Menu

2. Trauma MCQs

Practice Set 304 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 6061

Topic: 2. Trauma
A 35-year-old patient sustains a vertically oriented femoral neck fracture (Pauwels Type III). From a biomechanical perspective, the use of a sliding hip screw (SHS) with a derotation screw is often favored over three parallel cancellous screws. What is the primary biomechanical advantage of the SHS construct in this specific fracture pattern?
. Greater resistance to anterior-posterior shear forces
. Greater resistance to vertical shear forces
. Increased rotational stability through the barrel
. Prevention of varus collapse by preserving the lateral femoral wall
. Decreased risk of osteonecrosis of the femoral head

Correct Answer & Explanation

. Greater resistance to vertical shear forces

Explanation

Pauwels Type III femoral neck fractures have a fracture angle >50 degrees from the horizontal, leading to high vertical shear forces that predispose to varus collapse and nonunion. Biomechanical studies demonstrate that a fixed-angle device, such as a sliding hip screw (SHS), provides superior resistance to these vertical shear forces compared to three parallel cancellous screws.

Question 6062

Topic: 2. Trauma

A 28-year-old male presents with a closed spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). On initial examination in the emergency department, his neurological exam is completely normal. However, after closed reduction and application of a coaptation splint, he demonstrates a profound, new-onset inability to actively extend his wrist and fingers. What is the most appropriate next step in management?

. Reassure the patient and observe the nerve function for 3 months
. Perform an urgent MRI of the humerus to evaluate the nerve
. Surgical exploration of the radial nerve and internal fixation of the fracture
. Order baseline electromyography (EMG) to establish the level of injury
. Adjust the splint to relieve pressure and re-examine in 24 hours

Correct Answer & Explanation

. Surgical exploration of the radial nerve and internal fixation of the fracture

Explanation

A primary radial nerve palsy present at the time of injury with a closed humeral shaft fracture is generally managed with observation. However, a secondary radial nerve palsy that developsafterclosed reduction maneuvers is a classic, absolute indication for surgical exploration of the nerve. The nerve may be entrapped between the fracture fragments or lacerated, requiring immediate release and stable fracture fixation.

Question 6063

Topic: Pelvic & Acetabular Trauma

A 4-year-old girl is diagnosed with neglected left developmental dysplasia of the hip. She is scheduled for an open reduction, femoral shortening osteotomy, and a Dega pelvic osteotomy. Which of the following correctly describes the anatomical cuts of a Dega osteotomy?

. Complete trans-iliac osteotomy extending into the greater sciatic notch
. Incomplete trans-iliac osteotomy leaving the inner cortex and sciatic notch intact
. Osteotomies through the ilium, ischium, and pubis to allow free rotation
. Complete osteotomy of the ilium immediately above the acetabulum
. Dome-shaped osteotomy extending just superior to the joint capsule

Correct Answer & Explanation

. Incomplete trans-iliac osteotomy leaving the inner cortex and sciatic notch intact

Explanation

The Dega osteotomy is an incomplete trans-iliac pelvic osteotomy. The outer table is cut, but the inner table and the greater sciatic notch are left intact to act as a posterior hinge. This allows the acetabulum to be hinged downward, providing anterior, lateral, and posterior coverage.

Question 6064

Topic: Pelvic & Acetabular Trauma
A 30-year-old male sustains an APC-III pelvic ring injury in a motorcycle accident. He is hemodynamically unstable despite initial fluid resuscitation. A pelvic binder is applied, but he remains hypotensive. FAST exam is negative. What is the most appropriate next step in management?
. Immediate exploratory laparotomy
. Pre-peritoneal pelvic packing and/or angioembolization
. Application of a REBOA in Zone 1
. Application of an external fixator and transfer to the ICU
. Immediate open reduction and internal fixation of the symphysis pubis

Correct Answer & Explanation

. Pre-peritoneal pelvic packing and/or angioembolization

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, the source of bleeding is presumed retroperitoneal (venous or arterial). Pre-peritoneal pelvic packing (PPP) and/or pelvic angiography with embolization are the mainstays of controlling retroperitoneal pelvic hemorrhage. Laparotomy releases the tamponade effect and is contraindicated for isolated retroperitoneal bleeding.

