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2. Trauma MCQs

Practice Set 626 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 12501

Topic: 2. Trauma

A 32-year-old male sustains a high-energy closed tibial plateau fracture. Twelve hours later, he develops severe leg pain out of proportion to the injury, exacerbated by passive stretch of the toes. Which of the following pathophysiological mechanisms is the primary initiator of the tissue ischemia in this condition?

. Arterial vasospasm leading to decreased capillary perfusion
. Venous outflow obstruction leading to increased intracompartmental pressure and subsequent collapse of the capillary bed
. Direct mechanical compression of the major axial arteries
. Thrombosis of the deep venous system
. Lymphatic obstruction causing interstitial edema

Correct Answer & Explanation

. Venous outflow obstruction leading to increased intracompartmental pressure and subsequent collapse of the capillary bed

Explanation

Correct Answer: Venous outflow obstruction leading to increased intracompartmental pressure and subsequent collapse of the capillary bedAcute compartment syndrome occurs when increased pressure within a closed fascial space compromises tissue perfusion. The cascade begins with increased tissue pressure (from edema or hematoma) that exceeds venous pressure, leading to venous outflow obstruction. This further increases intracompartmental pressure, eventually exceeding capillary perfusion pressure. This causes capillary collapse and severe tissue ischemia. Arterial inflow is typically maintained until very late stages, which is why distal pulses are usually present even in severe compartment syndrome.

Question 12502

Topic: 2. Trauma

A 32-year-old male sustains a closed, spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture) after an arm-wrestling match. On examination, he has a wrist drop and absent sensation over the dorsal first web space. What is the most appropriate initial management for this patient's neurologic deficit?

. Immediate surgical exploration of the radial nerve and open reduction internal fixation.
. Closed reduction and functional bracing, with observation of the nerve palsy.
. Electromyography (EMG) and nerve conduction studies (NCS) prior to any intervention.
. Application of a long arm cast in 90 degrees of flexion and full supination.
. Immediate magnetic resonance imaging (MRI) of the humerus to evaluate nerve continuity.

Correct Answer & Explanation

. Closed reduction and functional bracing, with observation of the nerve palsy.

Explanation

Correct Answer: BPrimary radial nerve palsy in the setting of a closed humeral shaft fracture is generally treated observationally with closed reduction and functional bracing (e.g., Sarmiento brace). The majority of these injuries (up to 90%) represent neuropraxia or axonotmesis and will recover spontaneously over 3 to 4 months. Immediate surgical exploration is indicated for open fractures, associated vascular injury, or if the nerve palsy developsaftera closed reduction attempt (secondary palsy), which suggests nerve entrapment in the fracture site.

Question 12503

Topic: 2. Trauma

A 24-year-old male sustains a displaced fracture of the proximal pole of the scaphoid. He is counseled regarding the high risk of avascular necrosis and nonunion. The unique vulnerability of the proximal pole is primarily due to the scaphoid's intraosseous blood supply, which classically follows which of the following patterns?

. Enters the proximal pole and flows distally
. Enters the dorsal ridge distally and flows retrogradely
. Enters the volar tubercle and flows distally
. Enters via the scapholunate interosseous ligament and flows laterally
. Enters via the radioscaphocapitate ligament and flows medially

Correct Answer & Explanation

. Enters the dorsal ridge distally and flows retrogradely

Explanation

Correct Answer: Enters the dorsal ridge distally and flows retrogradelyThe scaphoid has a tenuous and unique blood supply that predisposes it to avascular necrosis (AVN) and nonunion, particularly following proximal pole fractures. The primary blood supply (70-80%) comes from the dorsal carpal branch of the radial artery, which enters the scaphoid at the dorsal ridge near the waist and distal pole. From there, the intraosseous blood flow is retrograde (distal to proximal) to supply the proximal pole. A fracture at the waist or proximal pole disrupts this retrograde flow, leaving the proximal fragment ischemic.

Question 12504

Topic: 2. Trauma

A 40-year-old male sustains a high-energy bicondylar tibial plateau fracture. Preoperative computed tomography (CT) reveals a large, displaced posteromedial coronal shear fragment. To achieve direct visualization and apply a buttress plate to this specific fragment, which of the following surgical approaches is most appropriate?

