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2. Trauma MCQs

Practice Set 298 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 5941

Topic: 2. Trauma

A 45-year-old male sustains a Schatzker IV tibial plateau fracture with a large, displaced posteromedial shear fragment. Which surgical approach provides the most optimal access for direct reduction and anti-glide plating of this specific fragment?

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

Correct Answer & Explanation

. Posteromedial approach

Explanation

Schatzker IV fractures involving a posteromedial shear fragment cannot be effectively reduced or buttressed from an anterior or anterolateral approach. A posteromedial approach allows direct visualization, anatomic reduction of the articular surface, and the application of a posterior buttress or anti-glide plate to neutralize the shear forces during weight-bearing.

Question 5942

Topic: 2. Trauma

A patient suffers a Holstein-Lewis fracture, an oblique/spiral fracture of the distal third of the humerus. In this specific injury pattern, the radial nerve is particularly vulnerable to entrapment or laceration because it is securely tethered as it passes through which anatomic structure?

. Spiral groove of the humerus
. Lateral intermuscular septum
. Arcade of Frohse
. Leash of Henry
. Medial intermuscular septum

Correct Answer & Explanation

. Lateral intermuscular septum

Explanation

The Holstein-Lewis fracture involves the distal third of the humeral shaft. The radial nerve is at high risk because it is tethered as it pierces the lateral intermuscular septum to pass from the posterior to the anterior compartment of the arm, approximately 10 cm proximal to the lateral epicondyle.

Question 5943

Topic: Pelvic & Acetabular Trauma
A 45-year-old male is brought to the trauma bay in hemorrhagic shock after a high-speed motorcycle crash. Pelvic radiographs demonstrate an Anteroposterior Compression Type III (APC III) injury. Which of the following ligamentous complexes are completely disrupted in this specific injury pattern?
. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments only
. Anterior sacroiliac, posterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Posterior sacroiliac and iliolumbar ligaments only
. Sacrospinous and sacrotuberous ligaments only
. Anterior and posterior sacroiliac ligaments only

Correct Answer & Explanation

. Anterior sacroiliac, posterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC III injury (Young-Burgess classification) involves complete symphyseal disruption (diastasis) accompanied by complete rupture of the anterior sacroiliac, posterior sacroiliac, sacrotuberous, and sacrospinous ligaments. This results in a hemipelvis that is both rotationally and vertically unstable, and it carries the highest risk of massive retroperitoneal hemorrhage among APC patterns.

Question 5944

Topic: 2. Trauma

Nine months after undergoing open reduction and internal fixation of a supracondylar femur fracture with a lateral locking plate, a 45-year-old male presents with persistent thigh pain. Radiographs reveal an intact construct with a 5 mm fracture gap and absent callus formation. What is the most likely mechanical cause of this atrophic nonunion?

. Plate placed too far anteriorly
. Construct is too flexible, promoting excessive strain
. Construct is too stiff, causing stress shielding and inadequate micromotion
. Use of a titanium rather than stainless steel plate
. Failure to use an orthogonal dual-plate construct

Correct Answer & Explanation

. Construct is too stiff, causing stress shielding and inadequate micromotion

Explanation

Locking plates create a highly rigid, fixed-angle construct. If placed with an inadequate working length (screws too close to the fracture site) and a fracture gap, the construct becomes too stiff. This suppresses the micromotion necessary for secondary bone healing (callus formation), leading to an atrophic nonunion.

Question 5945

Topic: Pelvic & Acetabular Trauma
In the Young-Burgess classification, an Anteroposterior Compression (APC) Type II pelvic ring injury results in the 'open book' deformity. This is characterized by diastasis of the symphysis pubis and rupture of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. Which critical ligamentous complex remains INTACT in an APC II injury, thereby preventing vertical instability?
. Anterior sacroiliac ligaments
. Symphysis pubis ligaments
. Posterior sacroiliac ligaments
. Iliolumbar ligaments
. Sacrotuberous ligaments

Correct Answer & Explanation

. Posterior sacroiliac ligaments

Explanation

An APC II injury involves disruption of the anterior sacroiliac ligaments and pelvic floor ligaments (sacrotuberous, sacrospinous), leading to rotational instability. However, the stout posterior sacroiliac ligaments remain intact, providing vertical stability. If these tear, the injury becomes an APC III, which is both rotationally and vertically unstable.

Question 5946

Topic: Pelvic & Acetabular Trauma

A 25-year-old male is brought to the emergency department after a motorcycle collision with a hemodynamically unstable suspected pelvic ring injury. A circumferential pelvic binder is to be applied. What is the correct anatomical landmark to center the binder for optimal reduction of pelvic volume?

