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2. Trauma MCQs

Practice Set 579 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 11561

Topic: 2. Trauma

A 24-year-old female is involved in a high-speed motor vehicle collision while wearing a rear-seat lap belt. Radiographs reveal a transverse fracture propagating through the spinous process, pedicles, and vertebral body of L1. Which of the following concomitant injuries is most highly associated with this specific fracture pattern?

. Thoracic aortic tear
. Diaphragmatic rupture
. Intra-abdominal hollow viscus injury
. Renal artery thrombosis
. Unstable pelvic ring disruption

Correct Answer & Explanation

. Intra-abdominal hollow viscus injury

Explanation

A Chance fracture is a flexion-distraction injury strongly associated with lap-belt use in motor vehicle collisions. It has a high association (up to 50%) with intra-abdominal hollow viscus injuries, such as small bowel perforations.

Question 11562

Topic: 2. Trauma

An 80-year-old male sustains a Type II odontoid fracture after a ground-level fall. He is neurologically intact. If this patient is treated conservatively with a rigid cervical orthosis (hard collar), which of the following factors represents the greatest independent risk for fracture nonunion?

. Patient age greater than 50 years
. Initial fracture displacement of 2 mm
. Anterior direction of displacement
. Concomitant C1 posterior arch fracture
. Delay in treatment of 3 days

Correct Answer & Explanation

. Patient age greater than 50 years

Explanation

Risk factors for nonunion of Type II odontoid fractures include patient age > 50 years, initial displacement > 5 mm, posterior displacement, and angulation > 10 degrees. Advanced age is a highly significant, independent predictor of nonunion.

Question 11563

Topic: Lower Extremity Trauma

During a posterior cruciate-retaining TKA, the surgeon enthusiastically resects the posterior aspect of the tibial plateau, accidentally injuring the popliteal artery. Anatomically, at what level relative to the joint line is the popliteal artery positioned closest to the posterior capsule?

. Exactly at the level of the knee joint line
. 1 cm proximal to the joint line
. 1 cm distal to the joint line
. 3 cm proximal to the joint line
. 3 cm distal to the joint line

Correct Answer & Explanation

. Exactly at the level of the knee joint line

Explanation

The popliteal artery lies closest to the posterior capsule directly at the level of the knee joint line. It is tethered proximally by the adductor hiatus and distally by the soleus arch, making it highly susceptible to injury during the tibial cut or overly aggressive posterior capsular releases.

Question 11564

Topic: Lower Extremity Trauma

When planning a medial opening-wedge high tibial osteotomy (HTO) for a 45-year-old male with medial compartment osteoarthritis and varus malalignment, the mechanical axis (weight-bearing line) is typically shifted to pass through a specific target point on the tibial plateau. What is the generally accepted target location (Fujisawa point) measured from the medial edge of the tibial plateau?

. 30%
. 40%
. 50%
. 62.5%
. 80%

Correct Answer & Explanation

. 62.5%

Explanation

The Fujisawa point is the optimal target for the mechanical axis following an HTO for medial compartment osteoarthritis. It is located at 62.5% of the tibial plateau width from the medial edge (slightly lateral to the lateral tibial spine), which moderately unloads the diseased medial compartment by shifting the weight-bearing axis into the healthy lateral compartment.

Question 11565

Topic: Pelvic & Acetabular Trauma
The Bernese periacetabular osteotomy (PAO) is an essential joint-preserving procedure for symptomatic acetabular dysplasia. Which of the following bony structures of the pelvis is intentionally left intact during a standard PAO to maintain the stability of the pelvic ring?
. Anterior column
. Pubic ramus
. Posterior column
. Ischium
. Ilium (supra-acetabular portion)

Correct Answer & Explanation

. Posterior column

Explanation

The Bernese PAO consists of a series of specific bone cuts: an incomplete ischial osteotomy, a complete pubic ramus osteotomy, and a complete supra-acetabular iliac osteotomy (anterior column). The posterior column of the ilium/ischium is intentionally left intact, which preserves the structural continuity of the pelvic ring and allows for immediate postoperative mobilization.

Question 11566

Topic: 2. Trauma

An 82-year-old female sustains a periprosthetic femur fracture around a cemented THA stem 12 years postoperatively. Radiographs demonstrate a fracture around the distal tip of the stem, with severe proximal femoral osteolysis, cortical thinning, and a completely loose implant. There is poor proximal bone stock, but the distal diaphyseal bone is robust. What is the most appropriate definitive management?

