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2. Trauma MCQs

Practice Set 26 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 501

Topic: 2. Trauma

A 24-year-old man sustains a closed femoral shaft fracture. 48 hours later, he develops acute confusion, tachypnea, and a petechial rash over his anterior chest and axillae. Which of the following is the most definitive primary preventative strategy for this patient's condition?

. High-dose intravenous corticosteroids
. Prophylactic low-molecular-weight heparin
. Early operative fracture stabilization
. Hyperbaric oxygen therapy
. Intravenous Vitamin C

Correct Answer & Explanation

. Early operative fracture stabilization

Explanation

The patient has clinical signs of Fat Embolism Syndrome (FES). Early operative stabilization (within 24 hours) of long bone fractures is the most effective proven method for reducing the incidence and severity of FES.

Question 502

Topic: 2. Trauma

A 22-year-old male with a severe traumatic brain injury (TBI) and a closed midshaft femur fracture undergoes intramedullary nailing. Which of the following statements is true regarding fracture healing in patients with concomitant severe TBI?

. There is a decreased rate of nonunion due to elevated systemic inflammatory markers.
. Fracture healing is severely delayed secondary to a prolonged comatose state.
. There is an increased volume of fracture callus and accelerated union.
. There is a significantly decreased risk of heterotopic ossification.
. Union rates are equivalent but remodeling takes twice as long.

Correct Answer & Explanation

. There is an increased volume of fracture callus and accelerated union.

Explanation

Patients with severe traumatic brain injuries exhibit an accelerated osteogenic response, resulting in a significantly increased volume of fracture callus, faster union times, and a high risk of heterotopic ossification due to circulating humoral osteogenic factors.

Question 503

Topic: 2. Trauma

A randomized controlled trial is proposed to compare sling immobilization versus operative fixation for displaced midshaft clavicle fractures. The researchers want a 90% probability of detecting a clinically significant difference if one truly exists, with the alpha level set at 0.05. The 90% parameter refers to the study's:

. Level of significance
. Positive predictive value
. Power
. Confidence interval
. Specificity

Correct Answer & Explanation

. Power

Explanation

Statistical power (1 - beta) is the probability that a study will correctly reject a false null hypothesis, effectively meaning the study's ability to detect a true difference if one exists. A power of 80% to 90% is typically desired.

Question 504

Topic: 2. Trauma

Immediate internal fixation of diaphyseal fractures in polytraumatized children has been shown to provide which of the following benefits:

. Increased survival rate
. Decreased incidence of fat emboli
. Decreased incidence of deep venous thrombosis
. Improved recovery of central nervous system function after head injury
. Greater ease of management

Correct Answer & Explanation

. Greater ease of management

Explanation

Acute internal fixation in children has not been shown to provide the same life-saving and morbidity-reducing benefits as in adults. However, it will ease the management of the polytraumatized patient.

Question 505

Topic: 2. Trauma

Which of the following statements is true about pin fixation of supracondylar humerus fractures:

. Fixation with two lateral pins is biomechanically stronger than crossed pins.
. Fixation with two lateral pins has a higher risk of iatrogenic nerve injury than medial and lateral pins.
. Pin fixation is associated with a higher risk of compartment syndrome than cast treatment alone.
. Fixation with medial and lateral pins carries a higher risk of iatrogenic ulnar nerve injury than two lateral pins.
. Use of two medial pins is the most biomechanically stable construct.

Correct Answer & Explanation

. Fixation with medial and lateral pins carries a higher risk of iatrogenic ulnar nerve injury than two lateral pins.

Explanation

Pin fixation of supracondylar humerus fractures in children decreases the risk of compartment syndrome as well as malreduction. Use of medial and lateral pins has been shown to be the most stable construct in biomechanical studies. The use of medial and lateral pins carries a risk of iatrogenic injury to the ulnar nerve. No nerve injuries have been demonstrated after the use of two lateral pins.

Question 506

Topic: Pelvic & Acetabular Trauma
The migration index of Reimers is best described as:
. The vertical migration of the center of the femoral head with respect to the lateral margin of the acetabulum.
. The distance between the medial wall of the acetabulum and the femoral head.
. The ratio of the uncovered portion of the femoral head to its total width.
. The difference in subluxation between neutral and abduction films.
. The angle between two lines through the center of the femoral head - one vertical and one through the lateral edge of the acetabulum.

Correct Answer & Explanation

. The ratio of the uncovered portion of the femoral head to its total width.

Explanation

The migration index of Reimers is used to quantitate hip subluxation in cerebral palsy. It is defined as the ratio of the uncovered portion of the femoral head (lateral to a vertical line through the outer edge of the acetabulum) to the total width of the head.

