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2. Trauma MCQs

Practice Set 133 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 2641

Topic: 2. Trauma

What is the primary risk factor for avascular necrosis (AVN) of the femoral head following a femoral neck fracture?

. Patient's age.
. Degree of fracture displacement.
. Associated nerve injury.
. Open fracture status.
. Comminution of the femoral head.

Correct Answer & Explanation

. Degree of fracture displacement.

Explanation

Correct Answer: BThe degree of fracture displacement is unequivocally the most significant risk factor for avascular necrosis (AVN) of the femoral head following a femoral neck fracture. Displaced femoral neck fractures disrupt the critical blood supply to the femoral head, primarily from the medial circumflex femoral artery. The greater the displacement, the higher the likelihood of complete vascular disruption and subsequent ischemia, leading to AVN. This is why Garden's classification, which assesses displacement, is so prognostic for AVN risk.Why other options are incorrect:A. Patient's age:While older patients are more prone to femoral neck fractures due to osteoporosis, age itself is not the primary direct risk factor for AVN. Displacement is the mechanical cause of vascular compromise.C. Associated nerve injury:Nerve injury is a complication of trauma but does not directly cause AVN of the femoral head.D. Open fracture status:Open fractures are associated with infection and soft tissue damage, but not directly with AVN of the femoral head in the context of a femoral neck fracture.E. Comminution of the femoral head:While comminution of the femoral head (Pipkin fractures) can lead to AVN, it is a specific type of femoral head injury, not the primary risk factor for AVN following afemoral neckfracture. The displacement of the neck fracture is the key factor for the femoral head's blood supply.

Question 2642

Topic: 2. Trauma
A 35-year-old male sustains a Gustilo-Anderson Type IIIB open tibia fracture requiring a rotational muscle flap for coverage. To minimize the risk of deep infection, soft tissue coverage should ideally be achieved within which time frame?
. Within 5 to 7 days
. Immediate closure within 6 hours
. After 3 weeks of continuous negative pressure therapy
. Following 6 weeks of external fixation
. Delayed beyond 2 weeks to allow clear demarcation

Correct Answer & Explanation

. Within 5 to 7 days

Explanation

Current trauma literature indicates that definitive soft tissue coverage of severe open lower extremity fractures within 5 to 7 days is associated with a significantly decreased rate of deep infection and improved outcomes.

Question 2643

Topic: 2. Trauma

An 82-year-old female sustains a displaced femoral neck fracture. Compared to internal fixation, treatment with a hemiarthroplasty offers which of the following primary advantages?

. Lower initial surgical mortality
. Shorter operative time
. Lower rate of reoperation
. Lower rate of hip dislocation
. Lower rate of surgical site infection

Correct Answer & Explanation

. Lower rate of reoperation

Explanation

In elderly patients with displaced femoral neck fractures, hemiarthroplasty provides a significantly lower rate of reoperation compared to internal fixation, avoiding complications like avascular necrosis and nonunion. However, arthroplasty typically involves longer surgical times and higher initial blood loss.

Question 2644

Topic: Pelvic & Acetabular Trauma
A 28-year-old patient arrives in the trauma bay hemodynamically unstable following a motorcycle collision. Pelvic radiographs demonstrate an "open book" anterior-posterior compression (APC-III) pelvic ring injury. A pelvic binder should be placed at which anatomic level?
. Above the umbilicus
. Over the iliac crests
. Mid-thigh
. Centered over the greater trochanters
. Over the symphysis pubis and L5

Correct Answer & Explanation

. Centered over the greater trochanters

Explanation

A pelvic binder provides the most effective mechanical advantage for reducing pelvic volume and controlling hemorrhage when it is centered over the greater trochanters, accurately targeting the pubic symphysis.

Question 2645

Topic: 2. Trauma

A 29-year-old male with a comminuted tibial shaft fracture complains of severe, unrelenting pain exacerbated by passive stretch of the hallux. Which of the following pressure criteria definitively indicates the need for emergent four-compartment fasciotomy?

. Absolute compartment pressure of 25 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Mean arterial pressure minus compartment pressure < 45 mmHg
. Systolic blood pressure minus compartment pressure < 30 mmHg
. Delta pressure greater than 40 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

Acute compartment syndrome is diagnosed when the delta pressure (diastolic blood pressure minus the absolute compartment pressure) is less than 30 mmHg. Relying on delta pressure is more accurate than absolute pressure alone.

