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2. Trauma MCQs

Practice Set 422 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 8421

Topic: 2. Trauma
A 25-year-old male sustains a high-energy trauma resulting in a vertically oriented femoral neck fracture (Pauwels Type III). What biomechanical construct provides the most superior fixation to resist the high shear forces in this fracture pattern?
. Sliding hip screw with an anti-rotation screw
. Three parallel partially threaded cancellous screws
. Proximal femoral locking plate
. Dynamic condylar screw
. Fully threaded parallel cancellous screws

Correct Answer & Explanation

. Sliding hip screw with an anti-rotation screw

Explanation

Pauwels Type III femoral neck fractures are highly vertical and inherently unstable, subjected to high shear forces. Biomechanical studies have demonstrated that a fixed-angle construct, such as a sliding hip screw (with an anti-rotation screw to control rotational forces), provides superior stability and higher load-to-failure compared to three parallel cancellous screws in these vertical fracture patterns.

Question 8422

Topic: 2. Trauma

A 30-year-old female sustains a Hawkins Type II talar neck fracture in a motor vehicle collision and undergoes timely open reduction and internal fixation. At the 8-week postoperative follow-up, an anteroposterior mortise radiograph reveals a subchondral radiolucent band in the dome of the talus. What is the clinical significance of this radiographic finding?

. It is an early sign of post-traumatic osteoarthritis.
. It represents an impending nonunion of the talar neck.
. It indicates early osteonecrosis of the talar body.
. It confirms the presence of intact vascularity to the talar body.
. It is indicative of a deep postoperative infection.

Correct Answer & Explanation

. It confirms the presence of intact vascularity to the talar body.

Explanation

The presence of a subchondral radiolucent band in the dome of the talus at 6 to 8 weeks post-injury is known as the Hawkins sign. It represents subchondral osteopenia secondary to disuse. Because bone resorption requires an active blood supply, the presence of the Hawkins sign is a highly reliable indicator that the vascularity to the talar body is intact, making osteonecrosis highly unlikely.

Question 8423

Topic: 2. Trauma

A 28-year-old male falls and sustains a closed middle-third humeral shaft fracture. In the emergency department, he is noted to have a complete inability to extend his wrist and fingers, with intact triceps function. A closed reduction is performed and a coaptation splint is applied. Post-reduction examination reveals the neurologic deficit is completely unchanged. What is the most appropriate next step in management?

. Immediate surgical exploration of the radial nerve
. Electromyography (EMG) and nerve conduction studies today
. Magnetic resonance imaging (MRI) of the humerus
. Observation and supportive care with a resting splint
. Corticosteroid injection into the spiral groove

Correct Answer & Explanation

. Observation and supportive care with a resting splint

Explanation

Primary radial nerve palsy associated with a closed humeral shaft fracture is typically a neurapraxia that spontaneously resolves in 70% to 90% of cases. The standard of care is observation and supportive management (e.g., a dynamic splint to prevent contractures). Immediate surgical exploration is generally not indicated for primary palsy unless it is an open fracture, there is a vascular injury, or if the palsy occurs secondary to (after) closed reduction (though even this is debated, observation remains standard for unchanged primary palsies). EMG is not useful until 3 to 6 weeks post-injury.

Question 8424

Topic: 2. Trauma
A 40-year-old farmer sustains an open tibial shaft fracture (Gustilo-Anderson IIIA) after his leg is pinned under a tractor in a muddy field. In addition to thorough surgical debridement, which of the following intravenous antibiotic regimens is most appropriate for initial management?
. First-generation cephalosporin alone
. First-generation cephalosporin and a fluoroquinolone
. Vancomycin and a third-generation cephalosporin
. Fluoroquinolone alone
. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin

Correct Answer & Explanation

. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin

Explanation

Open fractures occurring in heavily contaminated environments, such as farms or muddy fields, carry a significant risk for anaerobic infections, particularly Clostridium species. The standard antibiotic prophylaxis for Gustilo-Anderson Type III open fractures includes a first-generation cephalosporin (for Gram-positive coverage) and an aminoglycoside (for Gram-negative coverage). High-dose penicillin must be added specifically for anaerobic coverage in the setting of farm or soil contamination.

