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2. Trauma MCQs

Practice Set 446 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 8901

Topic: 2. Trauma
A 38-year-old female struck by a vehicle presents with a massive, fluctuant, soft tissue swelling over her greater trochanter with intact overlying skin. MRI confirms a Morel-Lavallée lesion. What is the fundamental pathophysiology defining this soft tissue injury?
. A localized compartment syndrome involving the vastus lateralis muscle belly
. A closed shearing injury forcefully separating the subcutaneous tissue from the underlying deep fascial layer
. A massive deep venous thrombosis of the proximal femoral vein extravasating into muscle
. An acute infectious necrotizing fasciitis following microscopic skin abrasions
. A traumatic aneurysm of the deep femoral artery

Correct Answer & Explanation

. A closed shearing injury forcefully separating the subcutaneous tissue from the underlying deep fascial layer

Explanation

A Morel-Lavallée lesion is a closed internal degloving injury. It is caused by severe shear forces that abruptly separate the subcutaneous fat from the underlying non-yielding deep fascia, creating a potential space that fills with blood, lymph, and necrotic fat.

Question 8902

Topic: 2. Trauma

A 40-year-old male is evaluated following a posterior hip dislocation with an associated posterior wall acetabular fracture. The hip is reduced in the emergency department. Which of the following findings is an absolute indication for operative fixation of the posterior wall fracture rather than non-operative management?

. Fracture fragment comprising 15 percent of the posterior wall on CT scan
. Concomitant non-displaced pubic ramus fracture
. The presence of a marginal impaction segment of 1 mm
. Radiographic evidence of a small intra-articular gas bubble
. Subluxation of the femoral head on dynamic stress fluoroscopy under anesthesia

Correct Answer & Explanation

. Subluxation of the femoral head on dynamic stress fluoroscopy under anesthesia

Explanation

The most critical determinant for fixing a posterior wall acetabular fracture is hip joint instability. A dynamic stress exam demonstrating subluxation of the femoral head (often occurring with >20-50% wall involvement) is an absolute indication for operative fixation.

Question 8903

Topic: 2. Trauma

A 28-year-old male presents with bilateral femur fractures and a blunt chest injury after a motor vehicle collision. His serum lactate is 4.5 mmol/L and base deficit is -8. What is the most appropriate initial management of his femoral fractures?

. Bilateral reamed intramedullary nailing
. Bilateral unreamed intramedullary nailing
. Bilateral external fixation
. Open reduction internal fixation with plates
. Skeletal traction only

Correct Answer & Explanation

. Bilateral external fixation

Explanation

This patient is in a borderline to unstable physiologic state with a lactate > 4.0 and base deficit < -6.0. Damage Control Orthopedics (DCO) with rapid external fixation is indicated to minimize the systemic inflammatory response and avoid the "second hit" phenomenon.

Question 8904

Topic: 2. Trauma

A 42-year-old female undergoes open reduction and internal fixation of a Schatzker VI tibial plateau fracture. Postoperatively, she develops severe pain out of proportion to examination and paresthesias in her first web space. What is the most reliable method to diagnose the suspected complication?

. Clinical examination alone
. Duplex ultrasound
. Intracompartmental pressure monitoring
. MRI of the leg
. CT angiography

Correct Answer & Explanation

. Intracompartmental pressure monitoring

Explanation

The patient exhibits classic signs of acute compartment syndrome affecting the deep peroneal nerve territory. Intracompartmental pressure monitoring is the most reliable objective diagnostic tool, particularly when clinical signs are ambiguous post-surgery or in obtunded patients.

Question 8905

Topic: 2. Trauma

During fixation of a supracondylar distal femur fracture (OTA/AO 33-C), a coronal plane fracture of the lateral femoral condyle is identified. What is the optimal fixation strategy for this specific articular fragment?

