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2. Trauma MCQs

Practice Set 237 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 4721

Topic: 2. Trauma

A 35-year-old male sustains a closed comminuted tibial shaft fracture. Two hours post-injury, he develops severe leg pain out of proportion. Which pressure threshold calculation is widely accepted as the most accurate indication for emergent four-compartment fasciotomy, especially in a hypotensive patient?

. Absolute compartment pressure > 20 mm Hg
. Absolute compartment pressure > 30 mm Hg
. Delta P (Diastolic BP - compartment pressure) < 30 mm Hg
. Delta P (Mean Arterial Pressure - compartment pressure) < 40 mm Hg
. Delta P (Systolic BP - compartment pressure) < 30 mm Hg

Correct Answer & Explanation

. Delta P (Diastolic BP - compartment pressure) < 30 mm Hg

Explanation

While an absolute intra-compartmental pressure of 30 mm Hg or greater is commonly used, calculating the Delta P (diastolic blood pressure minus compartment pressure) of less than 30 mm Hg is the most accurate indicator for fasciotomy, minimizing unnecessary surgery in normotensive patients.

Question 4722

Topic: 2. Trauma

In a 68-year-old female with a 4-part proximal humerus fracture, which of the following radiographic findings (Hertel's criteria) is the most reliable predictor of subsequent humeral head ischemia?

. Displacement of the greater tuberosity by more than 5 mm
. Varus angulation of the humeral head of 10 degrees
. Medial hinge disruption of greater than 2 mm
. Length of the posteromedial metaphyseal head extension less than 8 mm
. Extension of the fracture line into the bicipital groove

Correct Answer & Explanation

. Length of the posteromedial metaphyseal head extension less than 8 mm

Explanation

Hertel identified that a posteromedial metaphyseal head extension (calcar length) of less than 8 mm and disruption of the medial hinge (>2 mm) are strong positive predictors of humeral head ischemia and subsequent AVN.

Question 4723

Topic: Pelvic & Acetabular Trauma

A 35-year-old male is brought to the trauma bay following a high-speed motor vehicle collision. He has a mechanically unstable anterior-posterior compression (APC) type II pelvic ring injury. A pelvic binder is to be applied to temporarily stabilize the pelvis. To be most effective, where should the binder be centered?

. Directly over the iliac crests
. At the level of the umbilicus
. Over the greater trochanters
. Inferior to the pubic symphysis
. Over the anterior superior iliac spines (ASIS)

Correct Answer & Explanation

. Over the greater trochanters

Explanation

A pelvic binder or sheet must be centered over the greater trochanters to effectively reduce pelvic volume and stabilize the pelvic ring. Placement over the iliac crests is incorrect and can paradoxically worsen pelvic opening or fail to control hemorrhage.

Question 4724

Topic: Upper Extremity Trauma

Recent quantitative vascular studies assessing the blood supply to the proximal humerus have challenged historical anatomical teachings. Which artery is now recognized as providing the predominant blood supply (up to 64%) to the humeral head?

. Anterior circumflex humeral artery
. Arcuate artery of Laing
. Posterior circumflex humeral artery
. Thoracoacromial artery
. Profunda brachii artery

Correct Answer & Explanation

. Posterior circumflex humeral artery

Explanation

Historically, the anterior circumflex humeral artery was thought to be the main vascular supply to the humeral head. However, recent studies demonstrate that the posterior circumflex humeral artery provides the majority of the blood supply to the proximal humerus.

Question 4725

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented (Pauwels Type III) femoral neck fracture. Which of the following fixation constructs offers the greatest biomechanical stability against the high shear forces present in this fracture pattern?
. Three parallel cannulated screws in an inverted triangle configuration
. Two parallel cannulated screws
. A sliding hip screw (SHS) with an anti-rotation screw
. A cephalomedullary nail with a single lag screw
. Non-locking proximal femoral plate

Correct Answer & Explanation

. A sliding hip screw (SHS) with an anti-rotation screw

Explanation

Pauwels Type III fractures are highly unstable due to significant vertical shear forces. Biomechanical studies indicate that a fixed-angle device, such as a sliding hip screw combined with an anti-rotation screw, provides superior stability compared to parallel cannulated screws in young patients.

