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2. Trauma MCQs

Practice Set 95 of 640

This practice set contains high-yield board review questions covering key concepts in 2. Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1881

Topic: Pelvic & Acetabular Trauma

A 45-year-old female presents to the trauma bay in hemorrhagic shock following a high-speed motor vehicle collision. Her pelvis is clinically unstable to compression. The trauma team decides to place a non-invasive commercial pelvic binder. To be maximally effective at reducing pelvic volume, the binder should be centered directly over which anatomical landmark?

. Anterior superior iliac spines
. Iliac crests
. Greater trochanters
. Pubic symphysis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders should be placed centered over the greater trochanters to effectively close the pelvic ring and reduce volume. Placement over the iliac crests or ASIS is less effective and may paradoxically open the pelvic ring or cause localized pressure necrosis.

Question 1882

Topic: 2. Trauma

A 28-year-old male presents with a pelvic ring injury.

The orthopedic surgeon requests standard trauma pelvic views. What is the correct radiographic beam projection required to obtain a standard pelvic inlet view to best assess anterior-posterior hemipelvic translation?

. 45 degrees cephalad
. 45 degrees caudad
. Perpendicular to the symphysis pubis
. 30 degrees internally rotated
. 15 degrees cephalad

Correct Answer & Explanation

. 45 degrees caudad

Explanation

The pelvic inlet view is obtained by angling the x-ray beam 45 degrees caudad (from the head towards the feet). This view optimally evaluates anterior or posterior translation of the hemipelvis and internal/external rotational deformities.

Question 1883

Topic: 2. Trauma
A 22-year-old male sustains an APC-III pelvic fracture and arrives hypotensive. Fluid resuscitation and a pelvic binder are applied, but he remains persistently hypotensive with a blood pressure of 75/40 mmHg. FAST exam is negative. What is the most appropriate next step in the management of this patient?
. Exploratory laparotomy
. CT scan of the abdomen and pelvis
. Pelvic angiography and embolization
. Immediate definitive open internal fixation
. Application of an external fixator and transfer to ICU

Correct Answer & Explanation

. Pelvic angiography and embolization

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam (indicating no major intra-abdominal hemorrhage), the pelvic bleeding must be addressed. Pelvic angiography with embolization (or preperitoneal pelvic packing) is the standard of care for retroperitoneal hemorrhage.

Question 1884

Topic: 2. Trauma

A patient with a vertical shear pelvic fracture undergoes closed reduction and percutaneous iliosacral screw fixation. During placement of an S1 screw, the drill breaches the anterior cortex of the sacral ala. Which of the following neurologic structures is at greatest immediate risk of injury?

. L4 nerve root
. L5 nerve root
. S1 nerve root
. Pudendal nerve
. Sciatic nerve proper

Correct Answer & Explanation

. L5 nerve root

Explanation

The L5 nerve root courses directly anterior to the sacral ala. A drill or screw breaching the anterior cortex of the upper sacrum in this region places the L5 nerve root at high risk for iatrogenic injury.

Question 1885

Topic: 2. Trauma

A 55-year-old male presents with a pelvic ring injury following a crush mechanism. Radiographs demonstrate an impacted, stable fracture of the anterior sacral ala and fractures of the ipsilateral superior and inferior pubic rami. According to the Young-Burgess classification, which mechanism of injury is responsible for this pattern?

. Anteroposterior compression
. Lateral compression
. Vertical shear
. Combined mechanism
. Axial loading

Correct Answer & Explanation

. Lateral compression

Explanation

An anterior sacral ala impaction fracture combined with transverse or oblique pubic rami fractures is characteristic of a Lateral Compression Type 1 (LC-1) injury. This is a rotationally unstable but vertically stable injury pattern.

Question 1886

Topic: Pelvic & Acetabular Trauma

A 30-year-old male presents with a completely unstable pelvic ring injury and gross blood at the urethral meatus. A retrograde urethrogram demonstrates a posterior urethral disruption. What is the most appropriate initial urologic management before definitive pelvic ring fixation?

. Placement of a transurethral Foley catheter
. Placement of a suprapubic catheter
. Immediate primary end-to-end urethral anastomosis
. Flexible cystoscopy and stenting
. Observation and delayed catheterization

Correct Answer & Explanation

. Placement of a suprapubic catheter

Explanation

In the setting of a posterior urethral disruption associated with a pelvic ring injury, placement of a suprapubic catheter is the standard initial management. Transurethral catheterization is contraindicated as it may convert a partial tear into a complete tear.