. Anterolateral approach
. Direct medial approach
. Posteromedial approach
. Posterolateral approach
. Anterior midline approach

Correct Answer & Explanation

. Posteromedial approach

Explanation

Correct Answer: Posteromedial approachBicondylar tibial plateau fractures often involve a posteromedial coronal shear fragment (Moore Type I). This fragment cannot be adequately reduced or stabilized via a standard anterolateral approach. A dedicated posteromedial approach is required. This approach typically utilizes the interval between the medial head of the gastrocnemius (which is retracted laterally) and the pes anserinus tendons (which are retracted medially or anteriorly). This allows for direct visualization of the posteromedial cortex and the application of an anti-glide or buttress plate to counteract the deforming shear forces.

Question 12505

Topic: 2. Trauma

A 38-year-old male is admitted after sustaining a high-energy Schatzker type VI tibial plateau fracture. Twelve hours post-injury, he complains of severe, unrelenting leg pain that is out of proportion to the injury and not relieved by intravenous opioids. Passive stretch of the toes elicits excruciating pain. If compartment pressures are measured, which of the following thresholds is most widely accepted as an absolute indication for emergent four-compartment fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 25 mmHg
. Delta pressure (Diastolic blood pressure - Compartment pressure) < 30 mmHg
. Delta pressure (Mean arterial pressure - Compartment pressure) < 40 mmHg
. Delta pressure (Systolic blood pressure - Compartment pressure) < 30 mmHg

Correct Answer & Explanation

. Delta pressure (Diastolic blood pressure - Compartment pressure) < 30 mmHg

Explanation

Correct Answer: C (Delta pressure (Diastolic blood pressure - Compartment pressure) < 30 mmHg)Acute compartment syndrome is a surgical emergency characterized by increased pressure within a closed fascial space, compromising tissue perfusion. While absolute compartment pressures were historically used (e.g., > 30 mmHg), the "delta pressure" is now recognized as a much more accurate and reliable indicator, as it accounts for the patient's systemic perfusion pressure. A delta pressure (Diastolic Blood Pressure minus Compartment Pressure) of less than 30 mmHg is the widely accepted threshold that indicates inadequate capillary perfusion, necessitating emergent fasciotomy to prevent irreversible muscle and nerve necrosis.

Question 12506

Topic: 2. Trauma

A 25-year-old male sustains a closed tibial shaft fracture. Twelve hours post-admission, he develops out-of-proportion leg pain that is exacerbated by passive plantarflexion of the toes. Compartment pressure monitoring indicates an intracompartmental pressure of 45 mmHg in the anterior compartment. Which nerve is most at risk of ischemic injury in this specific compartment?

. Superficial peroneal nerve
. Deep peroneal nerve
. Tibial nerve
. Sural nerve
. Saphenous nerve

Correct Answer & Explanation

. Deep peroneal nerve

Explanation

The anterior compartment of the leg is the most commonly affected in compartment syndrome following tibial shaft fractures. It contains the deep peroneal nerve, which provides motor innervation to the dorsiflexors and sensation to the first dorsal webspace.

Question 12507

Topic: 2. Trauma

A 28-year-old male sustains a displaced talar neck fracture following a high-altitude fall. Eight weeks post-operatively, a subchondral radiolucent band is observed in the talar dome on the AP mortise radiograph. What does this radiographic finding (Hawkins sign) indicate?

. Imminent avascular necrosis
. Osteomyelitis of the talus
. Nonunion of the talar neck
. Intact vascular supply to the talar body
. Chondrolysis of the tibiotalar joint

Correct Answer & Explanation

. Intact vascular supply to the talar body

Explanation

The Hawkins sign is a subchondral radiolucent band in the talar dome indicating subchondral osteopenia. It demonstrates that the talar body has sufficient blood supply to undergo normal disuse osteopenia, making avascular necrosis highly unlikely.

Question 12508

Topic: 2. Trauma

A 21-year-old male presents with anatomic snuffbox tenderness after falling on an outstretched hand. Radiographs reveal a displaced fracture of the proximal pole of the scaphoid. Why is this specific fracture pattern at an exceptionally high risk for nonunion and avascular necrosis?