Question 4726

Topic: Pelvic & Acetabular Trauma
A 28-year-old male is brought to the trauma bay following a motorcycle collision. He is hypotensive with a heart rate of 130 bpm. Pelvic radiograph shows an anteroposterior compression type III (APC-III) injury. When applying a noninvasive pelvic binder, the device should be centered directly over which of the following anatomic landmarks to optimally reduce pelvic volume?
. The anterior superior iliac spines (ASIS)
. The iliac crests
. The greater trochanters
. The pubic symphysis
. The umbilicus

Correct Answer & Explanation

. The greater trochanters

Explanation

To effectively reduce pelvic volume and provide stability in an open-book pelvic ring injury (such as an APC-III), a pelvic binder must be applied directly over the greater trochanters. Placement over the iliac crests or ASIS can paradoxically open the pelvis further or fail to provide adequate closure of the posterior ring.

Question 4727

Topic: 2. Trauma

In the evaluation of proximal humerus fractures, which of the following combinations of radiographic findings represents the highest risk for developing avascular necrosis of the humeral head according to Hertel's criteria?

. Anatomic neck fracture, disrupted medial hinge, and calcar length less than 8 mm
. Surgical neck fracture, intact medial hinge, and calcar length greater than 8 mm
. Greater tuberosity fracture with 1 cm of displacement
. Valgus impacted fracture pattern with intact medial soft tissue envelope
. Three-part fracture with a calcar length of 12 mm

Correct Answer & Explanation

. Anatomic neck fracture, disrupted medial hinge, and calcar length less than 8 mm

Explanation

Hertel et al. described reliable radiographic predictors for humeral head ischemia following proximal humerus fractures. The highest risk of avascular necrosis occurs when there is a disruption of the medial hinge, a short metaphyseal head extension (calcar length) of < 8 mm, and an anatomic neck fracture pattern. These factors indicate severe disruption of the ascending branch of the anterior humeral circumflex artery and intraosseous collateral blood supply.

Question 4728

Topic: 2. Trauma
A 32-year-old healthy male sustains an isolated, displaced, vertically oriented (Pauwels type III) femoral neck fracture. Which of the following internal fixation constructs provides the greatest biomechanical stability against vertical shear forces for this specific fracture pattern?
. Three parallel cannulated cancellous screws placed in an inverted triangle
. A dynamic hip screw (DHS) with an additional anti-rotation screw
. Two parallel fully threaded cortical screws
. A single large-diameter fully threaded cancellous screw
. Three cannulated screws placed in a linear vertical configuration

Correct Answer & Explanation

. A dynamic hip screw (DHS) with an additional anti-rotation screw

Explanation

Pauwels type III femoral neck fractures have a high vertical angle, subjecting the fracture to massive vertical shear forces and high rates of nonunion and failure. Biomechanical studies have repeatedly demonstrated that a fixed-angle device, such as a dynamic hip screw (DHS) supplemented with a derotation screw, provides superior resistance to vertical shear and varus collapse compared to multiple parallel cannulated screws.

Question 4729

Topic: 2. Trauma

A 45-year-old male sustains a bicondylar tibial plateau fracture with a large, displaced posteromedial shear fragment. The surgeon elects to use a posteromedial approach for optimal buttress plating. Which of the following surgical intervals is primarily utilized in this approach?