Question 8425

Topic: 2. Trauma

A 22-year-old male sustains a low-velocity gunshot wound to the thigh resulting in a comminuted midshaft femur fracture. The bullet is lodged in the vastus lateralis. There is no expanding hematoma, and distal pulses are palpable and symmetric. Which of the following is the standard orthopedic management of the retained bullet in this scenario?

. Immediate operative extraction of the bullet to prevent lead toxicity
. Surgical debridement of the entire bullet tract before fixation
. Leave the bullet in situ and proceed with intramedullary nailing of the femur
. Application of an external fixator and delayed extraction of the bullet
. Excision of the bullet and placement of a local antibiotic spacer

Correct Answer & Explanation

. Leave the bullet in situ and proceed with intramedullary nailing of the femur

Explanation

For low-velocity gunshot wounds resulting in extra-articular long bone fractures, the heat generated by the bullet does not sterilize it, but routine bullet extraction and formal tract debridement are not required unless the bullet is intra-articular, within the spinal canal causing neurologic deficit, or causing mechanical block/vascular impingement. Standard treatment is local wound care, appropriate antibiotics, and standard internal fixation (such as intramedullary nailing for a femur fracture). Lead toxicity is exceedingly rare with extra-articular bullets in soft tissue.

Question 8426

Topic: 2. Trauma

A 45-year-old construction worker falls from a height, sustaining a high-energy closed Pilon fracture. He has tense swelling and hemorrhagic fracture blisters over the ankle. A spanning external fixator is applied on the day of injury. What is the most reliable clinical indicator that the soft tissues have recovered sufficiently to proceed with definitive open reduction and internal fixation?

. Normalization of the erythrocyte sedimentation rate (ESR)
. Re-epithelialization of all hemorrhagic fracture blisters
. A decrease in the patient's pain visual analog score to less than 3
. Return of skin wrinkles indicating decreased interstitial edema
. Exactly 14 days passing since the initial injury

Correct Answer & Explanation

. Return of skin wrinkles indicating decreased interstitial edema

Explanation

The timing of definitive fixation for high-energy Pilon fractures is dictated by the condition of the soft tissues to minimize the high risk of wound breakdown and deep infection. The most reliable clinical indicator that interstitial edema has resolved sufficiently to safely make surgical incisions is the return of skin creases or the 'wrinkle sign'. This typically occurs between 10 to 21 days post-injury.

Question 8427

Topic: 2. Trauma
A 30-year-old male is brought to the trauma bay after a severe motorcycle collision. His blood pressure is 70/40 mmHg and heart rate is 135 bpm. A pelvic radiograph shows an Anteroposterior Compression (APC-III) pelvic ring injury. A pelvic binder is appropriately applied, and he receives 2 units of uncrossmatched packed red blood cells, but remains hemodynamically unstable. A FAST (Focused Assessment with Sonography for Trauma) exam is negative. What is the most appropriate next step in management?
. Immediate open reduction and internal fixation of the symphysis pubis
. Application of a supra-acetabular pelvic external fixator in the ED
. Exploratory laparotomy to search for bowel injury
. Preperitoneal pelvic packing and/or pelvic angiography with embolization
. Computed tomography (CT) scan of the abdomen and pelvis

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angiography with embolization

Explanation

In a hemodynamically unstable patient with a pelvic fracture, the initial step is closing the pelvic volume (e.g., pelvic binder), which has already been done. If the patient remains unstable and the FAST exam is negative (ruling out massive intraperitoneal hemorrhage), the source of bleeding is presumed to be the retroperitoneal venous plexus or pelvic arterial injury. The next mandatory step is preperitoneal pelvic packing and/or pelvic angiography. CT is contraindicated in hemodynamically unstable patients.

Question 8428

Topic: 2. Trauma

A 35-year-old skier sustains a high-energy Schatzker VI tibial plateau fracture. Twelve hours post-injury, he complains of severe leg pain out of proportion to the injury. Examination reveals intense pain with passive stretch of the hallux and diminished sensation in the first web space. His diastolic blood pressure is 65 mmHg. Compartment pressures are measured: Anterior 45 mmHg, Lateral 30 mmHg, Deep Posterior 25 mmHg, Superficial Posterior 20 mmHg. What is the most appropriate next step in management?

