branches. Binder or sheet placement is the initial step to reduce pelvic volume. CT scan is contraindicated in a hemodynamically unstable patient.

Question 450

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the trauma bay following a high-speed motor vehicle collision. His blood pressure is 70/40 mm Hg and heart rate is 130 bpm. A pelvic radiograph demonstrates an anteroposterior compression type III (APC III) pelvic ring injury. A pelvic binder is applied correctly, and 2 units of uncrossmatched whole blood are administered. A FAST exam is negative for intraperitoneal fluid. His hemodynamics do not improve despite resuscitation. What is the most appropriate next step in management?
. Application of a pelvic external fixator
. Preperitoneal pelvic packing
. CT angiography of the abdomen and pelvis
. Exploratory laparotomy
. Immediate open reduction and internal fixation of the pubic symphysis

Correct Answer & Explanation

. Preperitoneal pelvic packing

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST exam, the primary source of bleeding is assumed to be the pelvic retroperitoneum (venous plexus and cancellous bone). Once a pelvic binder is applied to reduce pelvic volume and stabilize the fracture, if the patient remains unstable, immediate preperitoneal pelvic packing (PPP) and/or pelvic angioembolization is indicated. Sending a hemodynamically unstable patient to the CT scanner is contraindicated. Since the binder is already applied, exchanging it for an external fixator will not provide significantly better immediate hemorrhage control in a patient in extremis.

Question 451

Topic: Pelvic & Acetabular Trauma

A 22-year-old male hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. An AP pelvis radiograph demonstrates an abnormal pistol-grip deformity of the proximal femur.

Which of the following is the most likely initial intra-articular pathologic consequence of this specific deformity?

. Delamination of the acetabular cartilage at the anterosuperior chondrolabral junction
. Tear of the ligamentum teres
. Global pincer-type impingement with posterior chondral damage
. Isolated degeneration of the posterior labrum
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Delamination of the acetabular cartilage at the anterosuperior chondrolabral junction

Explanation

A cam deformity creates shear forces at the anterosuperior acetabulum during hip flexion and internal rotation. This classically leads to outside-in delamination of the acetabular cartilage at the chondrolabral junction.

Question 452

Topic: Pelvic & Acetabular Trauma

A 24-year-old male athlete presents with anterior groin pain exacerbated by hip flexion and internal rotation. Radiographs (

) demonstrate an abnormally elevated alpha angle. In this condition, what is the most likely location of the primary articular cartilage damage?

. Anterosuperior acetabulum
. Posteroinferior acetabulum
. Anteroinferior femoral head
. Posterosuperior femoral head
. Fovea capitis

Correct Answer & Explanation

. Anterosuperior acetabulum

Explanation

An elevated alpha angle indicates cam-type femoroacetabular impingement. The non-spherical femoral head engages the acetabulum during flexion, typically causing chondrolabral delamination and articular cartilage damage in the anterosuperior acetabulum.

Question 453

Topic: Pelvic & Acetabular Trauma

A 28-year-old woman with symptomatic developmental dysplasia of the hip (DDH) is undergoing a Bernese periacetabular osteotomy (PAO). Which of the following best describes the key biomechanical advantage and anatomical characteristic of this specific osteotomy technique?

. Complete detachment of the posterior column allowing maximal anterior coverage
. Preservation of an intact posterior column which maintains pelvic ring stability
. Utilization of a single iliac osteotomy hinged strictly at the pubic symphysis
. Requirement for rigid multi-segment posterior fixation extending to the sacrum
. Mandatory disruption of the obturator foramen to allow multiplanar rotation

Correct Answer & Explanation

. Preservation of an intact posterior column which maintains pelvic ring stability

Explanation

The Bernese periacetabular osteotomy (PAO), developed by Ganz, is unique in that it relies on incomplete osteotomies that preserve the continuity of the posterior column of the hemipelvis. By leaving the posterior column intact, the inherent stability of the pelvic ring is maintained. This major biomechanical advantage allows for extensive multiplanar correction of the acetabulum while minimizing blood loss and permitting early postoperative mobilization without the need for casting.

Question 454

Topic: Pelvic & Acetabular Trauma

A 28-year-old male athlete presents with anterior groin pain exacerbated by hip flexion and internal rotation. A lateral radiograph of the hip reveals an alpha angle of 75 degrees. Which of the following is the primary mechanism of cartilage injury in this condition?

. Pincer impingement causing global cartilage wear
. Shear stress at the chondrolabral junction
. Contrecoup lesion on the posterior acetabulum
. Labral hypertrophy leading to capsular laxity
. Dysplastic uncovering of the femoral head

Correct Answer & Explanation

. Shear stress at the chondrolabral junction

Explanation

Cam impingement, indicated by an alpha angle >50-55 degrees, involves a non-spherical femoral head compressing against the acetabulum. This creates shear stress that leads to delamination at the chondrolabral junction.

