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2. Trauma MCQs

Practice Set 256 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 5101

Topic: Pelvic & Acetabular Trauma

In a patient with an anteroposterior compression (APC) pelvic ring injury, at what threshold of pubic symphysis diastasis are the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments typically disrupted, signifying an APC II injury?

. > 1.0 cm
. > 1.5 cm
. > 2.5 cm
. > 3.5 cm
. > 5.0 cm

Correct Answer & Explanation

. > 2.5 cm

Explanation

A symphyseal diastasis greater than 2.5 cm is the classic threshold indicating rupture of the pelvic floor ligaments (sacrotuberous and sacrospinous) and the anterior sacroiliac ligaments. This injury pattern defines an APC II pelvic ring injury. A diastasis of less than 2.5 cm (APC I) usually indicates the posterior ligaments remain intact.

Question 5102

Topic: 2. Trauma

A 32-year-old male sustains a distal femur fracture in a motorcycle collision. CT imaging reveals a coronal plane fracture of the lateral femoral condyle. What is the most common mechanism of injury leading to this specific fracture pattern (Hoffa fracture)?

. Axial load with the knee in 90 degrees or more of flexion
. Valgus stress with the knee in full extension
. Direct blow to the anterior patella
. Hyperextension injury with rotational torque
. Avulsion via the lateral collateral ligament complex

Correct Answer & Explanation

. Axial load with the knee in 90 degrees or more of flexion

Explanation

Hoffa fractures are coronal shear fractures of the distal femoral condyles, most commonly affecting the lateral condyle. The classic mechanism of injury is an axial load transmitted through the femoral condyle while the knee is in 90 degrees or more of flexion, driving the posterior aspect of the condyle proximally.

Question 5103

Topic: 2. Trauma

During surgical planning for a 4-part proximal humerus fracture, understanding the vascular anatomy is critical. Which vessel has been shown in quantitative studies to supply the majority of the blood to the native humeral head?

. Arcuate artery
. Anterior humeral circumflex artery via the anterolateral branch
. Posterior humeral circumflex artery via the posteromedial vessels
. Suprascapular artery
. Thoracoacromial artery

Correct Answer & Explanation

. Posterior humeral circumflex artery via the posteromedial vessels

Explanation

Historically, the anterior humeral circumflex artery (specifically its arcuate branch) was believed to be the primary blood supply to the humeral head. However, landmark cadaveric studies by Brooks et al. and Hettrich et al. established that the posterior humeral circumflex artery provides approximately 64% of the blood supply to the humeral head, making it the major vascular contributor.

Question 5104

Topic: 2. Trauma

A 45-year-old roofer falls 15 feet and sustains a closed intra-articular calcaneus fracture. On the lateral radiograph, Bohler's angle is measured at 5 degrees. What is the normal physiological range for Bohler's angle?

. 0 to 10 degrees
. 10 to 20 degrees
. 20 to 40 degrees
. 40 to 60 degrees
. 60 to 80 degrees

Correct Answer & Explanation

. 20 to 40 degrees

Explanation

Bohler's angle is measured on a lateral radiograph by drawing one line from the highest point of the anterior process to the highest point of the posterior facet, and a second line from the highest point of the posterior facet to the highest point of the calcaneal tuberosity. The normal range is 20 to 40 degrees. A decreased angle (<20 degrees) indicates collapse of the posterior facet, which is typical in intra-articular calcaneus fractures.

Question 5105

Topic: 2. Trauma

A 24-year-old male is admitted with a comminuted midshaft tibia fracture. He develops severe leg pain out of proportion to the injury. Which of the following pressure readings or thresholds is most widely accepted as an absolute indication for emergent fasciotomy for acute compartment syndrome?

. Absolute compartment pressure > 20 mmHg
. Delta P (diastolic blood pressure minus compartment pressure) < 20 mmHg
. Delta P (diastolic blood pressure minus compartment pressure) < 30 mmHg
. Absolute compartment pressure > 15 mmHg with a normal physical exam
. Delta P (diastolic blood pressure minus compartment pressure) > 40 mmHg

Correct Answer & Explanation

. Delta P (diastolic blood pressure minus compartment pressure) < 30 mmHg

Explanation

A Delta P (diastolic blood pressure minus absolute compartment pressure) of less than or equal to 30 mmHg is the most reliable objective threshold for diagnosing acute compartment syndrome. Using a Delta P rather than an absolute pressure accounts for the patient's systemic perfusion pressure and minimizes unnecessary fasciotomies.

