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2. Trauma MCQs

Practice Set 637 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 12721

Topic: 2. Trauma

A 30-year-old male sustains a comminuted midshaft tibia fracture. Twelve hours post-injury, he develops severe, unrelenting leg pain that is out of proportion to the apparent injury and is not relieved by intravenous opioids. The pain is markedly exacerbated by passive stretch of his toes. What is the most appropriate definitive management?

. Elevation of the limb above heart level
. Application of a tight compressive dressing
. Immediate four-compartment fasciotomy
. Administration of intravenous antibiotics
. Closed reduction and cast application

Correct Answer & Explanation

. Immediate four-compartment fasciotomy

Explanation

Correct Answer: CThe patient is exhibiting classic signs of acute compartment syndrome, a surgical emergency characterized by increased pressure within a closed fascial space that compromises tissue perfusion. The hallmark symptom is severe pain out of proportion to the injury, which is exacerbated by passive stretch of the muscles within the affected compartment. The definitive and urgent treatment is a four-compartment fasciotomy of the leg to decompress the tissues and prevent irreversible ischemic necrosis. Elevating the limb above the heart can actually decrease arterial perfusion pressure and worsen ischemia.

Question 12722

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 35-year-old male is brought to the trauma bay following a motorcycle collision. Pelvic radiographs demonstrate an anteroposterior compression type III (APC-III) pelvic ring injury. Where is the correct anatomical landmark for the application of a circumferential pelvic sheet or commercial binder?
. Over the iliac crests
. Over the anterior superior iliac spines
. Directly over the greater trochanters
. At the level of the symphysis pubis
. Over the subtrochanteric femur

Correct Answer & Explanation

. Directly over the greater trochanters

Explanation

A pelvic binder must be placed and centered precisely over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is mechanically ineffective and can exacerbate an open-book deformity.

Question 12723

Topic: 2. Trauma

A 24-year-old male presents with a nonunion of a scaphoid waist fracture. Magnetic resonance imaging (MRI) suggests avascular necrosis of the proximal pole. Which artery provides the primary blood supply to the proximal pole of the scaphoid?

. Volar carpal branch of the radial artery
. Dorsal carpal branch of the radial artery
. Superficial palmar arch
. Deep palmar arch
. Anterior interosseous artery

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

The scaphoid receives 70-80% of its blood supply from the dorsal carpal branch of the radial artery, which enters at the distal third and flows in a retrograde fashion. This retrograde perfusion is why fractures of the waist and proximal pole have a high risk of avascular necrosis.

Question 12724

Topic: 2. Trauma

In the pathophysiological cascade of acute compartment syndrome, tissue ischemia begins when interstitial compartmental pressure progressively exceeds which of the following specific cardiovascular pressures?

. Arterial systolic pressure
. Arterial diastolic pressure
. Mean arterial pressure
. Venous outflow pressure
. Capillary hydrostatic pressure

Correct Answer & Explanation

. Venous outflow pressure

Explanation

Acute compartment syndrome begins when increased interstitial pressure exceeds venous outflow pressure, leading to venous collapse. This venous collapse causes further pooling, exacerbating the pressure rise until capillary perfusion is ultimately compromised.

Question 12725

Topic: 2. Trauma

A 45-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. Given the severe soft tissue injury, the patient is at high risk for acute lower leg compartment syndrome. Which muscular compartment of the lower leg is most commonly affected in this scenario?

. Anterior compartment
. Lateral compartment
. Superficial posterior compartment
. Deep posterior compartment
. Peroneal compartment

Correct Answer & Explanation

. Anterior compartment

Explanation

The anterior compartment of the lower leg is the most frequently affected compartment in acute compartment syndrome following tibia fractures. It contains the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and the deep peroneal nerve.

Question 12726

Topic: 2. Trauma

A 32-year-old male is evaluated for severe right leg pain 6 hours after sustaining a closed tibial shaft fracture. His leg is swollen and tense. Which of the following pressure measurements is the most definitive indication for emergent four-compartment fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 25 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

A delta pressure (diastolic blood pressure minus compartment pressure) of less than 30 mmHg is the most reliable threshold for diagnosing acute compartment syndrome and indicates emergent fasciotomy. Absolute pressure readings alone are less reliable due to systemic blood pressure variations.

