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2. Trauma MCQs

Practice Set 240 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 4781

Topic: Pelvic & Acetabular Trauma
An APC-III (anteroposterior compression type III) pelvic ring injury is characterized by complete disruption of the symphysis pubis and which of the following posterior ligamentous complexes?
. Anterior sacroiliac ligaments only
. Sacrotuberous and sacrospinous ligaments with intact posterior sacroiliac ligaments
. Complete disruption of the anterior and posterior sacroiliac ligaments
. Disruption of the iliolumbar ligament only
. Complete disruption of the sacrococcygeal ligaments

Correct Answer & Explanation

. Complete disruption of the anterior and posterior sacroiliac ligaments

Explanation

An APC-III injury involves complete anterior and posterior disruption. This includes the symphysis pubis, the sacrotuberous/sacrospinous ligaments, and both the anterior and posterior sacroiliac ligaments, leading to complete global instability.

Question 4782

Topic: 2. Trauma

A 22-year-old athlete sustains a fracture at the metaphyseal-diaphyseal junction of the fifth metatarsal (Jones fracture). The high propensity for nonunion in this region is attributed to a vascular watershed area. This watershed zone exists between the vascular supply of the metatarsal base and the diaphysis. Which of the following describes the primary blood supply to the diaphyseal side of this watershed zone?

. Extramedullary branches of the lateral plantar artery
. Intramedullary nutrient artery entering the medial cortex at the middle third
. Arcuate artery branches entering dorsally
. Metaphyseal vessels from the insertion of the peroneus brevis
. Anastomotic ring from the deep plantar arch

Correct Answer & Explanation

. Intramedullary nutrient artery entering the medial cortex at the middle third

Explanation

The fifth metatarsal has a predictable vascular watershed zone at the metaphyseal-diaphyseal junction (Zone 2). The base and tuberosity are supplied by metaphyseal arteries, while the diaphysis is supplied by a single intramedullary nutrient artery that typically enters the medial cortex at the junction of the proximal and middle thirds and courses proximally. The region between these two blood supplies is relatively avascular, contributing to the high nonunion rate of Jones fractures.

Question 4783

Topic: 2. Trauma

A 12-year-old boy presents with severe finger flexion contractures three months after an untreated forearm compartment syndrome secondary to a supracondylar humerus fracture. In established Volkmann ischemic contracture, which of the following muscles is typically the most profoundly ischemic and subsequently fibrotic?

. Flexor carpi ulnaris
. Pronator quadratus
. Flexor digitorum profundus
. Flexor carpi radialis
. Extensor digitorum communis

Correct Answer & Explanation

. Flexor digitorum profundus

Explanation

Volkmann's ischemic contracture results from untreated compartment syndrome in the forearm. The deep flexor compartment is the most severely affected due to its central location and reliance on the anterior interosseous artery, which is highly vulnerable to occlusion from elevated compartment pressures. The flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) are typically the most profoundly infarcted and fibrotic muscles.

Question 4784

Topic: 2. Trauma

A 21-year-old collegiate basketball player sustains an acute Zone 2 proximal fifth metatarsal fracture (Jones fracture) during a game. He wishes to return to play as safely and rapidly as possible. What is the recommended standard of care?

. Non-weight bearing in a short leg cast for 6-8 weeks
. Weight-bearing as tolerated in a stiff-soled shoe
. Open reduction and internal fixation with a lateral locking plate
. Intramedullary screw fixation
. Primary bone grafting without hardware fixation

Correct Answer & Explanation

. Intramedullary screw fixation

Explanation

Zone 2 fractures (Jones fractures) have a high risk of nonunion due to a tenuous blood supply. For elite or competitive athletes desiring early return to play, intramedullary screw fixation is the treatment of choice.

Question 4785

Topic: Lower Extremity Trauma

When utilizing suture button fixation for an ankle syndesmotic injury, what is a primary biomechanical advantage compared to traditional rigid trans-syndesmotic screw fixation?