Question 5106

Topic: 2. Trauma

In the initial management of a severely polytraumatized patient, which of the following physiological parameters is most suggestive that the patient is in an 'in extremis' state, favoring Damage Control Orthopedics (DCO) over Early Total Care (ETC)?

. Lactate of 2.0 mmol/L
. Base deficit of -2.0 mEq/L
. Core body temperature of 36.5 C
. Platelet count of 70,000/uL
. Arterial pH of 7.35

Correct Answer & Explanation

. Platelet count of 70,000/uL

Explanation

Parameters favoring Damage Control Orthopedics over Early Total Care include elements of the 'lethal triad' (hypothermia, coagulopathy, acidosis). Specific thresholds for 'in extremis' or borderline patients include: hypothermia (< 32-35 C), coagulopathy (platelets < 90,000/uL, INR > 1.5), and severe acidosis (pH < 7.24, base deficit more negative than -6, lactate > 2.5 mmol/L). A platelet count of 70,000/uL indicates significant coagulopathy, warranting DCO.

Question 5107

Topic: 2. Trauma

A 40-year-old male sustains a coronal shear fracture of the lateral femoral condyle (Hoffa fracture). Biomechanical studies have demonstrated that which of the following screw configurations provides the most stable construct against vertical shear forces?

. Anterior-to-posterior (AP) lag screws
. Posterior-to-anterior (PA) lag screws
. Medial-to-lateral lag screws
. Crossed K-wires
. A single large-fragment partially threaded screw

Correct Answer & Explanation

. Posterior-to-anterior (PA) lag screws

Explanation

A Hoffa fracture is a coronal plane fracture of the femoral condyle (most commonly lateral). While an anterior-to-posterior (AP) approach is frequently used clinically due to ease of surgical access, biomechanical studies demonstrate that posterior-to-anterior (PA) directed lag screws placed perpendicular to the fracture plane offer superior pull-out strength and structural stability compared to AP screws.

Question 5108

Topic: Upper Extremity Trauma

Recent quantitative anatomic studies evaluating the vascularity of the proximal humerus have challenged historical teachings regarding the primary blood supply to the humeral head. Based on contemporary understanding (e.g., Hertel et al.), which artery provides the predominant blood supply to the humeral head?

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

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

Historically, the arcuate artery (a branch of the ascending branch of the anterior humeral circumflex artery) was thought to be the principal blood supply to the humeral head. However, modern cadaveric studies using advanced perfusion techniques have definitively demonstrated that the posterior humeral circumflex artery provides the vast majority (up to 64%) of the robust intraosseous blood supply to the humeral head.

Question 5109

Topic: 2. Trauma
A 26-year-old previously healthy male sustains a high-energy Pauwels type III (vertical) femoral neck fracture. To minimize the risk of varus collapse and nonunion, which of the following internal fixation constructs provides the greatest biomechanical stability against vertical shear forces?
. Three parallel cannulated screws placed in an inverted triangle
. Fixed-angle sliding hip screw with an anti-rotation screw
. Proximal femoral nail with a single helical blade
. Hemiarthroplasty
. Non-spanning external fixator

Correct Answer & Explanation

. Fixed-angle sliding hip screw with an anti-rotation screw

Explanation

Pauwels type III femoral neck fractures have a vertical fracture line (angle >50 degrees), which subjects the fracture to immense vertical shear forces. Biomechanical studies have shown that multiple cannulated screws have a high failure rate due to varus collapse. A fixed-angle construct, such as a sliding hip screw (with an anti-rotation screw) or a modern femoral neck system, provides superior biomechanical stability against shear forces compared to parallel cannulated screws.

