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2. Trauma MCQs

Practice Set 300 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 5981

Topic: 2. Trauma

A 28-year-old man sustains a high-energy tibial plateau fracture with severe soft tissue crushing. Clinical suspicion for acute compartment syndrome is high. Which of the following objective measurements is widely accepted as the absolute threshold for performing an emergent four-compartment fasciotomy?

. Absolute compartment pressure strictly greater than 15 mmHg
. Delta P (Diastolic blood pressure minus compartment pressure) less than 30 mmHg
. Delta P (Systolic blood pressure minus compartment pressure) less than 30 mmHg
. Delta P (Mean arterial pressure minus compartment pressure) less than 40 mmHg
. Absolute compartment pressure equal to the patient's pulse pressure

Correct Answer & Explanation

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

Explanation

The Delta P concept is the most accurate parameter for diagnosing acute compartment syndrome, particularly in hypotensive patients. A Delta P (diastolic blood pressure minus intracompartmental pressure) of less than 30 mmHg indicates that tissue perfusion is critically compromised, mandating an emergent fasciotomy.

Question 5982

Topic: 2. Trauma
A 28-year-old male is brought to the trauma bay after a motorcycle collision. Radiographs demonstrate an anteroposterior compression type III (APC-III) pelvic ring injury with severe diastasis of the pubic symphysis and completely disrupted sacroiliac joints. He is hypotensive despite fluid resuscitation. What is the most common anatomical source of massive hemorrhage in this fracture pattern?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. External iliac artery
. Corona mortis

Correct Answer & Explanation

. Presacral venous plexus

Explanation

While arterial bleeding (e.g., from the superior gluteal or internal pudendal arteries) can occur and is often life-threatening, venous bleeding from the presacral venous plexus and fracture cancellous surfaces accounts for 80-90% of hemorrhage in pelvic ring injuries. This is why pelvic binders and volume reduction are critical first steps.

Question 5983

Topic: 2. Trauma

A 32-year-old female sustains a high-energy distal femur fracture. A CT scan confirms an isolated coronal shear fracture of the lateral femoral condyle (Hoffa fracture). Which of the following muscle attachments provides the primary deforming force on the distal fracture fragment?

. Anterior cruciate ligament
. Iliotibial band
. Popliteus and lateral head of the gastrocnemius
. Biceps femoris
. Lateral collateral ligament

Correct Answer & Explanation

. Popliteus and lateral head of the gastrocnemius

Explanation

In a lateral Hoffa fracture, the popliteus and the lateral head of the gastrocnemius muscles remain attached to the posterior condylar fragment, exerting a strong posterior and inferior deforming force that necessitates rigid internal fixation (typically with posteroanterior or anteroposterior lag screws).

Question 5984

Topic: 2. Trauma

A 25-year-old male sustains a closed comminuted tibial shaft fracture. Clinical examination for acute compartment syndrome is equivocal due to a concomitant traumatic brain injury. Intracompartmental pressures are measured. Which of the following hemodynamic parameters is the most reliable threshold indicator for performing an emergent fasciotomy?

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

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The delta pressure (Diastolic Blood Pressure minus Compartment Pressure) is considered the most reliable indicator for diagnosing acute compartment syndrome. A delta pressure of less than 30 mmHg (some literature states <20-30 mmHg) strongly suggests inadequate tissue perfusion and is an indication for fasciotomy.

Question 5985

Topic: Pelvic & Acetabular Trauma
In the Young-Burgess classification of pelvic ring injuries, which of the following specifically differentiates an Anteroposterior Compression (APC) Type III injury from an APC Type II injury?
. Disruption of the symphysis pubis
. Disruption of the sacrotuberous ligament
. Disruption of the sacrospinous ligament
. Disruption of the posterior sacroiliac ligament
. Disruption of the anterior sacroiliac ligament

Correct Answer & Explanation

. Disruption of the posterior sacroiliac ligament

Explanation

In the Young-Burgess classification, APC II injuries involve disruption of the symphysis pubis (or anterior ring) along with the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact, providing some rotational instability but maintaining vertical stability. In an APC III injury, the posterior sacroiliac ligaments are completely disrupted, resulting in both rotational and vertical instability (a completely unstable hemipelvis).

Question 5986

Topic: 2. Trauma

In 2013, the American Society for Bone and Mineral Research (ASBMR) updated the criteria for diagnosing atypical femur fractures (AFF) associated with long-term bisphosphonate use. Which of the following is NOT considered a major criterion for the diagnosis of an AFF?