. Open reduction internal fixation with a lateral locking plate and cerclage cables
. Revision to a standard uncemented fully porous-coated cylindrical long stem
. Revision to a cemented long stem with cortical strut allografts
. Revision to a modular fluted tapered titanium stem bypassing the fracture by 2 cortical diameters
. Proximal femoral replacement (megaprosthesis)

Correct Answer & Explanation

. Proximal femoral replacement (megaprosthesis)

Explanation

This is a Vancouver B3 periprosthetic fracture: the fracture is around or just distal to the stem (B), the stem is loose (3), and the proximal bone stock is poor/inadequate. While fluted tapered titanium stems are the gold standard for Vancouver B2 fractures (loose stem, good proximal bone stock), Vancouver B3 fractures in elderly, lower-demand patients are optimally treated with a proximal femoral replacement (tumor prosthesis). This allows for immediate weight-bearing and avoids the high complication rates of attempting to bypass massive proximal bone defects with complex allograft-prosthesis composites or standard revision stems in frail patients.

Question 11567

Topic: Lower Extremity Trauma

A 68-year-old male undergoes a primary TKA. During intraoperative trialing, the knee is completely stable in extension but exhibits significant laxity to varus and valgus stress at 90 degrees of flexion. Which of the following steps is the most appropriate next maneuver to balance the knee?

. Upsize the femoral component to increase the anteroposterior dimension
. Recut the distal femur to remove more bone
. Release the posterior cruciate ligament (PCL)
. Downsize the femoral component and use a thicker polyethylene insert
. Increase the posterior slope of the tibial cut

Correct Answer & Explanation

. Upsize the femoral component to increase the anteroposterior dimension

Explanation

Flexion instability (laxity in flexion but stable in extension) implies a flexion gap that is larger than the extension gap. To decrease the flexion gap without altering the extension gap, the surgeon can upsize the femoral component (increasing the posterior condylar offset/AP dimension) and use an offset tibial poly or shift the component posteriorly. Alternatively, translating the same-sized femoral component posteriorly decreases the flexion gap. Recutting the distal femur would increase the extension gap (making it symmetric but overall loose, requiring a thicker poly). Increasing posterior slope increases the flexion gap, worsening the instability.

Question 11568

Topic: 2. Trauma

A 34-year-old polytrauma patient arrives at the emergency department with a severe pelvic ring injury and bilateral femur fractures. The orthopedic team is deciding between early total care (ETC) and damage control orthopedics (DCO). Which of the following physiological parameters most strongly indicates the need for DCO?

. Serum lactate > 2.5 mmol/L
. Core body temperature of 35.5°C
. Arterial pH of 7.35
. Base excess of -2.0 mEq/L
. Systolic blood pressure of 100 mmHg

Correct Answer & Explanation

. Serum lactate > 2.5 mmol/L

Explanation

Damage control orthopedics (DCO) is indicated in unstable or borderline polytrauma patients to prevent a 'second hit' phenomenon from prolonged surgery. According to the Hannover criteria and standard polytrauma protocols, indicators for DCO include a serum lactate > 2.5 mmol/L, base excess < -5.0 mEq/L, pH < 7.24, core temperature < 34°C, and significant coagulopathy. A lactate level > 2.5 mmol/L reflects ongoing hypoperfusion and cellular hypoxia, making ETC contraindicated.

Question 11569

Topic: 2. Trauma
An obtunded 28-year-old man is admitted to the intensive care unit after sustaining severe bilateral tibial plateau fractures. The nursing staff notes extreme tightness in both calves. To accurately diagnose acute compartment syndrome in this unresponsive patient, which of the following objective measurement criteria is considered the most reliable threshold?
. Mean arterial pressure minus compartment pressure < 40 mmHg
. Absolute compartment pressure consistently > 30 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 30 mmHg
. Absolute compartment pressure > 20 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The delta pressure (ΔP) is the most reliable objective criteria for diagnosing acute compartment syndrome, particularly in obtunded or uncooperative patients. It is calculated by subtracting the intracompartmental pressure from the patient's diastolic blood pressure. A ΔP of less than 30 mmHg indicates inadequate tissue perfusion and is the standard threshold to indicate the need for emergent fasciotomy.

Question 11570

Topic: 2. Trauma

An orthopedic surgeon is evaluating different cortical bone screws for the fixation of a diaphyseal fracture. To maximize the pullout strength of the screw within the cortical bone, which of the following dimensional modifications would have the greatest mathematical effect?