Question 6065

Topic: 2. Trauma

A 40-year-old male sustains a coronal plane fracture of the lateral femoral condyle (Hoffa fracture). Which surgical approach and fixation trajectory provides the most biomechanically stable construct for this specific fracture pattern?

. Medial parapatellar approach with anterior-to-posterior lag screws
. Lateral parapatellar approach with anterior-to-posterior lag screws
. Lateral approach allowing posterior-to-anterior directed lag screws
. Direct anterior approach with an anterior neutralization plate
. Medial approach with fully threaded positioning screws

Correct Answer & Explanation

. Lateral approach allowing posterior-to-anterior directed lag screws

Explanation

Hoffa fractures are coronal shear fractures. Biomechanical studies demonstrate that posterior-to-anterior directed lag screws placed perpendicular to the fracture plane offer superior stability compared to anterior-to-posterior screws. A direct lateral or swashbuckler approach allows optimal posterior access to the lateral condyle for this trajectory.

Question 6066

Topic: 2. Trauma

Scapulothoracic dissociation is a devastating high-energy injury characterized by complete disruption of the scapulothoracic articulation. What is the most important determinant of long-term limb survival and overall functional prognosis in these patients?

. The degree of lateral displacement of the scapula on the chest radiograph
. The presence of a concomitant clavicle or sternoclavicular joint fracture
. The severity of the associated brachial plexus injury
. The timing of open reduction and internal fixation of the scapula
. The presence of a subclavian or axillary artery disruption

Correct Answer & Explanation

. The severity of the associated brachial plexus injury

Explanation

Scapulothoracic dissociation is essentially a closed forequarter amputation. While subclavian/axillary vascular injuries can be acutely life-threatening and require emergency repair, the ultimate functional survival and prognosis of the limb are dictated by the brachial plexus injury. Complete avulsions result in a flail, insensate limb that frequently requires eventual amputation.

Question 6067

Topic: 2. Trauma

Which of the following statements best describes the primary pathophysiologic mechanism leading to tissue ischemia in acute compartment syndrome?

. A decrease in the local arteriovenous pressure gradient leading to collapse of venules and cessation of capillary perfusion
. Direct mechanical arterial occlusion secondary to high compartment pressures exceeding systolic blood pressure
. Lymphatic obstruction resulting in massive toxic metabolite accumulation and cellular apoptosis
. Venous hypertension leading directly to large-vessel arterial spasm
. Direct mechanical compression of the peripheral nerves and motor endplates

Correct Answer & Explanation

. A decrease in the local arteriovenous pressure gradient leading to collapse of venules and cessation of capillary perfusion

Explanation

The pathophysiology of compartment syndrome is based on the arteriovenous (AV) gradient theory. As tissue pressure increases within a closed fascial space, it exceeds the venous pressure. This collapses the thin-walled venules, causing venous hypertension, which in turn decreases the local AV pressure gradient. When the gradient drops below a critical threshold, capillary perfusion ceases, leading to tissue ischemia well before arterial systolic occlusion occurs.

Question 6068

Topic: 2. Trauma
A 30-year-old patient sustains a displaced intracapsular femoral neck fracture oriented at an angle of 75 degrees to the horizontal (Pauwels type III). The surgeon aims to optimize the biomechanical stability of the construct to prevent varus collapse. Which of the following fixation constructs provides the highest biomechanical resistance to the high shear forces inherent in this fracture pattern?
. Three parallel cancellous screws in an inverted triangle configuration
. A dynamic hip screw (DHS) combined with a derotation screw
. Three parallel cancellous screws in a standard triangle configuration
. A standard short cephalomedullary nail without a derotation screw
. Two parallel fully threaded cortical screws

Correct Answer & Explanation

. A dynamic hip screw (DHS) combined with a derotation screw

Explanation

Pauwels type III femoral neck fractures are highly vertical and experience massive shear forces, leading to high rates of varus collapse and nonunion when fixed with standard cancellous screws. Biomechanical studies have demonstrated that a fixed-angle device, such as a Dynamic Hip Screw (DHS), paired with an anti-rotation screw, provides superior construct stiffness and resistance to vertical shear compared to multiple cancellous screws.