Question 1887

Topic: Pelvic & Acetabular Trauma
A patient with a severe lateral compression pelvic fracture is noted to have a large, fluctuant swelling over the left greater trochanteric region. Skin integrity is intact, but the skin feels highly mobile over the deep fascia. If left untreated, this specific lesion most strongly predisposes the patient to which of the following complications?
. Heterotopic ossification
. Deep surgical site infection after fixation
. Avascular necrosis of the femoral head
. Sciatic nerve compression
. Refractory hypovolemic shock

Correct Answer & Explanation

. Deep surgical site infection after fixation

Explanation

A Morel-Lavallée lesion is a closed internal degloving injury where skin and subcutaneous tissue are sheared from the underlying fascia, leading to a hemolymphatic fluid collection. If not adequately decompressed/debrided before internal fixation, it carries a very high risk of deep bacterial infection.

Question 1888

Topic: 2. Trauma

A 40-year-old female sustains a Denis Zone 3 sacral fracture in an equestrian accident. Which of the following neurologic deficits is most commonly associated with fractures occurring in this specific anatomic zone?

. Weakness in ankle dorsiflexion
. Weakness in hip abduction
. Loss of sensation over the medial calf
. Bowel and bladder dysfunction
. Weakness in knee extension

Correct Answer & Explanation

. Bowel and bladder dysfunction

Explanation

Denis Zone 3 involves the central sacral canal. Fractures in this zone have the highest rate of neurologic injury (over 50%), specifically involving the sacral nerve roots (S2-S4), which classically present with sphincter paralysis and bowel/bladder dysfunction.

Question 1889

Topic: 2. Trauma

Which of the following posterior pelvic ring injuries is classically described in a Lateral Compression Type 2 (LC-2) injury according to the Young-Burgess classification?

. Complete disruption of the posterior sacroiliac ligaments
. Iliac wing 'crescent' fracture
. Sacral ala impaction fracture
. Bilateral transforaminal sacral fractures
. Avulsion of the ischial tuberosity

Correct Answer & Explanation

. Iliac wing 'crescent' fracture

Explanation

The Young-Burgess LC-2 pattern is characterized by a lateral compression force that causes an anterior pubic rami fracture and an ipsilateral posterior iliac wing fracture extending into the sacroiliac joint, known as a 'crescent' fracture.

Question 1890

Topic: 2. Trauma

Which of the following veins is the most common anatomical source of massive retroperitoneal hemorrhage following a high-energy pelvic ring disruption?

. External iliac vein
. Internal iliac vein
. Common iliac vein
. Presacral venous plexus
. Inferior vena cava

Correct Answer & Explanation

. Presacral venous plexus

Explanation

The vast majority (80-90%) of bleeding in pelvic fractures is venous in origin. The highly vascular cancellous bone and the extensive presacral venous plexus are the most common sources of hemorrhage.

Question 1891

Topic: 2. Trauma

A 32-year-old construction worker falls from a height, sustaining bilateral vertical transforaminal sacral fractures combined with a transverse fracture through the S2 body. This injury is clinically classified as a spinopelvic dissociation. Which of the following is the most appropriate surgical treatment to address this specific pathology?

. Anterior plate fixation of the symphysis only
. Bilateral percutaneous iliosacral screws only
. Lumbopelvic fixation (triangular osteosynthesis)
. Anterior external fixator
. Sacral laminectomy without stabilization

Correct Answer & Explanation

. Lumbopelvic fixation (triangular osteosynthesis)

Explanation

A U-shaped or H-shaped sacral fracture represents a spinopelvic dissociation, disconnecting the axial spine from the pelvis. It requires extremely rigid stabilization to withstand vertical shear forces, best achieved through lumbopelvic fixation (spanning from the lower lumbar pedicles to the ilium).

Question 1892

Topic: 2. Trauma
A 45-year-old male sustains an APC-III pelvic injury and undergoes urgent pelvic packing and application of an external fixator. Forty-eight hours later, he is brought back to the OR for definitive open reduction and internal fixation of the pubic symphysis. The symphysis is reduced and fixed with a multi-hole plate. What is the most common mode of failure for isolated anterior plate fixation in a completely unstable posterior ring injury?
. Plate fracture
. Screw pull-out
. Infection
. Aseptic nonunion
. Osteolysis

Correct Answer & Explanation

. Screw pull-out

Explanation

If an APC-III injury (which has complete anterior and posterior instability) is treated with isolated anterior plate fixation without stabilizing the posterior ring, the anterior hardware will bear excessive stress, most commonly leading to screw pull-out or hardware failure.

Question 1893

Topic: 2. Trauma

A Day Type 1 crescent fracture involves the posterior iliac wing and extends into the sacroiliac joint. Based on the Day classification system, in which section of the sacroiliac joint does a Type 1 crescent fracture exit?

