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2. Trauma MCQs

Practice Set 513 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 10241

Topic: 2. Trauma
A 35-year-old male sustains a Gustilo-Anderson Type IIIB open tibia fracture with an extensive soft tissue defect over the distal third of the tibia. Following debridement, which of the following is the most appropriate flap option for coverage?
. Pedicled gastrocnemius flap
. Pedicled soleus flap
. Latissimus dorsi free flap
. Reverse sural artery flap
. V-Y advancement flap

Correct Answer & Explanation

. Latissimus dorsi free flap

Explanation

Soft tissue defects of the distal third of the tibia typically require free tissue transfer, such as a latissimus dorsi or anterolateral thigh free flap. Gastrocnemius flaps are used for the proximal third, and soleus flaps for the middle third.

Question 10242

Topic: 2. Trauma

A 22-year-old male is brought to the trauma bay after a high-speed motorcycle collision. He is hypotensive with a blood pressure of 80/50 mmHg and has a heart rate of 50 bpm. He is flaccid and areflexic below the C6 level. Which of the following is the primary mechanism for his hemodynamic instability?

. Loss of sympathetic vascular tone
. Massive occult hemorrhage
. Direct myocardial contusion
. Tension pneumothorax
. Adrenal insufficiency

Correct Answer & Explanation

. Loss of sympathetic vascular tone

Explanation

The patient is experiencing neurogenic shock, characterized by hypotension and bradycardia due to the loss of sympathetic tone. This allows unopposed vagal parasympathetic tone to slow the heart rate and dilate peripheral vessels.

Question 10243

Topic: 2. Trauma
A 40-year-old male sustains a severe anteroposterior compression (APC III) pelvic ring injury. In the setting of massive retroperitoneal hemorrhage associated with pelvic fractures, the primary anatomic source of bleeding is most commonly:
. Internal iliac artery
. Superior gluteal artery
. Presacral venous plexus and cancellous bone
. External iliac vein
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus and cancellous bone

Explanation

While arterial bleeding (e.g., superior gluteal or internal iliac) can be life-threatening and require embolization, 80-90% of pelvic hemorrhage is venous in origin, arising from the presacral venous plexus and exposed cancellous bone.

Question 10244

Topic: 2. Trauma

According to Perren's strain theory of fracture healing, different tissues tolerate varying levels of mechanical strain before failure. What is the maximum approximate strain tolerance of granulation tissue?

. 2 percent
. 10 percent
. 25 percent
. 50 percent
. 100 percent

Correct Answer & Explanation

. 100 percent

Explanation

Granulation tissue can tolerate up to 100% strain, allowing it to bridge highly mobile fracture gaps initially. As the tissue stiffens into cartilage (10% strain) and then bone (2% strain), the interfragmentary strain must decrease accordingly.

Question 10245

Topic: 2. Trauma

A patient suffers a closed distal humerus fracture resulting in a radial nerve palsy. Electromyography reveals fibrillation potentials but nerve conduction studies suggest continuity of the endoneurial tubes. According to Sunderland's classification, what grade of nerve injury has occurred?

. First-degree (Neuropraxia)
. Second-degree (Axonotmesis)
. Third-degree
. Fourth-degree
. Fifth-degree (Neurotmesis)

Correct Answer & Explanation

. Second-degree (Axonotmesis)

Explanation

Sunderland second-degree injury (axonotmesis) involves disruption of the axon with Wallerian degeneration, but the endoneurial sheath remains intact. This allows for excellent potential for spontaneous, directed axonal regeneration.

Question 10246

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay following a high-speed motorcycle collision. Pelvic radiographs show an Anterior Posterior Compression Type III (APC-III) pelvic ring injury. He remains hypotensive despite initial resuscitation, and a pelvic binder is applied. What is the most common anatomical source of massive hemorrhage in this fracture pattern?
. Superior gluteal artery
. Corona mortis
. Presacral venous plexus
. Internal pudendal vein
. External iliac vein

Correct Answer & Explanation

. Presacral venous plexus

Explanation

In severe pelvic ring disruptions, particularly open-book (APC) types, 80-90% of bleeding is of venous origin. The presacral venous plexus and prevesical veins are the most common sources. Arterial bleeding (e.g., superior gluteal, internal pudendal) accounts for only 10-20% of cases and is more common in lateral compression or severe vertical shear injuries.