. Higher maximum load to failure in external rotation forces
. Elimination of the need for an intact anterior inferior tibiofibular ligament
. Allowance of physiological fibular motion and rotation within the incisura
. Decreased risk of superficial peroneal nerve injury during placement
. Capability to rigidly over-compress a widened medial clear space

Correct Answer & Explanation

. Allowance of physiological fibular motion and rotation within the incisura

Explanation

Suture button fixation for syndesmotic injuries allows for physiological micromotion and fibular rotation within the incisura during ankle dorsiflexion. It also mitigates the need for routine hardware removal.

Question 4786

Topic: 2. Trauma

A 22-year-old collegiate basketball player sustains a Zone 2 proximal fifth metatarsal (Jones) fracture and is treated with intramedullary screw fixation. Which technical error during screw insertion most significantly increases the risk of nonunion?

. Screw threads stopping completely short of the fracture line
. Using a solid rather than a cannulated screw system
. Selecting a screw diameter that engages the medullary cortex fully
. Tapping the intramedullary canal prior to screw insertion
. Screw threads residing equally across both sides of the fracture site

Correct Answer & Explanation

. Screw threads residing equally across both sides of the fracture site

Explanation

When fixing a Jones fracture, if the screw threads cross the fracture site, the screw acts as a position screw rather than a lag screw. This prevents adequate interfragmentary compression and increases the risk of clinical failure or nonunion.

Question 4787

Topic: 2. Trauma
A 28-year-old sustains a Hawkins Type III talar neck fracture. At 8 weeks post-ORIF, a subchondral radiolucent line is seen in the talar dome on the AP mortise radiograph. What does this radiographic finding indicate?
. Impending avascular necrosis of the talar body
. Nonunion of the talar neck
. Infection of the tibiotalar joint
. Intact vascularity to the talar body
. Post-traumatic osteoarthritis of the subtalar joint

Correct Answer & Explanation

. Intact vascularity to the talar body

Explanation

The Hawkins sign is a subchondral radiolucent band typically seen 6 to 8 weeks after a talus fracture. It represents subchondral bone resorption secondary to disuse osteopenia, which requires an intact blood supply, thereby indicating viability of the talar body.

Question 4788

Topic: 2. Trauma

In the open reduction and internal fixation of a 3-part proximal humerus fracture using a locking plate, the placement of calcar screws in the inferomedial quadrant of the humeral head is critical to prevent which of the following complications?

. Axillary nerve injury
. Varus collapse of the humeral head
. Avascular necrosis of the articular segment
. Nonunion of the greater tuberosity
. Superior screw cutout

Correct Answer & Explanation

. Varus collapse of the humeral head

Explanation

Inferomedial calcar screws restore the medial hinge in proximal humerus fractures. Their precise placement is the most important mechanical factor in preventing postoperative varus collapse of the humeral head construct.

Question 4789

Topic: Lower Extremity Trauma

A 25-year-old sustains an external rotation ankle injury. On a standard AP mortise radiograph taken non-weight-bearing, which measurement threshold is most specifically indicative of syndesmotic instability?

. Tibiofibular overlap less than 1 mm
. Medial clear space greater than 2 mm
. Tibiofibular clear space greater than 5 mm
. Talar tilt greater than 5 degrees
. Lateral malleolar displacement greater than 2 mm

Correct Answer & Explanation

. Tibiofibular clear space greater than 5 mm

Explanation

A tibiofibular clear space of greater than 5 mm on an AP or mortise radiograph is widely considered abnormal and suggests a syndesmotic injury. The tibiofibular overlap can vary based on rotation, making the clear space a more reliable indicator.