. Increasing the inner root diameter
. Decreasing the pitch of the screw threads
. Increasing the outer thread diameter
. Decreasing the outer thread diameter
. Increasing the thread depth

Correct Answer & Explanation

. Increasing the outer thread diameter

Explanation

The pullout strength of a bone screw is directly proportional to its outer thread diameter, the length of thread engagement in the bone, and the shear strength of the surrounding bone. Mathematically, increasing the outer diameter has the most significant direct effect on pullout resistance. Increasing the inner root diameter increases the screw's tensile and torsional strength (resistance to breakage) but does not significantly increase pullout strength.

Question 11571

Topic: 2. Trauma

A 22-year-old male falls onto an outstretched hand and sustains a non-displaced fracture of the proximal pole of the scaphoid. The high risk of avascular necrosis (AVN) in this fracture pattern is due to the unique retrograde blood supply of the scaphoid. The primary blood supply to the scaphoid enters through the dorsal ridge and is a branch of which artery?

. Ulnar artery
. Anterior interosseous artery
. Radial artery
. Deep palmar arch
. Superficial palmar arch

Correct Answer & Explanation

. Radial artery

Explanation

The primary blood supply to the scaphoid is the dorsal carpal branch of the radial artery. It enters the scaphoid at the dorsal ridge (distal half of the bone) and provides blood flow retrogradely to the proximal pole. Fractures at the proximal pole disrupt this retrograde flow, leading to a high incidence of nonunion and avascular necrosis.

Question 11572

Topic: 2. Trauma

A 30-year-old male sustains a comminuted midshaft tibial fracture treated with intramedullary nailing. Postoperatively, he develops severe, unrelenting leg pain exacerbated by passive stretch of the toes. The surgeon suspects acute compartment syndrome and measures intracompartmental pressures. Which of the following pressure measurements (Delta P) is the most widely accepted threshold for urgent 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 < 20 mmHg
. Absolute compartment pressure > 15 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

The standard diagnostic criterion for acute compartment syndrome using continuous or absolute pressure measurements is the 'Delta P'. Delta P is defined as the diastolic blood pressure minus the intracompartmental pressure. A Delta P of less than 30 mmHg (meaning the compartment pressure is within 30 mmHg of the diastolic pressure) indicates inadequate tissue perfusion and is an absolute indication for emergency fasciotomies.

Question 11573

Topic: 2. Trauma
A 28-year-old male is brought to the trauma bay after a motorcycle accident. He has an anteroposterior compression (APC) type III pelvic ring injury. A pelvic binder is appropriately applied, but his systolic blood pressure remains 80 mmHg despite the administration of 2 units of packed red blood cells. A FAST exam is negative. What is the most appropriate next step in management?
. Immediate exploratory laparotomy
. Placement of a supracetabular external fixator and discharge to the ward
. Preperitoneal pelvic packing or pelvic angiography with embolization
. Application of a second pelvic binder
. Observation in the surgical intensive care unit with permissive hypotension

Correct Answer & Explanation

. Preperitoneal pelvic packing or pelvic angiography with embolization

Explanation

In a hemodynamically unstable patient with a pelvic ring fracture and a negative FAST exam (excluding intra-abdominal hemorrhage), the source of bleeding is presumed to be the retroperitoneal venous plexus or pelvic arterial branches. After initial mechanical stabilization (pelvic binder), the next step according to ATLS and orthopedic trauma protocols is preperitoneal pelvic packing (PPP) or pelvic angiography with embolization, depending on institutional availability and protocols.

Question 11574

Topic: 2. Trauma

A 42-year-old male sustains a closed tibia fracture and rapidly develops severe, unrelenting leg pain out of proportion to the injury. Which of the following intracompartmental pressure measurements is widely considered an absolute indication for a 4-compartment fasciotomy?

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

Correct Answer & Explanation

. Delta pressure (Diastolic blood pressure minus compartment pressure) < 30 mmHg

Explanation

The most reliable objective measurement for diagnosing acute compartment syndrome is the delta pressure, defined as the patient's diastolic blood pressure minus the measured intracompartmental pressure. A delta pressure of less than 30 mmHg (meaning the compartment pressure has risen to within 30 mmHg of the diastolic pressure) indicates inadequate tissue perfusion and is a strict indication for emergent fasciotomy.

Question 11575

Topic: 2. Trauma

A 24-year-old male sustains a proximal pole scaphoid fracture. Which of the following descriptions accurately characterizes the unique vascular anatomy of the scaphoid that predisposes this specific fracture pattern to a high rate of avascular necrosis (AVN)?