. Occurs in the subtrochanteric region or femoral shaft
. Transverse or short oblique fracture configuration
. Localized periosteal reaction of the lateral cortex (beaking)
. Lack of trauma or only minimal trauma
. Presence of significant comminution at the fracture site

Correct Answer & Explanation

. Presence of significant comminution at the fracture site

Explanation

According to the ASBMR criteria, to be defined as an atypical femur fracture, all major criteria must be met. These include: 1) location anywhere from just distal to the lesser trochanter to just proximal to the supracondylar flare; 2) associated with no or minimal trauma; 3) transverse or short oblique configuration; 4) complete fractures extend through both cortices and may be associated with a medial spike; incomplete fractures involve only the lateral cortex; 5) non-comminuted or minimally comminuted. Significant comminution is a negative criterion (i.e., its presence argues against an AFF).

Question 5987

Topic: 2. Trauma

In a classic Galeazzi fracture-dislocation (fracture of the distal third of the radius with disruption of the distal radioulnar joint), the radius often undergoes shortening and angulation. Which muscle represents the primary deforming force responsible for shortening of the radius in this injury?

. Pronator teres
. Pronator quadratus
. Brachioradialis
. Extensor carpi ulnaris
. Biceps brachii

Correct Answer & Explanation

. Brachioradialis

Explanation

In a Galeazzi fracture, the distal radial fragment is subjected to several deforming forces. The primary deforming force causing shortening of the radius is the Brachioradialis, which pulls the distal fragment proximally. The pronator quadratus causes volar displacement and rotation of the distal fragment. Due to these strong deforming forces, Galeazzi fractures are considered 'fractures of necessity' in adults and require open reduction and internal fixation.

Question 5988

Topic: 2. Trauma
A 25-year-old male sustains a vertically oriented (Pauwels Type III) intracapsular femoral neck fracture. To maximize biomechanical stability and minimize shear forces across the fracture site during internal fixation, which of the following constructs is most appropriate?
. Three parallel cancellous screws in an inverted triangle configuration
. Dynamic hip screw (DHS) with an anti-rotation screw
. Proximal femoral nail antirotation (PFNA)
. Three parallel cancellous screws with a medially placed buttress plate
. A fully threaded 7.3mm single screw

Correct Answer & Explanation

. Dynamic hip screw (DHS) with an anti-rotation screw

Explanation

A fixed-angle device such as a Dynamic Hip Screw (DHS), often supplemented with an anti-rotation screw, provides superior biomechanical stability for vertically oriented (Pauwels Type III) femoral neck fractures compared to multiple cancellous screws, as it better resists the high shear forces that predispose these vertical fracture patterns to varus collapse and nonunion.

Question 5989

Topic: 2. Trauma

A 72-year-old male falls from standing and sustains a Type II odontoid fracture with 5 mm of posterior displacement. If this patient is treated non-operatively with a rigid cervical collar, which of the following factors most strongly predicts the development of a nonunion?

. Age greater than 65 years
. Posterior displacement of 5 mm
. Concomitant C1 arch fracture
. Presence of osteoporosis
. Delay in diagnosis greater than 24 hours

Correct Answer & Explanation

. Age greater than 65 years

Explanation

Advanced age (> 50-65 years, specifically > 65 in most modern literature) is the most significant independent risk factor for nonunion in Type II odontoid fractures treated non-operatively. Other risk factors include initial displacement > 5 mm, fracture angulation > 10 degrees, and delayed treatment.

Question 5990

Topic: 2. Trauma
In the initial ATLS resuscitation of a hemodynamically unstable patient with an Anteroposterior Compression Type III (APC-III) pelvic ring injury, what is the most appropriate anatomical landmark for the application of a non-invasive pelvic circumferential compression device (pelvic binder)?
. Over the anterior superior iliac spines (ASIS)
. Over the greater trochanters of the femurs
. Just proximal to the iliac crests
. Around the mid-thighs
. Directly over the pubic symphysis

Correct Answer & Explanation

. Over the greater trochanters of the femurs

Explanation

Pelvic binders must be placed at the level of the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the ASIS or iliac crests is a common clinical error and can paradoxically open the true pelvis further in APC-type injuries by acting as a fulcrum.