. Anterior superior iliac spines (ASIS)
. Iliac crests
. Greater trochanters
. Pubic symphysis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder should be centered directly over the greater trochanters of the femurs. This location most effectively closes the pelvic ring and reduces pelvic volume, particularly in 'open book' (APC) type injuries. Placing the binder too high (over the iliac crests or ASIS) may paradoxically widen the pelvis or be ineffective.

Question 5947

Topic: 2. Trauma
A 45-year-old pedestrian is struck by a motor vehicle and sustains a varus-directed force to the knee. Radiographs reveal a medial tibial plateau fracture with depression. According to the Schatzker classification, what type of fracture is this, and what is the most critical associated complication to monitor for?
. Schatzker I; popliteal artery injury
. Schatzker II; common peroneal nerve injury
. Schatzker III; acute compartment syndrome
. Schatzker IV; popliteal artery injury and/or compartment syndrome
. Schatzker V; deep vein thrombosis

Correct Answer & Explanation

. Schatzker IV; popliteal artery injury and/or compartment syndrome

Explanation

A medial tibial plateau fracture is a Schatzker IV fracture. This represents a high-energy trauma mechanism (unlike lateral plateau fractures, which are often lower energy in older patients). Due to the high energy and valgus/varus disruptive forces, it carries a very high risk of popliteal artery injury and acute compartment syndrome. The medial condyle is more robust, so fracturing it requires significant force.

Question 5948

Topic: 2. Trauma

Which of the following factors is the strongest predictor of nonunion in a 75-year-old patient with a Type II odontoid fracture treated conservatively in a halo vest?

. Anterior displacement of 3 mm
. Posterior displacement of 2 mm
. Initial fracture displacement greater than 5 mm
. Angulation of 5 degrees
. Concomitant C1 arch fracture

Correct Answer & Explanation

. Initial fracture displacement greater than 5 mm

Explanation

Risk factors for nonunion in Type II odontoid fractures include age over 65 years, initial displacement > 5 mm, posterior displacement, and angulation > 10 degrees. Initial fracture displacement greater than 5 mm and advanced age are the strongest independent predictors of failure with conservative management.

Question 5949

Topic: 2. Trauma

The primary blood supply to the proximal pole of the scaphoid is derived from vessels that enter the bone at which location?

. The palmar tuberosity via the superficial palmar branch of the radial artery
. The dorsal ridge via branches of the radial artery
. The scapholunate interosseous ligament
. The volar capsule distal to the radioscaphocapitate ligament
. The proximal articular surface directly from the radiocarpal joint fluid

Correct Answer & Explanation

. The dorsal ridge via branches of the radial artery

Explanation

The major blood supply to the scaphoid is from the radial artery. Approximately 80% of the bone, including the entire proximal pole, is supplied by branches that enter the dorsal ridge (distal to the waist) and flow retrogradely. This retrograde vascular supply explains the high rate of avascular necrosis and nonunion in proximal pole fractures.

Question 5950

Topic: 2. Trauma

A 45-year-old male sustains a high-energy Schatzker Type IV tibial plateau fracture with a large posteromedial coronal shear fragment. To properly neutralize the vertical shear forces during weight bearing, which of the following is the most biomechanically sound fixation strategy?

. Lateral locked plating with divergent screws aimed posteromedially
. Anteroposterior lag screws placed percutaneously
. An isolated circular external fixator
. Posteromedial approach with an anti-glide (buttress) plate applied to the posterior aspect of the medial condyle
. Medial uniplanar external fixator

Correct Answer & Explanation

. Posteromedial approach with an anti-glide (buttress) plate applied to the posterior aspect of the medial condyle

Explanation

A posteromedial shear fragment in a tibial plateau fracture possesses a coronal fracture line and displaces vertically under physiological load. A laterally based locking plate alone cannot adequately resist these shear forces. The most stable construct is an anatomically contoured buttress plate applied directly to the posteromedial apex via a posteromedial approach.

Question 5951

Topic: 2. Trauma

In the operative treatment of intertrochanteric hip fractures with a sliding hip screw or a cephalomedullary nail, the concept of Tip-Apex Distance (TAD) as described by Baumgaertner is critical. To minimize the risk of lag screw cut-out, the combined TAD (measured on AP and lateral radiographs) should be less than:

. 10 mm
. 15 mm
. 25 mm
. 35 mm
. 45 mm

Correct Answer & Explanation

. 25 mm

Explanation

Baumgaertner et al. demonstrated that a Tip-Apex Distance (TAD) of less than 25 mm is a strong, independent predictor of successful lag screw fixation in intertrochanteric hip fractures. A combined TAD greater than 25 mm significantly increases the risk of the screw cutting out of the femoral head.