. Between the medial head of the gastrocnemius and the pes anserinus
. Between the lateral head of the gastrocnemius and the biceps femoris
. Between the semimembranosus and the medial collateral ligament
. Between the anterior tibialis and the extensor hallucis longus
. Between the soleus and the flexor hallucis longus

Correct Answer & Explanation

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

Explanation

The standard posteromedial approach to the tibial plateau utilizes the interval between the medial head of the gastrocnemius (which is retracted posteriorly/laterally) and the pes anserinus (which is retracted anteriorly). This provides excellent direct access to the posteromedial tibial metaphysis for placing an anti-glide or buttress plate to support a posteromedial shear fragment.

Question 4730

Topic: 2. Trauma

A 30-year-old female is evaluated 8 weeks after undergoing open reduction and internal fixation of a Hawkins Type II talar neck fracture. An AP radiograph of the ankle demonstrates a linear subchondral radiolucent band in the talar dome. What is the clinical significance of this radiographic finding?

. It indicates complete avascular necrosis of the talar body.
. It represents a deep infection of the talar body.
. It is a sign of intact vascularity to the talar body and indicates active resorption.
. It is a marker for impending early-onset post-traumatic arthritis.
. It suggests hardware loosening and impending construct failure.

Correct Answer & Explanation

. It is a sign of intact vascularity to the talar body and indicates active resorption.

Explanation

The finding described is the 'Hawkins sign,' which appears as a subchondral radiolucent band in the talar dome on an AP or mortise radiograph, typically seen 6 to 8 weeks after a talar neck fracture. It indicates subchondral osteopenia secondary to hyperemia and bone resorption. Because this resorptive process requires an intact blood supply, the presence of a Hawkins sign is a highly reliable indicator that the talar body retains its vascularity and is unlikely to develop avascular necrosis.

Question 4731

Topic: 2. Trauma

When evaluating a midshaft clavicle fracture for conservative versus operative management, which of the following patient or fracture characteristics is most strongly associated with an increased risk of nonunion if treated nonoperatively?

. Male gender
. Age under 30 years
. Fracture shortening of greater than 2 cm
. Associated single rib fracture
. A simple transverse fracture pattern without comminution

Correct Answer & Explanation

. Fracture shortening of greater than 2 cm

Explanation

Several factors increase the risk of nonunion in midshaft clavicle fractures treated nonoperatively. The most critical radiographic predictors include initial shortening of > 2 cm (or > 100% displacement) and significant comminution. Other clinical risk factors include advancing age and female gender. Simple transverse fractures and younger age are associated with higher union rates.

Question 4732

Topic: 2. Trauma

A 25-year-old male suffers a comminuted tibia fracture. In the emergency department, his blood pressure is 120/70 mmHg. He has severe pain out of proportion to the injury. Compartment pressure monitoring is performed. Which of the following absolute compartment pressure or 'Delta P' values is the universally accepted threshold indicating the need for emergent four-compartment fasciotomy?

. An absolute compartment pressure greater than 20 mmHg
. A Delta P (Diastolic BP minus compartment pressure) less than 30 mmHg
. A Delta P (Systolic BP minus compartment pressure) less than 40 mmHg
. An absolute compartment pressure of exactly 25 mmHg with normal pedal pulses
. A Delta P (Mean Arterial Pressure minus compartment pressure) less than 10 mmHg

Correct Answer & Explanation

. A Delta P (Diastolic BP minus compartment pressure) less than 30 mmHg

Explanation

The diagnosis of acute compartment syndrome is primarily clinical, but when objective measurement is needed, the 'Delta P' is the most reliable parameter. Delta P is calculated as the diastolic blood pressure minus the absolute intracompartmental pressure. A Delta P of 30 mmHg or less (e.g., Diastolic BP is 70, compartment pressure is 45; Delta P = 25) indicates severe ischemia and is an absolute indication for emergent fasciotomy.

