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2. Trauma MCQs

Practice Set 179 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 3561

Topic: 2. Trauma

When performing an extensile lateral approach for a displaced intra-articular calcaneal fracture, preservation of the full-thickness flap's corner is critical to prevent wound necrosis. Which artery primarily supplies the angiosome at the apex of this flap?

. Lateral calcaneal artery
. Sural artery
. Anterior lateral malleolar artery
. Perforating branch of the peroneal artery
. Lateral plantar artery

Correct Answer & Explanation

. Lateral calcaneal artery

Explanation

The lateral calcaneal artery, a terminal branch of the peroneal artery, provides the primary blood supply to the apex of the standard extensile lateral calcaneal flap. Protecting this vascular supply is essential to prevent tip necrosis.

Question 3562

Topic: 2. Trauma

A 65-year-old patient sustains a highly comminuted distal femur fracture (OTA/AO 33C) treated with a lateral locking plate. Which of the following mechanical factors most significantly increases the risk of fatigue failure or nonunion of the implant?

. Increasing the plate working length by omitting screws near the fracture
. Decreasing the plate working length by filling all screw holes near the fracture
. Using a titanium construct instead of a stainless steel construct
. Placing the plate precisely along the mid-lateral axis of the femur
. Using a plate that spans the entire diaphysis

Correct Answer & Explanation

. Increasing the plate working length by omitting screws near the fracture

Explanation

In comminuted fractures treated with bridge plating, decreasing the working length (placing screws too close to the fracture site) makes the construct too rigid over a short segment. This concentrates strain, increasing the risk of construct fatigue failure and nonunion.

Question 3563

Topic: 2. Trauma

A 30-year-old sustains a closed tibial shaft fracture. Continuous compartment pressure monitoring is initiated. Which of the following parameters is the most widely accepted and reliable threshold indicating the need for an emergent fasciotomy?

. Absolute compartment pressure greater than 20 mmHg
. Absolute compartment pressure greater than 30 mmHg
. Differential pressure (Diastolic BP minus compartment pressure) less than 30 mmHg
. Differential pressure (Mean arterial pressure minus compartment pressure) less than 40 mmHg
. Differential pressure (Systolic BP minus compartment pressure) less than 50 mmHg

Correct Answer & Explanation

. Absolute compartment pressure greater than 20 mmHg

Explanation

A differential pressure (Delta P) of less than 30 mmHg (diastolic blood pressure minus intracompartmental pressure) is the most reliable threshold for diagnosing acute compartment syndrome and indicating fasciotomy.

Question 3564

Topic: 2. Trauma

A 24-year-old track athlete is diagnosed with a high-risk tarsal navicular stress fracture. The navicular has a unique vascular anatomy that predisposes it to delayed union and nonunion. Which region of the navicular is relatively avascular and most prone to stress fractures?

. Plantar aspect
. Dorsal aspect
. Central third
. Medial tuberosity
. Lateral articular margin

Correct Answer & Explanation

. Plantar aspect

Explanation

The central third of the tarsal navicular is a relative watershed area with poor blood supply. This avascularity makes it the most common site for stress fractures and increases the risk of nonunion.

Question 3565

Topic: 2. Trauma
A 28-year-old patient sustains a vertical, Pauwels type III femoral neck fracture. To maximize biomechanical stability and resist the high shear forces inherent to this fracture pattern, which internal fixation construct is most appropriate?
. Three parallel cancellous lag screws in an inverted triangle
. A dynamic hip screw (DHS) with an anti-rotation screw
. Two parallel cancellous lag screws
. An intramedullary nail with a single cephalomedullary screw
. A fully threaded transcervical screw alone

Correct Answer & Explanation

. A dynamic hip screw (DHS) with an anti-rotation screw

Explanation

Pauwels type III fractures are highly vertical and experience massive shear forces. A fixed-angle device, such as a dynamic hip screw (DHS) combined with an anti-rotation screw, provides superior biomechanical resistance to shear compared to multiple cancellous screws.

Question 3566

Topic: 2. Trauma

A patient with a lateral compression pelvic ring injury is noted to have a crescent fracture of the ilium. According to the Day classification, a type II crescent fracture involves which of the following fracture patterns?