Question 507

Topic: 2. Trauma

An 8-year-old pedestrian sustains a pelvic fracture when struck by a car. The injury consists of a posterior iliac fracture in which the iliac wing is rotated internally, although it is not vertically displaced. An anterior fracture of both ipsilateral pubic rami is present with 2 cm of overlap. Recommended treatment includes:

. Open reduction and plate fixation of the rami
. Open reduction and plate fixation of the iliac wing
. Percutaneous sacral screw fixation
. External fixation
. Bedrest

Correct Answer & Explanation

. Bedrest

Explanation

A childs pelvis can absorb a significant amount of energy without serious displacement. There is rapid healing and good remodeling potential. Bedrest is the appropriate treatment for this patient because of the low risk of complications.

Question 508

Topic: 2. Trauma

In a hypotensive polytrauma patient suspected of having compartment syndrome of the lower leg, which of the following criteria is the standard threshold for performing a four-compartment fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 45 mmHg
. Mean arterial pressure minus compartment pressure < 40 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 20 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The delta P (Diastolic blood pressure minus compartment pressure) is the most accurate indicator for compartment syndrome, particularly in hypotensive patients. A delta P of less than 30 mmHg is the accepted threshold indicating the need for emergent fasciotomy.

Question 509

Topic: 2. Trauma

A 40-year-old male sustains a bicondylar tibial plateau fracture with a large posteromedial shear fragment. Which surgical approach is most appropriate for rigid fixation of this specific fragment?

. Anterolateral approach
. Direct anterior midline approach
. Posteromedial approach
. Posterolateral approach
. Medial parapatellar approach

Correct Answer & Explanation

. Posteromedial approach

Explanation

A posteromedial shear fragment in a tibial plateau fracture cannot be adequately reduced or buttressed from an anterior or lateral approach. A posteromedial approach is required to directly visualize the fragment and place an anti-glide or buttress plate.

Question 510

Topic: 2. Trauma

A 25-year-old male sustains a closed, completely displaced midshaft humerus fracture. In the emergency department, he is noted to have a complete radial nerve palsy that was present immediately after the injury. What is the most appropriate initial management?

. Immediate open reduction and internal fixation with nerve exploration
. Functional bracing and clinical observation
. External fixation
. Closed reduction and spica casting
. Immediate electromyography (EMG)

Correct Answer & Explanation

. Functional bracing and clinical observation

Explanation

A primary radial nerve palsy in the setting of a closed humeral shaft fracture is not an absolute indication for immediate surgical exploration. The initial management is functional bracing and observation, as the majority of these neuropraxias resolve spontaneously.

Question 511

Topic: 2. Trauma

A 32-year-old male sustains a closed tibial shaft fracture. Which of the following pressure measurements is considered the most reliable threshold for diagnosing acute compartment syndrome?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 30 mmHg
. Delta pressure (diastolic blood pressure minus compartment pressure) < 30 mmHg
. Delta pressure (mean arterial pressure minus compartment pressure) < 40 mmHg
. Delta pressure (systolic blood pressure minus compartment pressure) < 50 mmHg

Correct Answer & Explanation

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

Explanation

A delta pressure (diastolic blood pressure minus compartment pressure) of less than 30 mmHg is the most reliable objective indicator for fasciotomy. Absolute pressure thresholds are less reliable due to variations in patient hemodynamics.

Question 512

Topic: 2. Trauma

Which of the following vascular structures provides the primary blood supply to the humeral head, and is at greatest risk in a displaced surgical neck fracture of the humerus?

. Anterior humeral circumflex artery
. Posterior humeral circumflex artery
. Thoracoacromial artery
. Profunda brachii artery
. Circumflex scapular artery

Correct Answer & Explanation

. Posterior humeral circumflex artery

Explanation

Recent anatomical studies and quantitative analyses have demonstrated that the posterior humeral circumflex artery provides the predominant blood supply (up to 64%) to the humeral head. This refutes classical teaching that heavily emphasized the anterolateral branch of the anterior humeral circumflex artery.

Question 513

Topic: 2. Trauma
An 82-year-old male sustains a Type II odontoid fracture after a ground-level fall. He is neurologically intact. Which of the following radiographic parameters is the strongest predictor of nonunion for this injury if treated conservatively with a rigid cervical collar?
. Posterior displacement greater than 2 mm
. Initial fracture displacement greater than 5 mm
. Concomitant C1 posterior arch fracture
. Fracture angulation of 5 degrees
. Fracture extension into the C2 body

Correct Answer & Explanation

. Initial fracture displacement greater than 5 mm

Explanation

Major risk factors for nonunion in Type II odontoid fractures include initial displacement greater than 5 mm, angulation greater than 10 degrees, and age over 50 years. Fracture extension into the C2 body describes a Type III fracture, which has a much higher rate of union.