Question 4733

Topic: 2. Trauma
A 25-year-old male sustains a vertically oriented (Pauwels III) femoral neck fracture. He undergoes closed reduction and internal fixation with three parallel cancellous screws. Due to the biomechanics of this specific fracture pattern, which mode of mechanical failure is he at the greatest risk for?
. Varus collapse
. Valgus impaction
. Anterior translation of the femoral head
. Inferior screw cutout into the calcar
. Nonunion secondary to excessive interfragmentary compression

Correct Answer & Explanation

. Varus collapse

Explanation

Pauwels III fractures are characterized by a highly vertical fracture line (angle > 50 degrees). This orientation exposes the fracture site to high shear forces and minimizes compressive forces across the fracture during weight-bearing. Consequently, these fractures are highly unstable and prone to shear displacement, leading most commonly to varus collapse and nonunion when fixed with parallel screws. Many surgeons prefer a sliding hip screw or an off-axis screw (e.g., femoral neck system) to better resist these shear forces in young patients.

Question 4734

Topic: 2. Trauma

A 28-year-old motorcyclist sustains a complex intra-articular distal femur fracture. Computed tomography (CT) reveals a coronal shear fracture of the lateral femoral condyle. What is the optimal surgical fixation strategy for this specific fracture fragment?

. Lateral locking plate with exclusively unicortical screws
. Medial and lateral tension band wiring
. Anterior-to-posterior oriented interfragmentary lag screws
. Posterior-to-anterior oriented interfragmentary lag screws
. Excision of the fragment and advancement of the lateral collateral ligament

Correct Answer & Explanation

. Posterior-to-anterior oriented interfragmentary lag screws

Explanation

A coronal shear fracture of the femoral condyle is known as a Hoffa fracture. It most commonly affects the lateral condyle. Because it is an intra-articular shear fracture, it requires anatomical reduction and stable fixation, which is best achieved with anterior-to-posterior oriented interfragmentary lag screws (often countersunk or headless) placed perpendicular to the fracture plane. Depending on the size and comminution, an anti-glide plate may also be added.

Question 4735

Topic: Upper Extremity Trauma

In the surgical reconstruction of a chronic Type V acromioclavicular (AC) joint dislocation, anatomic reconstruction of the coracoclavicular (CC) ligaments is planned. What are the precise anatomical insertion sites of the conoid and trapezoid ligaments on the clavicle relative to the distal clavicle tip?

. Conoid is approximately 4.5 cm medial, and trapezoid is 3.0 cm medial
. Conoid is approximately 3.0 cm medial, and trapezoid is 4.5 cm medial
. Both insert conjointly at exactly 2.5 cm medial
. Conoid is approximately 1.5 cm medial, and trapezoid is 3.0 cm medial
. Conoid is approximately 4.5 cm medial on the anterior edge, and trapezoid is 3.0 cm medial on the posterior edge

Correct Answer & Explanation

. Conoid is approximately 4.5 cm medial, and trapezoid is 3.0 cm medial

Explanation

Anatomic studies of the coracoclavicular (CC) ligaments have demonstrated that the trapezoid inserts anterolaterally on the clavicle, averaging 3.0 cm medial to the distal tip. The conoid inserts posteromedially, averaging 4.5 cm medial to the distal tip. Knowledge of these footprints is crucial for anatomical CC ligament reconstruction.

Question 4736

Topic: 2. Trauma
A 35-year-old male sustains a Gustilo-Anderson Type IIIB open tibial shaft fracture. Following initial aggressive surgical debridement and skeletal stabilization, what is the optimal timeframe for definitive soft-tissue coverage to minimize the risk of deep infection?
. Within 12 hours
. Within 72 hours
. Between 7 and 10 days
. Between 14 and 21 days
. After evidence of early fracture callus formation

Correct Answer & Explanation

. Within 72 hours

Explanation

Early soft-tissue coverage for Gustilo-Anderson Type IIIB open tibia fractures is critical for minimizing infection and promoting bone healing. The classic Godina study (1986) demonstrated significantly lower infection and failure rates when flaps were performed within 72 hours. While some modern protocols extend this safely to 5-7 days under negative pressure wound therapy, 'within 72 hours' remains the gold standard benchmark answer for board examinations to define 'early coverage'.