. The blood supply enters volarly and flows proximal to distal
. The blood supply enters dorsally via the distal pole and flows retrograde (distal to proximal)
. The scaphoid has no direct intraosseous blood supply
. The blood supply enters solely via the scapholunate interosseous ligament
. The proximal pole receives a rich, redundant collateral circulation from the ulnar artery

Correct Answer & Explanation

. The blood supply enters dorsally via the distal pole and flows retrograde (distal to proximal)

Explanation

The primary blood supply to the scaphoid is derived from the dorsal carpal branch of the radial artery. This vessel enters the bone at a ridge near the distal pole and flows in a retrograde fashion (from distal to proximal). Fractures at the proximal pole effectively sever this single retrograde blood supply, leading to a high rate of avascular necrosis and nonunion in the proximal fragment.

Question 11576

Topic: 2. Trauma
A 25-year-old sustains a tibial shaft fracture treated with an intramedullary nail. During the reparative phase of secondary fracture healing, which type of collagen is predominantly synthesized first by chondrocytes in the soft callus?
. Type I
. Type II
. Type III
. Type IX
. Type X

Correct Answer & Explanation

. Type II

Explanation

During secondary bone healing, the soft callus is composed mainly of cartilage, which relies on Type II collagen produced by chondrocytes. As the soft callus mineralizes into a hard callus, it is replaced by Type I collagen.

Question 11577

Topic: 2. Trauma
A 45-year-old male sustains an open tibia fracture. Examination reveals a 12 cm soft tissue laceration with extensive periosteal stripping and exposed bone. Distal pulses are palpable and symmetrical. What is the appropriate Gustilo-Anderson classification?
. Type II
. Type IIIA
. Type IIIB
. Type IIIC
. Type IV

Correct Answer & Explanation

. Type IIIB

Explanation

Gustilo-Anderson Type IIIB involves extensive soft-tissue injury with periosteal stripping and bone exposure, requiring a soft-tissue coverage procedure. The presence of palpable pulses excludes Type IIIC, which necessitates arterial repair.

Question 11578

Topic: 2. Trauma

A 30-year-old male is undergoing assessment for suspected compartment syndrome of the lower leg after a closed tibia fracture. His blood pressure is 120/80 mmHg. Intracompartmental pressure monitoring is performed. Which of the following absolute measurements or delta pressures establishes the diagnosis and indicates the need for urgent fasciotomy?

. Absolute compartment pressure > 20 mmHg
. Absolute compartment pressure > 25 mmHg
. Delta pressure (Diastolic BP - Compartment Pressure) < 30 mmHg
. Delta pressure (Systolic BP - Compartment Pressure) < 30 mmHg
. Delta pressure (Mean Arterial Pressure - Compartment Pressure) < 40 mmHg

Correct Answer & Explanation

. Delta pressure (Diastolic BP - Compartment Pressure) < 30 mmHg

Explanation

Compartment syndrome is a clinical diagnosis, but when utilizing manometry, a delta pressure (diastolic blood pressure minus intracompartmental pressure) of less than 30 mmHg is the most reliable threshold for diagnosing acute compartment syndrome.

Question 11579

Topic: 2. Trauma

Perren's strain theory explains how the mechanical environment influences fracture healing. According to this theory, primary bone healing (direct osteonal remodeling) requires the strain across the fracture gap to be less than which of the following percentages?

. 2%
. 5%
. 10%
. 15%
. 20%

Correct Answer & Explanation

. 2%

Explanation

Perren's strain theory states that primary bone healing can only occur if the strain across the fracture gap is less than 2%. Strains between 2% and 10% promote secondary bone healing via callus formation.

Question 11580

Topic: Pelvic & Acetabular Trauma
A trauma patient arrives with a hemodynamically unstable pelvic ring injury (APC III). A pelvic binder is applied in the emergency department. To effectively close the pelvic ring and reduce pelvic volume, the binder must be centered precisely over which anatomical landmark?
. Anterior superior iliac spines (ASIS)
. Iliac crests
. Greater trochanters
. Pubic symphysis
. Umbilicus

Correct Answer & Explanation

. Greater trochanters

Explanation

For a pelvic binder to effectively reduce pelvic volume and stabilize the bony pelvis, it must be centered over the greater trochanters. Placement higher over the iliac crests can paradoxically open the pelvic ring further.

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