Question 514

Topic: Pelvic & Acetabular Trauma
A 45-year-old man sustains an APC-III (anteroposterior compression III) pelvic ring injury. Which of the following ligaments must be disrupted to classify this injury as an APC-III rather than an APC-II?
. Anterior sacroiliac ligament
. Sacrospinous ligament
. Sacrotuberous ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Posterior sacroiliac ligament

Explanation

In the Young-Burgess classification, an APC-II injury involves disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. An APC-III injury includes complete disruption of the posterior sacroiliac ligament, leading to complete spinopelvic instability.

Question 515

Topic: Lower Extremity Trauma

A 40-year-old man sustains a Schatzker VI tibial plateau fracture. Which of the following neurovascular structures is at the highest risk of injury during a posteromedial surgical approach to the proximal tibia?

. Common peroneal nerve
. Anterior tibial artery
. Great saphenous vein and saphenous nerve
. Popliteal artery
. Sural nerve

Correct Answer & Explanation

. Great saphenous vein and saphenous nerve

Explanation

The posteromedial approach to the proximal tibia exploits the interval between the medial gastrocnemius and the pes anserinus. The great saphenous vein and saphenous nerve lie in the superficial fascia of this region and are highly susceptible to injury.

Question 516

Topic: 2. Trauma
A 35-year-old man sustains a closed midshaft tibia fracture. He develops excruciating leg pain out of proportion to the injury, exacerbated by passive stretch of the hallux. Which absolute pressure or differential pressure threshold is the most widely accepted indication for immediate fasciotomy?
. Absolute pressure greater than 15 mmHg
. Absolute pressure greater than 20 mmHg
. Diastolic blood pressure minus intracompartmental pressure less than 30 mmHg
. Mean arterial pressure minus intracompartmental pressure less than 40 mmHg
. Absolute pressure equal to systolic blood pressure

Correct Answer & Explanation

. Diastolic blood pressure minus intracompartmental pressure less than 30 mmHg

Explanation

The most reliable indicator for acute compartment syndrome is the delta pressure (Δp). A difference of less than 30 mmHg between the diastolic blood pressure and the intracompartmental pressure is a widely accepted indication for surgical decompression.

Question 517

Topic: 2. Trauma
A 30-year-old man sustains a completely displaced, vertically oriented femoral neck fracture (Pauwels type III). What is the preferred surgical treatment to minimize the risk of nonunion?
. Hemiarthroplasty
. Total hip arthroplasty
. Cannulated screws in an inverted triangle
. Sliding hip screw with a derotational screw
. Retrograde intramedullary nail

Correct Answer & Explanation

. Sliding hip screw with a derotational screw

Explanation

In young adults with vertical, shear-pattern (Pauwels III) femoral neck fractures, a sliding hip screw (often supplemented with a derotational screw) provides superior biomechanical stability against shear forces compared to multiple cancellous screws.

Question 518

Topic: 2. Trauma

A 22-year-old soccer player sustains a twisting injury to the knee. Radiographs reveal a small avulsion fracture of the lateral tibial plateau. This radiographic finding is most highly associated with an injury to which of the following structures?

. Posterior cruciate ligament
. Anterior cruciate ligament
. Medial collateral ligament
. Lateral meniscus
. Popliteus tendon

Correct Answer & Explanation

. Anterior cruciate ligament

Explanation

A Segond fracture is an avulsion of the anterolateral ligament complex from the lateral tibial plateau. It is considered a pathognomonic radiographic sign for an anterior cruciate ligament (ACL) tear.

Question 519

Topic: 2. Trauma

A 35-year-old man with a highly comminuted closed tibia fracture complains of severe pain worsened by passive stretch of the hallux. Intracompartmental pressure is 35 mmHg and diastolic blood pressure is 60 mmHg. What is the most appropriate next step?

. Immediate four-compartment fasciotomy
. Administer IV pain medication and elevate the leg
. Bivalve the splint and recheck pressures in 2 hours
. Proceed with intramedullary nailing
. Application of a cold therapy unit

Correct Answer & Explanation

. Immediate four-compartment fasciotomy

Explanation

Clinical signs combined with a delta pressure (diastolic BP minus compartment pressure) of less than 30 mmHg confirm acute compartment syndrome. Emergent four-compartment fasciotomy is mandatory to prevent irreversible tissue necrosis.

Question 520

Topic: Pelvic & Acetabular Trauma
A 40-year-old male sustains an anteroposterior compression (APC) III pelvic ring injury. He remains hemodynamically unstable despite a pelvic binder and fluid resuscitation. FAST exam is negative. What is the most appropriate next step?
. Immediate open reduction and internal fixation of the symphysis pubis
. Preperitoneal pelvic packing and/or angiography
. Exploratory laparotomy
. Application of a halo-femoral traction
. Sacroiliac screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angiography

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic fracture and no evidence of intra-abdominal bleeding, the source of shock is likely pelvic vascular injury. Preperitoneal packing and/or angioembolization are critical to achieve hemostasis.

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