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2. Trauma MCQs

Practice Set 302 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 6021

Topic: 2. Trauma

A 40-year-old male sustains a Schatzker VI tibial plateau fracture with severe soft tissue swelling, initially managed with a spanning external fixator. When transitioning to definitive internal fixation, which of the following principles is most critical for addressing the metaphyseal-diaphyseal dissociation?

. Anatomic reduction of the articular surface prior to restoring limb alignment
. Application of an isolated rigid lateral locking plate
. Restoration of mechanical alignment and stable bridging fixation
. Use of intramedullary nailing directly through the fracture site
. Extensile anterior approach for direct visualization of both condyles simultaneously

Correct Answer & Explanation

. Restoration of mechanical alignment and stable bridging fixation

Explanation

Schatzker VI fractures inherently involve a complete metaphyseal-diaphyseal dissociation. While reconstructing the articular surface is important, the absolute most critical principle in definitive management is the restoration of mechanical alignment, length, and rotation. This must be secured with stable bridging fixation (typically dual plating or fine-wire circular fixation) to prevent catastrophic mechanical failure or varus/valgus collapse.

Question 6022

Topic: Pelvic & Acetabular Trauma
In the Young-Burgess classification of pelvic ring injuries, which of the following injury patterns is most strongly associated with massive retroperitoneal hemorrhage requiring urgent volume reduction with a pelvic binder?
. Lateral Compression Type I (LC-1)
. Anteroposterior Compression Type III (APC-3)
. Lateral Compression Type II (LC-2)
. Vertical Shear (VS)
. Anteroposterior Compression Type I (APC-1)

Correct Answer & Explanation

. Anteroposterior Compression Type III (APC-3)

Explanation

Anteroposterior Compression Type III (APC-3) injuries involve complete disruption of both the anterior and posterior pelvic ligaments (including the pubic symphysis, sacrospinous, sacrotuberous, and anterior/posterior sacroiliac ligaments). This creates an extreme 'open-book' pattern, leading to complete instability and the largest increase in pelvic volume. It is associated with the highest rate of catastrophic retroperitoneal venous and arterial hemorrhage.

Question 6023

Topic: 2. Trauma

A 25-year-old motorcyclist presents with a flail upper extremity, massively swollen shoulder, and an absent radial pulse following a high-speed collision. Radiographs show complete lateral displacement of the scapula. In the context of scapulothoracic dissociation, which of the following associated injuries is most predictive of the eventual need for a forequarter amputation?

. Axillary artery transection
. Complete brachial plexus avulsion
. Highly comminuted clavicle fracture
. Complete acromioclavicular dislocation
. Massive soft tissue degloving

Correct Answer & Explanation

. Complete brachial plexus avulsion

Explanation

Scapulothoracic dissociation involves complete disruption of the scapulothoracic articulation. The functional outcome and the necessity of forequarter amputation are almost entirely dictated by the neurological status. A complete brachial plexus avulsion carries a dismal prognosis for functional recovery of the limb, often leading to early or delayed amputation. Vascular injuries are common and require immediate attention, but isolated vascular injuries can be repaired with limb salvage if the plexus is intact.

Question 6024

Topic: 2. Trauma

A 40-year-old male sustains an acetabular fracture in an MVA. The CT scan demonstrates fracture lines involving both the anterior and posterior columns. Which radiographic feature definitively differentiates a 'Both-Column' fracture from a 'T-type' fracture according to the Letournel classification?

. Involvement of the quadrilateral plate
. A transverse fracture component across the cotyloid fossa
. Disruption of the obturator ring
. Medial displacement of the femoral head
. Detachment of all articular segments of the acetabulum from the intact ilium

Correct Answer & Explanation

. Detachment of all articular segments of the acetabulum from the intact ilium

Explanation

In the Letournel classification, a Both-Column fracture is an associated fracture pattern where both the anterior and posterior columns are fractured, and critically, no portion of the articular surface remains attached to the intact axial skeleton (the iliac wing/sacrum). The intact piece of ilium often creates a radiographic 'spur sign'. In contrast, a T-type fracture involves a transverse component and a vertical stem, but a portion of the superior acetabular roof remains attached to the intact ilium.

