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2. Trauma MCQs

Practice Set 383 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 7641

Topic: 2. Trauma

A 32-year-old man sustains a subtrochanteric femur fracture. Preoperatively, the proximal fragment is noted to be flexed, abducted, and externally rotated. Which muscle is primarily responsible for the external rotation of the proximal fragment?

. Gluteus medius
. Iliopsoas
. Short external rotators
. Tensor fasciae latae
. Adductor longus

Correct Answer & Explanation

. Gluteus medius

Explanation

In subtrochanteric femur fractures, the proximal fragment is flexed by the iliopsoas, abducted by the gluteus medius and minimus, and externally rotated by the short external rotators (e.g., piriformis, obturator internus, gemelli).

Question 7642

Topic: 2. Trauma

A 35-year-old construction worker sustains a Gustilo-Anderson Type IIIB open tibia fracture. According to current evidence-based guidelines, which of the following is the most critical factor in reducing the risk of deep infection?

. Time to definitive soft tissue coverage within 24 hours
. Time to administration of systemic antibiotics
. Time to initial surgical debridement within 6 hours
. Use of high-pressure pulsatile lavage
. Application of a negative pressure wound therapy device

Correct Answer & Explanation

. Time to definitive soft tissue coverage within 24 hours

Explanation

The most critical factor in reducing infection rates in open fractures is the early administration of appropriate systemic antibiotics, ideally within 1 hour of injury. The historical '6-hour rule' for surgical debridement has not been consistently supported by modern evidence.

Question 7643

Topic: 2. Trauma

Which of the following is an advantage of reamed intramedullary nailing compared to unreamed intramedullary nailing for the treatment of closed femoral shaft fractures?

. Decreased risk of fat embolism syndrome
. Lower rates of nonunion and delayed union
. Shorter operative time
. Decreased systemic inflammatory response
. Less compromise of endosteal blood supply

Correct Answer & Explanation

. Decreased risk of fat embolism syndrome

Explanation

Reamed intramedullary nailing of closed femoral shaft fractures provides higher union rates and lower implant failure rates compared to unreamed nailing. Reaming deposits osteogenic bone graft at the fracture site and allows for a larger, mechanically stronger nail.

Question 7644

Topic: 2. Trauma

A 22-year-old man with bilateral closed femoral shaft fractures develops hypoxemia, a petechial rash on his chest and axillae, and altered mental status 36 hours after presentation. What is the pathophysiologic mechanism most directly responsible for the cutaneous manifestations?

. Disseminated intravascular coagulation consuming platelets
. Endothelial damage and occlusion of dermal capillaries by lipid macroglobules
. Allergic reaction to systemic analgesics
. Microvascular thrombosis due to hypercoagulability
. Systemic inflammatory response to fracture hematoma

Correct Answer & Explanation

. Disseminated intravascular coagulation consuming platelets

Explanation

Fat embolism syndrome typically presents with the triad of hypoxemia, neurological abnormalities, and a petechial rash. The rash is caused by the occlusion of dermal capillaries by fat macroglobules, leading to local endothelial damage and erythrocyte extravasation.

Question 7645

Topic: 2. Trauma

When placing a blocking (Poller) screw to prevent a valgus deformity during intramedullary nailing of a proximal third tibial shaft fracture, the screw should be positioned in which location relative to the path of the reamer and nail?

. Lateral to the nail in the proximal fragment
. Medial to the nail in the proximal fragment
. Lateral to the nail in the distal fragment
. Medial to the nail in the distal fragment
. Anterior to the nail in the proximal fragment

Correct Answer & Explanation

. Lateral to the nail in the proximal fragment

Explanation

To prevent a valgus deformity in a proximal tibia fracture, the blocking screw should be placed on the concave side of the anticipated deformity (lateral side of the proximal fragment). This forces the nail medially, effectively narrowing the wide metaphysis and maintaining reduction.