Question 5952

Topic: 2. Trauma

A 40-year-old female sustains a high-energy trauma resulting in a distal femur fracture. CT scan reveals a coronal plane fracture of the lateral femoral condyle. What is the eponymous name of this fracture, and what is the optimal direction of screw fixation?

. Barton fracture; Anterior to posterior
. Hoffa fracture; Anterior to posterior
. Hoffa fracture; Posterior to anterior
. Tillaux fracture; Anterior to posterior
. Chopart fracture; Posterior to anterior

Correct Answer & Explanation

. Hoffa fracture; Anterior to posterior

Explanation

A Hoffa fracture is an intra-articular coronal plane fracture of the femoral condyle, typically the lateral condyle. Biomechanical studies have demonstrated that placing lag screws from anterior to posterior (A-P) provides significantly stronger fixation compared to posterior to anterior (P-A), as A-P screws engage the denser bone of the posterior condyle more effectively.

Question 5953

Topic: 2. Trauma

A 29-year-old male sustains a closed, isolated right scapular body fracture following a motorcycle collision. Radiographs and CT show a highly comminuted fracture with 5 mm of displacement. What is the most appropriate management?

. Immediate Open Reduction and Internal Fixation (ORIF)
. Sling immobilization for 1-2 weeks followed by early range of motion
. Skeletal traction via an olecranon pin for 3 weeks
. Application of a shoulder spica cast
. ORIF if displacement persists after 6 weeks of non-operative treatment

Correct Answer & Explanation

. Sling immobilization for 1-2 weeks followed by early range of motion

Explanation

The vast majority of isolated scapular body fractures, even those that are highly comminuted or displaced up to 1-2 cm, are treated non-operatively with excellent functional outcomes. Sling immobilization for comfort followed by early shoulder range of motion is the standard of care.

Question 5954

Topic: 2. Trauma

A 65-year-old female sustains a displaced 3-part proximal humerus fracture. According to Hertel's criteria, which combination of radiographic features is the most reliable predictor of humeral head ischemia and subsequent avascular necrosis (AVN)?

. Metaphyseal head extension > 8mm and an intact medial hinge
. Greater tuberosity displacement > 5mm and angulation > 45 degrees
. Surgical neck fracture line and valgus impaction
. Varus angulation > 20 degrees and lesser tuberosity displacement
. Metaphyseal head extension < 8mm and disrupted medial hinge > 2mm

Correct Answer & Explanation

. Metaphyseal head extension < 8mm and disrupted medial hinge > 2mm

Explanation

Hertel et al. described highly predictive radiographic criteria for humeral head ischemia in proximal humerus fractures. The most significant predictors for ischemia (AVN risk) are a short calcar segment attached to the articular fragment (metaphyseal extension < 8 mm), a disrupted medial hinge (> 2 mm displacement), and an anatomical neck fracture type. When a short calcar segment and a disrupted medial hinge are combined, the positive predictive value for ischemia is exceptionally high (up to 97%).

Question 5955

Topic: 2. Trauma

A 30-year-old male returns to the clinic 6 weeks following open reduction and internal fixation of a displaced talar neck fracture (Hawkins Type II). An AP radiograph of the ankle demonstrates a distinct, linear subchondral radiolucent band beneath the dome of the talus. What is the prognostic significance of this radiographic finding (Hawkins sign)?

. Impending avascular necrosis (AVN) of the talar body
. Subchondral collapse indicating early post-traumatic arthritis
. Intact vascular supply to the talar body with subchondral osteopenia
. Nonunion at the primary fracture site
. Occult infection of the talocalcaneal joint

Correct Answer & Explanation

. Intact vascular supply to the talar body with subchondral osteopenia

Explanation

The presence of a subchondral radiolucent band in the talar dome 6 to 8 weeks after a talar neck fracture is known as the Hawkins sign. This radiolucency represents subchondral atrophy/osteopenia secondary to disuse. Crucially, for bone resorption to occur, there must be active blood flow to deliver osteoclasts to the region. Therefore, a positive Hawkins sign is an excellent prognostic indicator that the talar body remains vascularized and the risk of avascular necrosis (AVN) is extremely low.

Question 5956

Topic: 2. Trauma
A 28-year-old male is admitted with a severe tibia-fibula fracture. You are monitoring him for acute compartment syndrome using continuous intracompartmental pressure measurements. The patient's blood pressure is 115/80 mmHg, and his mean arterial pressure (MAP) is 92 mmHg. According to the concept of delta pressure (ΔP), what intracompartmental pressure reading would yield a ΔP of exactly 25 mmHg?
. 25 mmHg
. 55 mmHg
. 67 mmHg
. 90 mmHg
. 105 mmHg

Correct Answer & Explanation

. 55 mmHg

Explanation

Delta pressure (ΔP) is considered the most reliable indicator for diagnosing acute compartment syndrome and the need for fasciotomy. It is calculated by subtracting the intracompartmental pressure from the patient's diastolic blood pressure (ΔP = Diastolic BP - Compartment Pressure). A delta pressure of < 30 mmHg is the classic threshold for fasciotomy. If the diastolic BP is 80 mmHg, an intracompartmental pressure of 55 mmHg yields a delta pressure of 25 mmHg (80 - 55 = 25).

