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2. Trauma MCQs

Practice Set 134 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 2661

Topic: Upper Extremity Trauma
A 28-year-old male sustains a Grade III acromioclavicular (AC) joint separation. If non-operative management fails and reconstruction is required, the surgeon must focus on reconstructing the primary stabilizers to superior translation of the distal clavicle. Which structures are these?
. Acromioclavicular ligaments
. Coracoclavicular ligaments
. Coracoacromial ligament
. Superior transverse scapular ligament
. Glenohumeral joint capsule

Correct Answer & Explanation

. Coracoclavicular ligaments

Explanation

The coracoclavicular (CC) ligaments, consisting of the conoid and trapezoid, act as the primary stabilizers against superior translation of the distal clavicle. The AC ligaments primarily restrict anterior-posterior translation.

Question 2662

Topic: 2. Trauma

A 68-year-old female sustains a 3-part proximal humerus fracture. Current anatomical studies have revised historical teachings regarding the primary blood supply to the humeral head. Which vessel is now recognized as providing the predominant vascular contribution to the humeral head?

. Anterior circumflex humeral artery
. Posterior circumflex humeral artery
. Thoracoacromial artery
. Subscapular artery
. Profunda brachii artery

Correct Answer & Explanation

. Posterior circumflex humeral artery

Explanation

Recent quantitative anatomical studies have demonstrated that the posterior circumflex humeral artery provides the primary blood supply (up to 64%) to the humeral head, superseding the traditional teaching of the anterior circumflex humeral artery.

Question 2663

Topic: 2. Trauma

An 82-year-old female presents after a mechanical fall with isolated neck pain. CT of the cervical spine reveals a Type II odontoid fracture with 6 mm of posterior displacement. Which of the following factors is the strongest predictor for nonunion if this fracture is treated nonoperatively in a hard cervical collar?

. Age greater than 50 years
. Female gender
. Posterior vs. anterior direction of displacement
. Concomitant C1 ring fracture
. Presence of cervical spondylosis

Correct Answer & Explanation

. Age greater than 50 years

Explanation

Risk factors for nonunion of Type II odontoid fractures include age >50 years, initial displacement >5 mm, and fracture comminution. Advanced age is one of the most consistently cited independent predictors of nonunion.

Question 2664

Topic: 2. Trauma

A 30-year-old male sustains a closed midshaft clavicle fracture. Which of the following radiographic findings is the strongest absolute or relative indication for operative fixation (ORIF) to prevent nonunion and symptomatic malunion?

. Fracture location in the middle third
. Shortening greater than 2 cm
. Presence of a greenstick component
. Superior displacement of 5 mm
. Transverse fracture pattern

Correct Answer & Explanation

. Shortening greater than 2 cm

Explanation

Shortening >2 cm and 100% displacement in adult midshaft clavicle fractures are associated with a significantly increased risk of nonunion and poor functional outcomes if treated nonoperatively.

Question 2665

Topic: Upper Extremity Trauma
A 24-year-old male cyclist falls directly onto the point of his shoulder. Radiographs show a 100% superior displacement of the distal clavicle relative to the acromion, with a coracoclavicular distance increased by 50% compared to the contralateral side. The deltotrapezial fascia is intact on physical exam. What is the most appropriate initial management?
. Immediate open reduction and coracoclavicular ligament reconstruction
. Hook plate fixation
. Sling immobilization, ice, and early range of motion as tolerated
. Arthroscopic Mumford procedure
. Figure-of-eight bracing for 6 weeks

Correct Answer & Explanation

. Sling immobilization, ice, and early range of motion as tolerated

Explanation

This represents a Type III acromioclavicular (AC) joint separation. Nonoperative management with a sling and early ROM yields excellent functional outcomes and is the standard initial treatment for uncomplicated Type III injuries.

Question 2666

Topic: 2. Trauma

Which of the following principles BEST explains why a long intramedullary nail is effective in stabilizing a diaphyseal fracture?