Question 12727

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented (Pauwels type III) basicervical femoral neck fracture following a motor vehicle collision. Which of the following internal fixation constructs provides the most biomechanically stable fixation for this specific fracture pattern?
. Three parallel cancellous screws in an inverted triangle
. Three parallel cancellous screws in an upright triangle
. Dynamic hip screw (DHS) with a derotational screw
. Proximal femoral nail with a single head screw
. Multiple threaded Kirschner wires

Correct Answer & Explanation

. Dynamic hip screw (DHS) with a derotational screw

Explanation

Pauwels type III fractures have a high vertical shear angle, predisposing them to varus collapse and nonunion. A sliding hip screw (DHS) paired with an anti-rotation screw provides superior biomechanical resistance to vertical shear compared to multiple parallel cancellous screws.

Question 12728

Topic: Pelvic & Acetabular Trauma
A 45-year-old man sustains an anteroposterior compression (APC) type III pelvic ring injury in a high-speed motorcycle crash. He is hemodynamically unstable upon arrival despite a properly placed pelvic binder and aggressive fluid resuscitation. What is the most likely primary source of his pelvic hemorrhage?
. Superior gluteal artery
. Presacral venous plexus and cancellous bone
. Corona mortis
. Internal pudendal artery
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus and cancellous bone

Explanation

In major pelvic ring fractures, approximately 80% to 90% of severe bleeding is venous in origin, primarily arising from the presacral venous plexus and the exposed fractured cancellous bone surfaces. While arterial bleeding can be life-threatening, venous sources are far more common overall.

Question 12729

Topic: 2. Trauma

During secondary fracture healing, the biochemical environment within the fracture hematoma undergoes significant changes. Which condition most accurately describes the local tissue environment during the initial inflammatory phase (first 1 to 7 days)?

. Hyperoxic and alkaline
. Hypoxic and acidic
. Hypoxic and alkaline
. Normoxic and neutral
. Hyperoxic and acidic

Correct Answer & Explanation

. Hypoxic and acidic

Explanation

The initial fracture hematoma disrupts local blood supply, creating a severely hypoxic environment. Concurrently, the accumulation of lactic acid from anaerobic metabolism and the influx of inflammatory cells render the local pH acidic, which is critical for initiating the angiogenesis and repair cascades.

Question 12730

Topic: Lower Extremity Trauma

A 7-year-old boy with Dysplasia epiphysealis hemimelica (Trevor disease) of the distal femur presents with a worsening mechanical block to knee flexion and increasing pain. What is the most appropriate management?

. Observation and physical therapy
. Intra-articular corticosteroid injection
. Radiofrequency ablation of the lesion
. Surgical excision of the lesion with preservation of the underlying articular surface
. Distal femoral epiphysiodesis

Correct Answer & Explanation

. Surgical excision of the lesion with preservation of the underlying articular surface

Explanation

Symptomatic Trevor disease causing a mechanical block or deformity is managed with surgical excision. It is critical to meticulously remove the epiphyseal mass while preserving the normal underlying chondral surface and joint congruity.

Question 12731

Topic: 2. Trauma

A 28-year-old male is involved in a motorcycle collision and sustains a comminuted midshaft tibia fracture. Four hours after admission, he complains of severe, unrelenting leg pain that is out of proportion to the injury and not relieved by intravenous opioids. On examination, his leg is tense and swollen. Passive stretch of his toes elicits excruciating pain. His pedal pulses are palpable. What is the most appropriate next step in management?

. Elevate the leg above the level of the heart and apply ice
. Administer a higher dose of intravenous opioids and reassess in 1 hour
. Obtain an urgent MRI of the lower extremity
. Perform immediate four-compartment fasciotomy of the leg
. Measure compartment pressures and proceed to surgery only if >40 mmHg

Correct Answer & Explanation

. Perform immediate four-compartment fasciotomy of the leg

Explanation

Correct Answer: DThe patient presents with classic signs of acute compartment syndrome: pain out of proportion, pain with passive stretch, and tense compartments. Palpable pulses do not rule out compartment syndrome, as arterial flow is maintained until late in the ischemic process. The diagnosis is primarily clinical. When the clinical picture is clear, immediate surgical decompression via a four-compartment fasciotomy is indicated without the need to delay for pressure measurements or imaging.

Question 12732

Topic: 2. Trauma

A 7-year-old boy presents with a severely displaced extension-type supracondylar humerus fracture after a fall from monkey bars. On examination, he has a weak hand grip and decreased sensation over the palmar aspect of the thumb, index, and middle fingers. He is unable to make an "A-OK" sign. Which nerve is most likely compromised?