. Anterior-to-posterior directed lag screws
. Posterior-to-anterior directed lag screws
. Medial-to-lateral directed lag screws
. Pre-contoured lateral locking plate alone
. Retrograde intramedullary nailing

Correct Answer & Explanation

. Anterior-to-posterior directed lag screws

Explanation

A Hoffa fracture is a coronal plane fracture of the femoral condyle. It is biomechanically best treated with anterior-to-posterior directed lag screws placed perpendicular to the fracture line to achieve compression prior to application of a lateral neutralization plate.

Question 8906

Topic: Pelvic & Acetabular Trauma
A 30-year-old female presents in hemorrhagic shock after a crush injury. Pelvic radiograph shows an APC-III injury with pubic symphysis diastasis of 4 cm and complete disruption of the sacroiliac joints bilaterally. After applying a pelvic binder, her hemodynamics remain unstable. What is the next most appropriate step?
. Immediate open reduction internal fixation
. Retrograde urethrogram
. Preperitoneal pelvic packing and/or angioembolization
. Bilateral lower extremity traction
. Immediate sacral screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angioembolization

Explanation

In an unstable pelvic ring injury with ongoing hemorrhagic shock despite mechanical stabilization, immediate hemorrhage control is mandatory. Preperitoneal pelvic packing or angioembolization are the standard interventions for refractory hemodynamic instability.

Question 8907

Topic: 2. Trauma
A 35-year-old male sustains a Gustilo-Anderson Grade IIIA open tibial shaft fracture. What is the single most critical factor in reducing his risk of deep infection?
. Immediate soft tissue coverage within 12 hours
. Early administration of intravenous antibiotics
. Use of a reamed versus unreamed nail
. Application of negative pressure wound therapy
. Addition of local antibiotic beads at index surgery

Correct Answer & Explanation

. Early administration of intravenous antibiotics

Explanation

The early administration of systemic intravenous antibiotics (ideally within 1 hour of injury) is the most critical and extensively proven factor in decreasing infection rates in open fractures.

Question 8908

Topic: 2. Trauma

A 40-year-old male sustains a displaced fracture of the scapular neck. Which of the following is a generally accepted indication for operative management of this injury?

. 5 mm of medial translation
. 10 degrees of angular deformity
. Glenopolar angle of 20 degrees
. Associated non-displaced clavicle fracture
. Scapular body comminution without displacement

Correct Answer & Explanation

. Glenopolar angle of 20 degrees

Explanation

Operative indications for scapular neck fractures typically include medial translation > 20 mm, angular deformity > 40 degrees, or a glenopolar angle < 22 degrees, as these significantly alter glenohumeral biomechanics and rotator cuff tension.

Question 8909

Topic: 2. Trauma
A 28-year-old male sustains a Pauwels type III (vertical) femoral neck fracture. What is the biomechanical rationale for utilizing a sliding hip screw with a derotational screw rather than three parallel cancellous screws?
. It prevents anterior capsular impingement
. It offers superior resistance to vertical shear forces
. It preserves the lateral epiphyseal artery
. It decreases the overall rate of osteonecrosis
. It allows immediate full weight-bearing safely

Correct Answer & Explanation

. It offers superior resistance to vertical shear forces

Explanation

Pauwels type III fractures have a highly vertical fracture line, subjecting them to massive vertical shear forces. A fixed-angle device like a sliding hip screw provides superior biomechanical resistance to these shear forces compared to parallel cancellous screws.

Question 8910

Topic: 2. Trauma

A 33-year-old man sustains a closed spiral fracture of the distal third of the humerus (Holstein-Lewis) and presents with a dense radial nerve palsy. What is the most appropriate initial management?

. Immediate surgical exploration of the nerve
. Application of a functional brace and observation
. Urgent electromyography (EMG)
. Open reduction and internal fixation with nerve exploration
. External fixation spanning the elbow

Correct Answer & Explanation

. Application of a functional brace and observation

Explanation

Most radial nerve palsies associated with closed humeral shaft fractures (including the Holstein-Lewis type) are neuropraxias that recover spontaneously. Initial management is closed reduction with functional bracing and observation for 3-4 months before considering exploration.