Question 7646

Topic: 2. Trauma

A 28-year-old man sustains a high-energy trauma resulting in a midshaft femur fracture. Routine trauma radiographs reveal no other obvious injuries. What is the most common fracture pattern of the commonly missed ipsilateral proximal femur fracture in this scenario?

. Transverse basicervical
. Vertical shear (Pauwels III)
. Subcapital compression
. Transverse transcervical
. Inferior neck avulsion

Correct Answer & Explanation

. Transverse basicervical

Explanation

Ipsilateral femoral neck fractures occur in 2-9% of femur shaft fractures and are often missed on initial presentation. They are typically vertical, non-displaced, and basilar or transcervical, behaving mechanically like high-shear Pauwels III fractures.

Question 7647

Topic: 2. Trauma

A 35-year-old polytrauma patient presents with severe chest trauma, a closed femur fracture, and a closed tibia fracture. Which of the following parameters most strongly indicates the need for Damage Control Orthopedics (external fixation) rather than Early Total Care (intramedullary nailing)?

. Base deficit of 2 mmol/L
. Serum lactate of 1.5 mmol/L
. Platelet count of 150,000
. Pulmonary artery pressure of 45 mm Hg
. Urine output of 1 mL/kg/hr

Correct Answer & Explanation

. Base deficit of 2 mmol/L

Explanation

Elevated pulmonary artery pressure (>24 mm Hg), profound acidemia (base deficit >8), and elevated lactate (>2.5) are markers of an under-resuscitated or unstable polytrauma patient. A pulmonary artery pressure of 45 mm Hg contraindicates early intramedullary nailing due to the high risk of fatal right heart failure or ARDS.

Question 7648

Topic: 2. Trauma

When treating a proximal third tibial shaft fracture with an intramedullary nail, what is the most common resulting malalignment if standard infrapatellar techniques are used without adjunctive reduction aids?

. Apex posterior and varus
. Apex posterior and valgus
. Apex anterior and valgus
. Apex anterior and varus
. Pure rotational deformity

Correct Answer & Explanation

. Apex posterior and varus

Explanation

Proximal third tibia fractures treated with standard intramedullary nailing typically fall into an apex anterior (procurvatum) and valgus deformity. This is driven by the pull of the patellar tendon anteriorly and the wedge effect of the nail in the wide metaphyseal flare.

Question 7649

Topic: 2. Trauma

A 22-year-old man with an isolated closed femur fracture becomes acutely dyspneic, confused, and develops a petechial rash on his chest 48 hours after admission. Which of the following is the most critical aspect of the initial management of his primary systemic condition?

. Administration of high-dose corticosteroids
. Immediate full-dose heparinization
. Supportive care with adequate oxygenation and ventilation
. Placement of an inferior vena cava filter
. Emergent administration of systemic fibrinolytics

Correct Answer & Explanation

. Administration of high-dose corticosteroids

Explanation

The classic triad of Fat Embolism Syndrome (FES) includes hypoxemia, neurologic compromise, and a petechial rash. The primary treatment is supportive care, particularly ensuring adequate oxygenation and ventilation, as corticosteroids and heparin have not shown definitive survival benefit.

Question 7650

Topic: 2. Trauma

A 45-year-old patient involved in a motor vehicle collision sustains a supracondylar distal femur fracture. CT imaging reveals an associated coronal plane fracture of the lateral femoral condyle. What is the standard operative approach to adequately visualize and reduce this specific condylar fragment?

. Standard medial parapatellar approach
. Direct medial approach
. Direct lateral approach with possible lateral parapatellar arthrotomy
. Subvastus approach
. Posterior approach to the popliteal fossa

Correct Answer & Explanation

. Standard medial parapatellar approach

Explanation

A Hoffa fracture is a coronal plane fracture of the femoral condyle, most commonly involving the lateral condyle. A direct lateral approach with articular visualization (often via lateral parapatellar arthrotomy) allows direct reduction and optimal anterior-to-posterior screw fixation.