Question 6069

Topic: 2. Trauma

According to Hertel's criteria, which of the following anatomic fracture characteristics is the strongest predictor of ischemia and subsequent avascular necrosis of the humeral head in proximal humerus fractures?

. Metaphyseal head extension less than 8 mm
. Intact medial hinge
. Medial calcar length greater than 15 mm
. Surgical neck fracture with 1 cm of translation
. Greater tuberosity displacement of 5 mm

Correct Answer & Explanation

. Metaphyseal head extension less than 8 mm

Explanation

Hertel described specific radiographic criteria that predict ischemia of the humeral head following proximal humerus fractures. The strongest predictors include a metaphyseal head extension (the length of the calcar attached to the articular segment) of less than 8 mm, disruption of the medial hinge, and a basicervical/anatomic neck fracture line. An intact medial hinge is protective.

Question 6070

Topic: 2. Trauma

A 35-year-old unrestrained driver sustains a highly comminuted distal femur fracture, including a coronal plane fracture of the lateral femoral condyle (Hoffa fracture). Which of the following muscle groups exerts a deforming force that typically displaces the lateral Hoffa fragment posteriorly and inferiorly?

. Biceps femoris
. Quadriceps femoris
. Popliteus and lateral gastrocnemius
. Soleus
. Plantaris alone

Correct Answer & Explanation

. Popliteus and lateral gastrocnemius

Explanation

A Hoffa fracture is a coronal shear fracture of the femoral condyle, most commonly involving the lateral condyle. The lateral head of the gastrocnemius and the popliteus tendon attach to the posterior and lateral aspects of the lateral femoral condyle. Their origin on the fragment creates a deforming force that pulls the lateral Hoffa fragment posteriorly and inferiorly, necessitating secure internal fixation (often with AP or PA lag screws).

Question 6071

Topic: 2. Trauma

A 22-year-old elite soccer player presents with acute lateral foot pain after an inversion injury. Radiographs show a fracture at the base of the fifth metatarsal. To be accurately classified as a true 'Jones fracture' (Zone 2), the fracture line must anatomically involve which of the following regions?

. Avulsion of the tuberosity of the fifth metatarsal
. Fracture through the metaphyseal-diaphyseal junction involving the fourth-fifth intermetatarsal articulation
. Fracture of the distal diaphysis of the fifth metatarsal
. Fracture of the base of the first metatarsal
. Stress fracture of the fifth metatarsal neck

Correct Answer & Explanation

. Fracture through the metaphyseal-diaphyseal junction involving the fourth-fifth intermetatarsal articulation

Explanation

Fractures of the proximal fifth metatarsal are divided into three zones. Zone 1 is a pseudo-Jones fracture, an avulsion at the tuberosity involving the peroneus brevis and plantar fascia. Zone 2 is a true Jones fracture, which occurs at the metaphyseal-diaphyseal junction and intra-articularly extends into the fourth-fifth intermetatarsal articulation. Zone 3 is a proximal diaphyseal stress fracture. Zone 2 and 3 fractures have a high risk of nonunion due to an interosseous watershed blood supply.