. The fracture line exits anterior to the sacroiliac joint
. The fracture line enters the sacroiliac joint directly, leaving a large posterior iliac fragment attached to the sacrum
. The fracture line involves only the sacral ala without iliac involvement
. The fracture is a pure ligamentous sacroiliac dislocation without bony avulsion
. The fracture extends inferiorly into the acetabular dome

Correct Answer & Explanation

. The fracture line exits anterior to the sacroiliac joint

Explanation

In the Day classification of crescent fractures, a Type II fracture enters the sacroiliac (SI) joint directly. This leaves a posterior fragment of the ilium securely attached to the sacrum while the anterior ilium is displaced.

Question 3567

Topic: Pelvic & Acetabular Trauma
A 40-year-old male is brought to the trauma bay following a motorcycle collision. He is hypotensive with a mechanically unstable anteroposterior compression (APC-III) pelvic ring injury. A pelvic binder is applied. To optimally reduce pelvic volume and stabilize the fracture, the binder should be centered over which of the following anatomical landmarks?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders are most effective at reducing pelvic volume and controlling hemorrhage when centered directly over the greater trochanters. Placement over the iliac crests is less effective and may inadvertently cause paradoxical widening of the pelvic ring.

Question 3568

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented, high-shear femoral neck fracture (Pauwels type III). Open reduction and internal fixation is planned. Biomechanically, which of the following construct choices provides the greatest resistance to vertical shear forces and varus collapse?
. Three parallel partially threaded cannulated screws
. Two crossed cannulated screws
. A sliding hip screw with a derotation screw
. A fixed-angle blade plate
. Three fully threaded cannulated screws

Correct Answer & Explanation

. A sliding hip screw with a derotation screw

Explanation

In young patients with vertically oriented (Pauwels III) femoral neck fractures, a fixed-angle construct such as a sliding hip screw with a derotation screw provides superior biomechanical stability. It resists vertical shear forces and varus collapse significantly better than multiple cannulated screws.

Question 3569

Topic: 2. Trauma

A 30-year-old male is undergoing intramedullary nailing of a proximal third tibial shaft fracture via an infrapatellar approach. What is the most common postoperative malalignment associated with this specific technique for this fracture pattern?

. Apex posterior (recurvatum) and varus
. Apex posterior (recurvatum) and valgus
. Apex anterior (procurvatum) and varus
. Apex anterior (procurvatum) and valgus
. Internal rotation and shortening

Correct Answer & Explanation

. Apex posterior (recurvatum) and varus

Explanation

Proximal third tibial shaft fractures fixed with an infrapatellar IM nail commonly displace into an apex anterior (procurvatum) and valgus deformity. This is driven by the pull of the patellar tendon and the geometric effect of the nail passing posterior to the anterior tibial cortex.

Question 3570

Topic: Pelvic & Acetabular Trauma
According to the Young-Burgess classification, which of the following injury patterns is the anatomical hallmark of an Anteroposterior Compression Type III (APC III) pelvic ring injury?
. Symphysis diastasis < 2.5 cm with intact posterior ligaments
. Symphysis diastasis > 2.5 cm with disrupted anterior SI ligaments but intact posterior SI ligaments
. Complete disruption of both the anterior and posterior sacroiliac ligaments
. Sacral fracture with spinous process avulsion
. Internal rotation of the hemipelvis with a compression fracture of the anterior sacrum

Correct Answer & Explanation

. Complete disruption of both the anterior and posterior sacroiliac ligaments

Explanation

An APC III injury is characterized by the complete disruption of the anterior sacroiliac (SI) ligaments, the sacrospinous and sacrotuberous ligaments, AND the posterior SI ligaments. This results in complete global (rotational and vertical) pelvic instability.

Question 3571

Topic: 2. Trauma

During fixation of a pronation-external rotation ankle fracture, the surgeon assesses syndesmotic stability via the Cotton test. Which ligament provides the greatest inherent resistance to anterior translation of the distal fibula relative to the tibia?