Question 6025

Topic: 2. Trauma

A 45-year-old male sustains a high-energy Schatzker IV tibial plateau fracture involving a significantly displaced posteromedial shear fragment. If the surgeon utilizes an isolated standard anterolateral surgical approach, what is the most significant mechanical failure risk associated with this strategy?

. Iatrogenic injury to the common peroneal nerve
. Inadequate visualization and inability to biomechanically buttress the posteromedial fragment
. Avulsion of the popliteal artery
. Development of severe post-operative patella baja
. Anterior cruciate ligament avulsion during retraction

Correct Answer & Explanation

. Inadequate visualization and inability to biomechanically buttress the posteromedial fragment

Explanation

Schatzker IV fractures involve the medial plateau. High-energy variants often possess a coronal fracture line resulting in a posteromedial shear fragment. This fragment cannot be directly visualized, reduced, or biomechanically stabilized (buttressed) via an anterolateral approach. A posteromedial approach is required to place an anti-glide or buttress plate on the posterior apex of the fragment to prevent displacement during knee flexion and weight-bearing.

Question 6026

Topic: Lower Extremity Trauma

A trauma surgeon decides to ream a tibial shaft and change the planned solid intramedullary nail from a 10 mm diameter to a 12 mm diameter. By approximately what factor does this change increase the torsional rigidity of the implant?

. 1.2
. 1.4
. 1.7
. 2.1
. 2.5

Correct Answer & Explanation

. 2.1

Explanation

The torsional rigidity of a solid cylinder is proportional to the radius (or diameter) raised to the fourth power (r^4). Therefore, increasing the diameter from 10 mm to 12 mm increases the rigidity by a factor of (12/10)^4 = 1.2^4 = 2.0736, which is approximately 2.1.

Question 6027

Topic: Pelvic & Acetabular Trauma

In the Graf ultrasound classification for developmental dysplasia of the hip (DDH) in an infant, the alpha angle is widely utilized to determine the severity of dysplasia. What anatomic feature does the alpha angle represent, and what is its generally accepted normal value?

. The cartilaginous roof of the acetabulum; greater than 55 degrees
. The bony roof of the acetabulum; greater than 60 degrees
. The cartilaginous roof of the acetabulum; less than 55 degrees
. The bony roof of the acetabulum; less than 60 degrees
. The fibrocartilaginous labrum; greater than 60 degrees

Correct Answer & Explanation

. The bony roof of the acetabulum; greater than 60 degrees

Explanation

In the Graf ultrasound evaluation of infantile hips, the alpha angle measures the concavity of the bony roof of the acetabulum (formed by the ilium). A normal alpha angle (Graf Type I) is greater than or equal to 60 degrees. The beta angle measures the cartilaginous roof and is normally less than 55 degrees.

Question 6028

Topic: 2. Trauma

A 28-year-old man falls on an outstretched hand and sustains a Galeazzi fracture-dislocation. Radiographs show a fracture of the distal third of the radius with dislocation of the distal radioulnar joint (DRUJ). Which muscle is primarily responsible for the volar displacement and pronation of the distal radial fracture fragment?

. Brachioradialis
. Pronator quadratus
. Flexor carpi radialis
. Extensor carpi ulnaris
. Pronator teres

Correct Answer & Explanation

. Pronator quadratus

Explanation

In a Galeazzi fracture, the distal radius fragment is subjected to distinct deforming forces: the brachioradialis pulls the fragment proximally, causing shortening, while the pronator quadratus pulls the fragment volarly and causes it to pronate. Therefore, the pronator quadratus is the primary force causing volar displacement and pronation.

Question 6029

Topic: 2. Trauma

A 35-year-old patient sustains a coronal shear fracture of the lateral femoral condyle (Hoffa fracture). When planning internal fixation with lag screws, which screw trajectory provides the greatest biomechanical strength?