Question 6072

Topic: 2. Trauma
A 28-year-old male is evaluated for acute compartment syndrome following a high-energy tibial plateau fracture. Clinical examination is equivocal, so intra-compartmental pressure monitoring is performed. Which of the following thresholds is universally considered the most reliable indicator for emergent fasciotomy?
. Diastolic BP minus Systolic BP < 30 mmHg
. Systolic BP minus Compartment Pressure < 30 mmHg
. Mean Arterial Pressure minus Compartment Pressure < 30 mmHg
. Diastolic BP minus Compartment Pressure < 30 mmHg
. Compartment Pressure greater than Systolic BP

Correct Answer & Explanation

. Diastolic BP minus Compartment Pressure < 30 mmHg

Explanation

The diagnosis of acute compartment syndrome using continuous or absolute pressure measurements has largely been replaced by the concept of 'delta P' (ΔP). Delta P is calculated as the Diastolic Blood Pressure minus the Intra-compartmental Pressure. A ΔP of less than 30 mmHg indicates inadequate capillary perfusion pressure, signifying tissue ischemia, and is an absolute indication for emergent fasciotomy.

Question 6073

Topic: Pelvic & Acetabular Trauma

In the acute management of a hemodynamically unstable patient with an anterior-posterior compression (APC) pelvic ring injury, what is the correct anatomic landmark for the placement of a circumferential pelvic sheet or binder?

. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Pubic symphysis
. Femoral shafts

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder or sheet must be placed at the level of the greater trochanters to effectively reduce the pelvic volume and close an 'open book' pelvis. Placement over the iliac crests is less mechanically effective and may paradoxically open the pelvis further or cause dangerous abdominal compression.

Question 6074

Topic: 2. Trauma

An 82-year-old male sustains a Type II odontoid fracture after a low-energy ground-level fall. He is neurologically intact. When discussing non-operative vs. operative management, what is the most significant concern regarding the use of a halo vest immobilizer in this specific patient demographic?

. Increased risk of nonunion compared to a rigid cervical collar
. High rate of pin site infection requiring IV antibiotics
. Significantly increased risk of mortality and severe morbidity
. Inability to achieve adequate fracture reduction
. Increased risk of delayed neurological deficit

Correct Answer & Explanation

. Significantly increased risk of mortality and severe morbidity

Explanation

The use of a halo vest in the elderly (generally >65, and especially >80 years old) is associated with high rates of morbidity (pneumonia, respiratory distress, dysphagia) and significantly increased mortality compared to rigid cervical collars or surgical fixation. Therefore, its use is largely contraindicated in this demographic.

Question 6075

Topic: 2. Trauma

A 34-year-old male presents with a closed spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). On initial examination, he has an intact radial nerve. Following a closed reduction maneuver and application of a coaptation splint, he develops a complete radial nerve palsy. What is the most appropriate next step in management?

. Immediate surgical exploration and fixation
. Observation with serial clinical exams for 3 months
. Electromyography (EMG) and nerve conduction studies (NCS)
. Switch the coaptation splint to a functional brace
. Administration of high-dose systemic corticosteroids

Correct Answer & Explanation

. Immediate surgical exploration and fixation

Explanation

A secondary (post-reduction) radial nerve palsy in the setting of a humeral shaft fracture is a widely accepted absolute indication for immediate surgical exploration. The primary concern is that the nerve may have become entrapped between the fracture fragments during the reduction.

Question 6076

Topic: 2. Trauma

In the pathophysiology of acute compartment syndrome, the initial microvascular event that initiates the cascade toward ischemic necrosis of muscle is a critical reduction in which of the following pressures?

. Arteriolar pressure
. Capillary perfusion pressure
. Venous outflow pressure
. Lymphatic drainage pressure
. Mean arterial pressure

Correct Answer & Explanation

. Capillary perfusion pressure

Explanation

Compartment syndrome occurs when increased tissue pressure within a closed fascial space compromises local circulation. The initial event is that tissue fluid pressure rises above capillary perfusion pressure (or venous pressure, thereby backing up the capillary bed). This leads to capillary collapse, hypoxia, and a vicious cycle of further edema and muscle necrosis.