. Posterior inferior tibiofibular ligament
. Interosseous ligament
. Anterior inferior tibiofibular ligament
. Deltoid ligament
. Calcaneofibular ligament

Correct Answer & Explanation

. Posterior inferior tibiofibular ligament

Explanation

The anterior inferior tibiofibular ligament (AITFL) is the primary restraint against anterior displacement of the fibula relative to the tibia. It is typically the first structure injured in syndesmotic sprains and rotational ankle fractures.

Question 3572

Topic: 2. Trauma

When performing open reduction and internal fixation of a 3-part proximal humerus fracture, anatomic restoration of the medial calcar hinge is critical. Failure to achieve medial cortical support is most strongly associated with which of the following mechanical complications?

. Hardware penetration into the joint secondary to varus collapse
. Subcoracoid impingement secondary to valgus overcorrection
. Nonunion of the greater tuberosity
. Iatrogenic axillary nerve palsy
. Biceps tendon subluxation

Correct Answer & Explanation

. Hardware penetration into the joint secondary to varus collapse

Explanation

Lack of medial calcar support in proximal humerus fractures predisposes the construct to biomechanical failure characterized by varus collapse. As the head collapses into varus, the superiorly directed locking screws can penetrate the articular surface, leading to joint destruction.

Question 3573

Topic: 2. Trauma
A 30-year-old male sustains a Pauwels type III femoral neck fracture. Due to the highly vertical fracture line, the site is subjected to immense shear forces. Which of the following fixation constructs offers the greatest biomechanical stability to counteract these forces and prevent varus collapse?
. Three parallel partially threaded cancellous lag screws
. Sliding hip screw (SHS) with a derotation screw
. Cephalomedullary nail with a single lag screw
. Fully threaded cannulated screws placed in an inverted triangle
. Dynamic condylar screw (DCS)

Correct Answer & Explanation

. Sliding hip screw (SHS) with a derotation screw

Explanation

For vertically oriented (Pauwels III) femoral neck fractures in young adults, the shear stresses are exceptionally high. A sliding hip screw (SHS) combined with an anti-rotation screw provides superior biomechanical resistance to shear and varus collapse compared to multiple cancellous screws.

Question 3574

Topic: 2. Trauma

When treating a proximal third tibial shaft fracture with an intramedullary nail via an infrapatellar approach, the fracture frequently drifts into a classic malalignment pattern. What is this typical deformity, and where should a Poller (blocking) screw be placed to prevent it?

. Valgus and procurvatum; Poller screw placed on the concavity (lateral and posterior to the nail)
. Varus and recurvatum; Poller screw placed on the concavity (medial and anterior to the nail)
. Valgus and procurvatum; Poller screw placed on the convexity (medial and anterior to the nail)
. Varus and procurvatum; Poller screw placed on the convexity (lateral and anterior to the nail)
. Varus and recurvatum; Poller screw placed centrally within the medullary canal

Correct Answer & Explanation

. Valgus and procurvatum; Poller screw placed on the concavity (lateral and posterior to the nail)

Explanation

Proximal third tibial fractures nailed in extension typically deform into valgus and procurvatum due to the pull of the patellar tendon and the wide metaphyseal flare. Poller screws should be placed on the concave side of the anticipated deformity (lateral and posterior) to centralize the nail and redirect its path.

Question 3575

Topic: 2. Trauma
A 25-year-old male sustains a vertically oriented (Pauwels type III) femoral neck fracture. Which of the following fixation constructs offers the highest biomechanical stability against the extreme shear forces characteristic of this specific fracture pattern?
. Three parallel partially threaded cancellous screws
. A sliding hip screw with an anti-rotation cancellous screw
. Two divergent fully threaded headless compression screws
. A standard cephalomedullary nail
. A dynamic condylar screw placed retrograde

Correct Answer & Explanation

. A sliding hip screw with an anti-rotation cancellous screw

Explanation

Pauwels type III fractures are highly unstable due to significant shear forces across the vertical fracture line. Biomechanical studies demonstrate that a fixed-angle construct, such as a sliding hip screw combined with a derotation screw, provides superior resistance to shear compared to multiple cancellous screws.