. It has a robust blood supply that causes rapid hematoma washout
. The blood supply enters distally and flows retrograde to the proximal pole
. The proximal pole is covered entirely by periosteum without articular cartilage
. It relies on the anterior interosseous artery for primary vascularization
. The fracture mechanism typically involves severe volar ligamentous stripping

Correct Answer & Explanation

. The blood supply enters distally and flows retrograde to the proximal pole

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters at the distal pole and flows retrograde. Proximal pole fractures often disrupt this retrograde flow, leading to ischemia of the proximal fragment.

Question 12509

Topic: Pelvic & Acetabular Trauma

A 45-year-old male presents in hemorrhagic shock after a motorcycle crash. Radiographs show a vertical shear pelvic fracture. A pelvic binder is applied, but he remains hypotensive. FAST exam is negative. According to orthopedic trauma guidelines, the source of massive retroperitoneal hemorrhage in pelvic ring disruptions most commonly originates from which of the following?

. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus and cancellous bone
. External iliac artery
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus and cancellous bone

Explanation

While arterial injuries can cause rapid exsanguination, up to 80% of hemorrhage in severe pelvic ring disruptions is venous in origin, primarily arising from the presacral venous plexus and bleeding from fractured cancellous bone.

Question 12510

Topic: 2. Trauma

A 28-year-old male sustains a closed comminuted tibial shaft fracture. Two hours post-injury, he reports severe pain out of proportion to examination. His diastolic blood pressure is 75 mmHg. Compartment pressure testing reveals an anterior compartment pressure of 50 mmHg and a deep posterior compartment pressure of 30 mmHg. Which of the following defines the absolute threshold for diagnosing acute compartment syndrome requiring emergent fasciotomy based on the delta pressure concept?

. Absolute compartment pressure greater than 30 mmHg
. Absolute compartment pressure greater than 40 mmHg
. Diastolic blood pressure minus compartment pressure less than 30 mmHg
. Mean arterial pressure minus compartment pressure less than 30 mmHg
. Systolic blood pressure minus compartment pressure less than 30 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure less than 30 mmHg

Explanation

The delta pressure, calculated as diastolic blood pressure minus the intracompartmental pressure, is the most reliable indicator for acute compartment syndrome. A delta pressure of less than 30 mmHg is an absolute indication for emergent four-compartment fasciotomy.

Question 12511

Topic: 2. Trauma
A 30-year-old male sustains a vertically oriented, displaced femoral neck fracture (Pauwels Type III) in a motor vehicle collision. Which of the following fixation constructs provides the most biomechanically stable environment to resist the high shear forces inherent to this specific fracture pattern?
. Three parallel cancellous lag screws
. A sliding hip screw with a derotation screw
. A cephalomedullary nail
. A dynamic condylar screw
. A modular hemiarthroplasty

Correct Answer & Explanation

. A sliding hip screw with a derotation screw

Explanation

Pauwels Type III femoral neck fractures have a vertical orientation and are subjected to high shear forces, increasing the risk of varus collapse and nonunion. A sliding hip screw, often supplemented with a derotation screw, provides superior biomechanical stability against vertical shear forces compared to multiple cancellous screws.

Question 12512

Topic: 2. Trauma

A 30-year-old male presents with recurrent episodes of lateral knee pain, especially when running or cycling. Examination reveals tenderness over the lateral femoral epicondyle, approximately 2-3 cm proximal to the joint line. Noble's compression test is positive. What is the most likely diagnosis?

. Lateral meniscal tear
. Popliteus tendinitis
. Fibular head fracture
. Iliotibial band friction syndrome (ITBFS)
. Biceps femoris tendinopathy

Correct Answer & Explanation

. Iliotibial band friction syndrome (ITBFS)

Explanation

The patient's presentation of lateral knee pain, especially with repetitive activities like running and cycling, tenderness over the lateral femoral epicondyle (where the ITB crosses), and a positive Noble's compression test (pain elicited with palpation of the ITB over the lateral epicondyle while the knee is flexed to 30 degrees and extended) are classic signs of Iliotibial Band Friction Syndrome (ITBFS). This overuse injury occurs when the distal ITB rubs against the lateral femoral epicondyle. Other options are less likely given the specific location of tenderness and mechanism.