Question 10247

Topic: 2. Trauma

A 25-year-old male is admitted with a comminuted tibia fracture. He complains of excruciating leg pain out of proportion to the injury. His blood pressure is 115/70 mmHg, and his Mean Arterial Pressure (MAP) is 85 mmHg. Intracompartmental pressure monitoring is performed. The anterior compartment pressure is 45 mmHg. Which of the following formulas represents the most widely accepted threshold (Delta P) for diagnosing acute compartment syndrome requiring fasciotomy?

. Absolute compartment pressure > 30 mmHg
. Absolute compartment pressure > 45 mmHg
. Delta P (Diastolic BP minus compartment pressure) < 30 mmHg
. Delta P (MAP minus compartment pressure) < 40 mmHg
. Delta P (Systolic BP minus compartment pressure) < 50 mmHg

Correct Answer & Explanation

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

Explanation

The most widely accepted and specific criterion for diagnosing acute compartment syndrome is a Delta P (Diastolic Blood Pressure minus the highest compartment pressure) of less than 30 mmHg. Relying solely on absolute pressures often leads to overdiagnosis and unnecessary fasciotomies, particularly in hypertensive patients.

Question 10248

Topic: 2. Trauma

An 80-year-old female sustains an un-displaced, transcervical femoral neck fracture. Despite non-operative or pinning treatment, she remains at significant risk for avascular necrosis (AVN) of the femoral head. Disruption of which primary blood vessel is the most significant cause of AVN in this injury?

. Artery of the ligamentum teres
. Medial femoral circumflex artery (MFCA)
. Lateral femoral circumflex artery (LFCA)
. Inferior gluteal artery
. Superior gluteal artery

Correct Answer & Explanation

. Medial femoral circumflex artery (MFCA)

Explanation

The primary blood supply to the adult femoral head is the deep branch of the medial femoral circumflex artery (MFCA), which gives rise to the lateral epiphyseal vessels. These vessels run along the superior-posterior aspect of the femoral neck and are highly susceptible to disruption or kinking in femoral neck fractures.

Question 10249

Topic: 2. Trauma

In a polytraumatized patient with severe bilateral lower extremity open fractures, closed head injury, and pulmonary contusions, the decision to proceed with damage control orthopedics (DCO) rather than early total care (ETC) is often guided by the systemic inflammatory state. Which of the following serum markers peaks early (within 12-24 hours) and is most predictive of the development of multiple organ dysfunction syndrome (MODS)?

. Interleukin-1 (IL-1)
. Interleukin-6 (IL-6)
. Interleukin-10 (IL-10)
. Tumor necrosis factor-alpha (TNF-alpha)
. C-reactive protein (CRP)

Correct Answer & Explanation

. Interleukin-6 (IL-6)

Explanation

IL-6 is a highly potent pro-inflammatory cytokine that peaks around 12-24 hours post-injury. Elevated IL-6 levels correlate strongly with the severity of tissue injury, the magnitude of the physiological 'second hit' from surgery, and the risk of developing MODS and ARDS in polytrauma patients.

Question 10250

Topic: 2. Trauma

A 28-year-old man sustains a closed tibial shaft fracture. Two hours post-admission, he develops severe pain out of proportion to the injury. Which of the following physiological pressure parameters is the most reliable threshold to definitively diagnose acute compartment syndrome and indicate emergency fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 30 mmHg
. Mean arterial pressure (MAP) minus compartment pressure < 40 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 50 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The delta pressure, calculated as diastolic blood pressure minus absolute compartment pressure, is the most reliable indicator for compartment syndrome. A delta pressure of less than 30 mmHg indicates inadequate tissue perfusion and is a strict indication for emergent fasciotomy.

Question 10251

Topic: 2. Trauma

Bone Morphogenetic Proteins (BMPs) are used clinically to enhance bone healing. Recombinant human BMP-2 (rhBMP-2) has FDA approval for which of the following specific orthopedic applications?