. Elevation of the leg strictly above heart level and application of ice
. Intravenous administration of mannitol and dexamethasone
. Application of a spanning external fixator and serial exams
. Reassessment of compartment pressures in 4 hours
. Immediate four-compartment fasciotomy of the leg

Correct Answer & Explanation

. Immediate four-compartment fasciotomy of the leg

Explanation

This patient has classic clinical signs of acute compartment syndrome (pain out of proportion, pain with passive stretch, and paresthesias in the deep peroneal nerve distribution). The diagnosis is confirmed objectively using the Delta P (Diastolic BP - Compartment Pressure). A Delta P of less than 30 mmHg is the accepted threshold for fasciotomy. Here, Delta P = 65 - 45 = 20 mmHg in the anterior compartment. Immediate four-compartment fasciotomy is required. Elevation above the heart is contraindicated as it further decreases arterial perfusion pressure to the compartment.

Question 8429

Topic: 2. Trauma

A 25-year-old man sustains a displaced basicervical femoral neck fracture following a motorcycle collision. He is otherwise healthy and is scheduled for surgical intervention. Which of the following biomechanical constructs provides the most stable fixation and is the preferred implant choice for this specific fracture pattern?

. Three parallel cancellous screws
. Sliding hip screw with a derotation screw
. Unipolar hemiarthroplasty
. Total hip arthroplasty
. Cannulated screws in an inverted triangle configuration

Correct Answer & Explanation

. Sliding hip screw with a derotation screw

Explanation

Basicervical femoral neck fractures are biomechanically distinct from subcapital fractures, behaving more like intertrochanteric fractures due to high shear forces. Fixation with cancellous screws alone has an unacceptably high rate of failure. A sliding hip screw (with or without a derotation screw) or a cephalomedullary nail provides superior biomechanical stability and is the standard of care.

Question 8430

Topic: 2. Trauma

A 30-year-old man sustains a closed spiral fracture of the distal third of his humerus (Holstein-Lewis fracture) during an arm-wrestling match. On presentation in the emergency department, he is unable to extend his wrist or fingers, and has numbness in the first dorsal web space. What is the most appropriate initial management of this nerve palsy?

. Immediate surgical exploration of the nerve and internal fixation
. Electromyography (EMG) and nerve conduction studies
. Closed reduction, coaptation splinting, and clinical observation
. Surgical exploration of the nerve without fracture fixation
. Immediate tendon transfers

Correct Answer & Explanation

. Closed reduction, coaptation splinting, and clinical observation

Explanation

The initial management for a closed humeral shaft fracture with a primary radial nerve palsy is conservative. The vast majority of these injuries represent neuropraxia (usually due to nerve tethering at the lateral intermuscular septum) and resolve spontaneously within 3 to 4 months. Surgical exploration is indicated for open fractures, secondary nerve palsies (developing after closed reduction), or failure to recover clinically or electrodiagnostically after 3 to 4 months.

Question 8431

Topic: 2. Trauma
A 40-year-old construction worker sustains a severe crush injury resulting in an open tibia fracture with a 12 cm wound, extensive periosteal stripping, and massive soft tissue loss requiring a free tissue transfer (Gustilo-Anderson IIIB). According to current evidence-based guidelines, what is the single most critical factor in reducing his risk of deep surgical site infection?
. Time to initial surgical debridement strictly within 6 hours
. Administration of systemic antibiotics within 1 hour of the injury
. Use of high-pressure pulsatile lavage
. Primary closure of the wound at the initial surgery
. Use of local antibiotic-impregnated polymethylmethacrylate (PMMA) beads alone

Correct Answer & Explanation

. Administration of systemic antibiotics within 1 hour of the injury

Explanation

In the management of open fractures, the most critical factor for reducing the infection rate is the early administration of appropriate systemic antibiotics, ideally within 1 hour of injury. While prompt surgical debridement is essential, modern literature does not support a rigid '6-hour rule' as an independent predictor of infection, provided antibiotics are administered promptly.

Question 8432

Topic: Pelvic & Acetabular Trauma

A 28-year-old man is struck by a car and sustains an anteroposterior compression type II (APC-II) pelvic ring injury. He is hemodynamically stable. Fluoroscopic examination under anesthesia demonstrates 3 cm of symphyseal diastasis and widening of the anterior sacroiliac joints. Which of the following ligaments must be disrupted to produce this specific injury pattern?