Question 5991

Topic: Pelvic & Acetabular Trauma
During the acute trauma bay management of a hemodynamically unstable patient with an anteroposterior compression (APC) type III pelvic ring injury, a circumferential pelvic binder is applied. To achieve the maximal mechanical advantage for reducing pelvic volume, the binder must be centered exactly over which anatomical landmark?
. Iliac crests
. Anterior superior iliac spines (ASIS)
. Greater trochanters
. Level of the pubic symphysis
. Subtrochanteric femurs

Correct Answer & Explanation

. Greater trochanters

Explanation

To effectively close the pelvic ring and reduce pelvic volume in open-book type fractures, the pelvic binder or sheet must be centered directly over the greater trochanters. Placement higher over the iliac crests is a common error and can paradoxically open the true pelvis further or fail to reduce the pubic symphysis effectively.

Question 5992

Topic: 2. Trauma

A 65-year-old male sustains a Type II odontoid fracture following a fall. Which of the following factors represents the strongest clinical predictor for nonunion if this injury is treated non-operatively with a halo vest?

. Concomitant anterior arch C1 fracture
. Anterior displacement of 3 mm
. Initial fracture displacement greater than 5 mm
. Patient gender
. Use of a rigid cervical collar instead of a halo vest

Correct Answer & Explanation

. Initial fracture displacement greater than 5 mm

Explanation

Risk factors for nonunion in Type II odontoid fractures include initial displacement > 5 mm, age > 50 years, angulation > 10 degrees, posterior displacement, and delayed treatment. A displacement greater than 5 mm is a classic and highly significant predictor of nonunion, often prompting surgical management (e.g., anterior screw fixation or posterior C1-C2 fusion).

Question 5993

Topic: 2. Trauma

A 40-year-old female sustains a high-energy trauma and presents with an isolated coronal plane shear fracture of the distal femoral condyle. Regarding this specific injury (Hoffa fracture), which of the following statements is most accurate?

. It most commonly involves the lateral femoral condyle
. It is classified as an AO/OTA type 33-A fracture
. It primarily occurs as a result of a direct varus blow to an extended knee
. Non-operative management with a hinged knee brace is standard of care
. It is typically best visualized on a standard anteroposterior (AP) radiograph

Correct Answer & Explanation

. It most commonly involves the lateral femoral condyle

Explanation

A Hoffa fracture is a coronal shear fracture of the distal femur (AO/OTA 33-B3). It most commonly involves the lateral femoral condyle due to the natural physiological valgus of the knee and the lateral vector of forces transmitted during the typical axial loading mechanism (often with the knee flexed). It is best visualized on a lateral radiograph or CT scan and requires surgical fixation.

Question 5994

Topic: Pelvic & Acetabular Trauma
A 26-year-old male is brought to the emergency department after a motorcycle collision. Pelvic radiographs reveal an anteroposterior compression (APC) injury. Which of the following findings defines an APC III pelvic ring injury according to the Young-Burgess classification?
. Symphysis widening less than 2.5 cm with intact posterior ligaments
. Disruption of the anterior sacroiliac ligaments with intact posterior sacroiliac ligaments
. Complete disruption of the pubic symphysis and both the anterior and posterior sacroiliac ligaments
. Sacral fracture with an ipsilateral superior and inferior rami fracture
. A crescent fracture of the posterior ilium

Correct Answer & Explanation

. Complete disruption of the pubic symphysis and both the anterior and posterior sacroiliac ligaments

Explanation

In the Young-Burgess classification, APC injuries are divided by severity. APC I is symphyseal diastasis <2.5 cm. APC II is symphyseal diastasis >2.5 cm with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but intact posterior sacroiliac ligaments. APC III involves complete disruption of both anterior and posterior sacroiliac ligaments, leading to a completely unstable hemipelvis.

Question 5995

Topic: 2. Trauma

A 45-year-old male sustains a high-energy varus directed force to his knee, resulting in a Schatzker IV tibial plateau fracture. CT scanning demonstrates a displaced coronal shear fracture of the posteromedial tibial plateau. Which surgical approach provides the most optimal visualization and biomechanical advantage for buttress plating of this specific fragment?

. Standard anterolateral approach
. Anterior midline approach
. Posteromedial approach
. Direct medial approach
. Lateral parapatellar approach

Correct Answer & Explanation

. Posteromedial approach

Explanation

A displaced posteromedial fragment of a tibial plateau fracture (often seen in Schatzker IV) is notoriously difficult to reduce and fix from an anterior or direct medial approach. The posteromedial approach allows direct visualization of the fracture apex and permits the application of a posteromedial buttress plate, which mechanically opposes the deforming forces.

