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2. Trauma MCQs

Practice Set 607 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 12121

Topic: 2. Trauma

A 28-year-old male sustains a high-energy closed tibia fracture. In evaluating the patient for acute compartment syndrome, which of the following pressure measurements is generally considered an absolute indication for emergent fasciotomy in a polytraumatized patient?

. Absolute compartment pressure of 15 mmHg
. Absolute compartment pressure of 25 mmHg
. Diastolic blood pressure minus compartment pressure (Delta P) < 30 mmHg
. Mean arterial pressure minus compartment pressure (Delta P) < 40 mmHg
. Systolic blood pressure minus compartment pressure (Delta P) < 20 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure (Delta P) < 30 mmHg

Explanation

The most reliable indicator for diagnosing acute compartment syndrome in an unresponsive or polytraumatized patient is a Delta P (Diastolic Blood Pressure - Compartment Pressure) of less than 30 mmHg. Perfusion depends on the driving pressure relative to the diastolic pressure.

Question 12122

Topic: 2. Trauma
According to the Gustilo-Anderson classification, an open diaphyseal tibia fracture with a 5-centimeter laceration, adequate soft tissue coverage of the bone, and minimal periosteal stripping is best classified as:
. Type I
. Type II
. Type IIIA
. Type IIIB
. Type IIIC

Correct Answer & Explanation

. Type II

Explanation

A Gustilo-Anderson Type II open fracture is defined by a laceration greater than 1 cm but less than 10 cm, without extensive soft tissue damage, flaps, or avulsions. There is adequate soft tissue coverage of the bone and minimal to moderate crushing component.

Question 12123

Topic: 2. Trauma

A 32-year-old male sustains a closed comminuted tibial shaft fracture. You have a high clinical suspicion for acute compartment syndrome and perform intracompartmental pressure testing. Which of the following pressure criteria is the generally accepted threshold indicating the need for an emergent fasciotomy?

. Delta pressure less than 30 mmHg
. Delta pressure greater than 30 mmHg
. Absolute compartment pressure greater than 15 mmHg
. Absolute compartment pressure greater than 20 mmHg
. Diastolic pressure minus compartment pressure greater than 45 mmHg

Correct Answer & Explanation

. Delta pressure less than 30 mmHg

Explanation

The Delta pressure is defined as the patient's Diastolic Blood Pressure minus the Intracompartmental Pressure. A delta pressure of less than 30 mmHg (meaning the compartment pressure is dangerously close to the diastolic pressure) indicates that capillary perfusion is critically compromised, serving as an objective threshold for emergent fasciotomy.

Question 12124

Topic: 2. Trauma

A 22-year-old male sustains a closed comminuted femur fracture. Forty-eight hours later, he develops confusion, a petechial rash over his axillae, and a respiratory rate of 28 breaths/min. Which of the following is the most appropriate initial management?

. Immediate prophylactic heparinization
. High-dose intravenous corticosteroids
. Administration of low molecular weight dextran
. Supportive care with supplemental oxygen and fluid resuscitation
. Emergent placement of an inferior vena cava filter

Correct Answer & Explanation

. Supportive care with supplemental oxygen and fluid resuscitation

Explanation

The patient meets Gurd's criteria for Fat Embolism Syndrome (FES). The mainstay of treatment is supportive care, particularly ensuring adequate oxygenation and maintaining intravascular volume.

Question 12125

Topic: 2. Trauma

In the development of acute compartment syndrome following a tibial shaft fracture, the critical pathophysiological event that initiates cellular ischemia is:

. Complete thrombotic occlusion of the major arterial inflow
. Vasospasm of the precapillary sphincters
. A decrease in the local arteriovenous pressure gradient
. Direct mechanical crush injury to the peripheral nerves
. A sudden exponential increase in systemic vascular resistance

Correct Answer & Explanation

. A decrease in the local arteriovenous pressure gradient

Explanation

As intracompartmental pressure rises, venous outflow is obstructed. This raises local venous pressure, which decreases the local arteriovenous pressure gradient, eventually halting capillary perfusion and leading to tissue ischemia.