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Posterior sacroiliac ligaments only
. Iliolumbar ligament
. Posterior sacroiliac and iliolumbar ligaments
. Sacrotuberous ligament only

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

An APC-II pelvic ring injury ('open book' pelvis) involves disruption of the symphysis pubis (or anterior rami) along with the anterior sacroiliac ligaments, sacrotuberous ligaments, and sacrospinous ligaments. The posterior sacroiliac ligaments remain intact, which preserves vertical stability while allowing rotational instability.

Question 8433

Topic: 2. Trauma

A 45-year-old man presents after a high-speed motor vehicle collision with a right-sided posterior hip dislocation and a posterior wall acetabular fracture. Following closed reduction of the hip, a computed tomography (CT) scan shows a posterior wall fragment comprising 45% of the posterior articular surface and a 5 mm intra-articular step-off due to marginal impaction. What is the most appropriate definitive management?

. Closed reduction and skeletal traction for 6 weeks
. Open reduction and internal fixation of the posterior wall only
. Open reduction, elevation of the marginal impaction, bone grafting, and internal fixation
. Total hip arthroplasty
. Percutaneous screw fixation of the posterior wall

Correct Answer & Explanation

. Open reduction, elevation of the marginal impaction, bone grafting, and internal fixation

Explanation

Posterior wall fractures involving more than 20-40% of the articular surface are highly unstable and require ORIF. Marginal impaction occurs when articular cartilage is driven into the underlying cancellous bone. It is crucial to elevate the impacted segment to restore joint congruity and fill the resulting metaphyseal void with bone graft prior to fixing the posterior wall fragment. Failure to do so leads to rapid post-traumatic osteoarthritis.

Question 8434

Topic: 2. Trauma

A 22-year-old collegiate football player sustains a closed midshaft tibia fracture. Eight hours later, he develops excruciating leg pain out of proportion to the injury that is completely unresponsive to intravenous opioids. On examination, the leg is visibly tense, and passive stretch of the great toe elicits severe pain. Distal pulses are palpable. Compartment pressure monitoring reveals an absolute anterior compartment pressure of 45 mmHg with a concurrent diastolic blood pressure of 70 mmHg. What is the most appropriate next step in management?

. Administer a fluid bolus and reassess pressures in 2 hours
. Bivalve the splint and elevate the leg above the level of the heart
. Perform immediate four-compartment fasciotomy of the leg
. Perform a CT angiogram to rule out vascular injury
. Proceed directly to intramedullary nailing of the tibia without fasciotomy

Correct Answer & Explanation

. Perform immediate four-compartment fasciotomy of the leg

Explanation

The patient is presenting with classic clinical signs of acute compartment syndrome. The delta pressure (diastolic blood pressure minus absolute compartment pressure) is 70 - 45 = 25 mmHg. A delta pressure of less than 30 mmHg is diagnostic for acute compartment syndrome and is an absolute indication for an emergent four-compartment fasciotomy to prevent irreversible muscle and nerve necrosis.

Question 8435

Topic: 2. Trauma
A 42-year-old male sustains an anteroposterior compression type III (APC-III) pelvic ring injury following a high-speed motorcycle crash. On arrival, his systolic blood pressure is 75 mm Hg, and his heart rate is 125 bpm. A pelvic binder is applied, and he receives 2 units of uncrossmatched packed red blood cells. His blood pressure remains 78 mm Hg. Extended focused assessment with sonography for trauma (eFAST) is negative. What is the most appropriate next step in his management?
. Application of a pelvic external fixator
. Emergent laparotomy
. Retrograde urethrogram
. Preperitoneal pelvic packing and/or pelvic angiography
. Resuscitative endovascular balloon occlusion of the aorta (REBOA) in Zone 1

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, the primary source of bleeding is presumed to be the pelvis (retroperitoneal venous plexus or arterial branches). According to the ATLS and orthopedic trauma algorithms, once a pelvic binder is applied to reduce pelvic volume and fluid resuscitation is underway, persistent instability warrants emergent preperitoneal pelvic packing (PPP) and/or pelvic angiography to address the hemorrhage. External fixation provides volume reduction similar to a binder but does not address ongoing major bleeding better than packing/angio in this emergent phase.