. Nonunions of the femoral shaft and acute scaphoid fractures
. Acute open tibial shaft fractures and anterior lumbar interbody fusion (ALIF)
. Recalcitrant nonunions of the humerus and posterior cervical fusions
. Acute closed distal radius fractures and posterolateral lumbar fusion
. Spinal pseudoarthrosis repair and delayed unions of the clavicle

Correct Answer & Explanation

. Acute open tibial shaft fractures and anterior lumbar interbody fusion (ALIF)

Explanation

rhBMP-2 (Infuse) is FDA-approved specifically for acute, open tibial shaft fractures stabilized with an intramedullary nail and for single-level anterior lumbar interbody fusion (ALIF) using an approved interbody cage.

Question 10252

Topic: 2. Trauma
A 25-year-old man sustains a highly vertical femoral neck fracture (Pauwels Type III) in a motor vehicle accident. Biomechanically, which fixation construct provides the highest resistance to the vertical shear forces inherent to this fracture pattern?
. Three parallel cancellous screws placed in an inverted triangle
. A sliding hip screw with a supplemental derotational cancellous screw
. Two divergent cannulated screws placed inferiorly
. A cephalomedullary nail with a single lag screw
. A fully threaded solid screw with a washer

Correct Answer & Explanation

. A sliding hip screw with a supplemental derotational cancellous screw

Explanation

Pauwels Type III femoral neck fractures in young patients have high vertical shear forces, leading to a high rate of varus collapse and nonunion. A sliding hip screw combined with a derotational screw provides superior biomechanical stability against vertical shear compared to multiple cancellous screws.

Question 10253

Topic: 2. Trauma
A 45-year-old construction worker sustains an open midshaft tibia fracture after a beam falls on his leg. There is an 8 cm soft tissue defect with exposed bone, massive muscle crush injury, and an absent dorsalis pedis pulse that requires surgical arterial repair to salvage the limb. What is the correct Gustilo-Anderson classification for this injury?
. Type II
. Type IIIA
. Type IIIB
. Type IIIC
. Type IV

Correct Answer & Explanation

. Type IIIC

Explanation

The Gustilo-Anderson Type IIIC classification is defined by any open fracture associated with an arterial injury that requires surgical repair for limb viability, regardless of the size of the soft tissue defect.

Question 10254

Topic: 2. Trauma

In a polytraumatized patient, which of the following physiologic markers is the most reliable early biochemical indicator of adequate resuscitation to allow clearance for definitive early total care (ETC) fracture fixation?

. Base deficit less than 2 mmol/L
. Serum lactate less than 2.0 mmol/L
. Urine output greater than 0.5 mL/kg/hr
. Mean arterial pressure greater than 65 mmHg
. Heart rate less than 100 bpm

Correct Answer & Explanation

. Serum lactate less than 2.0 mmol/L

Explanation

Serum lactate levels below 2.0 mmol/L and a normalizing base deficit are critical indicators of adequate tissue perfusion and end-organ resuscitation. Normalizing lactate is heavily relied upon to safely transition a patient from damage control orthopedics to definitive early total care.

Question 10255

Topic: 2. Trauma

In a patient with suspected acute compartment syndrome of the lower leg, what is the generally accepted critical delta pressure (Delta P) threshold that mandates emergency fasciotomy?

. Absolute pressure greater than 15 mmHg
. Absolute pressure greater than 20 mmHg
. Diastolic blood pressure minus compartment pressure less than 30 mmHg
. Mean arterial pressure minus compartment pressure less than 40 mmHg
. Systolic blood pressure minus compartment pressure less than 50 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure less than 30 mmHg

Explanation

The Delta P is calculated as the diastolic blood pressure minus the measured intracompartmental pressure. A Delta P of less than 30 mmHg indicates inadequate tissue perfusion and is an absolute indication for emergent fasciotomy.

Question 10256

Topic: Pelvic & Acetabular Trauma
When applying a circumferential pelvic binder for a hemodynamically unstable patient with an open-book pelvic ring injury (APC-III), over which specific anatomic landmarks should the binder be centered to maximize reduction force?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

To be mechanically effective, a pelvic binder or sheet must be centered directly over the greater trochanters. Placing it too cephalad (over the iliac crests) is a common error that fails to adequately close the pelvic volume and can actually paradoxically open the posterior ring.

