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2. Trauma MCQs

Practice Set 618 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 12341

Topic: Pelvic & Acetabular Trauma
A 35-year-old male presents after a motorcycle crash with a hemodynamically unstable anteroposterior compression type III (APC-III) pelvic ring injury. A pelvic binder is urgently indicated. What is the most appropriate anatomic landmark for the optimal placement of the pelvic binder to effectively reduce pelvic volume?
. Iliac crests
. Anterior superior iliac spines (ASIS)
. Greater trochanters
. Pubic symphysis
. Subtrochanteric femur

Correct Answer & Explanation

. Greater trochanters

Explanation

The optimal placement for a pelvic binder is centered directly over the greater trochanters. Placing it higher (over the iliac crests or ASIS) is a common error that can fail to reduce the pelvic volume effectively and may even paradoxically open the pelvic ring in some fracture patterns.

Question 12342

Topic: 2. Trauma

A 25-year-old male is evaluated 6 hours after intramedullary nailing of a closed tibia fracture. He complains of severe pain out of proportion, unrelieved by opioids. His blood pressure is 110/70 mmHg. Compartment pressures of the anterior, lateral, superficial posterior, and deep posterior compartments are 35 mmHg, 30 mmHg, 25 mmHg, and 45 mmHg, respectively. What is the most appropriate next step in management?

. Elevate the leg above heart level and reassess in 2 hours
. Administer an IV fluid bolus to increase perfusion pressure
. Immediate four-compartment fasciotomy
. Administer IV mannitol and measure pressures again
. Order a stat lower extremity venous Doppler ultrasound

Correct Answer & Explanation

. Immediate four-compartment fasciotomy

Explanation

The diagnosis of compartment syndrome can be confirmed using the Delta P (Diastolic BP - highest compartment pressure). A Delta P of less than 30 mmHg is an absolute indication for fasciotomy. In this patient, Delta P = 70 (diastolic) - 45 (deep posterior compartment) = 25 mmHg. Immediate four-compartment fasciotomy is required.

Question 12343

Topic: 2. Trauma

Under which of the following mechanical and biological conditions does primary (contact) bone healing predominantly occur?

. Absolute stability with no fracture gap and intact viable bone ends
. Absolute stability with a fracture gap of 2 mm
. Relative stability with a strain environment of 2-10%
. Intramedullary nailing of a diaphyseal fracture
. Application of a bridge plate for a highly comminuted fracture

Correct Answer & Explanation

. Absolute stability with no fracture gap and intact viable bone ends

Explanation

Primary (contact) bone healing occurs via direct cutting cone remodeling (Haversian remodeling) across the fracture site without callus formation. This requires absolute stability (strain <2%), viable bone ends, and no fracture gap. Any gap or movement leads to secondary healing with callus formation.

Question 12344

Topic: 2. Trauma

In damage control orthopedics (DCO) for a polytraumatized patient, which metabolic marker is considered the most reliable indicator of adequate end-organ resuscitation to clear the patient for definitive fracture fixation?

. Serum bicarbonate greater than 20 mEq/L
. Serum lactate less than 2.5 mmol/L
. Base deficit of -6
. Core temperature greater than 34 degrees C
. Hemoglobin greater than 9 g/dL

Correct Answer & Explanation

. Serum lactate less than 2.5 mmol/L

Explanation

Serum lactate less than 2.0-2.5 mmol/L and a resolving base deficit (approaching zero) are highly reliable markers of restored tissue perfusion. Normalizing these values suggests the patient has moved past the initial systemic inflammatory response and can safely undergo definitive surgery.

Question 12345

Topic: 2. Trauma

In the evaluation of a patient with suspected acute compartment syndrome of the leg, which pressure measurement parameter is the most universally accepted absolute threshold for performing an emergency fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Delta pressure (Diastolic BP - Compartment Pressure) < 30 mmHg
. Absolute compartment pressure > 45 mmHg
. Delta pressure (Systolic BP - Compartment Pressure) < 40 mmHg
. Mean arterial pressure (MAP) minus compartment pressure < 20 mmHg

Correct Answer & Explanation

. Delta pressure (Diastolic BP - Compartment Pressure) < 30 mmHg

Explanation

A delta pressure (defined as the diastolic blood pressure minus the intracompartmental pressure) of less than 30 mmHg is the standard threshold indicating critical tissue ischemia. Absolute pressures are less reliable due to individual variations in baseline perfusion pressure.