Question 5996

Topic: 2. Trauma

In the context of fracture healing and bone grafting, various Bone Morphogenetic Proteins (BMPs) have been extensively studied. Which specific recombinant human BMP is currently FDA-approved for use as an adjunct in the treatment of acute, open tibial shaft fractures treated with an intramedullary nail?

. rhBMP-2
. rhBMP-3
. rhBMP-4
. rhBMP-7
. rhBMP-9

Correct Answer & Explanation

. rhBMP-2

Explanation

rhBMP-2 (Infuse) is FDA-approved for use in acute, open tibial shaft fractures stabilized with an intramedullary nail, as well as for anterior lumbar interbody fusion (ALIF). rhBMP-7 (OP-1) was previously available under a Humanitarian Device Exemption for recalcitrant long bone nonunions but is no longer widely commercialized. The others are not FDA-approved for these indications.

Question 5997

Topic: 2. Trauma
A 6-year-old boy presents to the emergency department after falling off monkey bars. Radiographs demonstrate a fracture of the ulnar diaphysis with an associated anterior dislocation of the radial head. According to the Bado classification of Monteggia fracture-dislocations, what type of injury is this, and what is its relative frequency in the pediatric population?
. Type I; it is the most common type in children
. Type II; it is the most common type in children
. Type III; it is the least common type in children
. Type IV; it is the most common type in children
. Type I; it is exclusively seen in adults

Correct Answer & Explanation

. Type I; it is the most common type in children

Explanation

The Bado classification describes Monteggia fractures based on the direction of radial head dislocation. Type I involves an anterior dislocation, Type II posterior, Type III lateral, and Type IV involves fractures of both the radius and ulna with an anterior radial head dislocation. Type I is the most common variant, especially in pediatric populations.

Question 5998

Topic: 2. Trauma

Historical anatomical teachings suggested that the anterior circumflex humeral artery was the primary blood supply to the humeral head. However, recent quantitative anatomical studies utilizing gadolinium enhancement have redefined this vascularity. Which vessel has been definitively shown to supply the vast majority (over 60%) of the blood flow to the humeral head?

. Anterolateral branch of the anterior circumflex humeral artery
. Posterior circumflex humeral artery
. Acromial branch of the thoracoacromial artery
. Suprascapular artery
. Circumflex scapular artery

Correct Answer & Explanation

. Posterior circumflex humeral artery

Explanation

Classic teachings by Gerber et al. suggested the arcuate branch of the anterior circumflex humeral artery provided the main blood supply to the humeral head. However, more recent landmark quantitative studies (e.g., Hettrich et al., Jbone Joint Surg Am, 2010) demonstrated that the posterior circumflex humeral artery supplies approximately 64% of the blood to the humeral head, challenging older concepts and changing our understanding of avascular necrosis risk in proximal humerus fractures.

Question 5999

Topic: Pelvic & Acetabular Trauma

In an anteroposterior compression type II (APC II) pelvic ring injury, which of the following ligamentous structures is primarily disrupted to allow widening of the pubic symphysis greater than 2.5 cm, while vertical stability is maintained?

. Posterior sacroiliac ligament
. Sacrotuberous and sacrospinous ligaments
. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Iliolumbar ligament
. Sacrospinous ligament only

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC II pelvic ring injury is characterized by symphyseal diastasis > 2.5 cm and widening of the anterior SI joint. The anterior sacroiliac, sacrotuberous, and sacrospinous ligaments are torn, causing rotational instability. The strong posterior sacroiliac ligaments remain intact, which prevents vertical displacement and maintains vertical stability.

Question 6000

Topic: 2. Trauma

In a patient with a displaced proximal humerus fracture, which of the following Hertel criteria is the most reliable predictor for the development of avascular necrosis (AVN) of the humeral head?

. A posteromedial metaphyseal hinge measuring > 8 mm
. Displacement of the greater tuberosity by > 5 mm
. An intact medial calcar hinge
. A posteromedial metaphyseal head extension < 8 mm
. Varus angulation of the humeral head > 20 degrees

Correct Answer & Explanation

. A posteromedial metaphyseal head extension < 8 mm

Explanation

Hertel described predictors for ischemia of the humeral head in proximal humerus fractures. The strongest predictors include a posteromedial metaphyseal extension (calcar length) of less than 8 mm, disruption of the medial hinge (>2mm displacement), and an anatomic neck fracture pattern. An intact medial hinge or calcar length > 8 mm is protective against AVN.

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