. Anterior-to-posterior, directed perpendicular to the fracture plane
. Posterior-to-anterior, engaging the intact anterior cortex
. Inferior-to-superior, utilizing fully threaded screws
. Medial-to-lateral, parallel to the joint line
. Superior-to-inferior, utilizing a blade plate

Correct Answer & Explanation

. Posterior-to-anterior, engaging the intact anterior cortex

Explanation

Biomechanical studies have demonstrated that lag screws placed from posterior-to-anterior are significantly stronger for fixing Hoffa fractures because they allow the screw threads to engage the denser anterior cortical bone of the distal femur, providing superior compression.

Question 6030

Topic: 2. Trauma

When treating a proximal third extra-articular tibia fracture with an intramedullary nail, the fracture typically drifts into apex anterior (procurvatum) and valgus deformity. To prevent this, blocking (Poller) screws should be placed in the proximal segment in which position relative to the planned path of the nail?

. Anterior and medial
. Anterior and lateral
. Posterior and lateral
. Posterior and medial
. Directly anterior and directly lateral

Correct Answer & Explanation

. Posterior and lateral

Explanation

Proximal tibia fractures treated with IM nails tend to deform into procurvatum (apex anterior) and valgus (apex medial). Blocking screws are placed on the concave side of the expected deformity to keep the nail centered in the wide metaphysis. The concavity for procurvatum is posterior, and for valgus is lateral. Therefore, blocking screws in the proximal segment go posterior and lateral to the nail path.

Question 6031

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the ED after a high-speed motorcycle crash. His blood pressure is 70/40 mmHg. Pelvic radiographs reveal an anteroposterior compression (APC) Type III pelvic ring injury with complete disruption of the symphysis and bilateral sacroiliac joints. A massive transfusion protocol is initiated. What is the most appropriate immediate orthopedic intervention?
. Immediate open reduction and internal fixation of the pubic symphysis
. Application of a pelvic binder centered over the iliac crests
. Application of a pelvic binder centered over the greater trochanters
. Retrograde urethrogram to assess for urologic injury
. Angiography for bilateral internal iliac artery embolization

Correct Answer & Explanation

. Application of a pelvic binder centered over the greater trochanters

Explanation

In a hemodynamically unstable patient with an open-book pelvic fracture, the immediate step is to mechanically reduce pelvic volume to tamponade venous bleeding. A pelvic binder or sheet must be applied accurately over the greater trochanters to effectively close the pelvic ring. Placement over the iliac crests is incorrect and can exacerbate the deformity.

Question 6032

Topic: 2. Trauma

A 30-year-old male sustains a severely comminuted closed fracture of the tibial shaft. He complains of excruciating leg pain that is unresponsive to IV opioids. His blood pressure is 120/80 mmHg. Intracompartmental pressure monitoring is performed. Which of the following measured values represents the most universally accepted absolute threshold indicating the need for emergent four-compartment fasciotomy?

. Absolute intracompartmental pressure > 20 mmHg
. Absolute intracompartmental pressure > 30 mmHg
. Delta pressure (Diastolic BP - Compartment Pressure) < 30 mmHg
. Delta pressure (Mean Arterial Pressure - Compartment Pressure) < 40 mmHg
. Delta pressure (Systolic BP - Compartment Pressure) < 30 mmHg

Correct Answer & Explanation

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

Explanation

Acute compartment syndrome is primarily a clinical diagnosis, but when objective pressure measurements are required, the Delta pressure (calculated as the Diastolic Blood Pressure minus the Intracompartmental Pressure) is the most reliable parameter. A Delta pressure of less than 30 mmHg signifies a critical loss of tissue perfusion gradient and is an absolute indication for immediate fasciotomy.

Question 6033

Topic: 2. Trauma

A 75-year-old male presents with severe neck pain following a low-energy ground-level fall. Cervical CT demonstrates a displaced Anderson and D'Alonzo Type II odontoid fracture. What distinct anatomical feature of the dens makes this specific fracture pattern highly prone to nonunion, particularly in the elderly population?