Question 12346

Topic: 2. Trauma

Hypertrophic nonunions are radiographically characterized by the classic "elephant foot" appearance with abundant callus formation that fails to bridge. The primary etiology of this specific type of nonunion is:

. Inadequate biological environment and cellular activity
. Excessive mechanical instability at the fracture site
. Chronic low-grade medullary infection
. Disrupted endosteal blood supply
. Underlying systemic metabolic bone disease

Correct Answer & Explanation

. Excessive mechanical instability at the fracture site

Explanation

Hypertrophic nonunions occur when the fracture has an excellent biological environment and blood supply (evident by exuberant callus) but lacks sufficient mechanical stability to allow bridging. Management consists of improving fixation rigidity (e.g., reamed exchange nailing).

Question 12347

Topic: 2. Trauma
Under the Gustilo-Anderson classification system, how would you classify an open tibial shaft fracture featuring a 10 cm laceration, severe periosteal stripping, and exposed desiccated bone that will necessitate a free vascularized tissue transfer for closure?
. Type II
. Type IIIA
. Type IIIB
. Type IIIC
. Type IV

Correct Answer & Explanation

. Type IIIB

Explanation

A Gustilo-Anderson Type IIIB fracture involves extensive soft-tissue injury with periosteal stripping and inadequate soft-tissue coverage, mandating a local or free flap for closure. Type IIIC would additionally require major arterial repair.

Question 12348

Topic: 2. Trauma
According to the Anderson and D'Alonzo classification, a fracture through the base of the dens is classified as which type, and what is the typical initial treatment for a non-displaced fracture in an elderly patient?
. Type I; rigid cervical collar
. Type II; rigid cervical collar
. Type II; immediate surgical fixation
. Type III; halo vest immobilization
. Type III; rigid cervical collar

Correct Answer & Explanation

. Type II; rigid cervical collar

Explanation

A fracture through the base of the dens is a Type II fracture. In elderly patients, initial treatment of non-displaced Type II fractures is generally a rigid cervical collar. Halo vests are associated with unacceptably high morbidity and mortality in the elderly.

Question 12349

Topic: Pelvic & Acetabular Trauma
A patient sustains an anteroposterior compression (APC) Type III pelvic ring injury. Which primary ligamentous complex is ruptured, leading to complete global instability of the hemipelvis?
. Sacrospinous ligament only
. Sacrotuberous ligament only
. Anterior sacroiliac ligaments
. Anterior and posterior sacroiliac ligaments
. Iliolumbar ligaments

Correct Answer & Explanation

. Anterior and posterior sacroiliac ligaments

Explanation

An APC III injury implies complete disruption of the pubic symphysis anteriorly, as well as rupture of both the anterior AND posterior sacroiliac ligaments posteriorly, resulting in complete rotational and vertical instability of the hemipelvis.

Question 12350

Topic: 2. Trauma
A 32-year-old male sustains a vertically oriented, displaced femoral neck fracture (Pauwels Type III). What is the primary biomechanical rationale for using a sliding hip screw with a derotation screw rather than multiple cancellous screws?
. Increased rotational stability
. Resistance to vertical shear forces
. Prevention of avascular necrosis
. Promotion of endochondral ossification
. Decreased risk of infection

Correct Answer & Explanation

. Resistance to vertical shear forces

Explanation

Pauwels Type III fractures have a highly vertical fracture line and are subjected to massive vertical shear forces. A sliding hip screw (a fixed-angle device) provides superior resistance to these shear forces compared to multiple parallel cancellous screws, reducing the risk of varus collapse and nonunion.

Question 12351

Topic: 2. Trauma

A 28-year-old male is recovering from an intramedullary nailing of a closed tibial shaft fracture. He develops disproportionate pain. Delta pressure is measured. What is the formula for calculating delta pressure, and what threshold strongly suggests acute compartment syndrome?

