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2. Trauma MCQs

Practice Set 278 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 5541

Topic: Pelvic & Acetabular Trauma
A 45-year-old female pedestrian is struck by a bus and presents hemodynamically unstable in the trauma bay. A pelvic radiograph shows a severely displaced anterior-posterior compression (APC-III) pelvic ring injury with a widened pubic symphysis. A pelvic binder is immediately applied to reduce pelvic volume. To maximize biomechanical efficacy and achieve optimal reduction of the symphysis, the binder should be centered exactly over which anatomic landmark?
. The iliac crests
. The anterior superior iliac spines (ASIS)
. The greater trochanters
. The pubic symphysis
. The umbilicus

Correct Answer & Explanation

. The greater trochanters

Explanation

In the emergent management of open-book pelvic fractures (APC injuries), a pelvic binder or sheet must be centered directly over the greater trochanters of the femur. This placement efficiently translates compressive forces across the pelvic ring, closing the pubic symphysis and reducing pelvic volume to help tamponade venous and cancellous bone bleeding. Placing the binder too high (over the iliac crests) can paradoxically widen the pelvic outlet or fail to compress the true pelvis.

Question 5542

Topic: Pelvic & Acetabular Trauma

A 25-year-old male is brought to the emergency department after a high-speed motorcycle collision. He is hemodynamically unstable. A pelvic binder is appropriately placed. Radiographs reveal a rotationally unstable but vertically stable pelvic ring injury with symphyseal widening greater than 2.5 cm (APC-II pattern).

Which of the following ligaments is predominantly disrupted at the sacroiliac joint in this specific injury pattern?

. Anterior sacroiliac ligament
. Posterior sacroiliac ligament
. Sacrotuberous ligament
. Sacrospinous ligament
. Iliofemoral ligament

Correct Answer & Explanation

. Anterior sacroiliac ligament

Explanation

An Anteroposterior Compression Type II (APC-II) injury involves diastasis of the pubic symphysis > 2.5 cm, with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact, maintaining vertical stability. Thus, at the sacroiliac joint, the anterior sacroiliac ligament is the one disrupted.

Question 5543

Topic: 2. Trauma

A 32-year-old male sustains a closed tibial shaft fracture. You suspect acute compartment syndrome. His diastolic blood pressure is 80 mmHg. What is the absolute minimum intracompartmental pressure reading that would typically mandate emergency fasciotomy based on the Delta-P concept?

. 20 mmHg
. 30 mmHg
. 40 mmHg
. 50 mmHg
. 60 mmHg

Correct Answer & Explanation

. 50 mmHg

Explanation

The Delta-P is defined as Diastolic Blood Pressure minus Intracompartmental Pressure. A Delta-P of 30 mmHg or less is an absolute indication for fasciotomy. Therefore, 80 mmHg - Compartment Pressure <= 30 mmHg means the pressure must be at least 50 mmHg to mandate fasciotomy.

Question 5544

Topic: 2. Trauma
A 30-year-old male sustains a high-energy vertical shear fracture of the femoral neck (Pauwels Type III). What biomechanical force predominantly contributes to the high risk of nonunion and loss of fixation in this specific fracture pattern?
. Compressive forces
. Tensile forces
. Shear forces
. Torsional forces
. Bending forces

Correct Answer & Explanation

. Shear forces

Explanation

Pauwels Type III femoral neck fractures have a fracture line angle >50 degrees relative to the horizontal. This vertical orientation subjects the fracture site to high shear forces rather than compressive forces, drastically increasing the risk of varus collapse and nonunion.

Question 5545

Topic: Pelvic & Acetabular Trauma
A 35-year-old male sustains a severe crushing injury to his pelvis. Examination reveals a large, fluctuant swelling over the greater trochanter with ecchymosis. Aspiration of the lesion yields serosanguinous fluid with fat globules. Which of the following is the most appropriate definitive management for a large, chronic lesion of this type?
. Immediate open debridement and primary closure
. Percutaneous aspiration
. Open debridement and delayed closure or secondary intention
. Observation
. Sclerotherapy

Correct Answer & Explanation

. Open debridement and delayed closure or secondary intention

Explanation

A Morel-Lavallée lesion is a closed degloving injury. Chronic lesions with a mature capsule often require open debridement, capsulectomy, and either delayed closure, use of dead-space management, or secondary intention, as simple aspiration has a high recurrence rate.

