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2. Trauma MCQs

Practice Set 621 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 12401

Topic: 2. Trauma

A 9-year-old boy presents with a mildly painful right shoulder after a minor fall. Radiographs demonstrate a centrally located, completely lytic lesion in the proximal humerus metaphysis with a "fallen leaf" sign. Which of the following is the most appropriate initial management for this lesion if an undisplaced fracture is present?

. Immediate curettage and bone grafting
. En bloc resection
. Immobilization in a sling and observation
. Intralesional injection of methylprednisolone
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Immobilization in a sling and observation

Explanation

The presentation and "fallen leaf" sign are pathognomonic for a simple (unicameral) bone cyst with a pathologic fracture. The initial treatment for an undisplaced pathologic fracture through a UBC is immobilization and observation, as the fracture healing process may spontaneously obliterate the cyst.

Question 12402

Topic: 2. Trauma

When using a bridge plate construct for a comminuted diaphyseal fracture, increasing the 'working length' of the plate will have which of the following biomechanical effects?

. Increase the torsional stiffness of the construct
. Decrease the axial stiffness of the construct
. Decrease the micro-motion at the fracture site
. Increase the risk of plate failure due to stress concentration
. Decrease the elastic deformation of the plate

Correct Answer & Explanation

. Decrease the axial stiffness of the construct

Explanation

The working length is the distance between the two innermost screws on either side of the fracture. Increasing this distance decreases the axial stiffness of the construct, allowing more beneficial micro-motion for secondary bone healing.

Question 12403

Topic: 2. Trauma

In the pathophysiology of acute compartment syndrome, the initial microvascular compromise occurs primarily due to which of the following events?

. Arterial occlusion
. Venous outflow obstruction
. Capillary endothelial damage
. Lymphatic obstruction
. Direct nerve compression

Correct Answer & Explanation

. Venous outflow obstruction

Explanation

As tissue pressure rises within a non-yielding fascial compartment, it first exceeds venous pressure, causing venous outflow obstruction. This leads to further capillary engorgement, fluid extravasation, and a vicious cycle of increasing pressure.

Question 12404

Topic: 2. Trauma

In the pathophysiology of acute compartment syndrome, the earliest critical event leading to tissue ischemia is a decline in which of the following?

. Arterial inflow pressure
. Arteriovenous pressure gradient
. Venous capacitance
. Interstitial fluid oncotic pressure
. Lymphatic drainage capacity

Correct Answer & Explanation

. Arteriovenous pressure gradient

Explanation

The earliest physiologic change in compartment syndrome is an increase in interstitial pressure that collapses the compliant venules. This outflow obstruction increases local venous pressure, which decreases the local arteriovenous (A-V) pressure gradient. A decreased A-V gradient stops capillary perfusion, leading to tissue ischemia, even though arterial pressure remains normal until very late.

Question 12405

Topic: 2. Trauma

A 45-year-old smoker presents with a hypertrophic nonunion of the tibial shaft 9 months after intramedullary nailing. Which of the following is the most appropriate management principle for this type of nonunion?

. Bone grafting alone to provide osteoinduction
. Electrical bone stimulation
. Improving mechanical stability of the construct
. Pulsed electromagnetic field therapy
. Administration of bisphosphonates

Correct Answer & Explanation

. Improving mechanical stability of the construct

Explanation

A hypertrophic nonunion is characterized by abundant callus formation ('elephant shoe' or 'horse hoof' appearance on X-ray) and excellent biological potential (vascularity), but it fails to heal due to excessive mechanical instability. The treatment of choice is improving mechanical stability (e.g., exchange nailing with a larger reamed nail or plating), not bone grafting.

Question 12406

Topic: 2. Trauma

Which of the following represents the primary pathophysiologic mechanism leading to tissue necrosis in acute compartment syndrome?