. Systolic Blood Pressure minus Intracompartmental Pressure; < 30 mmHg
. Diastolic Blood Pressure minus Intracompartmental Pressure; < 30 mmHg
. Mean Arterial Pressure minus Intracompartmental Pressure; < 40 mmHg
. Diastolic Blood Pressure minus Intracompartmental Pressure; > 30 mmHg
. Intracompartmental Pressure minus Central Venous Pressure; > 40 mmHg

Correct Answer & Explanation

. Diastolic Blood Pressure minus Intracompartmental Pressure; < 30 mmHg

Explanation

Delta pressure is calculated as Diastolic Blood Pressure minus Intracompartmental Pressure. A delta pressure of less than 30 mmHg (meaning the compartment pressure is approaching the diastolic pressure) strongly indicates impaired tissue perfusion and is a recognized threshold for diagnosing acute compartment syndrome.

Question 12352

Topic: 2. Trauma

A 25-year-old male sustains a low-velocity gunshot wound to the thigh. Radiographs demonstrate a non-displaced midshaft femur fracture. The bullet is lodged in the vastus lateralis. There is no hard sign of vascular injury. What is the most appropriate management of the bullet?

. Immediate operative exploration and bullet retrieval to prevent lead toxicity
. Operative debridement of the bullet track and retrieval
. Local wound care and leaving the bullet in place
. Retrieval of the bullet only if the fracture requires internal fixation
. Administration of chelating agents followed by delayed retrieval

Correct Answer & Explanation

. Local wound care and leaving the bullet in place

Explanation

Low-velocity gunshot wounds (GSWs) with bullets lodged in soft tissue or muscle do not routinely require bullet extraction, as the heat of the firing process generally sterilizes the missile, and the soft tissue will encapsulate it. Indications for bullet removal include intra-articular or trans-articular trajectory (risk of lead arthropathy and mechanical wear), location within the central nervous system, compression of a neurovascular structure, or signs of local infection/abscess. A non-displaced femur fracture from a low-velocity GSW can typically be treated non-operatively with local wound care and appropriate bracing or casting.

Question 12353

Topic: Pelvic & Acetabular Trauma
In the Young-Burgess classification, an Anteroposterior Compression Type III (APC III) pelvic ring injury is characterized by the complete disruption of which primary stabilizing posterior ligaments?
. Anterior sacroiliac ligaments only
. Sacrotuberous and sacrospinous ligaments only
. Anterior and posterior sacroiliac ligaments
. Iliolumbar ligaments only
. Symphyseal ligaments only

Correct Answer & Explanation

. Anterior and posterior sacroiliac ligaments

Explanation

An APC III injury involves a severe anteroposterior force that causes symphyseal diastasis and complete disruption of the anterior sacroiliac, sacrotuberous, sacrospinous, AND posterior sacroiliac ligaments, leading to complete global (rotational and vertical) instability of the hemipelvis. APC II involves anterior SI, sacrotuberous, and sacrospinous disruption, but the posterior SI ligaments remain intact (rotationally unstable, vertically stable).

Question 12354

Topic: 2. Trauma
A 35-year-old agricultural worker sustains an open tibia fracture when a tractor rolls over his leg in a muddy field. The wound over the anterior shin measures 1.5 cm, with moderate periosteal stripping but adequate soft tissue coverage. The distal pulses are intact. According to the Gustilo-Anderson classification, this fracture is best classified as:
. Type I
. Type II
. Type IIIA
. Type IIIB
. Type IIIC

Correct Answer & Explanation

. Type IIIA

Explanation

Any open fracture occurring in a highly contaminated environment (such as a farm injury, barnyard, or stagnant water) is automatically classified as a Gustilo-Anderson Type III injury due to the high risk of severe infection (especially Clostridium perfringens). Because there is adequate soft tissue coverage and no requirement for a free flap or rotational flap, it is classified as Type IIIA, despite the wound measuring only 1.5 cm.

Question 12355

Topic: 2. Trauma

Following a displaced talar neck fracture, a radiograph taken at 6 to 8 weeks demonstrates a subchondral radiolucent band in the talar dome. This radiographic finding (Hawkins sign) indicates which of the following?

