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2. Trauma MCQs

Practice Set 625 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 12481

Topic: 2. Trauma
According to the Advanced Trauma Life Support (ATLS) classification of hemorrhagic shock, which of the following vital sign changes is the defining characteristic that separates Class III shock from Class I and II shock?
. Tachycardia > 100 bpm
. Decreased urine output
. Drop in measurable systolic blood pressure
. Tachypnea > 20 breaths per minute
. Altered mental status

Correct Answer & Explanation

. Drop in measurable systolic blood pressure

Explanation

The hallmark of Class III hemorrhagic shock (which represents 31-40% blood volume loss) is a drop in measurable systolic blood pressure. In Class I and Class II shock, compensatory mechanisms (such as tachycardia and peripheral vasoconstriction) maintain the systolic blood pressure within normal limits.

Question 12482

Topic: 2. Trauma

Recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) has been utilized to augment bone healing. The FDA specifically approved rhBMP-2 for use in which of the following clinical scenarios?

. Nonunions of the scaphoid
. Closed femoral shaft fractures treated with an intramedullary nail
. Open tibial shaft fractures treated with an intramedullary nail
. Avascular necrosis of the femoral head
. Posterior spinal fusions in adolescents with idiopathic scoliosis

Correct Answer & Explanation

. Open tibial shaft fractures treated with an intramedullary nail

Explanation

The FDA originally approved rhBMP-2 (Infuse) for acute, open tibial shaft fractures treated with an intramedullary nail (within 14 days of injury) and for single-level anterior lumbar interbody fusion (ALIF). It is not FDA-approved for closed femur fractures or pediatric spinal fusions (often used off-label but with FDA warnings).

Question 12483

Topic: Lower Extremity Trauma

According to the principles of intramedullary nailing, increasing the radius of a solid intramedullary nail by a factor of 2 will increase its torsional rigidity by what factor?

. 2
. 4
. 8
. 16
. 32

Correct Answer & Explanation

. 16

Explanation

The torsional rigidity of a solid cylinder is proportional to the polar moment of inertia, which scales with the radius to the fourth power (r^4). Therefore, doubling the radius increases torsional rigidity by a factor of 16.

Question 12484

Topic: 2. Trauma

A 32-year-old male sustains a closed tibial shaft fracture. Twelve hours post-admission, he complains of severe leg pain out of proportion to the injury. Which of the following intracompartmental pressure measurements is an absolute indication for a four-compartment fasciotomy?

. Absolute pressure of 20 mmHg
. Absolute pressure of 25 mmHg
. Delta pressure (Diastolic BP minus Compartment Pressure) < 30 mmHg
. Delta pressure (Mean Arterial Pressure minus Compartment Pressure) < 40 mmHg
. Delta pressure (Systolic BP minus Compartment Pressure) < 20 mmHg

Correct Answer & Explanation

. Delta pressure (Diastolic BP minus Compartment Pressure) < 30 mmHg

Explanation

The delta pressure (Diastolic Blood Pressure minus Intracompartmental Pressure) of less than 30 mmHg is considered the most reliable indicator for diagnosing acute compartment syndrome and is an absolute indication for emergency fasciotomy. Relying strictly on absolute pressure readings can be misleading due to varying baseline systemic blood pressures.

Question 12485

Topic: Pelvic & Acetabular Trauma

In the Young-Burgess classification of pelvic ring injuries, an Anterior Posterior Compression Type II (APC-II) injury is characterized by rupture of which primary ligamentous structures, leading to rotational instability but maintained vertical stability?

. Symphysis pubis, anterior sacroiliac, and posterior sacroiliac ligaments
. Symphysis pubis, anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Symphysis pubis and posterior sacroiliac ligaments only
. Posterior sacroiliac, sacrotuberous, and sacrospinous ligaments only
. Iliolumbar and posterior sacroiliac ligaments

Correct Answer & Explanation

. Symphysis pubis, anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC-II pelvic ring injury involves widening of the pubic symphysis (>2.5 cm) and disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. This results in rotational instability ('open book' pelvis) but maintains vertical stability because the strong posterior sacroiliac ligaments remain intact.

Question 12486

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable trauma patient is brought to the emergency department with an anteroposterior compression type III (APC-III) pelvic ring injury. In the initial resuscitation phase, where is the most anatomically appropriate location to apply a circumferential pelvic binder?
. Over the iliac crests
. Over the anterior superior iliac spines
. Directly over the greater trochanters
. Inferior to the pubic symphysis
. Around the proximal thighs

Correct Answer & Explanation

. Directly over the greater trochanters

Explanation

A pelvic binder should be centered directly over the greater trochanters to effectively reduce pelvic volume and control venous bleeding. Placement higher over the iliac crests is less effective and may cause paradoxical pelvic widening.