. It provides absolute stability at the fracture site.
. It acts as a load-sharing device, reducing stress shielding of the bone.
. It creates an environment conducive to primary bone healing.
. It primarily provides torsional and bending stability.
. It relies on biological fixation, promoting periosteal callus formation.

Correct Answer & Explanation

. It acts as a load-sharing device, reducing stress shielding of the bone.

Explanation

Correct Answer: BAn intramedullary nail acts as a load-sharing device. It shares the load with the bone, rather than rigidly fixing it and completely shielding the bone from stress (as a plate might, leading to stress shielding). This load sharing allows for controlled micromotion at the fracture site, which is conducive to secondary (callus) bone healing. Nails are very effective at resisting bending and torsional forces along the length of the diaphysis. While they promote biological fixation and periosteal callus (secondary healing), 'load-sharing' is the fundamental biomechanical principle distinguishing their function from rigid plating.

Question 2667

Topic: Lower Extremity Trauma

A resident is designing a custom intramedullary nail for a research study. To maximize the torsional and bending rigidity of the solid cylindrical nail, which of the following design modifications is most effective?

. Increasing the working length of the nail
. Increasing the inner diameter by 2 mm
. Increasing the outer diameter by 1 mm
. Changing the material from stainless steel to titanium
. Adding additional interlocking screw holes

Correct Answer & Explanation

. Increasing the outer diameter by 1 mm

Explanation

The bending and torsional rigidity of a solid cylindrical implant are most significantly influenced by its radius. Biomechanically, bending rigidity is proportional to the radius to the fourth power, making an increase in outer diameter the most effective modification.

Question 2668

Topic: 2. Trauma

During open reduction and internal fixation of a comminuted femoral shaft fracture, the surgeon decides to place the innermost screws further away from the fracture site. What biomechanical effect does increasing the 'working length' of the plate have on the construct?

. Increases the construct's torsional stiffness
. Decreases the construct's overall flexibility
. Decreases the construct's bending stiffness
. Increases the risk of primary bone healing
. Has no effect on construct rigidity

Correct Answer & Explanation

. Decreases the construct's bending stiffness

Explanation

The working length of a plate is the distance between the closest screws on either side of a fracture. Increasing the working length decreases the bending and torsional stiffness of the construct, allowing for more interfragmentary motion which promotes secondary bone healing.

Question 2669

Topic: 2. Trauma
A 28-year-old male sustains a high-energy Pauwels type III (vertical) femoral neck fracture. Which of the following fixation constructs provides the greatest biomechanical stability against the predominant shear forces seen in this fracture pattern?
. Three parallel cancellous screws placed in an inverted triangle
. A sliding hip screw with a derotational cancellous screw
. Two parallel fully threaded cortical screws
. A cephalomedullary nail with a single head screw
. A short barrel plate without compression

Correct Answer & Explanation

. A sliding hip screw with a derotational cancellous screw

Explanation

Pauwels type III fractures have a highly vertical orientation (>50 degrees), generating immense shear forces and a high risk of varus collapse. A fixed-angle device, such as a sliding hip screw (often combined with a derotational screw), provides superior resistance to these vertical shear forces compared to multiple cancellous screws.

Question 2670

Topic: Pelvic & Acetabular Trauma
A trauma patient arrives hypotensive with an unstable pelvis. Radiographs show complete diastasis of the pubic symphysis and profound widening of both sacroiliac joints. Based on the Young-Burgess classification, an anterior-posterior compression (APC) type III injury is diagnosed. Which of the following ligaments must be disrupted in an APC III injury?
. Sacrospinous ligaments only
. Anterior sacroiliac ligaments only
. Sacrotuberous ligaments only
. Anterior and posterior sacroiliac ligaments
. Iliolumbar ligaments only

Correct Answer & Explanation

. Anterior and posterior sacroiliac ligaments

Explanation

An APC III pelvic ring injury involves complete disruption of both the anterior ring (symphysis) and the posterior ring. This requires tearing of both the anterior and the robust posterior sacroiliac ligaments, leading to complete rotational and vertical instability.