Question 12513

Topic: 2. Trauma

Which of the following is considered an absolute contraindication to closed reduction and percutaneous pinning of a supracondylar humerus fracture in a child?

. Significant swelling and ecchymosis
. Presence of a palpable radial pulse
. Open fracture with skin compromise
. Neuropraxia of the median nerve
. Absence of gross deformity

Correct Answer & Explanation

. Open fracture with skin compromise

Explanation

An open fracture is an absolute contraindication to closed reduction and percutaneous pinning. Open fractures require urgent open reduction, irrigation, and debridement to prevent infection. Significant swelling and ecchymosis, while concerning, are common in these injuries and typically do not preclude closed reduction. A palpable radial pulse is a good sign. Neuropraxia (e.g., median nerve palsy) is common and often resolves with reduction and stabilization; it is not a contraindication to closed reduction. Absence of gross deformity doesn't mean the fracture isn't displaced or unstable.

Question 12514

Topic: 2. Trauma

A 22-year-old male sustains a dislocated hip secondary to a high-energy trauma. After successful closed reduction, what is the most important follow-up imaging study to assess for common complications?

. Repeat plain radiographs immediately post-reduction
. CT scan of the hip and pelvis
. MRI of the hip at 6 weeks post-injury
. Ultrasound of the hip at 2 weeks post-injury
. Bone scan at 3 months post-injury

Correct Answer & Explanation

. CT scan of the hip and pelvis

Explanation

After closed reduction of a traumatic hip dislocation, a CT scan of the hip and pelvis is essential. The most important reason is to evaluate for concentric reduction, identify any incarcerated bone fragments (especially from the femoral head or acetabulum), and assess for occult fractures (e.g., acetabular rim, femoral head impaction fractures) that might not be visible on plain radiographs. Missed fragments can lead to poor outcomes, including post-traumatic arthritis. While repeat radiographs are done immediately post-reduction, they are often insufficient. MRI is used later to assess for avascular necrosis, but not immediately. Ultrasound and bone scans are not primary assessments for acute post-reduction complications.

Question 12515

Topic: 2. Trauma

Which type of nonunion is characterized by a hypertrophic, 'elephant foot' appearance on radiographs, often responding well to biological stimulation without extensive debridement or bone grafting, provided stability is achieved?

. Atrophic nonunion
. Oligotrophic nonunion
. Hypertrophic nonunion
. Pseudoarthrosis
. Infected nonunion

Correct Answer & Explanation

. Hypertrophic nonunion

Explanation

Hypertrophic nonunion is characterized by abundant callus formation at the fracture site, giving it an 'elephant foot' or 'horse hoof' appearance on radiographs, but without bridging bone. This indicates that the fracture has biological activity (sufficient blood supply and cellular response) but lacks mechanical stability. The primary treatment for hypertrophic nonunion is achieving mechanical stability, often through rigid internal fixation (e.g., larger plate, longer nail, external fixation with increased rigidity), sometimes with dynamization. Atrophic nonunion lacks callus and has poor biology. Oligotrophic nonunion has minimal callus. Pseudoarthrosis is a synovial-lined false joint. Infected nonunion has signs of infection.

Question 12516

Topic: 2. Trauma

Which of the following describes the most common classification system for hip fractures?

. Garden classification for femoral neck fractures
. AO/OTA classification for all hip fractures
. Evans classification for intertrochanteric fractures
. Pauwels classification for femoral neck fractures
. All of the above are commonly used for different types of hip fractures.

Correct Answer & Explanation

. All of the above are commonly used for different types of hip fractures.

Explanation

All the listed classifications are commonly used for different types of hip fractures, reflecting the complexity and need for specific guidance depending on the fracture location. Garden classification is specifically for femoral neck fractures (Garden I-IV based on displacement and impaction). Pauwels classification also applies to femoral neck fractures, based on the angle of the fracture line to the horizontal, predicting nonunion risk. Evans classification is used for intertrochanteric fractures, assessing stability. The comprehensive AO/OTA classification system can be applied to all hip fractures, providing detailed morphological descriptions for surgical planning and research.