. Arterial occlusion leading to profound distal ischemia
. Direct mechanical compression of peripheral nerves causing axonal disruption
. Increased interstitial pressure causing a decreased local arteriovenous gradient
. Rupture of intramuscular venules leading to localized hematoma
. Venous thrombosis secondary to hypercoagulability

Correct Answer & Explanation

. Increased interstitial pressure causing a decreased local arteriovenous gradient

Explanation

Acute compartment syndrome occurs when elevated tissue pressure within a closed fascial space reduces capillary perfusion. The increased interstitial pressure decreases the local arteriovenous (AV) gradient, causing capillary collapse and severe tissue ischemia. Major arterial pulses usually remain palpable until late in the process.

Question 12407

Topic: 2. Trauma

When selecting a cortical bone screw for fracture fixation, which of the following design alterations will maximize the biomechanical pullout strength of the screw?

. Increasing inner diameter and increasing thread pitch
. Decreasing outer diameter and decreasing thread pitch
. Increasing outer diameter, decreasing inner diameter, and decreasing thread pitch
. Decreasing outer diameter, increasing inner diameter, and increasing thread pitch
. Increasing both inner and outer diameters equally

Correct Answer & Explanation

. Increasing outer diameter, decreasing inner diameter, and decreasing thread pitch

Explanation

Pullout strength is directly proportional to the formula: (Outer Diameter^2 - Inner Diameter^2) x Thread Length. To maximize pullout strength, the surgeon should select a screw with a larger outer diameter, a smaller inner diameter (increasing thread depth), and a decreased thread pitch (which increases the number of threads engaged per unit length).

Question 12408

Topic: 2. Trauma
During the remodeling phase of tendon healing, which of the following cellular and biochemical changes is most characteristic?
. Peak inflammatory cell infiltration
. Maximum production of Type III collagen
. Replacement of Type III collagen with Type I collagen
. Formation of a fracture hematoma
. Angiogenesis and peak vascularity

Correct Answer & Explanation

. Replacement of Type III collagen with Type I collagen

Explanation

The remodeling phase of tendon healing typically begins at 6 weeks and lasts up to a year. It is characterized by decreased cellularity and the gradual replacement of disorganized Type III collagen with stronger, longitudinally oriented Type I collagen.

Question 12409

Topic: 2. Trauma

A 28-year-old male sustains a closed comminuted tibial shaft fracture. Two hours post-injury, he develops severe pain out of proportion to the injury and pain with passive stretch of his toes. Which of the following objective measurements is the most accepted threshold to indicate the need for an emergent fasciotomy?

. Mean arterial pressure minus compartment pressure < 30 mm Hg
. Diastolic blood pressure minus compartment pressure < 30 mm Hg
. Systolic blood pressure minus compartment pressure < 30 mm Hg
. Absolute compartment pressure > 20 mm Hg
. Absolute compartment pressure > 25 mm Hg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mm Hg

Explanation

The most reliable objective criterion for diagnosing acute compartment syndrome is the delta pressure (Delta P), calculated as the diastolic blood pressure minus the intracompartmental pressure. A Delta P of less than 30 mm Hg is a widely accepted threshold indicating inadequate tissue perfusion, necessitating emergent fasciotomy. Absolute pressure alone (e.g., > 30 mm Hg) is less reliable as it does not account for the patient's systemic blood pressure.

Question 12410

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is struck by a car, sustaining an anteroposterior compression (APC) pelvic ring injury. According to the Young-Burgess classification, which specific ligamentous disruption differentiates an APC Type II injury from a highly unstable APC Type III injury?
. Symphysis pubis disruption
. Sacrotuberous ligament disruption
. Sacrospinous ligament disruption
. Anterior sacroiliac ligament disruption
. Posterior sacroiliac ligament disruption

Correct Answer & Explanation

. Posterior sacroiliac ligament disruption

Explanation

In the Young-Burgess classification, APC injuries involve varying degrees of diastasis of the symphysis pubis. APC II involves disruption of the symphysis, sacrotuberous, sacrospinous, and anterior sacroiliac ligaments, but the posterior sacroiliac ligaments remain intact (opening book injury). An APC III injury is characterized by the additional complete disruption of the posterior sacroiliac ligaments, resulting in complete hemipelvic instability (both rotational and vertical).