Question 7651

Topic: 2. Trauma

A 38-year-old woman sustains a high-energy varus directed force to her knee, resulting in a medial tibial plateau fracture with metaphyseal-diaphyseal dissociation. Which of the following associated injuries must be evaluated with the highest priority?

. Deep vein thrombosis
. Anterior tibial artery disruption
. Popliteal artery injury
. Superficial peroneal nerve neuropraxia
. Patellar tendon avulsion

Correct Answer & Explanation

. Deep vein thrombosis

Explanation

Schatzker IV (medial plateau) fractures typically occur from high-energy trauma and are considered equivalent to a knee dislocation. There is a significantly elevated risk of popliteal artery injury and common peroneal nerve injury, necessitating careful vascular evaluation.

Question 7652

Topic: 2. Trauma

A 40-year-old man sustains a closed, highly comminuted tibial plafond fracture with severe soft tissue swelling and fracture blisters. What is the primary rationale for placing a spanning external fixator rather than proceeding with immediate open reduction and internal fixation?

. To definitively treat the fracture without further surgery
. To allow for soft tissue resuscitation and decrease the risk of wound necrosis
. To accelerate endochondral ossification
. To prevent the development of deep vein thrombosis
. To completely avoid the need for articular reduction

Correct Answer & Explanation

. To definitively treat the fracture without further surgery

Explanation

High-energy pilon fractures are associated with significant soft-tissue injury. A staged approach (spanning external fixation followed by delayed ORIF at 10-21 days) allows the soft-tissue envelope to recover, dramatically reducing the risk of wound breakdown and deep infection.

Question 7653

Topic: 2. Trauma

A 25-year-old man is recovering from an intramedullary nailing of a tibial shaft fracture. He complains of increasing leg pain not relieved by opioids. His diastolic blood pressure is 70 mm Hg. What intracompartmental pressure reading would definitively support the diagnosis of acute compartment syndrome?

. 15 mm Hg
. 25 mm Hg
. 30 mm Hg
. 35 mm Hg
. 45 mm Hg

Correct Answer & Explanation

. 15 mm Hg

Explanation

Compartment syndrome is clinically supported when the delta P (Diastolic Blood Pressure minus Intracompartmental Pressure) is less than 30 mm Hg. With a diastolic BP of 70 mm Hg, an intracompartmental pressure of 45 mm Hg yields a delta P of 25 mm Hg, indicating acute compartment syndrome.

Question 7654

Topic: 2. Trauma

A 45-year-old smoker presents with an aseptic oligotrophic nonunion of the tibial diaphysis 9 months after initially undergoing intramedullary nailing. The fracture is mechanically stable but not healed. What is the most appropriate next step in management?

. Immediate removal of hardware and functional casting
. Exchange intramedullary nailing with reaming to a larger diameter
. Application of an Ilizarov ring external fixator
. Bone grafting alone without altering the implant
. Plate osteosynthesis leaving the current nail in situ

Correct Answer & Explanation

. Immediate removal of hardware and functional casting

Explanation

For aseptic nonunions of the tibial shaft following intramedullary nailing, exchange nailing with reaming to a larger diameter is the treatment of choice. Reaming stimulates the local biological environment, and a larger nail provides increased mechanical stability.

Question 7655

Topic: 2. Trauma

A 28-year-old male presents with a closed femoral shaft fracture, pulmonary contusions, and a closed head injury following a motor vehicle collision. His initial lactate is 4.5 mmol/L, base deficit is -8, and IL-6 is highly elevated. What is the most appropriate initial management of his femur fracture?

. Reamed antegrade intramedullary nailing
. Unreamed antegrade intramedullary nailing
. External fixation
. Plate osteosynthesis
. Skeletal traction only

Correct Answer & Explanation

. Reamed antegrade intramedullary nailing

Explanation

This patient is in an unstable physiological state (lactate >4, base deficit >6) with multiple injuries, making him an ideal candidate for Damage Control Orthopedics (DCO). External fixation provides rapid stability while avoiding the physiological 'second hit' associated with intramedullary nailing.