Question 12517

Topic: 2. Trauma

What is the primary indication for surgical management of a pediatric femoral shaft fracture?

. Any displaced fracture in a child over 6 months of age.
. Children aged 6 months to 5 years with a stable, non-displaced fracture.
. Length discrepancy of less than 1 cm.
. Open fractures or multiple trauma in older children and adolescents.
. Fractures with less than 15 degrees of angulation.

Correct Answer & Explanation

. Open fractures or multiple trauma in older children and adolescents.

Explanation

The primary indication for surgical management of a pediatric femoral shaft fracture, particularly in older children and adolescents, includes open fractures, multiple trauma, and polytrauma where early mobilization is crucial, as well as unstable fractures that cannot be adequately managed with casting or flexible nailing. While specific age cutoffs and displacement criteria influence management, open fractures and polytrauma universally point towards surgical stabilization to facilitate wound care, minimize complications, and aid in overall patient recovery. Young children often undergo casting or flexible nailing. Length discrepancy of less than 1 cm or angulation less than 15 degrees are typically managed non-operatively.

Question 12518

Topic: 2. Trauma

Which of the following is the primary deforming force that causes varus angulation and apex anterior displacement in a midshaft clavicle fracture?

. Sternocleidomastoid muscle pull
. Pectoralis major muscle pull
. Weight of the arm and pull of the deltoid muscle
. Trapezius muscle pull
. Biceps brachii muscle pull

Correct Answer & Explanation

. Weight of the arm and pull of the deltoid muscle

Explanation

In a midshaft clavicle fracture, the weight of the arm (unsupported by the clavicle) and the pull of the deltoid muscle (which originates from the clavicle and inserts onto the humerus) are the primary deforming forces that cause inferior (apex anterior, varus) displacement and shortening of the distal fragment. The sternocleidomastoid pulls the medial fragment superiorly. The pectoralis major and trapezius contribute to maintaining shoulder position but are not the primary cause of inferior displacement of the distal fragment. Biceps brachii is not directly involved in clavicle fracture displacement.

Question 12519

Topic: 2. Trauma

What is the recommended treatment for a traumatic posterior dislocation of the hip in an otherwise healthy 30-year-old male with no associated fractures?

. Open reduction and internal fixation within 24 hours.
. Emergent closed reduction within 6 hours.
. Skeletal traction for 6 weeks.
. Delayed closed reduction after swelling subsides.
. Conservative management with pain medication and immobilization.

Correct Answer & Explanation

. Emergent closed reduction within 6 hours.

Explanation

Traumatic hip dislocations are orthopedic emergencies. The most crucial factor for preventing avascular necrosis (AVN) of the femoral head is prompt reduction. Emergent closed reduction should be attempted as soon as possible, ideally within 6 hours of injury. Delay in reduction significantly increases the risk of AVN. Open reduction is reserved for failed closed reduction or incarcerated fragments. Skeletal traction is not the primary treatment for acute dislocation without fracture. Delayed reduction or conservative management would lead to poor outcomes and high AVN rates.

Question 12520

Topic: 2. Trauma
Which factor is most predictive of persistent instability and the need for surgical stabilization in a patient with a Grade III acromioclavicular (AC) joint separation?
. Patient age over 40 years.
. Disruption of the deltoid and trapezius muscle attachments.
. Associated glenohumeral instability.
. Recreational athlete involved in contact sports.
. Concomitant fracture of the coracoid process.

Correct Answer & Explanation

. Disruption of the deltoid and trapezius muscle attachments.

Explanation

In a Grade III AC joint separation (disruption of AC and coracoclavicular ligaments), the stability is primarily maintained by the deltoid and trapezius muscles. If the fascial attachments of the deltoid and trapezius muscles from the distal clavicle are also significantly disrupted, it can lead to more severe and persistent instability, often manifesting as a 'step-off' deformity and pain, increasing the likelihood of surgical intervention. Patient age, activity level, or associated injuries like coracoid fracture are important but the integrity of the muscle-fascial envelope is a key determinant of stability in Type III injuries and therefore the need for surgery. Grade III AC joint injuries are often managed non-operatively unless there is significant symptomatic instability or patient preference for reduction.

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