Question 12411

Topic: 2. Trauma

A 45-year-old skier sustains a Schatzker II tibial plateau fracture (split depression of the lateral plateau). He undergoes open reduction and internal fixation. During the procedure, the surgeon elevates the depressed articular fragment. What intra-articular pathology is most commonly associated with this specific fracture pattern and must be evaluated intraoperatively?

. Medial meniscus tear
. Lateral meniscus tear
. Anterior cruciate ligament tear
. Posterior cruciate ligament tear
. Popliteal artery avulsion

Correct Answer & Explanation

. Lateral meniscus tear

Explanation

Schatzker II fractures (lateral plateau split-depression) are highly associated with tears of the lateral meniscus. The lateral meniscus is frequently incarcerated within the fracture site or suffers a peripheral tear as the lateral femoral condyle drives into the tibial plateau. The surgeon must carefully inspect the lateral meniscus during arthrotomy or arthroscopy, often needing to elevate it (submeniscal arthrotomy) to visualize the joint surface and subsequently repair it.

Question 12412

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay in hemorrhagic shock following a high-speed motorcycle collision. Pelvic radiographs reveal an anteroposterior compression type III (APC-III) pelvic ring injury. A circumferential pelvic binder is requested. Over which specific anatomic landmark should the binder be centered to be most effective?
. Anterior superior iliac spines
. Iliac crests
. Pubic symphysis
. Sacral promontory
. Greater trochanters

Correct Answer & Explanation

. Greater trochanters

Explanation

To effectively reduce pelvic volume and control venous bleeding in mechanically unstable pelvic ring injuries, a pelvic binder or sheet must be centered directly over the greater trochanters. Placing it higher (e.g., over the iliac crests) can paradoxically distract the pelvic brim.

Question 12413

Topic: 2. Trauma

A 32-year-old male presents 9 months after undergoing intramedullary nailing for a closed tibial shaft fracture. He reports persistent pain with weight-bearing. Radiographs demonstrate an "elephant foot" appearance at the fracture site with abundant bridging callus that fails to cross the fracture gap. What is the most appropriate management?

. Autologous iliac crest bone grafting alone
. Platelet-rich plasma (PRP) injection into the fracture site
. Application of an external bone stimulator
. Exchange intramedullary nailing to a larger diameter nail
. Pulsed electromagnetic field therapy

Correct Answer & Explanation

. Exchange intramedullary nailing to a larger diameter nail

Explanation

An "elephant foot" nonunion is a hypertrophic nonunion, indicating excellent biological healing potential but inadequate mechanical stability. The treatment of choice is optimizing stability, most commonly through exchange nailing to a larger diameter implant.

Question 12414

Topic: 2. Trauma
A 40-year-old agricultural worker sustains an open tibia fracture (Gustilo-Anderson Type IIIA) after his leg is caught in a tractor mechanism. Soil and manure contamination are present. According to established guidelines, what is the most appropriate initial empiric antibiotic regimen?
. Cefazolin monotherapy
. Ceftriaxone and Vancomycin
. Vancomycin monotherapy
. Cefazolin, an aminoglycoside, and Penicillin
. Clindamycin monotherapy

Correct Answer & Explanation

. Cefazolin, an aminoglycoside, and Penicillin

Explanation

For severe open fractures (Type III) in a highly contaminated agricultural setting, standard prophylaxis historically includes a first-generation cephalosporin, an aminoglycoside (for Gram-negative coverage), and Penicillin to cover anaerobic organisms such as Clostridium species.

Question 12415

Topic: 2. Trauma

A 45-year-old smoker presents with a hypertrophic nonunion of the tibial shaft 8 months after intramedullary nailing. Laboratory markers (WBC, ESR, CRP) are normal. What is the most appropriate next step in management?