Question 8911

Topic: 2. Trauma
A 32-year-old male sustains a closed Hawkins type III talar neck fracture. Following prompt open reduction and internal fixation, what is the most reliable early radiographic indicator that the talar body has maintained its vascular supply?
. Sclerosis of the talar dome on the AP radiograph
. Subchondral radiolucency of the talar dome on the mortise view
. Increased radiodensity of the entire talus on the lateral view
. Periosteal reaction along the talar neck
. Subchondral collapse of the talar dome

Correct Answer & Explanation

. Subchondral radiolucency of the talar dome on the mortise view

Explanation

Hawkins sign, a subchondral radiolucency in the talar dome seen 6-8 weeks post-injury, indicates intact vascularity and active bone resorption. Its presence makes the development of avascular necrosis highly unlikely.

Question 8912

Topic: 2. Trauma

According to Hertel's criteria, which combination of radiographic findings most accurately predicts humeral head ischemia following a proximal humerus fracture?

. Calcar length > 8 mm and an intact medial hinge
. Calcar length < 8 mm and a disrupted medial hinge
. Greater tuberosity displacement > 1 cm and a split humeral head
. Varus angulation > 20 degrees and bicipital groove extension
. Surgical neck displacement > 1 cm and an intact medial hinge

Correct Answer & Explanation

. Calcar length < 8 mm and a disrupted medial hinge

Explanation

Hertel identified a metaphyseal head extension (calcar length) of < 8 mm and a disrupted medial hinge as the most reliable predictors of humeral head ischemia. Combined, these findings have a positive predictive value of nearly 97% for ischemia.

Question 8913

Topic: 2. Trauma

A 25-year-old man is treated with an intramedullary nail for a proximal third tibial shaft fracture. To prevent the most common malalignment associated with this procedure, how should blocking (Poller) screws be placed relative to the nail?

. On the convex side of the anticipated deformity in the proximal fragment
. On the concave side of the anticipated deformity in the proximal fragment
. Only in the distal fragment to prevent distal translation
. In a purely anteroposterior direction, regardless of the deformity plane
. Parallel to the locking screws in the metaphysis

Correct Answer & Explanation

. On the concave side of the anticipated deformity in the proximal fragment

Explanation

Blocking screws are placed on the concave side of the anticipated deformity (or the acute angle of the fracture) to direct the nail toward the central axis. For proximal tibia fractures, this typically means placing the screw posterior and lateral to the nail.

Question 8914

Topic: 2. Trauma

A 35-year-old man sustains a completely displaced diaphyseal fracture of the radius and ulna (both-bone forearm fracture). During open reduction and internal fixation, which of the following principles is critical for restoring maximum forearm rotation?

. Plating the ulna on its volar surface
. Restoring the anatomical radial bow
. Using a single plate bridging both bones
. Fixing the radius with an intramedullary device
. Immobilizing the arm in supination for 6 weeks postoperatively

Correct Answer & Explanation

. Restoring the anatomical radial bow

Explanation

Restoring the normal anatomical radial bow is essential during the fixation of both-bone forearm fractures. Failure to restore this bow is highly correlated with restricted pronation and supination.

Question 8915

Topic: Pelvic & Acetabular Trauma
A 42-year-old trauma patient has an unstable pelvic ring injury with a widened pubic symphysis (APC-III). A pelvic binder is applied in the trauma bay. For maximal mechanical effectiveness in reducing the pelvic volume, at what anatomical landmark should the binder be centered?
. The iliac crests
. The greater trochanters
. The anterior superior iliac spines
. The level of the umbilicus
. The pubic tubercle

Correct Answer & Explanation

. The greater trochanters

Explanation

To effectively reduce pelvic volume and stabilize the bony ring, a pelvic binder must be centered directly over the greater trochanters. Placement higher over the iliac crests is less mechanically effective and can limit abdominal access.