Question 4790

Topic: Pelvic & Acetabular Trauma
Figure 33a shows a line drawing of a normal hemipelvis. The anterior acetabular rim is bold. Figure 33b illustrates a hemipelvis with a crossover sign, which is indicative of what acetabular pathology?
. Low acetabular index
. Excessive acetabular retroversion
. Deficient anterior column bone
. Labral detachment
. Pelvic discontinuity

Correct Answer & Explanation

. Excessive acetabular retroversion

Explanation

In a normal AP pelvis radiograph, the anterior rim of the acetabulum runs medially and distally, diverging from the posterior rim which runs much more vertically. In excessive acetabular retroversion, the anterior rim (bold line in Figure 33b) and posterior rim start laterally, and as these lines progress medially and distally, the anterior line crosses the posterior line. This predisposes to femoral acetabular impingement.

Question 4791

Topic: 2. Trauma
A 28-year-old male sustains a high-energy Pauwels III (vertical shear) femoral neck fracture. Which of the following fixation constructs provides the highest biomechanical stability against the predominant deforming forces in this fracture pattern?
. Multiple cancellous screws in an inverted triangle configuration
. A sliding hip screw used as a standalone device
. A sliding hip screw combined with a partially threaded derotational cancellous screw
. A short cephalomedullary nail
. A standard hemiarthroplasty

Correct Answer & Explanation

. A sliding hip screw combined with a partially threaded derotational cancellous screw

Explanation

Pauwels III femoral neck fractures (angle > 50 degrees) experience massive vertical shear forces. A sliding hip screw (SHS) provides superior biomechanical resistance to shear compared to cancellous screws, and adding a derotational screw controls the rotational instability inherent to the SHS.

Question 4792

Topic: Lower Extremity Trauma

During a posteromedial approach to the tibia for open reduction and internal fixation of a Schatzker IV tibial plateau fracture, the dissection utilizes the interval between the medial head of the gastrocnemius and the pes anserinus. Which of the following structures is at greatest risk of iatrogenic injury during the superficial dissection?

. Common peroneal nerve
. Saphenous nerve
. Sural nerve
. Anterior tibial artery
. Medial superior genicular artery

Correct Answer & Explanation

. Saphenous nerve

Explanation

The posteromedial approach to the tibial plateau requires careful superficial dissection. The saphenous nerve and the great saphenous vein run superficially in this region and are at significant risk of injury during the surgical approach.

Question 4793

Topic: 2. Trauma
A 35-year-old male sustains a Gustilo-Anderson IIIB open tibial shaft fracture following a motorcycle collision. After emergent debridement and external fixation, soft tissue coverage is required. Based on classic orthopedic trauma principles, soft tissue flap coverage should ideally be performed within what timeframe to minimize the risk of deep infection?
. Within 6 hours
. Within 72 hours
. After 7 days of negative pressure wound therapy
. Between 2 to 3 weeks
. Once granulation tissue fully covers the exposed bone

Correct Answer & Explanation

. Within 72 hours

Explanation

Godina's classic study demonstrated that early soft tissue coverage (within 72 hours) for severe open tibia fractures significantly decreases the rates of deep infection and nonunion compared to delayed coverage.

Question 4794

Topic: 2. Trauma

A 45-year-old male undergoes open reduction and internal fixation of a displaced transverse patella fracture using a tension band wiring technique. Which biomechanical principle best explains the efficacy of this fixation method?

. It converts shear forces into distraction forces during extension.
. It converts tensile forces at the anterior cortex into dynamic compressive forces at the articular surface during flexion.
. It prevents superior migration of the tibial tubercle.
. It acts as a static block to knee flexion to protect the extensor mechanism.
. It neutralizes rotational forces across the fracture site during active extension.

Correct Answer & Explanation

. It converts tensile forces at the anterior cortex into dynamic compressive forces at the articular surface during flexion.

Explanation

Tension band wiring operates by placing the implant on the tension side (the anterior surface) of the patella. During knee flexion, it converts the distracting tensile forces of the extensor mechanism into dynamic compressive forces at the articular surface, promoting primary bone healing.