Question 3576

Topic: 2. Trauma
In the management of a Gustilo-Anderson Type IIIB open tibia fracture, current evidence suggests that definitive soft-tissue flap coverage should optimally be performed within what timeframe to most effectively minimize deep infection rates?
. Within 72 hours
. Between 5 and 7 days
. Between 10 and 14 days
. Immediately after the first debridement, regardless of contamination
. After a healthy bed of granulation tissue forms

Correct Answer & Explanation

. Within 72 hours

Explanation

Early soft-tissue coverage of Type IIIB open tibia fractures, ideally within 72 hours of injury, is associated with significantly lower rates of deep infection and flap failure. Delays beyond this window dramatically increase colonization and complication rates.

Question 3577

Topic: 2. Trauma
A patient is brought to the trauma bay with an APC III pelvic ring injury and a blood pressure of 80/50 mmHg. To effectively reduce pelvic volume and stabilize the fracture, an external pelvic binder should be centered directly over which anatomic landmark?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

To maximize the reduction of pelvic volume in anterior-posterior compression (APC) injuries, pelvic binders must be centered over the greater trochanters. Placement over the iliac crests is a common error and can paradoxically open the pelvis further.

Question 3578

Topic: 2. Trauma

An elite soccer player sustains a zone II proximal fifth metatarsal fracture (Jones fracture). To minimize the risk of nonunion and hardware failure during intramedullary screw fixation, which technical parameter is most crucial?

. Using a fully threaded cannulated screw
. Ensuring the screw threads cross the fracture site to allow distraction
. Maximizing the solid screw diameter to closely match the intramedullary canal
. Using a bioabsorbable screw to avoid stress shielding
. Placing the screw exclusively in the lateral cortex

Correct Answer & Explanation

. Using a fully threaded cannulated screw

Explanation

In the intramedullary fixation of Jones fractures, utilizing the largest solid screw diameter that safely fits the canal (often 4.5mm, 5.5mm, or 6.5mm) provides maximum bending stiffness and resistance to failure. The threads must bypass the fracture site entirely to achieve compression.

Question 3579

Topic: 2. Trauma

A 70-year-old female sustains a Lewis-Rorabeck Type II periprosthetic distal femur fracture above a well-fixed posterior-stabilized (PS) total knee arthroplasty component. Which fixation strategy is considered the gold standard for providing mechanical stability while accommodating the prosthesis design?

. Standard straight intramedullary retrograde nail
. Lateral locked plating spanning the fracture with bicortical fixation proximal to the component
. Medial non-locking compression plating
. Exchange revision arthroplasty with a distal femoral replacement
. Flexible intramedullary nailing

Correct Answer & Explanation

. Standard straight intramedullary retrograde nail

Explanation

A Lewis-Rorabeck Type II fracture is displaced but has a well-fixed component. Lateral locked plating is the standard of care. Retrograde nails often cannot be used due to the closed box design of many posterior-stabilized knee components blocking the intercondylar entry portal.

Question 3580

Topic: 2. Trauma
Figures 48a and 48b show the elbow radiographs of a 5-year-old boy who fell from a tree after dinner. Examination reveals that he is unable to extend his wrist. Management should consist of immediate:
. closed reduction and pinning of the fracture in the operating room.
. closed reduction, pinning of the fracture, and radial nerve exploration in the operating room.
. closed reduction and splinting in the emergency department.
. splinting of the arm and observation of neurovascular function, followed by closed reduction and pinning in the operating room the following morning.
. olecranon skeletal traction for reduction, followed by casting when the reduction has been stabilized by callus.

Correct Answer & Explanation

. splinting of the arm and observation of neurovascular function, followed by closed reduction and pinning in the operating room the following morning.

Explanation

In the absence of vascular compromise, there has been no proven value to proceeding immediately to surgery, especially when the patient has a full stomach and runs a significant risk of perioperative aspiration. It would be more prudent to wait until the next morning with a surgical plan of closed reduction and pinning. Open reduction should be reserved for the unusual case where closed treatment has not been successful. The implication that there may be a radial nerve injury associated with this fracture does not alter the treatment plan, and with a high level of certainty would be expected to resolve.

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