. Ulnar nerve
. Radial nerve
. Median nerve
. Axillary nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Median nerve

Explanation

Correct Answer: CAnatomy & Injury:Supracondylar humerus fractures are the most common elbow fractures in children. Extension-type fractures account for >95% of cases, where the distal fragment is displaced posteriorly.Nerve Injury:The median nerve (specifically its anterior interosseous branch) is the most frequently injured nerve in extension-type supracondylar fractures, often due to tethering or direct contusion by the proximal fracture fragment. Median nerve compromise presents with weakness in wrist flexion, forearm pronation, and inability to flex the IP joint of the thumb and DIP joint of the index finger (weak "A-OK" sign), along with sensory deficits over the palmar aspect of the radial 3.5 digits.Complications:A severe, feared complication of displaced supracondylar fractures is Volkmann's ischemic contracture, resulting from untreated vascular compromise or compartment syndrome.

Question 12733

Topic: 2. Trauma

A 25-year-old male sustains a comminuted midshaft tibia fracture in a motorcycle collision. Twelve hours after intramedullary nailing, he develops severe, unrelenting leg pain that is out of proportion to the injury and not relieved by intravenous opioids. Passive stretch of the toes elicits excruciating pain. What is the most appropriate next step in management?

. Elevation of the leg above heart level
. Administration of a regional nerve block
. Urgent four-compartment fasciotomy
. Application of a tight compression dressing
. Immediate removal of the intramedullary nail

Correct Answer & Explanation

. Urgent four-compartment fasciotomy

Explanation

Correct Answer: CPathophysiology:Acute compartment syndrome occurs when increased pressure within a closed osteofascial compartment compromises tissue perfusion, leading to ischemia and potential necrosis of muscles and nerves. It is a surgical emergency.Clinical Presentation:The classic "6 Ps" are Pain out of proportion, Pallor, Paresthesias, Pulselessness, Paralysis, and Poikilothermia. However, pain with passive stretch of the muscles in the affected compartment is the most sensitive and earliest clinical sign.Management:Urgent surgical decompression via a four-compartment fasciotomy is the definitive treatment. Elevating the leg above the heart is contraindicated as it further decreases arterial perfusion pressure to the compartment.

Question 12734

Topic: 2. Trauma

A 28-year-old male sustains a closed comminuted tibial shaft fracture. Twelve hours later, he develops severe pain out of proportion to the injury, exacerbated by passive stretch of his toes. The pathophysiology of his suspected condition is primarily driven by which of the following mechanisms?

. Arterial vasospasm leading to distal ischemia
. Venous outflow obstruction leading to increased intracompartmental pressure
. Direct mechanical compression of the deep peroneal nerve
. Lymphatic disruption causing interstitial fluid accumulation
. Microvascular thrombosis within the muscle capillary beds

Correct Answer & Explanation

. Venous outflow obstruction leading to increased intracompartmental pressure

Explanation

Correct Answer: B (Venous outflow obstruction leading to increased intracompartmental pressure)The patient is presenting with acute compartment syndrome. The pathophysiologic cascade begins when tissue pressure within a closed fascial compartment exceeds the venous capillary pressure. This leads to venous outflow obstruction, which causes further fluid transudation into the interstitial space. This secondary increase in intracompartmental pressure eventually exceeds arteriolar pressure, leading to arteriolar collapse, muscle ischemia, and nerve necrosis if not urgently decompressed via fasciotomy.

Question 12735

Topic: 2. Trauma

A 28-year-old male is brought to the emergency department after a motorcycle collision. He has a severely comminuted, closed fracture of the tibial diaphysis. Over the next 6 hours, he develops excruciating leg pain out of proportion to the injury, which is exacerbated by passive stretch of the toes. What is the primary pathophysiologic mechanism leading to tissue ischemia in this condition?

. Arterial vasospasm
. Venous outflow obstruction leading to decreased arteriovenous pressure gradient
. Direct mechanical compression of the major axial arteries
. Microvascular thrombosis
. Endothelial damage leading to massive fluid extravasation

Correct Answer & Explanation

. Venous outflow obstruction leading to decreased arteriovenous pressure gradient

Explanation

Correct Answer: BThe patient is presenting with acute compartment syndrome. The primary pathophysiologic mechanism is an increase in interstitial pressure within a closed osteofascial compartment. This elevated pressure first collapses the low-pressure venous system, causing venous outflow obstruction. This leads to a decrease in the arteriovenous (AV) pressure gradient, which ultimately impairs local tissue perfusion. When the local tissue pressure exceeds capillary perfusion pressure, capillary collapse occurs, leading to muscle and nerve ischemia. Direct arterial occlusion is a late and rare finding, as compartment pressures rarely exceed systolic arterial pressure; thus, distal pulses are usually maintained until very late in the process.