Question 2646

Topic: 2. Trauma

Damage Control Orthopedics (DCO) involving temporary external fixation is favored over Early Total Care (ETC) in polytrauma patients presenting in extremis. Which of the following physiologic parameters is an indication for DCO?

. Serum lactate > 2.5 mmol/L
. Core temperature > 36.5°C
. Base excess of -1
. Platelet count of 150,000
. Systolic BP > 100 mmHg

Correct Answer & Explanation

. Serum lactate > 2.5 mmol/L

Explanation

Indications for Damage Control Orthopedics (DCO) include profound shock or inadequate resuscitation markers such as serum lactate > 2.5 mmol/L, pH < 7.25, base excess worse than -5.5, core temperature < 35°C, or significant coagulopathy.

Question 2647

Topic: 2. Trauma

A 35-year-old male sustains a spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). Initial examination shows an intact radial nerve. Following closed reduction and splint application, the patient exhibits a new complete radial nerve palsy. What is the most appropriate next step in management?

. Observation and electromyography (EMG) at 6 weeks
. Immediate surgical exploration and nerve release
. Immediate closed manipulation to reverse the reduction
. Application of a functional fracture brace
. Corticosteroid injection into the radial tunnel

Correct Answer & Explanation

. Immediate surgical exploration and nerve release

Explanation

While primary radial nerve palsies with closed humeral shaft fractures are typically observed, a secondary radial nerve palsy appearing after closed reduction indicates potential nerve entrapment in the fracture site, warranting immediate surgical exploration.

Question 2648

Topic: Pelvic & Acetabular Trauma
A trauma patient arrives hemodynamically unstable with a mechanically unstable anteroposterior compression (APC) type III pelvic ring injury. A circumferential pelvic binder is applied. What is the primary mechanism by which the binder achieves hemostasis?
. Direct compression of the common iliac artery
. Direct compression of the presacral venous plexus
. Reduction of pelvic volume allowing for a tamponade effect of venous bleeding
. Occlusion of the internal pudendal artery
. Immediate stimulation of the intrinsic coagulation cascade

Correct Answer & Explanation

. Reduction of pelvic volume allowing for a tamponade effect of venous bleeding

Explanation

Pelvic binders provide acute stabilization and reduce pelvic volume. This apposes cancellous bone surfaces and creates a tamponade effect that is primarily effective in slowing venous and cancellous bone bleeding.

Question 2649

Topic: 2. Trauma

A 30-year-old male is 12 hours post-intramedullary nailing of a tibial shaft fracture. He complains of rapidly worsening leg pain that requires escalating doses of opioids. His blood pressure is 110/70 mmHg. The anterior compartment pressure measures 45 mmHg. What is the most appropriate next step in management?

. Elevation of the leg above the level of the heart
. Administration of intravenous mannitol
. Immediate four-compartment fasciotomy
. Observation and re-check pressures in 4 hours
. Administration of a nerve block for pain control

Correct Answer & Explanation

. Immediate four-compartment fasciotomy

Explanation

The delta pressure (diastolic blood pressure minus compartment pressure) is 70 - 45 = 25 mmHg. A delta pressure of less than 30 mmHg is an absolute indication for an immediate four-compartment fasciotomy.

Question 2650

Topic: 2. Trauma
A 45-year-old farmer sustains a Gustilo-Anderson Type IIIB open tibia fracture heavily contaminated with soil and manure. In addition to a first-generation cephalosporin and an aminoglycoside, which antibiotic must be added to his initial prophylactic regimen?
. Vancomycin
. Clindamycin
. Penicillin
. Ciprofloxacin
. Doxycycline

Correct Answer & Explanation

. Penicillin

Explanation

For open fractures highly contaminated with soil or organic matter (such as farm injuries), high-dose Penicillin should be added to the prophylactic antibiotic regimen to provide coverage against Clostridium species and prevent gas gangrene.

Question 2651

Topic: 2. Trauma

A 45-year-old male presents 8 months after non-operative management of a midshaft humerus fracture with persistent motion and pain at the fracture site. Radiographs demonstrate a 'horse hoof' or 'elephant foot' hypertrophic nonunion. What is the primary underlying cause of this nonunion and the treatment of choice?