. The dens lacks any ligamentous capsular attachments, preventing a cellular healing response
. The fracture line passes directly through a persistent accessory ossification center
. The primary blood supply via the paired ascending branches of the vertebral arteries enters at the base and is disrupted
. Constant mandatory motion of the atlanto-occipital joint incessantly shears the fracture site
. The dens is entirely composed of cortical bone with virtually zero cancellous reserve

Correct Answer & Explanation

. The primary blood supply via the paired ascending branches of the vertebral arteries enters at the base and is disrupted

Explanation

An Anderson and D'Alonzo Type II fracture occurs at the junction of the dens and the body of the axis (the base of the dens). The primary blood supply to the dens is retrograde, supplied by the anterior and posterior ascending arteries (branches of the vertebral arteries) that enter precisely at its base. A fracture at this level disrupts this vascular watershed, causing a high rate of avascular necrosis and nonunion, especially in older adults.

Question 6034

Topic: 2. Trauma

A 28-year-old male is admitted after a motorcycle accident resulting in a closed, comminuted tibial shaft fracture. Two hours post-admission, he complains of severe leg pain out of proportion to the injury. His blood pressure is 110/70 mmHg. The anterior compartment pressure is measured at 45 mmHg using a slit-catheter technique. What is the calculated delta pressure and the recommended intervention?

. Delta pressure is 25 mmHg; continue to monitor clinically
. Delta pressure is 65 mmHg; continue to monitor clinically
. Delta pressure is 25 mmHg; administer IV mannitol and elevate leg
. Delta pressure is 65 mmHg; perform urgent four-compartment fasciotomy
. Delta pressure is 25 mmHg; perform urgent four-compartment fasciotomy

Correct Answer & Explanation

. Delta pressure is 25 mmHg; perform urgent four-compartment fasciotomy

Explanation

Acute compartment syndrome is a surgical emergency. The 'delta pressure' is calculated as the Diastolic Blood Pressure minus the Intracompartmental Pressure. A delta pressure of < 30 mmHg (some texts say < 20-30 mmHg) is widely accepted as an absolute indication for fasciotomy, as capillary perfusion is significantly compromised. Here, Diastolic BP (70) - Compartment Pressure (45) = 25 mmHg. Because 25 mmHg is less than the 30 mmHg threshold, immediate four-compartment fasciotomy is indicated.

Question 6035

Topic: Pelvic & Acetabular Trauma
A 45-year-old male presents in hemorrhagic shock following a high-speed motorcycle accident. Anteroposterior pelvis radiograph demonstrates an Anteroposterior Compression Type III (APC-III) pelvic ring injury. A pelvic binder is applied, and a massive transfusion protocol is initiated. Despite these measures, his hemodynamics remain unstable. A FAST (Focused Assessment with Sonography for Trauma) exam is negative. What is the most appropriate next step in management?
. Exploratory laparotomy
. Preperitoneal pelvic packing and/or pelvic angiography
. Application of a supra-acetabular external fixator
. Open reduction and internal fixation of the pubic symphysis
. Computed tomography angiography of the abdomen and pelvis

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angiography

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST exam, the source of bleeding is predominantly retroperitoneal (venous plexus or arterial). The accepted standard algorithms recommend either preperitoneal pelvic packing or pelvic angiography/embolization. CT scan is contraindicated in a hemodynamically unstable patient. Laparotomy is indicated for intra-abdominal bleeding (positive FAST), but opening the retroperitoneum during laparotomy can release the tamponade effect and worsen pelvic bleeding.

Question 6036

Topic: 2. Trauma

An 80-year-old male sustains a Type II odontoid fracture following a ground-level fall. Which of the following initial injury characteristics is most predictive of nonunion if this fracture is treated nonoperatively with a rigid cervical orthosis?

. Initial fracture displacement > 5 mm
. Concomitant fracture of the C1 posterior arch
. Posterior displacement of the dens
. Patient age between 50 and 65 years
. Associated osteoporosis on DEXA scan

Correct Answer & Explanation

. Initial fracture displacement > 5 mm

Explanation

In Type II odontoid fractures, the highest risk factors for nonunion with conservative management include initial fracture displacement > 5 mm (or 6 mm in some series), angulation > 10 degrees, and advanced patient age (especially > 50-65 years). Among these, displacement > 5 mm has been consistently shown to have the highest correlation with nonunion, with rates exceeding 50-80% in older adults when displacement is severe.