Question 7656

Topic: 2. Trauma

A 32-year-old male sustains a high-energy diaphyseal femur fracture. What is the most common concomitant fracture that is historically missed in this setting, and what imaging is mandatory?

. Patella fracture; MRI of the knee
. Ipsilateral femoral neck fracture; dedicated CT or fine-cut radiographs through the femoral neck
. Acetabular fracture; Judet views
. Pelvic ring injury; inlet/outlet views
. Tibial plateau fracture; CT of the knee

Correct Answer & Explanation

. Patella fracture; MRI of the knee

Explanation

Ipsilateral femoral neck fractures occur in 2-6% of femoral shaft fractures and are missed initially in up to 30% of cases. A dedicated CT scan or fine-cut protocol through the femoral neck is mandatory to rule out this injury.

Question 7657

Topic: 2. Trauma

A 45-year-old male presents with a distal femur fracture. CT imaging demonstrates a coronal plane fracture of the lateral femoral condyle (Hoffa fracture). If utilizing screw fixation from anterior to posterior, where must the screws be placed to avoid articular cartilage damage while providing optimal compression?

. Through the weight-bearing articular surface
. Proximal to the articular margin, un-countersunk
. Intersecting the intercondylar notch
. Through the non-weight-bearing articular cartilage, countersunk
. Distal to the joint line completely

Correct Answer & Explanation

. Through the weight-bearing articular surface

Explanation

Hoffa fractures (coronal shear fractures) are typically stabilized with anterior-to-posterior lag screws placed through the anterior non-weight-bearing articular surface of the condyle. These screws must be countersunk to prevent patellofemoral articulation impingement.

Question 7658

Topic: 2. Trauma

A 24-year-old male with a comminuted tibial shaft fracture complains of severe pain out of proportion to the injury. Which of the following parameters is the most accurate diagnostic threshold for acute compartment syndrome requiring fasciotomy?

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

Correct Answer & Explanation

. Absolute compartment pressure > 20 mmHg

Explanation

The Delta P (diastolic blood pressure minus the intracompartmental pressure) is the most reliable threshold for diagnosing acute compartment syndrome. A Delta P of less than 30 mmHg is a strict indication for four-compartment fasciotomies.

Question 7659

Topic: 2. Trauma

A 35-year-old male sustains a Gustilo-Anderson Type IIIB open fracture of the proximal third of the tibia. Following aggressive debridement and skeletal stabilization, a soft tissue defect with exposed bone remains. What is the most appropriate soft tissue coverage option?

. Medial gastrocnemius rotational flap
. Soleus rotational flap
. Reverse sural artery flap
. Free latissimus dorsi flap
. Split-thickness skin graft

Correct Answer & Explanation

. Medial gastrocnemius rotational flap

Explanation

For Gustilo IIIB open tibia fractures, soft tissue coverage is dictated by the zone of injury. The proximal third of the tibia is classically covered with a medial gastrocnemius rotational flap, whereas the middle third utilizes a soleus flap.

Question 7660

Topic: 2. Trauma

A 60-year-old male presents with a subtrochanteric femur fracture. During closed reduction for intramedullary nailing, the proximal segment is difficult to control. Which of the following best describes the typical deformity of the proximal fragment and the primary muscle responsible for its flexion?

. Flexed and externally rotated; Iliopsoas
. Extended and internally rotated; Gluteus maximus
. Flexed and internally rotated; Gluteus medius
. Extended and externally rotated; Iliopsoas
. Flexed and abducted; Adductor longus

Correct Answer & Explanation

. Flexed and externally rotated; Iliopsoas

Explanation

In a subtrochanteric fracture, the proximal fragment is typically flexed by the iliopsoas, abducted by the gluteus medius and minimus, and externally rotated by the short external rotators.

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