Question 5110

Topic: 2. Trauma

The Sanders classification system is widely used for guiding the management of intra-articular calcaneus fractures. This classification is determined by the number and location of primary fracture lines through which of the following structures on a coronal CT scan?

. Anterior articular facet
. Middle articular facet
. Posterior articular facet
. Calcaneocuboid joint surface
. Sustentaculum tali

Correct Answer & Explanation

. Posterior articular facet

Explanation

The Sanders classification system utilizes coronal CT images at the widest portion of the posterior facet of the calcaneus. It classifies fractures into types I through IV based strictly on the number and location of articular fracture lines through the posterior articular facet. The classification helps guide surgical decision-making and provides prognostic information.

Question 5111

Topic: 2. Trauma

When counseling a 35-year-old male with an acute, closed midshaft clavicle fracture regarding non-operative management, which of the following represents the most significant independent predictor for the development of a nonunion?

. Obesity
. Shortening greater than 2 cm
. Male sex
. Presence of a butterfly fragment
. Concomitant rib fractures

Correct Answer & Explanation

. Shortening greater than 2 cm

Explanation

While several factors influence midshaft clavicle fracture healing (including advanced age, female gender, and comminution), the degree of initial displacement and fracture shortening is widely considered the strongest predictor of nonunion. Specifically, shortening greater than 20 mm (2 cm) or 100% displacement dramatically increases the nonunion risk in non-operatively treated clavicle fractures.

Question 5112

Topic: 2. Trauma

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

. Metaphyseal extension >8 mm and an intact medial hinge
. Anatomical neck fracture with <2 mm medial hinge disruption
. Calcar length <8 mm and a disrupted medial hinge
. Greater tuberosity displacement >5 mm and intact calcar
. Valgus impaction with >10 mm metaphyseal extension

Correct Answer & Explanation

. Calcar length <8 mm and a disrupted medial hinge

Explanation

Hertel described predictors for humeral head ischemia in proximal humerus fractures. A short calcar segment (<8 mm), a disrupted medial hinge, and an anatomical neck fracture are the strongest positive predictive factors for avascular necrosis.

Question 5113

Topic: 2. Trauma

A 40-year-old male sustains a high-energy Schatzker IV tibial plateau fracture. Which associated injury should the surgeon have the highest index of suspicion for compared to lateral-sided plateau fractures?

. Common peroneal nerve palsy
. Popliteal artery injury secondary to a knee dislocation equivalent
. Isolated lateral meniscus tear
. Patellar tendon rupture
. Anterior cruciate ligament avulsion fracture

Correct Answer & Explanation

. Popliteal artery injury secondary to a knee dislocation equivalent

Explanation

Schatzker IV (medial plateau) fractures are often high-energy injuries involving varus forces and are frequently considered fracture-dislocations of the knee. They carry a significantly higher risk of popliteal artery injury and multiple ligamentous disruptions than simple lateral plateau fractures.

Question 5114

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented (Pauwels type III) femoral neck fracture. Which of the following fixation constructs provides the most biomechanically stable fixation for this specific fracture pattern?
. Three parallel cannulated screws
. A sliding hip screw with an anti-rotation screw
. A fixed-angle dynamic condylar screw
. A proximal femoral locking plate
. Two crossed cannulated screws

Correct Answer & Explanation

. A sliding hip screw with an anti-rotation screw

Explanation

Pauwels type III fractures experience high shear forces and varus stress. A sliding hip screw with an anti-rotation screw provides superior biomechanical stability compared to multiple cancellous screws by allowing controlled compression and resisting shear.

Question 5115

Topic: 2. Trauma

A 45-year-old male presents with a Schatzker type IV medial tibial plateau fracture. An open reduction and internal fixation via a posteromedial approach is planned. Which internervous/intermuscular interval is primarily utilized in this approach?

. Between the medial head of the gastrocnemius and the soleus
. Between the semimembranosus and semitendinosus
. Between the pes anserinus anteriorly and the medial head of the gastrocnemius posteriorly
. Between the tibialis posterior and the flexor digitorum longus
. Between the popliteus and the lateral head of the gastrocnemius

Correct Answer & Explanation

. Between the pes anserinus anteriorly and the medial head of the gastrocnemius posteriorly

Explanation

The standard posteromedial approach to the tibial plateau utilizes the interval between the pes anserinus tendons anteriorly and the medial head of the gastrocnemius posteriorly. This allows excellent and safe visualization of the posteromedial fracture fragment.