. Poor biology; requires autologous bone grafting alone
. Infection; requires debridement and antibiotic spacers
. Inadequate mechanical stability; requires rigid internal fixation
. Poor vascularity; requires a free vascularized fibular graft
. Metabolic bone disease; requires endocrine workup and bisphosphonates

Correct Answer & Explanation

. Inadequate mechanical stability; requires rigid internal fixation

Explanation

A hypertrophic nonunion ('elephant foot') indicates excellent biology and vascularity but inadequate mechanical stability. The treatment of choice is rigid internal fixation (e.g., compression plating) to allow the already present callus to consolidate.

Question 2652

Topic: Upper Extremity Trauma
A 45-year-old cyclist falls directly onto his shoulder. Clinical examination reveals a prominent clavicle, and radiographs show an acromioclavicular (AC) joint dislocation with 150% superior displacement of the clavicle relative to the acromion. Which of the following describes the injured structures in a Type III AC separation?
. Acromioclavicular ligaments torn, coracoclavicular ligaments intact
. Acromioclavicular ligaments intact, coracoclavicular ligaments torn
. Both acromioclavicular and coracoclavicular ligaments torn, with deltotrapezial fascia stripping
. Both acromioclavicular and coracoclavicular ligaments torn, deltotrapezial fascia intact
. Clavicle displaced inferiorly under the coracoid process

Correct Answer & Explanation

. Both acromioclavicular and coracoclavicular ligaments torn, deltotrapezial fascia intact

Explanation

In a Type III AC separation, both the AC and CC ligaments are completely torn, but the deltotrapezial fascia remains intact, allowing for 25-100% superior displacement. A Type V separation involves tearing of the AC, CC, and the deltotrapezial fascia, resulting in >100% superior displacement of the clavicle.

Question 2653

Topic: 2. Trauma

A 21-year-old elite collegiate basketball player sustains a fracture of the fifth metatarsal. Radiographs demonstrate a transverse fracture at the metaphyseal-diaphyseal junction. Which of the following is the most appropriate management for this specific patient?

. Non-weight-bearing cast for 6 weeks
. Weight-bearing as tolerated in a stiff-soled shoe
. Immediate intramedullary screw fixation
. Open reduction and plate fixation
. Excision of the proximal fragment

Correct Answer & Explanation

. Immediate intramedullary screw fixation

Explanation

This describes a Zone 2 (Jones) fracture of the fifth metatarsal. Because this region has a watershed blood supply, these fractures are prone to nonunion or delayed union. In a high-level competitive athlete, immediate intramedullary screw fixation is recommended to minimize nonunion risk and expedite return to play.

Question 2654

Topic: 2. Trauma

A 34-year-old male falls from his bicycle and sustains a completely displaced midshaft clavicle fracture. Which of the following radiographic findings is a universally accepted relative indication for open reduction and internal fixation?

. Presence of a single butterfly fragment
. Shortening greater than 2 centimeters
. Displacement less than 50% of the shaft diameter
. Angulation of 10 degrees
. Fracture location in the medial third of the clavicle

Correct Answer & Explanation

. Shortening greater than 2 centimeters

Explanation

Shortening of greater than 2 centimeters in a midshaft clavicle fracture is a recognized indication for operative intervention. Severe shortening alters shoulder girdle mechanics, leading to decreased endurance, weakness, and patient dissatisfaction if managed nonoperatively.

Question 2655

Topic: Upper Extremity Trauma

A 30-year-old male weightlifter feels a pop in his anterior chest while performing a bench press. Examination reveals an asymmetric axillary fold and weakness with resisted adduction and internal rotation. Where does the pectoralis major most commonly tear in this mechanism?

. At the musculotendinous junction
. At the tendinous insertion on the humerus
. At the sternal origin
. At the clavicular origin
. Mid-substance of the muscle belly

Correct Answer & Explanation

. At the tendinous insertion on the humerus

Explanation

Pectoralis major ruptures most commonly occur in weightlifters (specifically during bench press) and almost exclusively happen at the tendinous insertion onto the proximal humerus. The sternal head, which inserts deep and superiorly, is typically injured first as it stretches maximally during the eccentric phase of the lift.

Question 2656

Topic: 2. Trauma

A 65-year-old woman sustains a 3-part proximal humerus fracture.