Question 12126

Topic: 2. Trauma

In a patient with a suspected acute compartment syndrome of the lower extremity, which of the following delta pressure calculations (Diastolic blood pressure minus compartment pressure) is the widely accepted threshold indicating the need for emergent fasciotomy?

. Less than 10 mmHg
. Less than 30 mmHg
. Greater than 45 mmHg
. Greater than 60 mmHg
. Equal to systolic blood pressure

Correct Answer & Explanation

. Less than 30 mmHg

Explanation

A delta pressure (Diastolic BP - Compartment Pressure) of less than 30 mmHg is considered a highly sensitive threshold for diagnosing acute compartment syndrome. Values below this threshold indicate inadequate capillary perfusion pressure, necessitating emergent fasciotomy.

Question 12127

Topic: 2. Trauma

A 24-year-old man presents with a symptomatic scaphoid proximal pole nonunion recognized 8 months post-injury. MRI demonstrates avascular necrosis (AVN) of the proximal pole. There is no radiocarpal arthritis. Which of the following is the most appropriate surgical treatment?

. Radial styloidectomy
. Scaphoid excision and four-corner fusion
. 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) vascularized bone graft
. Non-vascularized iliac crest bone graft
. Proximal row carpectomy

Correct Answer & Explanation

. 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) vascularized bone graft

Explanation

For a scaphoid nonunion with AVN of the proximal pole (without established secondary osteoarthritis), a vascularized bone graft is the treatment of choice to optimize healing. The 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) graft, pedicled from the distal radius, is a standard and high-yield board answer for this scenario.

Question 12128

Topic: 2. Trauma

In the setting of crush injuries to the upper extremity, acute compartment syndrome of the hand may necessitate emergent fasciotomy. Anatomically, how many distinct fascial compartments are recognized within the human hand for this procedure?

. 4
. 7
. 10
. 14
. 18

Correct Answer & Explanation

. 10

Explanation

There are 10 recognized compartments in the hand that require decompression in acute compartment syndrome: four dorsal interosseous compartments, three volar interosseous compartments, the thenar compartment, the hypothenar compartment, and the adductor pollicis compartment.

Question 12129

Topic: 2. Trauma

In the physiological cascade that leads to acute compartment syndrome following a severe closed tibial fracture, which of the following microvascular events occurs first, setting off the cycle of ischemia?

. Arterial inflow occlusion
. Venous outflow obstruction
. Irreversible loss of nerve conduction
. Myocyte necrosis
. Capillary endothelial cell rupture

Correct Answer & Explanation

. Venous outflow obstruction

Explanation

The pathophysiology of acute compartment syndrome initiates with rising tissue pressure within an unyielding fascial space. Because the venous system operates at a much lower pressure than the arterial system, the thin-walled veins collapse first. This venous outflow obstruction leads to congestion, further increasing intracompartmental pressure, ultimately halting capillary perfusion and, much later, compromising arterial inflow.

Question 12130

Topic: 2. Trauma
A 35-year-old man arrives in the trauma bay following a motorcycle crash. His blood pressure is 80/40 mmHg. A pelvic radiograph reveals an APC-III pelvic ring injury. A pelvic binder is applied, and he receives massive transfusion protocol, but remains hemodynamically unstable. FAST exam is negative. What is the most common anatomic source of the hemorrhage?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus and cancellous bone
. Obturator artery
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus and cancellous bone

Explanation

In the majority (approximately 80-90%) of hemodynamically unstable pelvic fractures, the source of bleeding is venous (presacral and prevesical venous plexuses) or from the exposed cancellous bone at fracture sites. While arterial bleeding (e.g., superior gluteal, internal pudendal) can be life-threatening and require embolization, it accounts for a smaller percentage (10-20%) of massive pelvic hemorrhage.