Question 5546

Topic: Pelvic & Acetabular Trauma



A 32-year-old male is brought to the trauma bay following a high-speed motorcycle collision. He is hemodynamically unstable. An anteroposterior radiograph of the pelvis demonstrates a 'symphysis pubis diastasis of 4 cm and disruption of the anterior sacroiliac ligaments with intact posterior ligaments' (an APC II injury). During surgical exploration to control hemorrhage, brisk arterial bleeding is encountered posterior to the superior pubic ramus. This vessel is most likely an anastomosis between which two vascular distributions?

. Internal pudendal and superior gluteal arteries
. Inferior epigastric (or external iliac) and obturator arteries
. Superior mesenteric and inferior mesenteric arteries
. Internal iliac and median sacral arteries
. Femoral and superficial circumflex iliac arteries

Correct Answer & Explanation

. Inferior epigastric (or external iliac) and obturator arteries

Explanation

The vessel described is the 'corona mortis' (crown of death). It is an anatomic variant anastomosis between the external iliac or inferior epigastric system and the obturator artery (internal iliac system). It traverses over the superior pubic ramus at an average distance of 4 to 5 cm from the pubic symphysis. Disruption of this vascular connection during high-energy pelvic trauma, particularly anterior ring injuries, can lead to severe, life-threatening hemorrhage.

Question 5547

Topic: 2. Trauma

A 34-year-old male sustains a closed talar neck fracture following a fall from height. He undergoes urgent open reduction and internal fixation. At his 8-week postoperative follow-up, an anteroposterior radiograph of the ankle demonstrates a linear subchondral radiolucent band in the dome of the talus. What does this radiographic finding indicate regarding the prognosis of his injury?

. Early onset of post-traumatic osteoarthritis
. Imminent collapse of the talar dome
. High likelihood of nonunion
. Presence of adequate vascularity and low risk of avascular necrosis
. Establishment of deep bone infection

Correct Answer & Explanation

. Presence of adequate vascularity and low risk of avascular necrosis

Explanation

The finding described is the 'Hawkins sign'. It is a subchondral radiolucent band (osteopenia) in the talar dome that typically appears 6 to 8 weeks after injury. Because bone resorption requires an intact blood supply, the presence of the Hawkins sign is a highly reliable indicator of preserved vascularity to the talar body, forecasting a low risk of avascular necrosis (AVN). Conversely, the absence of this sign (retention of subchondral radiodensity while the surrounding bone becomes osteopenic) suggests AVN.

Question 5548

Topic: 2. Trauma

A 22-year-old male suffers a highly comminuted tibia-fibula fracture. Within hours, he develops extreme leg pain out of proportion to the injury, pain with passive stretch of the toes, and a tense, woody swelling of the leg. Compartment syndrome is suspected. If the anterior compartment is predominantly involved, which of the following sensory deficits is most likely to be found on examination?

. Numbness over the plantar aspect of the foot
. Numbness in the first web space of the dorsum of the foot
. Numbness over the lateral aspect of the foot
. Numbness over the medial malleolus
. Numbness over the posterior calf

Correct Answer & Explanation

. Numbness in the first web space of the dorsum of the foot

Explanation

The anterior compartment of the lower leg contains the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertius muscles, along with the deep peroneal nerve and anterior tibial artery. Increased pressure in this compartment will compress the deep peroneal nerve, leading to sensory deficits in its isolated cutaneous distribution: the dorsal first web space of the foot. The superficial peroneal nerve (lateral compartment) provides sensation to the rest of the dorsum of the foot. The tibial nerve (posterior compartment) innervates the plantar foot.