Question 10257

Topic: 2. Trauma

In the context of Damage Control Orthopedics (DCO), which of the following criteria best classifies a polytrauma patient as 'borderline' according to the Pape/Hannover classification?

. Initial lactate < 2.0 mmol/L
. ISS > 40 without thoracic trauma
. Bilateral pulmonary contusion on initial radiograph
. Base deficit > 15 mEq/L
. Systolic BP < 90 mmHg unresponsive to fluids

Correct Answer & Explanation

. Bilateral pulmonary contusion on initial radiograph

Explanation

Borderline criteria in polytrauma patients include ISS >20 with additional severe thoracic trauma, such as bilateral pulmonary contusions, an initial pulmonary artery pressure >24 mmHg, or multiple injuries with severe pelvic/abdominal trauma. Patients with a base deficit >15 or persistent shock (BP < 90 unresponsive) are classified as 'unstable' or 'in extremis' and mandate DCO rather than definitive fixation.

Question 10258

Topic: 2. Trauma

A 32-year-old man sustains a closed high-energy tibial shaft fracture. Two hours post-injury, he complains of severe leg pain out of proportion. Intracompartmental pressure monitoring is performed. According to current literature, which parameter is the most reliable threshold for diagnosing acute compartment syndrome and indicating fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 25 mmHg
. Delta P (Diastolic BP - Compartment Pressure) < 30 mmHg
. Delta P (Mean Arterial Pressure - Compartment Pressure) < 40 mmHg
. Delta P (Systolic BP - Compartment Pressure) < 50 mmHg

Correct Answer & Explanation

. Delta P (Diastolic BP - Compartment Pressure) < 30 mmHg

Explanation

Delta P, calculated as the diastolic blood pressure minus the intracompartmental pressure, is the most accurate diagnostic threshold for acute compartment syndrome. A Delta P of less than 30 mmHg indicates critically impaired tissue perfusion and is a firm indication for emergent fasciotomy.

Question 10259

Topic: Pelvic & Acetabular Trauma
A 40-year-old pedestrian is struck by a vehicle. Pelvic radiographs demonstrate a symphysis pubis diastasis of 3.5 cm and a widened anterior sacroiliac joint, but intact posterior sacroiliac ligaments. According to the Young-Burgess classification, what type of pelvic ring injury is this?
. APC-I
. APC-II
. APC-III
. LC-I
. LC-II

Correct Answer & Explanation

. APC-II

Explanation

An Anteroposterior Compression Type II (APC-II) injury is defined by symphyseal diastasis >2.5 cm with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. Crucially, the posterior sacroiliac ligaments remain intact, rendering the pelvis rotationally unstable but vertically stable. APC-III involves complete disruption of both anterior and posterior SI ligaments.

Question 10260

Topic: 2. Trauma
A 28-year-old farmer sustains a tibial shaft fracture after his leg is trapped in a soil-tilling machine. The wound is 8 cm long with significant soft tissue stripping, but adequate periosteal coverage of the bone remains. According to the Gustilo-Anderson classification and standard antibiotic guidelines, what is the grade and appropriate initial empiric antibiotic regimen?
. Type II; First-generation cephalosporin only
. Type IIIA; First-generation cephalosporin and an aminoglycoside
. Type IIIB; First-generation cephalosporin and an aminoglycoside
. Type IIIA; First-generation cephalosporin, an aminoglycoside, and high-dose penicillin
. Type IIIC; First-generation cephalosporin, an aminoglycoside, and high-dose penicillin

Correct Answer & Explanation

. Type IIIA; First-generation cephalosporin, an aminoglycoside, and high-dose penicillin

Explanation

The fracture is a Gustilo Type IIIA (>10 cm or high-energy/severe contamination, but with adequate bone coverage). Because it is a farm injury involving soil, there is a high risk of anaerobic infection (e.g., Clostridium). Classic orthopedic guidelines mandate adding high-dose penicillin for anaerobic coverage, in addition to a first-generation cephalosporin and an aminoglycoside for Gram-positive and Gram-negative coverage.

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