Question 12131

Topic: 2. Trauma
A 25-year-old male is admitted following intramedullary nailing of a closed tibial shaft fracture. Twelve hours post-operatively, he develops severe leg pain out of proportion to the injury, refractory to opioids. Which of the following compartment pressure measurements is universally accepted as an absolute indication for emergency fasciotomy?
. An absolute compartment pressure greater than 15 mmHg
. A delta pressure (Diastolic Blood Pressure - Compartment Pressure) of less than 30 mmHg
. A delta pressure (Mean Arterial Pressure - Compartment Pressure) of less than 45 mmHg
. An absolute compartment pressure greater than 20 mmHg
. A delta pressure (Systolic Blood Pressure - Compartment Pressure) of less than 20 mmHg

Correct Answer & Explanation

. A delta pressure (Diastolic Blood Pressure - Compartment Pressure) of less than 30 mmHg

Explanation

Compartment syndrome is a clinical diagnosis, but when pressure monitoring is used, the 'delta pressure' (ΔP) is the most reliable threshold. ΔP is calculated as Diastolic Blood Pressure minus absolute Compartment Pressure. A ΔP of less than 30 mmHg (meaning the compartment pressure is approaching the diastolic pressure) is an absolute indication for emergent four-compartment fasciotomy. Absolute pressures alone can be misleading, especially in hypotensive patients.

Question 12132

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented (Pauwels Type III, 70-degree angle) femoral neck fracture. To minimize the high risk of shear failure and nonunion, which of the following internal fixation constructs provides the greatest biomechanical stability for this specific fracture pattern?
. Three parallel cancellous cannulated screws in an inverted triangle configuration
. Two crossed cannulated screws
. A sliding hip screw (dynamic hip screw) with an added derotational cancellous screw
. A standard short cephalomedullary nail
. A long cephalomedullary nail

Correct Answer & Explanation

. A sliding hip screw (dynamic hip screw) with an added derotational cancellous screw

Explanation

Pauwels Type III femoral neck fractures have a high vertical shear angle (>50 degrees), placing them at extremely high risk for varus collapse and nonunion. Biomechanical studies have consistently shown that a fixed-angle device, such as a sliding hip screw (SHS), provides superior resistance to vertical shear forces compared to three parallel cannulated screws. The addition of a derotational screw above the SHS lag screw controls rotational instability.

Question 12133

Topic: Pelvic & Acetabular Trauma
In a patient with an anteroposterior compression (APC) type II pelvic ring injury, which of the following ligaments remains primarily intact, preventing vertical instability?
. Anterior sacroiliac ligament
. Sacrospinous ligament
. Sacrotuberous ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

In the Young-Burgess classification, an APC II injury involves disruption of the symphysis pubis, as well as the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments, causing rotational instability ('open book'). However, the strong posterior sacroiliac ligaments remain intact, providing vertical stability to the hemipelvis. An APC III injury involves disruption of the posterior sacroiliac ligaments as well, leading to both rotational and vertical instability.

Question 12134

Topic: 2. Trauma

A 30-year-old man sustains a closed tibial shaft fracture. Two hours later, he develops severe pain out of proportion to the injury. Which of the following objective measurements is the most accepted threshold to perform an emergent fasciotomy for acute compartment syndrome?

. Absolute compartment pressure > 20 mm Hg
. Absolute compartment pressure > 45 mm Hg
. Diastolic blood pressure minus compartment pressure < 30 mm Hg
. Mean arterial pressure minus compartment pressure < 40 mm Hg
. Systolic blood pressure minus compartment pressure < 30 mm Hg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mm Hg

Explanation

The Delta P (Diastolic blood pressure minus compartment pressure) is the most reliable objective indicator for compartment syndrome. A Delta P of less than 30 mm Hg is an absolute indication for emergent fasciotomy. Absolute pressure readings can be misleading, as tissue perfusion depends on the pressure gradient, especially in hypotensive patients.

Question 12135

Topic: 2. Trauma

During the insertion of a cortical screw for fracture fixation, the surgeon wishes to maximize the pullout strength of the construct. According to biomechanical principles, increasing which of the following screw parameters will have the greatest effect on maximizing pullout strength?

. Inner core diameter
. Outer thread diameter
. Thread pitch
. Screw length
. Head diameter

Correct Answer & Explanation

. Outer thread diameter

Explanation

The outer thread diameter is the most important factor in determining the pullout strength of a screw. Pullout strength is directly proportional to the outer diameter, thread engagement length, and the shear strength of the bone.

Question 12136

Topic: 2. Trauma

A 22-year-old male with closed bilateral femur fractures develops hypoxia, confusion, and a petechial rash over his axilla 36 hours after injury. Which of the following is the most critical initial step in the management of this syndrome?