Question 6037

Topic: Upper Extremity Trauma

During an olecranon osteotomy for open reduction and internal fixation of an intra-articular distal humerus fracture (AO/OTA 13-C3), the osteotomy should be directed to enter the joint at which of the following landmarks?

. Through the center of the coronoid process
. Into the deepest, non-articular portion of the trochlear notch (bare area)
. Proximal to the sublime tubercle
. Through the olecranon tip 5 mm from the insertion of the triceps tendon
. Distal to the attachment of the brachialis muscle

Correct Answer & Explanation

. Into the deepest, non-articular portion of the trochlear notch (bare area)

Explanation

An olecranon osteotomy is typically performed as a chevron osteotomy directed into the 'bare area' of the greater sigmoid (trochlear) notch. This bare area is devoid of articular cartilage and represents the deepest portion of the notch. Entering the joint here minimizes damage to the articular surface of the proximal ulna and facilitates an anatomic reduction upon repair.

Question 6038

Topic: 2. Trauma

A 40-year-old male sustains a bicondylar tibial plateau fracture (Schatzker VI). Preoperative CT scanning reveals a large, displaced posteromedial shear fragment. Which of the following surgical approaches is most appropriate for achieving direct visualization and applying a buttress plate to this specific fragment?

. Anterolateral approach with an extended capsulotomy
. Standard medial approach via pes anserinus elevation
. Posteromedial approach utilizing the interval between the medial gastrocnemius and pes anserinus
. Posterior approach splitting the medial and lateral heads of the gastrocnemius
. Anteromedial approach exploring anterior to the medial collateral ligament

Correct Answer & Explanation

. Posteromedial approach utilizing the interval between the medial gastrocnemius and pes anserinus

Explanation

The posteromedial shear fragment is common in bicondylar tibial plateau fractures. To adequately reduce and buttress this fragment, an anti-glide or buttress plate must be applied to the posterior aspect of the medial plateau. The optimal approach is the posteromedial approach, which exploits the interval between the medial head of the gastrocnemius (retracted posteriorly/laterally) and the pes anserinus tendons (retracted anteriorly/medially).

Question 6039

Topic: 2. Trauma

A 12-year-old boy is evaluated for a Volkmann's ischemic contracture, which developed following an unrecognized compartment syndrome of the forearm after a supracondylar humerus fracture. Which of the following muscles is typically the most severely affected by ischemia in this condition?

. Flexor carpi ulnaris
. Flexor digitorum profundus
. Flexor digitorum superficialis
. Pronator teres
. Extensor digitorum communis

Correct Answer & Explanation

. Flexor digitorum profundus

Explanation

Volkmann's ischemic contracture is the late sequela of an untreated volar compartment syndrome of the forearm. The deepest muscles of the volar compartment, specifically the flexor digitorum profundus (FDP, especially to the middle and ring fingers) and the flexor pollicis longus (FPL), lie directly against the bone and are subjected to the highest intracompartmental pressures. Consequently, they suffer the most severe ischemic necrosis and subsequent fibrotic contracture.

Question 6040

Topic: Pelvic & Acetabular Trauma
A 35-year-old cyclist falls and sustains a closed degloving injury over the greater trochanter. Two weeks later, a fluctuant swelling is present. Aspiration yields serosanguinous fluid. What is the pathophysiological hallmark of this lesion?
. Subperiosteal hematoma formation
. Separation of the skin and subcutaneous tissue from the underlying deep fascia
. Rupture of the vastus lateralis with intramuscular hematoma
. Herniation of muscle through a fascial defect
. Lymphatic disruption within the superficial dermal layer

Correct Answer & Explanation

. Separation of the skin and subcutaneous tissue from the underlying deep fascia

Explanation

A Morel-Lavallée lesion is a closed degloving injury caused by shearing forces that separate the skin and subcutaneous fat from the underlying deep fascia. This creates a potential space that fills with blood, lymph, and necrotic fat.

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