Question 4737

Topic: Upper Extremity Trauma

Recent quantitative anatomical studies of humeral head perfusion (e.g., Hettrich et al.) have challenged traditional teaching regarding the primary blood supply to the proximal humerus. Based on current evidence, which vessel provides the majority of the blood supply to the humeral head?

. Anterior humeral circumflex artery (arcuate branch)
. Posterior humeral circumflex artery
. Suprascapular artery
. Thoracoacromial artery
. Profunda brachii artery

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

Historically, the arcuate branch of the anterior humeral circumflex artery was taught as the primary blood supply to the humeral head. However, landmark modern quantitative studies (e.g., Hettrich et al., JBJS 2010) demonstrated that the posterior humeral circumflex artery actually provides the vast majority (approximately 64%) of the blood supply to the humeral head. This is frequently tested on OITE and ABOS exams.

Question 4738

Topic: Pelvic & Acetabular Trauma
A 42-year-old male is brought to the trauma bay after a crush injury. Radiographs reveal a completely disrupted pubic symphysis with a diastasis of 4 cm, and vertical displacement with complete widening of the posterior sacroiliac joint bilaterally. He is hemodynamically unstable. According to the Young-Burgess classification, what type of pelvic ring injury does this represent?
. Anteroposterior Compression Type I (APC I)
. Anteroposterior Compression Type II (APC II)
. Anteroposterior Compression Type III (APC III)
. Lateral Compression Type II (LC II)
. Vertical Shear (VS)

Correct Answer & Explanation

. Anteroposterior Compression Type III (APC III)

Explanation

Anteroposterior Compression Type III (APC III) injuries are characterized by complete disruption of the anterior ring (symphysis diastasis) AND complete disruption of the posterior ring, including both the anterior AND posterior sacroiliac ligaments. This results in complete hemipelvic instability (external rotation). The key distinguishing factor between APC II and APC III is the disruption of the posterior SI ligaments in APC III. While it mentions vertical displacement, the primary vector described by the 4cm diastasis and complete anterior/posterior widening fits an APC III. (Note: True vertical shear requires cranial displacement of the hemipelvis, but extreme APC forces cause massive diastasis and total SI disruption).

Question 4739

Topic: 2. Trauma

Following a severe bicondylar tibial plateau fracture, a patient develops acute compartment syndrome of the leg and undergoes a four-compartment fasciotomy via a standard two-incision technique. Through the medial incision, the superficial posterior compartment is released. To ensure complete release of the deep posterior compartment through this medial incision, the surgeon must detach the soleus bridge from which specific structure?

. Medial aspect of the fibular shaft
. Posterior aspect of the lateral malleolus
. Posteromedial border of the tibia
. Interosseous membrane
. Medial intermuscular septum

Correct Answer & Explanation

. Posteromedial border of the tibia

Explanation

In a two-incision fasciotomy of the leg, the medial incision is used to release the superficial and deep posterior compartments. The deep posterior compartment is located deep to the soleus. To access and adequately release the fascia of the deep posterior compartment (containing the tibialis posterior, FDL, FHL, and posterior tibial vessels/tibial nerve), the surgeon must detach the soleus muscle from its origin along the posteromedial border of the tibia.

Question 4740

Topic: 2. Trauma

When evaluating a displaced 4-part proximal humerus fracture, which of the following vessels is currently recognized as providing the primary intraosseous blood supply to the humeral head, and whose disruption strongly correlates with avascular necrosis?

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

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

Historically, the arcuate artery (a branch of the anterior humeral circumflex artery) was considered the main blood supply to the humeral head. However, modern cadaveric perfusion studies (e.g., Brooks et al., Hettrich et al.) have conclusively demonstrated that the posterior humeral circumflex artery provides the vast majority (approximately 64% to 80%) of the intraosseous blood supply to the humeral head. Preservation of the posteromedial hinge is critical to protecting this vascular supply.

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