Question 5549

Topic: 2. Trauma

A 45-year-old male presents with a high-energy knee injury. Representative radiographs and CT cuts are shown.

Based on the principles of treating a bi-condylar tibial plateau fracture with a posteromedial shear fragment, which surgical approach is most appropriately utilized first to stabilize the medial column?

. Anterolateral
. Direct medial
. Posteromedial
. Posterior (Carlson)
. Anterior midline

Correct Answer & Explanation

. Posteromedial

Explanation

A posteromedial shear fragment in a bicondylar tibial plateau fracture (Schatzker VI or Moore Type I) requires a posteromedial approach for optimal buttress plating. Stabilizing the medial column first via a posteromedial approach converts the complex fracture into a lateral plateau fracture, which can then be addressed via a standard anterolateral approach.

Question 5550

Topic: Pelvic & Acetabular Trauma
According to the Young-Burgess classification, an Antero-Posterior Compression (APC) Type II pelvic ring injury is characterized by:
. Symphysis widening < 2.5 cm with intact posterior ligaments
. Symphysis widening > 2.5 cm with disruption of anterior sacroiliac and sacrotuberous ligaments but intact posterior sacroiliac ligaments
. Disruption of both anterior and posterior sacroiliac ligaments resulting in global instability
. Vertical translation of the hemipelvis
. A transforaminal sacral fracture on the affected side

Correct Answer & Explanation

. Symphysis widening > 2.5 cm with disruption of anterior sacroiliac and sacrotuberous ligaments but intact posterior sacroiliac ligaments

Explanation

In the Young-Burgess classification, APC I involves symphyseal diastasis < 2.5 cm with intact posterior elements. APC II involves diastasis > 2.5 cm with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but the posterior sacroiliac ligaments remain intact, causing rotational but not vertical instability. APC III involves complete disruption of both anterior and posterior sacroiliac ligaments, leading to complete spinopelvic dissociation.

Question 5551

Topic: 2. Trauma

What is considered the most sensitive early clinical sign of acute compartment syndrome in an awake, alert patient?

. Absent distal pulses
. Pallor of the distal extremity
. Pain out of proportion to the injury with passive stretch
. Motor paralysis
. Decreased capillary refill

Correct Answer & Explanation

. Pain out of proportion to the injury with passive stretch

Explanation

Pain out of proportion to the apparent injury, specifically exacerbated by passive stretch of the muscles within the involved compartment, is widely regarded as the earliest and most sensitive clinical finding of acute compartment syndrome. The '5 Ps' (pallor, pulselessness, paresthesia, paralysis) are typically late signs indicating irreversible nerve and muscle damage.

Question 5552

Topic: Pelvic & Acetabular Trauma
A 28-year-old female is brought to the trauma bay after a high-speed motor vehicle collision. She is hypotensive and tachycardic. A pelvic radiograph is obtained. It demonstrates a symphyseal diastasis of 3.5 cm and widening of the anterior sacroiliac joints bilaterally. Which of the following describes the status of the posterior pelvic ligaments in this specific injury pattern?
. Both the anterior and posterior sacroiliac ligaments are disrupted.
. The anterior sacroiliac ligaments are disrupted, but the posterior sacroiliac ligaments remain intact.
. The posterior sacroiliac ligaments are disrupted, but the sacrotuberous ligaments remain intact.
. The iliolumbar ligaments are disrupted, but the sacrospinous ligaments remain intact.
. All sacroiliac and pelvic floor ligaments are disrupted.

Correct Answer & Explanation

. The anterior sacroiliac ligaments are disrupted, but the posterior sacroiliac ligaments remain intact.

Explanation

The clinical scenario describes an Anteroposterior Compression Type II (APC-II) pelvic ring injury. By definition, an APC-II injury involves disruption of the pubic symphysis (typically >2.5 cm) along with tearing of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The critical distinguishing factor of an APC-II injury from an APC-III injury is that the strong posterior sacroiliac ligaments remain intact, providing vertical stability while allowing rotational instability.