Question 8916

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented (Pauwels III) femoral neck fracture. When treating this with multiple cancellous screws, which of the following describes the most biomechanically stable screw configuration?
. Two screws placed inferiorly and one screw placed superiorly
. Two screws placed superiorly and one screw placed inferiorly along the calcar
. Three screws placed in a vertical line
. Four screws placed in a square configuration
. Two crossed screws

Correct Answer & Explanation

. Two screws placed superiorly and one screw placed inferiorly along the calcar

Explanation

The inverted triangle configuration (two superior screws and one inferior screw resting on the calcar) is the most biomechanically stable pattern for fixing femoral neck fractures. It optimally resists both shear forces and varus displacement.

Question 8917

Topic: 2. Trauma

A 45-year-old man sustains a comminuted distal femur fracture. CT imaging reveals a coronal plane fracture of the lateral femoral condyle (Hoffa fragment). Which of the following describes the most appropriate fixation strategy for this specific fragment?

. Lag screws placed from anterior to posterior
. A single lateral locking plate capturing the fragment with unicortical screws
. Lag screws placed from posterior to anterior
. An intramedullary nail with dynamic locking
. External fixation spanning the knee

Correct Answer & Explanation

. Lag screws placed from anterior to posterior

Explanation

A Hoffa fracture is a coronal shear fracture of the femoral condyle. It is best stabilized with anterior-to-posterior (AP) directed lag screws, placed perpendicular to the fracture plane to provide interfragmentary compression.

Question 8918

Topic: 2. Trauma
A 30-year-old patient with an open tibial shaft fracture (Gustilo-Anderson Grade IIIA) is brought to the emergency department. According to current guidelines, what is the optimal timing and regimen for prophylactic antibiotic administration?
. Within 6 hours of injury using a first-generation cephalosporin alone
. Within 1 hour of injury using a first-generation cephalosporin and an aminoglycoside or third-generation cephalosporin
. At the time of surgical debridement using a first-generation cephalosporin
. Within 24 hours of injury using a fluoroquinolone
. Within 1 hour of injury using vancomycin and piperacillin-tazobactam

Correct Answer & Explanation

. Within 1 hour of injury using a first-generation cephalosporin and an aminoglycoside or third-generation cephalosporin

Explanation

For severe open fractures (Gustilo Type III), early antibiotic administration within 1 hour is critical. The recommended regimen includes a first-generation cephalosporin for Gram-positives, plus an aminoglycoside or third-generation cephalosporin for Gram-negatives.

Question 8919

Topic: 2. Trauma

A 50-year-old patient sustains a diaphyseal humerus fracture and is noted to have a radial nerve palsy upon presentation. Closed reduction and splinting are performed. Post-reduction radiographs show acceptable alignment, but the radial nerve deficit persists. What is the most appropriate next step in management?

. Immediate surgical exploration of the radial nerve
. Electromyography (EMG) at 1 week post-injury
. Observation and expectant management
. Immediate intramedullary nailing
. Magnetic resonance imaging (MRI) of the humerus

Correct Answer & Explanation

. Observation and expectant management

Explanation

Primary radial nerve palsy associated with a closed humeral shaft fracture is typically a neurapraxia that resolves spontaneously. Observation is indicated initially; surgical exploration is reserved for open fractures, penetrating injuries, or failure to recover by 3-4 months.

Question 8920

Topic: 2. Trauma

A 25-year-old man falls from a height and sustains an unstable burst fracture of L1 with retropulsion of bone into the spinal canal. He is neurologically intact. Which of the following is considered an absolute indication for operative stabilization?

. Canal compromise > 50%
. Loss of anterior vertebral body height > 30%
. Translational deformity (subluxation) in the coronal or sagittal plane
. Kyphotic angulation > 15 degrees
. The presence of a concurrent calcaneus fracture

Correct Answer & Explanation

. Translational deformity (subluxation) in the coronal or sagittal plane

Explanation

A translational or rotatory deformity indicates failure of all three columns and profound mechanical instability, which is an absolute indication for operative stabilization. Canal compromise alone in a neurologically intact patient is not an absolute surgical indication.

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