Question 12736

Topic: 2. Trauma

A 25-year-old male sustains a comminuted tibial shaft fracture in a motorcycle collision. Twelve hours post-injury, he develops severe, unremitting leg pain that is out of proportion to the injury and exacerbated by passive stretch of his toes. The attending surgeon suspects acute compartment syndrome. Which of the following objective measurements is the most reliable threshold for indicating the need for an emergent fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 25 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

Correct Answer: Diastolic blood pressure minus compartment pressure < 30 mmHgThe diagnosis of acute compartment syndrome is primarily clinical, but intracompartmental pressure monitoring is crucial in obtunded or polytrauma patients. The most reliable objective threshold for performing a fasciotomy is a "delta P" (diastolic blood pressure minus the compartment pressure) of less than 30 mmHg. This measurement accounts for the patient's systemic perfusion pressure, which dictates capillary blood flow. Relying solely on absolute compartment pressures (e.g., > 30 mmHg) can lead to unnecessary fasciotomies in hypertensive patients or missed diagnoses in hypotensive patients.

Question 12737

Topic: 2. Trauma

A 35-year-old male sustains a closed comminuted tibial shaft fracture. He complains of pain out of proportion to his injury. His diastolic blood pressure is 80 mmHg. Intracompartmental pressure monitoring of the anterior compartment reads 55 mmHg. What is his delta pressure, and what is the indicated treatment?

. 25 mmHg; emergent four-compartment fasciotomy
. 25 mmHg; elevate the leg and observe
. 35 mmHg; emergent four-compartment fasciotomy
. 80 mmHg; observation
. 135 mmHg; emergent four-compartment fasciotomy

Correct Answer & Explanation

. 25 mmHg; emergent four-compartment fasciotomy

Explanation

Delta pressure is calculated as diastolic blood pressure minus intracompartmental pressure (80 - 55 = 25 mmHg). A delta pressure of less than 30 mmHg is diagnostic for acute compartment syndrome and requires emergent fasciotomy.

Question 12738

Topic: 2. Trauma

A 24-year-old male sustains a scaphoid waist fracture. He is counseled regarding the risk of avascular necrosis (AVN) or nonunion. The precarious blood supply to the proximal pole of the scaphoid is primarily derived from branches of which of the following arteries?

. Ulnar artery
. Anterior interosseous artery
. Superficial palmar arch
. Dorsal carpal branch of the radial artery
. Deep palmar arch

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

The primary blood supply to the scaphoid enters distally via the dorsal carpal branch of the radial artery and flows in a retrograde fashion. Fractures at the waist or proximal pole disrupt this flow, leading to a high risk of AVN.

Question 12739

Topic: Pelvic & Acetabular Trauma
A 42-year-old farmer is brought to the trauma bay after a tractor rollover. He has a widely displaced symphysis pubis and bilateral sacroiliac joint disruption. Which of the following vascular structures is at greatest risk of injury leading to massive hemorrhage in this classic anteroposterior compression (APC-III) pelvic ring injury?
. Superior gluteal artery
. Internal pudendal artery
. Venous presacral plexus
. Femoral artery
. Obturator artery

Correct Answer & Explanation

. Venous presacral plexus

Explanation

While lateral compression injuries often tear the superior gluteal artery, anteroposterior compression (APC) injuries typically cause massive hemorrhage by disrupting the extensive presacral venous plexus and anterior branches of the internal iliac artery.

Question 12740

Topic: 2. Trauma

A 28-year-old male sustains a closed tibia fracture and develops out-of-proportion leg pain. The surgeon measures compartment pressures using a slit catheter. Which of the following measurements is the most reliable threshold indicating the need for an emergent fasciotomy?

. Absolute compartment pressure > 20 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
. Absolute compartment pressure > 15 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

Acute compartment syndrome is reliably diagnosed using the Delta P, calculated as the diastolic blood pressure minus the absolute compartment pressure. A Delta P of less than 30 mmHg signifies inadequate tissue perfusion and is an absolute indication for fasciotomy.

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