Question 5553

Topic: 2. Trauma

A 25-year-old male sustains a comminuted fracture of the tibial shaft. Twelve hours post-admission, he develops severe pain out of proportion to the injury, significantly exacerbated by passive stretch of the toes. Compartment syndrome is suspected. Which of the following best describes the primary pathophysiologic mechanism leading to muscle ischemia in this condition?

. Direct arterial spasm resulting from the initial trauma
. Decreased local arteriovenous pressure gradient due to increased interstitial fluid pressure
. Primary venous thrombosis leading to retrograde cellular death
. Release of oxygen free radicals causing direct myocyte apoptosis
. Systemic hypotension causing selective distal extremity hypoperfusion

Correct Answer & Explanation

. Decreased local arteriovenous pressure gradient due to increased interstitial fluid pressure

Explanation

Acute compartment syndrome occurs when elevated intracompartmental pressure leads to decreased local blood flow. The primary pathophysiologic event is an increase in tissue fluid pressure that eventually surpasses venous pressure, causing venous outflow obstruction. This leads to a collapse of the local arteriovenous pressure gradient. Without a sufficient AV gradient, capillary perfusion ceases, leading to microvascular compromise and subsequent tissue ischemia. Arterial pulses often remain palpable because the pressure required to occlude a major artery is much higher than that required to arrest capillary flow.

Question 5554

Topic: 2. Trauma
Which of the following combinations of injuries strictly defines a "floating shoulder"?
. Fracture of the anatomical neck of the humerus and clavicle shaft fracture
. Displaced fracture of the scapular neck and an ipsilateral clavicle shaft fracture
. Acromioclavicular joint dislocation and coracoid process fracture
. Glenohumeral dislocation and a displaced fracture of the acromion
. Scapular body fracture and a sternoclavicular joint dislocation

Correct Answer & Explanation

. Displaced fracture of the scapular neck and an ipsilateral clavicle shaft fracture

Explanation

A "floating shoulder" refers to a double disruption of the superior shoulder suspensory complex (SSSC). Classically, it is defined as an ipsilateral fracture of the clavicle shaft and the surgical neck of the scapula. This injury can lead to instability of the shoulder girdle, and surgical fixation of one or both fractures may be indicated depending on the degree of displacement (e.g., >2 cm medial translation, altered glenoid polar angle).

Question 5555

Topic: 2. Trauma

A 28-year-old male sustains a Hawkins Type II talar neck fracture. Radiographs taken 8 weeks post-operatively demonstrate a subchondral radiolucent band in the dome of the talus on the AP view (Hawkins sign). What does this finding indicate regarding the talus?

. Impending avascular necrosis
. Nonunion of the fracture
. Intact vascularity to the talar body
. Post-traumatic arthritis
. Osteochondral defect

Correct Answer & Explanation

. Intact vascularity to the talar body

Explanation

The Hawkins sign is a subchondral radiolucent band seen in the talar dome on an AP radiograph 6 to 8 weeks after a talar neck fracture. It represents subchondral disuse osteopenia. The process of bone resorption requires an active blood supply; therefore, the presence of a Hawkins sign is a highly reliable indicator that the vascularity to the talar body is intact and avascular necrosis (AVN) is unlikely.

Question 5556

Topic: 2. Trauma
A 35-year-old male sustains a femoral neck fracture in a motor vehicle accident. The fracture line is oriented 75 degrees relative to the horizontal (Pauwels Type III). What is the predominant biomechanical force acting on this fracture pattern, making it highly unstable?
. Compressive force
. Tensile force
. Torsional force
. Shear force
. Bending force

Correct Answer & Explanation

. Shear force

Explanation

The Pauwels classification for femoral neck fractures in young adults is based on the angle of the fracture line relative to the horizontal. Type I: < 30 degrees (predominantly compressive forces, stable). Type II: 30-50 degrees. Type III: > 50 degrees (predominantly shear forces, highly unstable). The high shear forces in vertical fracture patterns (Pauwels III) increase the risk of varus collapse and nonunion.