Question 5116

Topic: 2. Trauma

According to the Hertel criteria, which of the following radiographic findings is the strongest predictor of humeral head ischemia following a proximal humerus fracture?

. Greater tuberosity displacement > 5 mm
. Varus angulation > 20 degrees
. Anatomic neck fracture combined with a medial calcar hinge < 2 mm
. Surgical neck fracture with metaphyseal head extension > 8 mm
. Disruption of the bicipital groove

Correct Answer & Explanation

. Anatomic neck fracture combined with a medial calcar hinge < 2 mm

Explanation

Hertel criteria for humeral head ischemia include a short metaphyseal head extension (< 8 mm) and disruption of the medial hinge (< 2 mm). An anatomic neck fracture combined with an absent or severely disrupted medial hinge has the highest predictive value for ischemia.

Question 5117

Topic: Pelvic & Acetabular Trauma
A 30-year-old male arrives in the trauma bay in hemorrhagic shock following a motorcycle accident. Radiographs reveal an anteroposterior compression (APC) type III pelvic ring injury. What is the correct anatomical landmark for the application of a circumferential pelvic sheet or binder?
. Just proximal to the iliac crests
. Directly over the anterior superior iliac spines (ASIS)
. Centered over the greater trochanters
. Mid-thigh level to compress the femoral vessels
. Over the lower abdomen, just superior to the pubic symphysis

Correct Answer & Explanation

. Centered over the greater trochanters

Explanation

Pelvic binders should be centered directly over the greater trochanters. Placement higher over the iliac crests or abdomen is ineffective for reducing the pelvic volume and can paradoxically widen the pelvis in open-book injuries.

Question 5118

Topic: 2. Trauma

When fixing a 3-part proximal humerus fracture with a locking plate, which of the following surgical techniques best minimizes the risk of varus collapse and subsequent screw cutout?

. Placing the plate superior to the greater tuberosity
. Using purely unicortical locking screws in the humeral head
. Placement of an inferomedial calcar screw
. Avoiding rotator cuff sutures to the plate
. Using a non-locking plate design

Correct Answer & Explanation

. Placement of an inferomedial calcar screw

Explanation

The placement of an inferomedial calcar screw into the inferomedial quadrant of the humeral head mechanically supports the medial hinge. This significantly reduces the risk of varus collapse and superior screw cutout.

Question 5119

Topic: 2. Trauma
A 30-year-old male sustains a Hawkins type III talar neck fracture. Six weeks postoperatively, an AP radiograph of the ankle demonstrates a subchondral radiolucent band in the talar dome. What does this radiographic finding indicate?
. Avascular necrosis of the talar body
. Infection of the talocrural joint
. Intact vascular supply to the talar body
. Impending post-traumatic arthritis
. Nonunion of the talar neck

Correct Answer & Explanation

. Intact vascular supply to the talar body

Explanation

This finding is the Hawkins sign, which represents subchondral osteopenia secondary to hyperemia from disuse. It is a highly reliable indicator that the vascular supply to the talar body is intact, thereby ruling out avascular necrosis.

Question 5120

Topic: 2. Trauma
A 25-year-old male sustains a displaced Pauwels type III femoral neck fracture. Which of the following fixation constructs provides the most biomechanically stable construct against vertical shear forces?
. Three parallel cancellous lag screws in an inverted triangle
. Three parallel cancellous lag screws in a standard triangle
. A dynamic hip screw (DHS) with a derotation screw
. Two parallel cancellous lag screws
. A single large-diameter fully threaded screw

Correct Answer & Explanation

. A dynamic hip screw (DHS) with a derotation screw

Explanation

A Pauwels type III fracture has a highly vertical fracture line that experiences significant shear forces. A fixed-angle construct like a dynamic hip screw (DHS), supplemented with a derotation screw, provides superior biomechanical resistance to shear compared to multiple cancellous screws.

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