Question 4795

Topic: 2. Trauma

In a 30-year-old patient with a displaced femoral neck fracture, which of the following biomechanical factors most significantly increases the risk of nonunion and fixation failure?

. Increased posterior comminution
. Increased Pauwels angle
. Decreased neck-shaft angle
. Shortening of the femoral neck
. Presence of a prominent calcar

Correct Answer & Explanation

. Increased Pauwels angle

Explanation

A higher Pauwels angle indicates a more vertical fracture line, which translates to increased shear forces across the fracture site. This significantly increases the risk of varus collapse, nonunion, and fixation failure in young patients.

Question 4796

Topic: 2. Trauma

When treating an intertrochanteric femur fracture with a sliding hip screw, maintaining a Tip-Apex Distance (TAD) of less than 25 mm is primarily associated with a decreased risk of which of the following complications?

. Nonunion
. Avascular necrosis
. Lag screw cut-out
. Femoral shaft fracture
. Infection

Correct Answer & Explanation

. Lag screw cut-out

Explanation

Baumgaertner et al. demonstrated that a Tip-Apex Distance (TAD) of less than 25 mm is the most important surgeon-controlled variable to prevent lag screw cut-out in the treatment of intertrochanteric fractures.

Question 4797

Topic: 2. Trauma

A 68-year-old woman presents with vague, aching thigh pain for 3 months. She has been taking alendronate for 8 years. Radiographs reveal focal lateral cortical thickening of the subtrochanteric femur with a transverse radiolucent line. What is the most appropriate prophylactic surgical management?

. Dynamic hip screw
. Cephalomedullary nailing
. Plate osteosynthesis
. Core decompression
. External fixation

Correct Answer & Explanation

. Cephalomedullary nailing

Explanation

Incomplete atypical femur fractures associated with long-term bisphosphonate use that are symptomatic (painful) should be treated with prophylactic cephalomedullary or intramedullary nailing to span the entire bone and prevent complete displacement.

Question 4798

Topic: 2. Trauma

A 25-year-old man sustains a traumatic knee dislocation. Following closed reduction, his Ankle-Brachial Index (ABI) is measured at 0.85. What is the most appropriate next step in management?

. Observation and serial clinical exams
. Immediate external fixation
. CT angiography
. Duplex ultrasonography
. Immediate surgical exploration of the popliteal artery

Correct Answer & Explanation

. CT angiography

Explanation

An ABI less than 0.9 in the setting of a knee dislocation is highly suspicious for a popliteal artery injury. The most appropriate next step is advanced vascular imaging, typically CT angiography, to localize and characterize the lesion.

Question 4799

Topic: 2. Trauma

Which of the following is true regarding a Hoffa fracture (coronal shear fracture) of the distal femur?

. It most commonly involves the medial femoral condyle.
. It is best visualized on a standard anteroposterior radiograph.
. Nonoperative management is the standard of care for non-displaced fractures.
. It is frequently associated with supracondylar femur fractures.
. Fixation typically requires posterior-to-anterior directed lag screws only.

Correct Answer & Explanation

. It is frequently associated with supracondylar femur fractures.

Explanation

Hoffa fractures are coronal shear fractures that most commonly involve the lateral condyle and are highly associated with supracondylar femur fractures. They require open reduction and rigid internal fixation, typically with anterior-to-posterior lag screws.

Question 4800

Topic: 2. Trauma

During intramedullary nailing of a proximal third tibial shaft fracture, utilizing a standard infrapatellar entry portal most commonly leads to which of the following malalignments?

. Varus and recurvatum
. Valgus and recurvatum
. Varus and procurvatum
. Valgus and procurvatum
. Pure varus

Correct Answer & Explanation

. Valgus and procurvatum

Explanation

Proximal third tibia fractures are notorious for displacing into valgus and procurvatum (apex anterior) during intramedullary nailing with a standard infrapatellar starting point, due to the pull of the patellar tendon and the eccentric starting point.

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