. Impending avascular necrosis of the talar body
. Presence of an intra-articular infection
. Nonunion of the fracture site
. Intact vascularity to the talar body
. Chondrolysis of the tibiotalar joint

Correct Answer & Explanation

. Intact vascularity to the talar body

Explanation

The Hawkins sign is subchondral osteopenia observed in the talar dome 6-8 weeks post-injury. It is a highly reliable indicator of intact vascular supply to the talar body, as it requires active blood flow to resorb the bone during disuse.

Question 12356

Topic: 2. Trauma

Which compartment of the forearm is most severely affected in cases of acute compartment syndrome, and which muscle's passive stretch is the most sensitive clinical indicator?

. Dorsal compartment; Extensor digitorum communis
. Volar compartment; Flexor digitorum profundus
. Mobile wad; Brachioradialis
. Volar compartment; Pronator teres
. Dorsal compartment; Extensor pollicis longus

Correct Answer & Explanation

. Volar compartment; Flexor digitorum profundus

Explanation

The deep volar compartment is the most commonly and severely involved compartment in forearm compartment syndrome. Passive extension of the fingers stretches the ischemic flexor digitorum profundus, causing severe, disproportionate pain.

Question 12357

Topic: Pelvic & Acetabular Trauma
A 35-year-old male sustains an anterior posterior compression (APC-III) pelvic ring injury. During an anterior intrapelvic approach (Stoppa) to the acetabulum, massive bleeding is encountered over the superior pubic ramus. This bleeding is most likely from an anastomosis between the external iliac system and which of the following?
. Internal pudendal artery
. Superior gluteal artery
. Obturator artery
. Inferior gluteal artery
. Ilioiolumbar artery

Correct Answer & Explanation

. Obturator artery

Explanation

The corona mortis is a vascular anastomosis between the external iliac (or inferior epigastric) and obturator vessels. It is located on the posterior aspect of the superior pubic ramus and is at high risk during anterior pelvic exposures.

Question 12358

Topic: 2. Trauma

A 30-year-old male sustains a closed tibial shaft fracture. Two hours post-admission, he develops severe pain out of proportion to the injury and pain with passive toe stretch. His blood pressure is 130/80 mmHg. What compartment pressure measurement confirms the need for an emergent fasciotomy?

. Absolute compartment pressure of 20 mmHg
. Absolute compartment pressure of 25 mmHg
. Difference between diastolic blood pressure and compartment pressure less than 30 mmHg
. Difference between systolic blood pressure and compartment pressure less than 30 mmHg
. Difference between mean arterial pressure and compartment pressure less than 40 mmHg

Correct Answer & Explanation

. Difference between diastolic blood pressure and compartment pressure less than 30 mmHg

Explanation

Acute compartment syndrome is diagnosed when the Delta P (Diastolic Blood Pressure minus Compartment Pressure) is less than 30 mmHg. Relying strictly on absolute pressures can lead to misdiagnosis, particularly in hypotensive patients.

Question 12359

Topic: 2. Trauma

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

. Absolute compartment pressure greater than 30 mmHg
. Absolute compartment pressure greater than 45 mmHg
. Delta P (Diastolic blood pressure minus compartment pressure) less than 30 mmHg
. Mean arterial pressure (MAP) minus compartment pressure less than 40 mmHg
. Systolic blood pressure minus compartment pressure less than 30 mmHg

Correct Answer & Explanation

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

Explanation

Delta P, calculated as the diastolic blood pressure minus the absolute compartment pressure, is the most reliable indicator for compartment syndrome. A Delta P of less than 30 mmHg is the standard threshold indicating the need for emergent fasciotomy.

Question 12360

Topic: 2. Trauma
According to current guidelines, what is the optimal prophylactic antibiotic regimen for a Gustilo-Anderson Type IIIA open tibia fracture heavily contaminated with soil?
. First-generation cephalosporin alone
. First-generation cephalosporin and an aminoglycoside
. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin
. Fluoroquinolone alone
. Vancomycin and piperacillin-tazobactam

Correct Answer & Explanation

. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin

Explanation

For Type III open fractures, a first-generation cephalosporin and an aminoglycoside are standard to cover Gram-positive and Gram-negative organisms. The addition of high-dose penicillin is indicated when there is heavy soil contamination to cover Clostridium species.

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