Question 455

Topic: Pelvic & Acetabular Trauma

A 24-year-old woman presents with hip pain secondary to developmental dysplasia. Radiographs show a lateralized center of rotation, unroofed femoral head, and a sharply sloping sourcil. A periacetabular osteotomy (PAO) is planned. The cuts for a Ganz PAO involve which of the following pelvic bones?

. Ilium, ischium, and pubis
. Ilium and pubis only
. Ilium and ischium only
. Ischium and pubis only
. Ilium, ischium, pubis, and sacrum

Correct Answer & Explanation

. Ilium, ischium, and pubis

Explanation

The Ganz periacetabular osteotomy (PAO) involves cuts through the ilium, ischium, and pubis while preserving the posterior column. This allows for multiplanar correction while maintaining pelvic ring stability.

Question 456

Topic: Pelvic & Acetabular Trauma

A 19-year-old rugby player sustains a lateral compression injury to his left shoulder. He presents with severe chest pain, shortness of breath, and dysphagia. Examination shows a depression at the left sternoclavicular (SC) joint. Which of the following imaging modalities is the gold standard for diagnosing and assessing the direction of this dislocation?

. Anteroposterior chest radiograph
. Serendipity view radiograph
. Magnetic Resonance Imaging (MRI)
. Computed Tomography (CT) scan
. Ultrasound

Correct Answer & Explanation

. Computed Tomography (CT) scan

Explanation

Posterior sternoclavicular joint dislocations are orthopedic emergencies due to the proximity of the great vessels and trachea. A CT scan of the chest is the gold standard for confirming the dislocation and evaluating the compression of critical mediastinal structures.

Question 457

Topic: Pelvic & Acetabular Trauma

When placing an iliosacral screw into the S1 vertebral body for pelvic ring fixation, anterior misplacement of the screw out of the sacral ala places which nerve root at greatest risk of direct injury?

. L4
. L5
. S1
. S2
. S3

Correct Answer & Explanation

. L5

Explanation

The L5 nerve root courses directly anterior to the sacral ala after exiting the L5-S1 foramen. Therefore, errant anterior placement of an S1 iliosacral screw places the L5 nerve root in immediate jeopardy.

Question 458

Topic: Pelvic & Acetabular Trauma

During which phase of the overhead throwing motion do the highest compressive forces occur at the radiocapitellar joint, potentially leading to valgus extension overload?

. Wind-up
. Early cocking
. Late cocking
. Acceleration
. Deceleration

Correct Answer & Explanation

. Acceleration

Explanation

During the acceleration phase of throwing, tremendous valgus torque is placed on the elbow. This causes medial tension (stressing the UCL) and lateral compression, which can lead to radiocapitellar chondromalacia and valgus extension overload.

Question 459

Topic: Pelvic & Acetabular Trauma

A 24-year-old female with residual dysplasia of the hip presents with groin pain.

Radiographs demonstrate a closed triradiate cartilage, a center-edge (CE) angle of 12 degrees, and an anteriorly deficient acetabulum. She is scheduled for a Bernese periacetabular osteotomy (PAO). Which of the following is the primary advantage of the PAO over a standard Salter osteotomy in this patient?

. It hinges on the pubic symphysis to maintain pelvic volume
. It preserves the posterior column, maintaining immediate pelvic ring stability
. It relies on an open triradiate cartilage to achieve correction
. It is performed strictly through a minimally invasive posterior approach
. It inherently lengthens the operated limb by at least 2 cm

Correct Answer & Explanation

. It preserves the posterior column, maintaining immediate pelvic ring stability

Explanation

The Bernese periacetabular osteotomy (PAO) is indicated for skeletally mature hips and preserves the posterior column of the hemipelvis. This structural preservation allows for immediate postoperative pelvic stability and permits extensive, multi-planar correction of the acetabulum.

Question 460

Topic: Pelvic & Acetabular Trauma



A 40-year-old woman with severe developmental dysplasia of the hip (Crowe Type IV) is undergoing THA. The femoral head is entirely superior to the true acetabulum. Placing the cup in the true acetabulum will most likely require which concurrent procedure?

. Greater trochanteric advancement
. Subtrochanteric shortening osteotomy
. Isolated adductor tenotomy
. Iliopsoas fractional lengthening only
. Pelvic support osteotomy

Correct Answer & Explanation

. Subtrochanteric shortening osteotomy

Explanation

In Crowe IV dysplasia, restoring the anatomic hip center requires significant distal translation of the femur. A subtrochanteric shortening osteotomy is typically necessary to safely reduce the hip without causing sciatic nerve stretch injury.

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