Question 5957

Topic: 2. Trauma

A 28-year-old unrestrained driver sustains an isolated coronal shear fracture of the lateral femoral condyle (Hoffa fracture). When managing this injury, what is the biomechanically optimal direction for lag screw fixation to resist the primary deforming forces?

. Anterior-to-posterior screws placed perpendicular to the fracture line
. Posterior-to-anterior screws placed perpendicular to the fracture line
. Medial-to-lateral screws placed parallel to the joint line
. Anterior-to-posterior screws placed parallel to the mechanical axis
. Anterior-to-posterior screws supplemented with a lateral neutralizing plate

Correct Answer & Explanation

. Posterior-to-anterior screws placed perpendicular to the fracture line

Explanation

A Hoffa fracture is a coronal shear fracture of the femoral condyle. While anterior-to-posterior (AP) screws are clinically easier to place via an anterior exposure, biomechanical studies demonstrate that posterior-to-anterior (PA) lag screws are significantly stronger. This is because the screw threads engage the thicker, denser anterior diaphyseal/metaphyseal cortex, providing superior pullout strength and resisting the shear forces of the condyle.

Question 5958

Topic: 2. Trauma
A 25-year-old male falls from a height of 30 feet, landing on both feet. He sustains a U-shaped sacral fracture, with a transverse fracture line through S2 connecting bilateral transforaminal longitudinal fractures. Neurological exam reveals absent perianal sensation. This highly unstable injury pattern implies which of the following biomechanical phenomena?
. An isolated injury to the pelvic ring that remains mechanically stable in axial loading
. Spinopelvic dissociation
. A highly unstable anterior pelvic ring disruption (APC III)
. An injury predominantly managed with isolated anterior symphyseal plating
. A fracture pattern that typically spares the sacral nerve roots

Correct Answer & Explanation

. Spinopelvic dissociation

Explanation

A U-shaped sacral fracture consists of bilateral longitudinal sacral fractures joined by a transverse fracture line (commonly at S1 or S2). This injury pathomechanism uncouples the upper sacrum (and therefore the entire axial spine) from the lower sacrum and pelvis, resulting in 'spinopelvic dissociation'. It is highly unstable, is associated with a high incidence of sacral nerve root injury (bowel/bladder dysfunction), and typically requires surgical stabilization with lumbopelvic fixation.

Question 5959

Topic: 2. Trauma

A Jones fracture (Zone 2 fracture of the fifth metatarsal) occurs at the metaphyseal-diaphyseal junction and is prone to delayed union or nonunion due to a vascular watershed area. Which of the following arteries provides the primary retrograde intramedullary blood supply to this region, which is disrupted by the fracture?

. Dorsalis pedis artery
. First dorsal metatarsal artery
. Nutrient artery branch from the fibular artery
. Nutrient artery branch from the posterior tibial artery
. Nutrient artery entering the medial cortex of the middle third of the diaphysis

Correct Answer & Explanation

. Nutrient artery entering the medial cortex of the middle third of the diaphysis

Explanation

The intramedullary blood supply of the fifth metatarsal is primarily derived from a nutrient artery that enters the medial cortex at the junction of the proximal and middle thirds of the diaphysis. It then courses proximally in a retrograde fashion. A fracture at the metaphyseal-diaphyseal junction (Zone 2) disrupts this retrograde intramedullary flow, creating a vascular watershed area that significantly increases the risk of nonunion.

Question 5960

Topic: Pelvic & Acetabular Trauma

In the setting of a severe vertical shear (VS) pelvic ring disruption with profound hemodynamic instability, life-threatening arterial hemorrhage from the posterior pelvic elements is most commonly due to injury of which of the following vessels?

. Obturator artery
. Superior gluteal artery
. Internal pudendal artery
. External iliac artery
. Inferior epigastric artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

Vertical shear (VS) pelvic ring injuries involve massive disruption of the posterior sacroiliac complex. Due to its intimate anatomic relationship with the upper border of the greater sciatic notch and the sacroiliac joint, the superior gluteal artery (the largest branch of the posterior division of the internal iliac artery) is highly vulnerable to laceration or avulsion in posterior disruption patterns. Anterior ring disruptions (like APC injuries) are more commonly associated with bleeding from the obturator or internal pudendal vessels.

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