Question 2671

Topic: 2. Trauma
A 30-year-old male sustains a Hawkins Type III talar neck fracture. Six weeks post-operatively, a subchondral radiolucent band is seen on the AP radiograph of the ankle. What does this radiographic finding indicate?
. Infection
. Nonunion
. Intact vascularity to the talar body
. Avascular necrosis of the talar head
. Post-traumatic arthritis

Correct Answer & Explanation

. Intact vascularity to the talar body

Explanation

The presence of a subchondral radiolucent band in the talar dome 6 to 8 weeks after injury is known as Hawkins sign. It represents subchondral atrophy (osteopenia) due to disuse, indicating that the vascular supply to the talar body remains intact.

Question 2672

Topic: 2. Trauma
A 45-year-old farmer sustains a severe open tibia fracture (Gustilo-Anderson Type IIIA) highly contaminated with soil. In addition to a first-generation cephalosporin, which of the following antibiotics is classically recommended to cover the most likely atypical organism?
. Vancomycin
. Clindamycin
. Penicillin
. Gentamicin
. Ciprofloxacin

Correct Answer & Explanation

. Penicillin

Explanation

In farm-related injuries or injuries heavily contaminated with soil, there is an elevated risk of Clostridium perfringens infection. Penicillin is classically added to the antibiotic regimen to provide specific coverage against these anaerobes.

Question 2673

Topic: 2. Trauma

A 22-year-old male is admitted with a closed midshaft tibia fracture. Which of the following pressure measurements is generally considered the threshold indicating the need for a four-compartment fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 40 mmHg
. Mean arterial pressure minus compartment pressure < 50 mmHg
. Absolute compartment pressure > 15 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The Delta P (diastolic blood pressure minus the intracompartmental pressure) is the most reliable clinical indicator for acute compartment syndrome. A Delta P of less than 30 mmHg is the widely accepted threshold for surgical fasciotomy.

Question 2674

Topic: 2. Trauma

When using a locking plate for fracture fixation, stability is primarily achieved through which of the following mechanisms?

. Friction between the plate and the bone surface
. Compression of the fracture ends via eccentric screw placement
. The threaded interaction between the screw head and the plate creating a fixed-angle construct
. Cortical hypertrophy induced by micromotion
. The utilization of a dynamic compression slot

Correct Answer & Explanation

. The threaded interaction between the screw head and the plate creating a fixed-angle construct

Explanation

Locking plates achieve stability through the threaded coupling between the screw head and the plate hole, creating a rigid fixed-angle construct. This mechanism does not rely on plate-to-bone friction, thereby preserving the periosteal blood supply.

Question 2675

Topic: 2. Trauma

During an oral board examination, a candidate is asked to formulate a management plan for a complex periarticular fracture. According to assessment blueprints, what specific cognitive domain is being tested when synthesizing clinical and radiographic data into a surgical plan?

. Recall of isolated facts
. Procedural dexterity
. Higher-order clinical reasoning and decision-making
. Interpersonal communication skills
. Basic scientific knowledge

Correct Answer & Explanation

. Higher-order clinical reasoning and decision-making

Explanation

Board exam blueprints structure viva cases to explicitly test higher-order cognitive skills such as synthesis, evaluation, and complex decision-making. Simple recall is typically assessed via foundational written examinations.

Question 2676

Topic: 2. Trauma
A 25-year-old male sustains a high-energy trauma resulting in a vertically oriented (Pauwels Type III) femoral neck fracture. Which of the following internal fixation constructs provides the highest biomechanical stability against shear forces for this specific fracture pattern?
. Three parallel cancellous lag screws in an inverted triangle
. A fixed-angle sliding hip screw (DHS) with a derotational screw
. Fully threaded headless compression screws
. A short proximal femoral nail with a single head screw
. Two parallel cortical screws placed at the calcar

Correct Answer & Explanation

. A fixed-angle sliding hip screw (DHS) with a derotational screw

Explanation

Pauwels Type III fractures are highly vertical and unstable, experiencing profound shear forces rather than compression. Biomechanical studies demonstrate that a fixed-angle device, such as a sliding hip screw combined with an anti-rotation screw, provides superior resistance to shear compared to multiple cancellous screws.