Question 12487

Topic: 2. Trauma
A 28-year-old male sustains a high-energy, vertically oriented, displaced femoral neck fracture (Pauwels Type III). What is the predominant blood supply to the femoral head that is critically compromised in this injury?
. Lateral femoral circumflex artery
. Inferior gluteal artery
. Artery of the ligamentum teres
. Medial femoral circumflex artery
. Pudendal artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The medial femoral circumflex artery (MFCA) provides the primary blood supply to the adult femoral head via its lateral epiphyseal branches. Displaced femoral neck fractures place this vasculature at high risk, leading to avascular necrosis.

Question 12488

Topic: 2. Trauma

Which of the following fracture fixation constructs relies entirely on primary (direct) bone healing, thereby preventing the formation of an intermediate fracture callus?

. Intramedullary nailing of a diaphyseal femur fracture
. Bridge plating of a comminuted tibial shaft fracture
. Lag screw and neutralization plate for a transverse radius fracture
. External fixation of an open tibial fracture
. Casting of a nondisplaced distal radius fracture

Correct Answer & Explanation

. Lag screw and neutralization plate for a transverse radius fracture

Explanation

Primary bone healing requires absolute stability and intimate cortical contact, achieved clinically through interfragmentary compression (such as a lag screw and plate). This process occurs via cutting cones without macroscopic callus formation.

Question 12489

Topic: 2. Trauma
A 35-year-old farmer sustains a Grade III open tibial shaft fracture highly contaminated with soil. In addition to surgical debridement and standard broad-spectrum cephalosporin and aminoglycoside coverage, what additional antibiotic should be administered to prevent a specific life-threatening infection?
. Vancomycin
. High-dose Penicillin
. Ciprofloxacin
. Clindamycin
. Doxycycline

Correct Answer & Explanation

. High-dose Penicillin

Explanation

Farm injuries with heavy soil contamination carry a high risk of Clostridium perfringens infection, which can cause rapidly progressive gas gangrene. High-dose Penicillin must be added to the prophylactic antibiotic regimen to cover this pathogen.

Question 12490

Topic: 2. Trauma
A 30-year-old male sustains a vertically oriented femoral neck fracture (Pauwels Type III). What is the most appropriate fixation method to minimize the risk of nonunion and shear failure?
. Three parallel cancellous screws
. Sliding hip screw with an anti-rotation screw
. Cephalomedullary nail
. Hemiarthroplasty
. Cannulated screws in an inverted triangle

Correct Answer & Explanation

. Sliding hip screw with an anti-rotation screw

Explanation

Pauwels Type III fractures have high vertical shear forces. A sliding hip screw (fixed-angle device) with an anti-rotation screw provides superior biomechanical stability against shear compared to multiple cancellous screws.

Question 12491

Topic: 2. Trauma

According to current evidence-based guidelines, what is the most critical factor in reducing infection rates in patients with open long bone fractures?

. Time to operative debridement within 6 hours
. Early administration of systemic antibiotics
. Use of high-pressure pulsatile lavage
. Application of a wound vacuum-assisted closure
. Immediate definitive internal fixation

Correct Answer & Explanation

. Early administration of systemic antibiotics

Explanation

The early administration of systemic antibiotics (ideally within 1 hour of injury) is the most important factor in reducing infection rates in open fractures. The historic "6-hour rule" for surgical debridement is no longer supported as an absolute cutoff.

Question 12492

Topic: 2. Trauma

An 82-year-old patient sustains a Type II odontoid fracture after a low-energy fall. Which of the following factors is the strongest mechanical predictor of nonunion and indication for surgical fixation?

. Age greater than 80 years
. Displacement greater than 5 mm
. Posterior angulation
. Anterior angulation
. Concomitant C1 ring fracture

Correct Answer & Explanation

. Displacement greater than 5 mm

Explanation

Fracture displacement greater than 5 mm in a Type II odontoid fracture is a strong predictor of nonunion and a major indication for surgical fixation. While advanced age also increases nonunion risk, displacement is the strongest mechanical factor.

Question 12493

Topic: Pelvic & Acetabular Trauma

An unstable pelvic ring injury is suspected in a hypotensive trauma patient. A pelvic binder is applied in the trauma bay. To optimally reduce pelvic volume and control venous hemorrhage, the binder should be centered directly over which anatomic landmarks?

. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Pubic symphysis
. Ischial tuberosities

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder should be centered directly over the greater trochanters to generate the appropriate force vector to close the pelvic ring. Placement over the iliac crests is incorrect and can paradoxically widen the true pelvis, worsening hemorrhage.

Question 12494

Topic: 2. Trauma

A 24-year-old male undergoes intramedullary nailing of a femur fracture. On postoperative day 2, he develops confusion, tachypnea, and a petechial rash over his axilla. Which of the following is the most important initial management?

. Intravenous corticosteroids
. Immediate administration of heparin
. Supportive care with supplemental oxygen
. Surgical decompression of the femur
. Administration of a tissue plasminogen activator

Correct Answer & Explanation

. Supportive care with supplemental oxygen

Explanation

The patient is presenting with Fat Embolism Syndrome (FES), classically featuring the triad of hypoxemia, neurologic abnormalities, and a petechial rash. The mainstay of treatment is supportive care, primarily ensuring adequate oxygenation and ventilation.