Knowledge of the blood supply to the humeral head is critical for predicting the risk of avascular necrosis (AVN). Which vessel provides the primary blood supply to the articular segment of the humeral head?

. Anterior circumflex humeral artery
. Thoracoacromial artery
. Suprascapular artery
. Posterior circumflex humeral artery
. Profunda brachii artery

Correct Answer & Explanation

. Posterior circumflex humeral artery

Explanation

Historically, the anterior circumflex humeral artery (via the arcuate artery) was thought to be the primary blood supply. However, more recent quantitative studies (e.g., Hettrich et al.) demonstrated that the posterior circumflex humeral artery supplies over 64% of the blood to the humeral head, making it the major vascular contributor.

Question 2657

Topic: Upper Extremity Trauma

A 33-year-old professional overhead laborer falls directly onto his acromion, sustaining an acromioclavicular (AC) joint injury. Radiographs show superior displacement of the clavicle by 150% compared to the acromion, with an increased coracoclavicular distance. What is the most appropriate management for this Type V AC joint injury?

. Sling immobilization for 6 weeks followed by progressive therapy
. Surgical reconstruction of the coracoclavicular (CC) ligaments
. Distal clavicle excision alone
. Primary repair of the AC capsule without CC ligament stabilization
. Figure-of-eight bracing for 12 weeks

Correct Answer & Explanation

. Surgical reconstruction of the coracoclavicular (CC) ligaments

Explanation

Type V AC joint injuries involve severe superior displacement (>100%) due to disruption of both the AC and CC ligaments, along with deltotrapezial fascial stripping. Surgical reconstruction is generally indicated, especially in laborers and active patients.

Question 2658

Topic: Lower Extremity Trauma

A 45-year-old male with isolated medial compartment knee osteoarthritis and a varus mechanical axis is undergoing a medial opening-wedge high tibial osteotomy (HTO). To achieve optimal unloading, where should the weight-bearing line be transposed in the coronal plane?

. Directly through the center of the tibial plateau (50%)
. Through the medial spine of the tibial plateau (40%)
. Through the Fujisawa point (62% of the tibial plateau width from the medial edge)
. Through the lateral edge of the tibial plateau (100%)
. Through the center of the medial femoral condyle (25%)

Correct Answer & Explanation

. Through the Fujisawa point (62% of the tibial plateau width from the medial edge)

Explanation

The goal of an HTO for medial compartment OA is to shift the mechanical axis into slight valgus. The optimal target is the Fujisawa point, located approximately 62% of the total tibial plateau width measured from the medial cortex.

Question 2659

Topic: 2. Trauma
A 32-year-old male sustains a Hawkins type III talar neck fracture following a motor vehicle collision. Which of the following indicates a positive Hawkins sign on a 6-week follow-up radiograph, and what does it signify?
. Subchondral sclerosis of the talar dome signifying AVN
. Subchondral radiolucency of the talar dome signifying intact vascularity
. Flattening of the talar dome signifying early collapse
. Talar dome osteophyte formation signifying osteoarthritis
. Diffuse osteopenia of the entire foot signifying complex regional pain syndrome

Correct Answer & Explanation

. Subchondral radiolucency of the talar dome signifying intact vascularity

Explanation

A positive Hawkins sign is a subchondral radiolucent band in the talar dome observed 6-8 weeks post-injury. It indicates active bone resorption, which requires an intact blood supply, thereby serving as a reliable negative predictor for avascular necrosis (AVN).

Question 2660

Topic: 2. Trauma

A 45-year-old female sustains a 4-part proximal humerus fracture. According to the Hertel criteria, which of the following radiographic findings is the most reliable predictor of an intact blood supply to the humeral head, thereby decreasing the risk of avascular necrosis?

. Integrity of the posterior humeral circumflex artery
. Integrity of the anterior humeral circumflex artery
. Medial calcar hinge length greater than 8 mm
. Intact superior capsule
. Less than 45 degrees of varus angulation

Correct Answer & Explanation

. Medial calcar hinge length greater than 8 mm

Explanation

Hertel et al. demonstrated that a medial hinge length of >8 mm and an intact medial calcar attached to the articular segment are the strongest predictors of preserved humeral head perfusion in proximal humerus fractures.

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