Question 2677

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented (Pauwels Type III) femoral neck fracture. Which of the following internal fixation constructs provides the greatest biomechanical stability against the predominant shear forces at the fracture site?
. Three parallel cancellous screws in an inverted triangle
. A sliding hip screw with a derotational screw
. Two parallel cannulated screws
. An unreamed retrograde intramedullary nail
. Four parallel cancellous screws placed at the periphery

Correct Answer & Explanation

. A sliding hip screw with a derotational screw

Explanation

Pauwels Type III fractures are characterized by high shear forces. A fixed-angle device, such as a sliding hip screw (often supplemented with a derotational screw), provides superior biomechanical stability against vertical shear compared to multiple parallel cancellous screws.

Question 2678

Topic: Pelvic & Acetabular Trauma
In the initial trauma bay resuscitation of a hemodynamically unstable patient with an anterior-posterior compression (APC-III) pelvic ring injury, what is the optimal anatomical landmark for the correct placement of a pelvic circumferential compression device (binder)?
. At the level of the superior iliac crests
. Centered directly over the greater trochanters
. Midway between the umbilicus and the pubic symphysis
. Just proximal to the anterior superior iliac spines (ASIS)
. At the level of the inferior pubic rami

Correct Answer & Explanation

. Centered directly over the greater trochanters

Explanation

Pelvic binders must be centered precisely over the greater trochanters to effectively compress the pelvic ring and reduce intrapelvic volume. Placement too proximally over the iliac crests is biomechanically inferior and can paradoxically open the true pelvis further.

Question 2679

Topic: 2. Trauma

During a viva examination, you are asked to discuss the differential diagnosis for a patient presenting with acute knee pain and swelling after trauma. Which approach best demonstrates a high-yield understanding for the examiner?

. Listing all possible causes without prioritization.
. Stating only the single most likely diagnosis based on your initial assessment.
. Prioritizing diagnoses based on likelihood and severity, justifying each briefly, and mentioning 'must-not-miss' conditions.
. Immediately asking for imaging results before offering any differentials.
. Focusing exclusively on rare orthopedic conditions to appear comprehensive.

Correct Answer & Explanation

. Prioritizing diagnoses based on likelihood and severity, justifying each briefly, and mentioning 'must-not-miss' conditions.

Explanation

Correct Answer: CIn a viva, examiners look for structured thought. Prioritizing differential diagnoses based on likelihood (common vs. rare), severity (life- or limb-threatening), and specific historical/physical findings demonstrates critical thinking. Mentioning 'must-not-miss' conditions, even if less likely, shows a safe and comprehensive approach to patient care. Simply listing everything or only the most common diagnosis misses the opportunity to display nuanced understanding.

Question 2680

Topic: 2. Trauma
A 35-year-old male sustains a Type IIIA open tibia fracture following a motorcycle collision. Based on current literature, which of the following interventions is the most critical factor in preventing deep infection?
. Time to initial administration of intravenous antibiotics.
. Surgical debridement within exactly 6 hours of the injury.
. The use of a multi-planar external fixator.
. Application of negative pressure wound therapy in the emergency department.
. Definitive soft tissue coverage within 24 hours.

Correct Answer & Explanation

. Time to initial administration of intravenous antibiotics.

Explanation

The early administration of appropriate intravenous antibiotics (ideally within 1 hour of injury) has been proven to be the single most important factor in reducing infection rates in open fractures. The traditional '6-hour rule' for debridement is less strongly supported by modern evidence.

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