Question 6077

Topic: Lower Extremity Trauma

A 24-year-old elite skier presents with lateral ankle pain and a snapping sensation behind the lateral malleolus. Physical examination confirms subluxation of the peroneal tendons with resisted eversion and dorsiflexion. Which anatomical structure is primarily responsible for preventing this condition, and is likely deficient or torn?

. Calcaneofibular ligament
. Superior peroneal retinaculum
. Inferior peroneal retinaculum
. Anterior talofibular ligament
. Peroneus brevis tendon sheath

Correct Answer & Explanation

. Superior peroneal retinaculum

Explanation

The superior peroneal retinaculum (SPR) is the primary static restraint to subluxation and dislocation of the peroneal tendons out of the retromalleolar groove. Disruption, stripping, or avulsion (e.g., 'fleck sign') of the SPR is the hallmark of peroneal tendon instability.

Question 6078

Topic: Pelvic & Acetabular Trauma
Anterior posterior compression type III (APC-III) pelvic ring injuries involve complete disruption of the symphysis pubis. Which posterior ligamentous structures are disrupted in an APC-III injury?
. Sacrospinous ligament only
. Sacrotuberous ligament only
. Anterior sacroiliac ligaments only
. Anterior sacroiliac, posterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Iliolumbar ligaments only

Correct Answer & Explanation

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

Explanation

According to the Young-Burgess classification, an APC-III pelvic ring injury is a highly unstable 'open book' injury characterized by disruption of the symphysis pubis anteriorly and complete disruption of the posterior arch globally. This includes tearing of the anterior sacroiliac, interosseous sacroiliac, and posterior sacroiliac ligaments, as well as the sacrotuberous and sacrospinous ligaments, leading to complete spinopelvic dissociation on the affected side.

Question 6079

Topic: 2. Trauma

When assessing a complex proximal humerus fracture for the risk of avascular necrosis (AVN), which of the following Hertel radiographic criteria is considered the most reliable predictor of subsequent humeral head ischemia?

. Calcar length less than 5 mm
. Length of the dorsomedial metaphyseal head extension less than 8 mm
. Medial hinge displacement greater than 2 mm
. Greater tuberosity displacement greater than 5 mm
. Head-shaft angle less than 100 degrees

Correct Answer & Explanation

. Length of the dorsomedial metaphyseal head extension less than 8 mm

Explanation

Hertel et al. defined several criteria that predict ischemia of the humeral head following proximal humerus fractures. The most highly predictive factors include a lack of medial metaphyseal head extension (calcar length < 8 mm attached to the articular segment), disruption of the medial hinge (> 2 mm displacement), and an anatomical neck fracture pattern. 'Length of the dorsomedial metaphyseal extension less than 8 mm' is a key indicator that the arcuate artery blood supply has likely been compromised.

Question 6080

Topic: 2. Trauma

A 40-year-old male sustains a Schatzker IV tibial plateau fracture. Which of the following best describes the typical pathological mechanism of this specific injury pattern and its most feared associated complication?

. Valgus force causing a lateral plateau split; Lateral meniscal tear
. Valgus force causing a lateral plateau split-depression; Anterior compartment syndrome
. Axial load causing pure central depression; Posterior cruciate ligament rupture
. Varus force causing a medial plateau fracture; Popliteal artery and peroneal nerve injury due to subluxation
. Axial load causing bicondylar fracture; Deep vein thrombosis

Correct Answer & Explanation

. Varus force causing a medial plateau fracture; Popliteal artery and peroneal nerve injury due to subluxation

Explanation

A Schatzker IV fracture involves the medial tibial plateau. It typically results from a high-energy varus and axial loading force. Because the medial plateau is dense and strong, this fracture often represents a variant of a knee fracture-dislocation. Consequently, the proximal tibia may subluxate or dislocate, placing traction and shear on the popliteal artery and the common peroneal nerve. A thorough vascular examination (often including ABI or CT angiogram) is mandatory.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page