Question 5557

Topic: 2. Trauma
A 45-year-old female sustains a knee injury following a motor vehicle collision. Assuming the representative image demonstrates a medial tibial plateau fracture with articular depression (Schatzker IV), what is the most likely mechanism of injury?
. Valgus force combined with an axial load
. Varus force combined with an axial load
. Hyperextension injury
. Direct anterior blow to a flexed knee
. Low-energy rotational twisting on a planted foot

Correct Answer & Explanation

. Varus force combined with an axial load

Explanation

A Schatzker IV fracture involves the medial tibial plateau. The medial plateau is structurally denser and stronger than the lateral plateau, meaning fractures here typically require higher energy. The classic mechanism is a varus force combined with an axial load. In contrast, lateral plateau fractures (Schatzker I-III) are typically caused by a valgus force with an axial load. High-energy trauma to the medial plateau is also highly associated with injury to the peroneal nerve, popliteal artery, and ligamentous structures (like the ACL or LCL).

Question 5558

Topic: Pelvic & Acetabular Trauma
A 30-year-old male presents in hypotensive shock following a motorcycle crash. Pelvic radiographs and CT demonstrate an anteroposterior compression type III (APC-III) injury according to the Young-Burgess classification. Which of the following ligamentous complexes are completely disrupted in this specific injury pattern?
. Symphysis pubis only
. Symphysis pubis, sacrotuberous, and sacrospinous ligaments
. Symphysis pubis, sacrotuberous, sacrospinous, and anterior sacroiliac ligaments
. Symphysis pubis, sacrotuberous, sacrospinous, anterior and posterior sacroiliac ligaments
. Posterior sacroiliac ligaments and iliolumbar ligaments only

Correct Answer & Explanation

. Symphysis pubis, sacrotuberous, sacrospinous, and anterior sacroiliac ligaments

Explanation

The Young-Burgess classification for APC injuries relies on progressive disruption of the pelvic ring from anterior to posterior. APC-I involves pubic diastasis <2.5 cm with intact posterior ligaments. APC-II involves diastasis >2.5 cm with disruption of the anterior sacroiliac (SI), sacrotuberous, and sacrospinous ligaments, but intact posterior SI ligaments (rotationally unstable, vertically stable). APC-III involves complete disruption of both the anterior and posterior SI ligaments, resulting in a globally (rotationally and vertically) unstable hemipelvis.

Question 5559

Topic: 2. Trauma

A 25-year-old male suffers a highly comminuted, closed tibial shaft fracture. Two hours later, he complains of severe leg pain out of proportion to the injury, worsening with passive stretch of the toes. Which of the following absolute or differential pressure readings is the most widely accepted and evidence-based threshold for diagnosing acute compartment syndrome and proceeding with fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 45 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

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The threshold for diagnosing acute compartment syndrome is generally based on the differential pressure (Delta P), calculated as the Diastolic Blood Pressure minus the Absolute Compartment Pressure. A Delta P of less than 30 mmHg indicates that perfusion to the capillary beds is critically impaired, leading to muscle and nerve ischemia. Absolute pressures alone are less reliable because systemic blood pressure variations significantly affect tissue perfusion thresholds.

Question 5560

Topic: 2. Trauma
A 28-year-old male sustains a closed midshaft tibia fracture. He is treated with a reamed intramedullary nail. Which of the following is the most significant advantage of reaming the canal prior to nail insertion compared to unreamed nailing for closed tibia fractures?
. Lower rates of compartment syndrome
. Decreased incidence of malunion
. Higher rates of union and lower rates of implant failure
. Reduced operation time
. Lower incidence of anterior knee pain

Correct Answer & Explanation

. Higher rates of union and lower rates of implant failure

Explanation

The SPRINT (Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures) trial demonstrated that for closed tibia fractures, reamed intramedullary nailing is associated with significantly higher rates of union and lower rates of implant failure compared to unreamed nailing. Anterior knee pain rates are similar between both techniques.

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