Question 12495

Topic: 2. Trauma

A 35-year-old male sustains a spiral fracture of the distal third of the humerus (Holstein-Lewis fracture). He has an isolated radial nerve palsy on initial presentation. What is the most appropriate initial management of the nerve palsy?

. Immediate surgical exploration of the radial nerve
. Electromyography (EMG) within 24 hours
. Observation and supportive splinting
. Ultrasound-guided nerve block
. Corticosteroid injection at the fracture site

Correct Answer & Explanation

. Observation and supportive splinting

Explanation

A primary radial nerve palsy associated with a closed humeral shaft fracture is managed with observation, as the vast majority resolve spontaneously within 3 to 4 months. Immediate surgical exploration is reserved for open fractures, severe vascular compromise, or palsies occurring after closed reduction.

Question 12496

Topic: 2. Trauma

The major retrograde blood supply to the scaphoid bone enters primarily at which anatomical location?

. Volar aspect of the proximal pole
. Dorsal ridge near the distal pole
. Directly into the articular surface of the radioscaphoid joint
. Through the scapholunate interosseous ligament
. Volar aspect of the waist

Correct Answer & Explanation

. Dorsal ridge near the distal pole

Explanation

The scaphoid receives 70-80% of its blood supply via the dorsal carpal branch of the radial artery. This vessel enters the dorsal ridge at the distal pole and flows in a retrograde fashion to supply the proximal pole, making proximal fractures prone to nonunion and AVN.

Question 12497

Topic: Pelvic & Acetabular Trauma
In the emergent management of a hemodynamically unstable patient with an anteroposterior compression type III (APC-III) pelvic ring injury, where is the optimal anatomical position for a pelvic circumferential compression device?
. At the level of the iliac crests
. Just proximal to the umbilicus
. Centered directly over the greater trochanters
. At the level of the anterior superior iliac spines
. Around the proximal thighs

Correct Answer & Explanation

. Centered directly over the greater trochanters

Explanation

A pelvic binder must be centered precisely over the greater trochanters to effectively close the pelvic volume and safely stabilize the pelvic ring. Placement over the iliac crests is a common error that can exacerbate the deformity or provide inadequate compression.

Question 12498

Topic: 2. Trauma

Which of the following radiographic fracture patterns in an infant is considered highly specific for non-accidental trauma?

. Linear skull fracture
. Mid-clavicular fracture
. Spiral fracture of the tibial shaft in a walking toddler
. Classic metaphyseal lesion (corner fracture)
. Transverse fracture of the radius

Correct Answer & Explanation

. Classic metaphyseal lesion (corner fracture)

Explanation

The classic metaphyseal lesion, often referred to as a corner or bucket-handle fracture, is highly specific for non-accidental trauma in infants. It occurs from excessive torsional and tractional shearing forces applied to the child's extremity.

Question 12499

Topic: 2. Trauma

A 72-year-old female sustains a displaced femoral neck fracture after a mechanical fall. The primary blood supply at risk of disruption, which leads to a high incidence of avascular necrosis of the femoral head in this injury pattern, originates directly from which of the following arteries?

. Medial circumflex femoral artery
. Lateral circumflex femoral artery
. Artery of the ligamentum teres
. Inferior gluteal artery
. Superior gluteal artery

Correct Answer & Explanation

. Medial circumflex femoral artery

Explanation

Correct Answer: A. Medial circumflex femoral arteryAvascular necrosis (AVN) of the femoral head is a major complication following displaced femoral neck fractures. The primary blood supply to the adult femoral head is derived from the medial circumflex femoral artery (MCFA), specifically its lateral epiphyseal branches. Displaced fractures disrupt this retinacular blood supply. The MCFA is a branch of the profunda femoris artery. The artery of the ligamentum teres provides a negligible amount of blood in adults, and the lateral circumflex femoral artery primarily supplies the anterior portion of the femoral neck and greater trochanter.

Question 12500

Topic: 2. Trauma

A 28-year-old male is struck by a motor vehicle and sustains a severely displaced, high-energy Schatzker VI tibial plateau fracture. Twelve hours post-admission, he complains of excruciating leg pain that is out of proportion to the injury and not relieved by intravenous opioids. Which of the following is the most sensitive early clinical finding for the suspected complication?

. Absence of the dorsalis pedis pulse
. Pallor of the distal extremity
. Pain with passive stretch of the involved compartment muscles
. Paresthesias in the first web space
. Motor paralysis of the extensor hallucis longus

Correct Answer & Explanation

. Pain with passive stretch of the involved compartment muscles

Explanation

Correct Answer: C. Pain with passive stretch of the involved compartment musclesAcute compartment syndrome is a devastating complication of high-energy fractures, particularly tibial plateau and tibial shaft fractures. The earliest and most sensitive clinical sign is pain out of proportion to the injury, specifically exacerbated by passive stretch of the muscles within the involved compartment. The classic "5 Ps" (pain, pallor, pulselessness, paresthesias, paralysis) are often taught, but pallor, pulselessness, and paralysis are late signs indicating irreversible tissue ischemia and muscle necrosis.

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