. Administration of high-dose systemic corticosteroids
. Immediate internal fixation of the bilateral femur fractures
. Systemic heparinization
. Supportive care with aggressive oxygenation and mechanical ventilation if needed
. Administration of fresh frozen plasma and platelets

Correct Answer & Explanation

. Supportive care with aggressive oxygenation and mechanical ventilation if needed

Explanation

Fat embolism syndrome is a clinical diagnosis based on Gurd's criteria, presenting with hypoxemia, neurologic compromise, and petechial rash. The primary treatment is entirely supportive, focusing aggressively on respiratory support and adequate oxygenation.

Question 12137

Topic: 2. Trauma

A 55-year-old diabetic patient presents with rapid onset of severe leg pain out of proportion to examination findings, swelling, and early bullae formation. Non-contrasted imaging shows gas in the soft tissues. What is the most critical intervention?

. Immediate administration of systemic steroids to reduce swelling
. Broad-spectrum intravenous antibiotics and urgent hyperbaric oxygen therapy
. Immediate radical surgical debridement of all necrotic tissue
. Four-compartment fasciotomy of the leg
. Percutaneous drainage and placement of antibiotic-impregnated beads

Correct Answer & Explanation

. Immediate radical surgical debridement of all necrotic tissue

Explanation

Necrotizing fasciitis is a rapid-onset, life-threatening surgical emergency. While antibiotics are necessary, the cornerstone of definitive treatment is immediate, radical surgical debridement of all nonviable fascia and soft tissue.

Question 12138

Topic: 2. Trauma

In the development of acute compartment syndrome, which of the following pathophysiologic events is the initial step that triggers the cascade leading to muscle and nerve ischemia?

. Arterial spasm and subsequent macrovascular occlusion
. Venous outflow obstruction due to elevated interstitial pressure
. Direct mechanical crush injury to large nerve fascicles
. Capillary endothelial damage leaking large molecular weight proteins
. Arteriovenous shunting bypassing the capillary beds

Correct Answer & Explanation

. Venous outflow obstruction due to elevated interstitial pressure

Explanation

The pathophysiology of compartment syndrome begins when intracompartmental interstitial pressure rises above venous capillary pressure. This causes venous outflow obstruction, creating a vicious cycle of increasing pressure that ultimately compromises arteriolar microcirculation.

Question 12139

Topic: 2. Trauma

A 30-year-old male sustains a closed tibial shaft fracture. Two hours later, he complains of disproportionate pain. His diastolic blood pressure is 80 mmHg. At which of the following intracompartmental pressures is a fasciotomy most clearly indicated based on the delta P threshold concept?

. 20 mmHg
. 30 mmHg
. 40 mmHg
. 55 mmHg
. Intracompartmental pressure > 20 mmHg regardless of diastolic pressure

Correct Answer & Explanation

. 30 mmHg

Explanation

The delta P is defined as the diastolic blood pressure minus the absolute intracompartmental pressure. A delta P of less than 30 mmHg indicates critical tissue perfusion loss and is an absolute indication for fasciotomy. In this patient (Diastolic BP = 80 mmHg), a compartment pressure of 55 mmHg yields a delta P of 25 mmHg, warranting immediate surgery.

Question 12140

Topic: 2. Trauma

In the management of a severely polytraumatized patient, the concept of 'Damage Control Orthopedics' (DCO) aims to avoid the 'second hit' phenomenon. Which of the following cytokines is most widely monitored as a highly sensitive marker for the magnitude of the initial systemic inflammatory response?

. Interleukin-1 (IL-1)
. Interleukin-4 (IL-4)
. Interleukin-6 (IL-6)
. Interleukin-10 (IL-10)
. Tumor necrosis factor-alpha (TNF-alpha)

Correct Answer & Explanation

. Interleukin-6 (IL-6)

Explanation

Interleukin-6 (IL-6) is an acute pro-inflammatory cytokine that rapidly peaks after major trauma. Its serum levels closely correlate with the severity of tissue injury, the magnitude of the systemic inflammatory response syndrome (SIRS), and the subsequent risk of multi-organ failure. It is a key biomarker in deciding between early total care (ETC) and DCO.

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