. Anterior third of the sacroiliac joint
. Middle third of the sacroiliac joint
. Posterior third of the sacroiliac joint
. It completely bypasses the sacroiliac joint
. It exits through the greater sciatic notch

Correct Answer & Explanation

. Anterior third of the sacroiliac joint

Explanation

The Day classification describes the amount of ilium remaining attached to the sacrum. Type 1 enters the anterior aspect of the SI joint (leaving a large crescent attached to the sacrum). Type 2 enters the middle aspect, and Type 3 enters the posterior aspect (leaving a small crescent attached).

Question 1894

Topic: 2. Trauma

A trauma patient has an open pelvic ring fracture with a large laceration extending from the perineum into the anal sphincter. Fecal contamination is present. In addition to thorough debridement and pelvic stabilization, what is the most critical adjunctive procedure to minimize mortality from pelvic sepsis?

. Primary closure of the perineal wound
. Application of a negative pressure wound therapy device only
. Diverting colostomy
. Prolonged intravenous administration of carbapenems
. Prophylactic internal iliac artery embolization

Correct Answer & Explanation

. Diverting colostomy

Explanation

Open pelvic fractures with massive perineal soft tissue injury and rectal involvement carry an exceptionally high risk of overwhelming sepsis. A diverting colostomy is critical to prevent ongoing fecal contamination of the open fracture hematoma.

Question 1895

Topic: Pelvic & Acetabular Trauma

During radiographic evaluation of a pelvic ring injury, the 'outlet' view is best utilized to assess which of the following deformities?

. Internal rotation of the hemipelvis
. External rotation of the hemipelvis
. Anterior-posterior translation
. Vertical displacement of the hemipelvis
. Acetabular wall comminution

Correct Answer & Explanation

. Vertical displacement of the hemipelvis

Explanation

The pelvic outlet view (angled 45 degrees cephalad) projects the sacrum in its true en face orientation. It is the most accurate radiographic view for evaluating superior-inferior (vertical) displacement of the hemipelvis and sacral foraminal asymmetry.

Question 1896

Topic: Pelvic & Acetabular Trauma

What is the correct anatomical landmark for the optimal placement of a pelvic circumferential compression device (binder) to most effectively reduce pelvic volume in a hemodynamically unstable trauma patient?

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

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders should be placed centered over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is incorrect and can paradoxically widen the true pelvis.

Question 1897

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable patient with an Anteroposterior Compression Type III (APC-III) pelvic injury remains hypotensive despite initial fluid resuscitation, blood transfusion, and application of a pelvic binder. The FAST scan is negative. What is the next most appropriate step in management?
. CT abdomen and pelvis
. Pelvic angiography/embolization or pre-peritoneal pelvic packing
. Diagnostic peritoneal lavage
. Immediate exploratory laparotomy
. Removal of the binder to assess for expansion

Correct Answer & Explanation

. Pelvic angiography/embolization or pre-peritoneal pelvic packing

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST scan, the source of bleeding is likely retroperitoneal. The standard of care is immediate hemorrhage control via pelvic angiography with embolization or pre-peritoneal pelvic packing.

Question 1898

Topic: Pelvic & Acetabular Trauma

Which nerve root is most commonly injured in a vertical shear pelvic ring injury that involves a displaced transforaminal sacral fracture?

. L4
. L5
. S1
. S2
. S3

Correct Answer & Explanation

. L5

Explanation

The L5 nerve root is highly susceptible to traction injury during vertical shear injuries as it drapes over the sacral ala. Cephalad displacement of the hemipelvis places significant tension on this nerve.

Question 1899

Topic: Pelvic & Acetabular Trauma

Which intraoperative fluoroscopic view is most critical to evaluate for anterior-posterior translation of the sacroiliac joint during percutaneous iliosacral screw fixation?

. AP pelvis
. Inlet view
. Outlet view
. Judet obturator oblique
. Judet iliac oblique

Correct Answer & Explanation

. Inlet view

Explanation

The pelvic inlet view best demonstrates anterior-posterior translation of the pelvic ring. It is essential for verifying reduction of the sacroiliac joint and confirming the screw does not violate the anterior sacral cortex.

Question 1900

Topic: 2. Trauma

A male patient presents with an APC-II pelvic ring fracture and blood at the urethral meatus. A retrograde urethrogram confirms a posterior urethral injury. What is the most common anatomical site of urethral disruption in this setting?

. Pendulous urethra
. Bulbar urethra
. Bulbomembranous junction
. Prostatic urethra
. Bladder neck

Correct Answer & Explanation

. Bulbomembranous junction

Explanation

The bulbomembranous junction is the most frequent site of posterior urethral injury in males with severe anterior pelvic ring disruptions. The firm attachment of the membranous urethra to the pubic bone causes shearing forces during diastasis.

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