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2. Trauma MCQs

Practice Set 565 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 11281

Topic: 2. Trauma
A 30-year-old male sustains a forced dorsiflexion injury to his foot. Radiographs reveal a talar neck fracture with subluxation of the subtalar joint and a preserved tibiotalar joint. Based on the Hawkins classification, what is the approximate risk of developing avascular necrosis (AVN) of the talar body?
. 0-10%
. 20-50%
. 70-90%
. 100%
. AVN does not occur in this injury pattern

Correct Answer & Explanation

. 20-50%

Explanation

This is a Hawkins type II talar neck fracture, which involves subluxation or dislocation of the subtalar joint. The risk of AVN is approximately 20-50%, compared to 0-10% for type I and >90% for type III.

Question 11282

Topic: 2. Trauma

A 30-year-old male is admitted with a closed tibial shaft fracture. Overnight, he develops disproportionate leg pain. His blood pressure is 120/80 mmHg. Intra-compartmental pressure monitoring reveals a pressure of 45 mmHg in the anterior compartment. What is the patient's delta pressure, and what is the indicated management?

. 30 mmHg; Observation
. 35 mmHg; Immediate fasciotomy
. 45 mmHg; Immediate fasciotomy
. 75 mmHg; Elevation of the limb
. 80 mmHg; Intravenous mannitol

Correct Answer & Explanation

. 30 mmHg; Observation

Explanation

Delta pressure is calculated as diastolic blood pressure minus intra-compartmental pressure (80 - 45 = 35 mmHg). A delta pressure of less than or equal to 30 mmHg is the classic threshold for acute compartment syndrome, but clinical signs combined with a narrowing delta pressure strongly indicate the need for fasciotomy.

Question 11283

Topic: 2. Trauma

A 45-year-old male involved in a motor vehicle collision sustains a high-energy, bicondylar tibial plateau fracture. CT imaging demonstrates a large, displaced posteromedial fragment. What is the optimal surgical approach to directly visualize and buttress this specific fragment?

. Anterolateral approach
. Direct medial approach
. Posteromedial approach
. Posterior midline approach
. Anterior midline approach

Correct Answer & Explanation

. Anterolateral approach

Explanation

Posteromedial tibial plateau fragments occur secondary to vertical shear forces and require stable anti-glide or buttress plating. A posteromedial approach allows direct visualization and perpendicular plate application to neutralize these shear forces.

Question 11284

Topic: 2. Trauma
A 28-year-old male sustains a high-energy injury resulting in a nearly vertical femoral neck fracture. According to the Pauwels classification, Type III fractures have a high rate of nonunion and fixation failure primarily due to which biomechanical factor?
. Excessive compressive forces across the fracture site
. High shear forces promoting varus displacement
. Poor blood supply from the ligamentum teres
. Lack of robust periosteal callus formation
. Interposition of the dense joint capsule

Correct Answer & Explanation

. High shear forces promoting varus displacement

Explanation

The Pauwels classification evaluates the angle of the fracture line relative to the horizontal. Type III fractures (>50 degrees) are steep and vertical, which translates axial loads into massive shear forces, causing varus instability and increasing nonunion risk.

Question 11285

Topic: 2. Trauma

An 18-year-old male complains of severe, unrelenting leg pain out of proportion to the injury after sustaining a closed tibial shaft fracture. Which pressure parameter is the most reliable threshold for diagnosing acute compartment syndrome?

. Absolute intra-compartmental pressure greater than 15 mmHg
. Absolute intra-compartmental pressure greater than 20 mmHg
. Delta pressure (diastolic blood pressure minus compartment pressure) less than 30 mmHg
. Delta pressure (systolic blood pressure minus compartment pressure) less than 30 mmHg
. Delta pressure (mean arterial pressure minus compartment pressure) less than 10 mmHg

Correct Answer & Explanation

. Absolute intra-compartmental pressure greater than 15 mmHg

Explanation

A delta pressure (diastolic blood pressure minus intra-compartmental pressure) of less than 30 mmHg is the most reliable and widely accepted indicator for acute compartment syndrome. Relying on delta pressure prevents unnecessary fasciotomies in hypotensive patients compared to absolute pressure limits.

Question 11286

Topic: Pelvic & Acetabular Trauma
In the emergency management of a hemodynamically unstable patient with an anteroposterior compression (APC-III) pelvic ring injury, over which exact anatomical landmarks should a pelvic binder be centered?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

To effectively reduce pelvic volume, close the pelvic ring, and provide tamponade effect, a pelvic binder must be centered directly over the greater trochanters. Misplacement over the iliac crests is common but incorrect, as it can worsen the deformity in certain fracture patterns.

Question 11287

Topic: 2. Trauma

According to the Denis three-column classification of spinal fractures, a typical thoracolumbar burst fracture involves biomechanical failure of which columns?