. Exchange nailing with a larger diameter nail
. Removal of hardware, debridement, and circular frame application
. Plate augmentation leaving the current nail in place
. Bone morphogenetic protein (BMP) injection at the nonunion site
. Pulsed electromagnetic field therapy

Correct Answer & Explanation

. Exchange nailing with a larger diameter nail

Explanation

Hypertrophic nonunions are primarily biologically viable but mechanically unstable. Exchange nailing with a larger diameter nail provides the necessary mechanical stability to allow the already present biologic response to bridge the fracture.

Question 12416

Topic: 2. Trauma

Following a crush injury to the forearm, a patient develops acute compartment syndrome. The fundamental pathophysiologic mechanism leading to muscle necrosis in this condition is primarily driven by an increase in:

. Arterial inflow pressure
. Capillary permeability
. Intracompartmental venous pressure
. Lymphatic drainage
. Arteriovenous shunting

Correct Answer & Explanation

. Intracompartmental venous pressure

Explanation

Acute compartment syndrome is initiated by a rise in tissue pressure that exceeds the local venous pressure. This collapses the venules, halting capillary perfusion, and leading to anoxic muscle necrosis despite continued arterial inflow initially.

Question 12417

Topic: 2. Trauma
A polytrauma patient presents with an anteroposterior compression (APC) type III pelvic ring injury. After pelvic binder application and aggressive fluid resuscitation, the patient remains hemodynamically unstable. FAST exam is negative. What is the most appropriate next step?
. Emergent laparotomy
. Preperitoneal pelvic packing and/or angioembolization
. Application of a definitive external fixator
. Administration of tranexamic acid and observation
. Bilateral internal iliac artery ligation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or angioembolization

Explanation

In a hemodynamically unstable patient with a stabilized pelvic fracture and no other source of bleeding (negative FAST), the primary source of hemorrhage is pelvic retroperitoneal bleeding. Preperitoneal pelvic packing and/or angiography with embolization are the life-saving interventions of choice.

Question 12418

Topic: 2. Trauma

A polytrauma patient arrives hemodynamically unstable with an "open book" anterior-posterior compression (APC) pelvic ring injury. A pelvic binder is ordered. To maximize mechanical reduction of the pelvic volume, over which anatomic landmark should the binder be centered?

. Anterior superior iliac spines (ASIS)
. Iliac crests
. Greater trochanters
. Pubic symphysis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder must be centered directly over the greater trochanters to effectively provide internal rotation forces to the innominate bones. Placing it higher over the ASIS or iliac crests is less effective and can inappropriately flare the pelvis.

Question 12419

Topic: 2. Trauma
A 35-year-old male is brought to the trauma bay after a severe motorcycle crash. He is hemodynamically unstable despite initial fluid resuscitation. A pelvic binder is in place. Radiographs demonstrate an anteroposterior compression (APC) type III pelvic ring injury. A FAST exam is negative. What is the most appropriate next step in acute management?
. CT angiography of the pelvis
. Preperitoneal pelvic packing and/or external fixation
. Exploratory laparotomy
. Removal of the pelvic binder to assess true deformity
. Percutaneous iliosacral screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or external fixation

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST exam, the primary source of bleeding is usually venous or from cancellous bone. Preperitoneal pelvic packing and external fixation provide rapid hemorrhage control.

Question 12420

Topic: 2. Trauma

What is the most reliable clinical indicator for the early diagnosis of acute compartment syndrome in a conscious, alert patient following a tibial shaft fracture?

. Absence of distal pulses
. Pallor of the distal extremity
. Pain out of proportion to the injury and exacerbated by passive stretch
. Paresthesias in the web space
. Motor weakness or paralysis

Correct Answer & Explanation

. Pain out of proportion to the injury and exacerbated by passive stretch

Explanation

The most sensitive and earliest clinical sign of acute compartment syndrome in a conscious patient is pain out of proportion to the apparent injury, which is classically worsened by passive stretching of the muscles in the involved compartment. Pulselessness and paralysis are late signs and usually indicate irreversible ischemic damage.

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