. Anterior column only
. Middle column only
. Anterior and middle columns
. Middle and posterior columns
. Anterior, middle, and posterior columns

Correct Answer & Explanation

. Anterior column only

Explanation

In the Denis classification, a burst fracture requires structural failure of both the anterior and middle columns under axial compression. This is the crucial distinction from a simple compression fracture, which involves isolated failure of the anterior column.

Question 11288

Topic: 2. Trauma

A 35-year-old male sustains a comminuted fracture of the femoral shaft in a motor vehicle accident. Approximately 36 hours post-injury, he acutely develops hypoxia, a petechial rash on his chest and axillae, and acute confusion. Which pathophysiological phenomenon best explains his clinical deterioration?

. Deep venous thrombosis with subsequent pulmonary embolism
. Fat embolism syndrome
. Acute respiratory distress syndrome secondary to undetected pulmonary contusion
. Acute myocardial infarction
. Aspiration pneumonia

Correct Answer & Explanation

. Deep venous thrombosis with subsequent pulmonary embolism

Explanation

The classic triad of progressive hypoxia, an upper-body petechial rash, and neurologic abnormalities developing 24-72 hours after a long bone fracture is highly diagnostic for fat embolism syndrome. Early stabilization of long bone fractures is the single most effective preventative measure.

Question 11289

Topic: 2. Trauma

A 45-year-old male with a tibial shaft fracture treated with a reamed intramedullary nail presents 9 months post-op with continued pain. Radiographs reveal a hypertrophic nonunion (elephant shoe appearance). What is the best treatment?

. Autologous bone grafting alone
. Plate augmentation and bone grafting
. Exchange nailing with a larger diameter reamed nail
. Application of an Ilizarov frame
. Pulsed electromagnetic field therapy

Correct Answer & Explanation

. Autologous bone grafting alone

Explanation

Hypertrophic nonunions have excellent biological healing potential but lack mechanical stability. Exchange nailing with a larger diameter reamed nail provides the necessary biomechanical stability to induce fracture consolidation.

Question 11290

Topic: 2. Trauma

A 28-year-old male sustains a traumatic knee dislocation. Following closed reduction, his Ankle-Brachial Index (ABI) is measured at 0.8. What is the most appropriate next step in management?

. Observation with serial neurovascular checks
. Duplex ultrasound of the lower extremity
. CT Angiography
. Immediate vascular surgery consult for open exploration
. Fasciotomy of the lower leg

Correct Answer & Explanation

. Observation with serial neurovascular checks

Explanation

An Ankle-Brachial Index (ABI) less than 0.9 following a knee dislocation strongly suggests a popliteal artery injury. A CT angiogram is the gold standard next step to anatomically define the injury prior to operative intervention.

Question 11291

Topic: 2. Trauma

A 25-year-old male sustains an isolated, vertically oriented medial malleolus fracture. According to the Lauge-Hansen classification, what is the most likely mechanism of injury?

. Supination-Adduction
. Supination-External Rotation
. Pronation-Abduction
. Pronation-External Rotation
. Axial loading

Correct Answer & Explanation

. Supination-Adduction

Explanation

A vertically oriented medial malleolus fracture is characteristic of a Supination-Adduction (SAD) injury. It is typically treated with anti-glide plating to counteract the vertical shear forces.

Question 11292

Topic: 2. Trauma

A 40-year-old male is brought to the trauma bay with an open-book pelvic fracture (APC-II) after a motorcycle collision. He is hemodynamically unstable despite massive transfusion protocol initiation. What is the most appropriate immediate intervention?

. Internal iliac artery embolization
. Application of a pelvic binder centered over the greater trochanters
. Placement of an anterior external fixator
. Exploratory laparotomy and pelvic packing
. Open reduction and internal fixation of the pubic symphysis

Correct Answer & Explanation

. Internal iliac artery embolization

Explanation

In a hemodynamically unstable patient with an open-book pelvic ring injury, the immediate first step is to reduce pelvic volume. This is best achieved rapidly by applying a pelvic binder centered over the greater trochanters to provide tamponade.

Question 11293

Topic: 2. Trauma

Which of the following osteoinductive agents is currently FDA-approved for use in acute, open tibial shaft fractures treated with intramedullary nailing?

. Recombinant human BMP-2 (rhBMP-2)
. Recombinant human BMP-7 (OP-1)
. Recombinant human BMP-3
. Demineralized bone matrix (DBM)
. Platelet-rich plasma (PRP)

Correct Answer & Explanation

. Recombinant human BMP-2 (rhBMP-2)

Explanation

Recombinant human BMP-2 (rhBMP-2) is specifically FDA-approved for acute, open tibial shaft fractures stabilized with an intramedullary nail. It is also approved for use in anterior lumbar interbody fusions (ALIF).

Question 11294

Topic: 2. Trauma

A 35-year-old trauma patient presents with a hemodynamically unstable open-book pelvic fracture (APC type II). You decide to apply a non-invasive circumferential pelvic binder. To achieve maximal reduction of the symphysis pubis, over which anatomical landmark should the binder be centered?

. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Sacral promontory

Correct Answer & Explanation

. Iliac crests

Explanation

Circumferential pelvic binders are most effective at reducing pelvic volume when placed directly over the greater trochanters. Placement over the iliac crests is biomechanically less effective and can paradoxically widen the pelvic ring.

Question 11295

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 absolute criteria is most specific for diagnosing acute compartment syndrome and indicating fasciotomy?

. Absolute compartment pressure greater than 15 mmHg
. Absolute compartment pressure greater than 20 mmHg
. Delta pressure (diastolic blood pressure minus compartment pressure) less than 30 mmHg
. Delta pressure (mean arterial pressure minus compartment pressure) less than 40 mmHg
. Delta pressure (systolic blood pressure minus compartment pressure) less than 30 mmHg

Correct Answer & Explanation

. Absolute compartment pressure greater than 15 mmHg

Explanation

A delta pressure (diastolic blood pressure minus the measured compartment pressure) of less than 30 mmHg is considered the most reliable indicator for acute compartment syndrome. Relying purely on an absolute pressure threshold can lead to overtreatment or undertreatment depending on systemic hemodynamics.

Question 11296

Topic: Pelvic & Acetabular Trauma
A 40-year-old male presents with an APC III pelvic ring injury and hemodynamic instability. Despite a correctly placed pelvic binder, he remains hypotensive. What is the most common anatomical source of the hemorrhage in this scenario?
. Superior gluteal artery
. Obturator artery
. Presacral venous plexus
. Internal pudendal artery
. Middle sacral artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

The presacral venous plexus and cancellous bone bleeding are the most common sources of hemorrhage in pelvic ring injuries. Arterial bleeding occurs in about 10-20% of cases, typically involving the superior gluteal or internal pudendal arteries.

Question 11297

Topic: 2. Trauma
A 30-year-old male sustains a vertical, high-shear femoral neck fracture (Pauwels Type III). Which of the following biomechanical constructs provides the greatest resistance to vertical shear forces and varus collapse?
. Three parallel cancellous screws in an inverted triangle
. A sliding hip screw with a derotation screw
. A fully threaded single 7.3 mm screw
. Proximal femoral nail antirotation
. Two parallel 6.5 mm screws

Correct Answer & Explanation

. A sliding hip screw with a derotation screw

Explanation

A sliding hip screw (SHS) combined with a derotation screw provides superior biomechanical resistance to vertical shear forces compared to multiple cancellous screws in high-angle fractures. This reduces the risk of varus collapse and nonunion in young adults.

Question 11298

Topic: 2. Trauma

A 25-year-old female sustains a closed middle-third humeral shaft fracture with a primary radial nerve palsy. A closed reduction and splinting are performed. Post-reduction, the radial nerve palsy persists. What is the most appropriate management of the nerve injury?

. Immediate surgical exploration of the nerve
. Electromyography (EMG) immediately
. Observation for spontaneous recovery
. Magnetic resonance imaging (MRI) of the humerus
. Corticosteroid injection at the fracture site

Correct Answer & Explanation

. Immediate surgical exploration of the nerve

Explanation

Primary radial nerve palsy in the setting of a closed humeral shaft fracture is managed with observation, as spontaneous recovery occurs in over 90% of cases. Exploration is reserved for open fractures, penetrating injuries, or palsy developing secondary to reduction.

Question 11299

Topic: 2. Trauma

A 30-year-old male undergoes antegrade intramedullary nailing for a distal third femoral shaft fracture. Which of the following coronal and sagittal plane malalignments is most commonly seen post-operatively in this specific fracture pattern?

. Varus and apex posterior
. Valgus and apex posterior
. Varus and apex anterior
. Valgus and apex anterior
. Neutral alignment with significant shortening

Correct Answer & Explanation

. Varus and apex posterior

Explanation

Distal third femur fractures are prone to a valgus and apex anterior (procurvatum) deformity during intramedullary nailing. This is due to the pull of the gastrocnemius posteriorly and the adductor magnus medially.

Question 11300

Topic: 2. Trauma

A 35-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. Severe soft tissue swelling and fracture blisters are present. What is the most appropriate clinical indicator that the soft tissues are ready for definitive open reduction and internal fixation?

. Resolution of fracture blisters within 48 hours
. Reappearance of skin wrinkles
. Normal erythrocyte sedimentation rate (ESR)
. Clearance of ecchymosis
. Ability to actively dorsiflex the ankle

Correct Answer & Explanation

. Resolution of fracture blisters within 48 hours

Explanation

High-energy tibial plateau fractures often require delayed definitive fixation using a spanning external fixator. Definitive surgery should be delayed until the reappearance of skin wrinkles, indicating that swelling has subsided enough to allow safe surgical incisions.

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