Question 8436

Topic: 2. Trauma

A 65-year-old woman with severe rheumatoid arthritis on chronic corticosteroids sustains a highly comminuted, intra-articular distal femur fracture (AO/OTA 33-C3). Radiographs demonstrate profound osteopenia. She is treated with open reduction and internal fixation. Which of the following surgical strategies provides the most mechanically robust construct to minimize the risk of varus collapse?

. Single lateral locked plating with titanium
. Single lateral locked plating with stainless steel
. Lateral locked plating combined with a medial anatomical locking plate
. Retrograde intramedullary nailing
. Lateral locked plating with an intramedullary fibular allograft strut

Correct Answer & Explanation

. Lateral locked plating combined with a medial anatomical locking plate

Explanation

Highly comminuted distal femur fractures in severely osteopenic bone have a high failure rate, most commonly presenting as varus collapse and hardware pullout when treated with isolated lateral locked plating. Biomechanical studies demonstrate that dual plating (adding a medial structural plate) significantly increases the construct stiffness, torque to failure, and overall axial load to failure compared to isolated lateral locked plating or the addition of an endosteal fibular strut.

Question 8437

Topic: 2. Trauma
A 30-year-old man sustains a Gustilo-Anderson IIIB open midshaft tibia fracture following a motorcycle accident. He undergoes emergent irrigation and debridement, and placement of a spanning external fixator. According to the Lower Extremity Assessment Project (LEAP) study, which of the following factors is the most significant predictor of poor long-term functional outcome for this limb?
. Timing of definitive soft tissue coverage (within 72 hours vs. after 72 hours)
. The use of an intramedullary nail vs. external fixation for definitive stabilization
. The presence of a concomitant insensate plantar surface at presentation
. Patient psychosocial and socioeconomic factors
. The specific type of flap used for coverage (muscle vs. fasciocutaneous)

Correct Answer & Explanation

. Patient psychosocial and socioeconomic factors

Explanation

The LEAP study profoundly impacted the understanding of severe lower extremity trauma by showing that patient characteristics (such as lower socioeconomic status, lack of insurance, smoking, poor psychosocial support) are the strongest predictors of poor long-term functional outcomes, regardless of whether the limb was salvaged or amputated. An insensate foot on presentation does not necessarily correlate with poor long-term functional salvage and is not an absolute indication for primary amputation.

Question 8438

Topic: 2. Trauma
A 28-year-old man sustains a vertical, high-shear femoral neck fracture (Pauwels type III) after a fall from height. He undergoes closed reduction and internal fixation with three cannulated screws. Which of the following best describes the mechanical environment and the most likely mode of failure for this specific fracture pattern?
. Compressive forces predominating; failure via screw cut-out
. Torsional forces predominating; failure via fracture nonunion
. Shear forces predominating; failure via varus collapse and shortening
. Tensile forces predominating; failure via screw pull-out
. Bending forces predominating; failure via screw breakage

Correct Answer & Explanation

. Shear forces predominating; failure via varus collapse and shortening

Explanation

Pauwels type III fractures are highly vertical fractures (angle > 50 degrees). Because the fracture line is nearly parallel to the vector of joint reactive forces, shear forces predominate at the fracture site rather than compressive forces. This high shear environment makes standard parallel cannulated screw fixation biomechanically inferior, leading to a high rate of failure via varus collapse, shortening, and nonunion. A fixed-angle device (like a sliding hip screw or cephalomedullary nail) is generally preferred to counteract these shear forces.

Question 8439

Topic: 2. Trauma
A 34-year-old snowboarder sustains a Hawkins type III fracture of the talar neck. He undergoes prompt open reduction and internal fixation. At the 8-week postoperative visit, plain radiographs reveal a subchondral radiolucent band in the dome of the talus (Hawkins sign). What does this radiographic finding indicate?
. Impending avascular necrosis (AVN) of the talar body
. Presence of an active infection in the talocrural joint
. Intact vascular supply to the talar body
. Nonunion of the talar neck fracture
. Post-traumatic osteoarthritis of the subtalar joint

Correct Answer & Explanation

. Intact vascular supply to the talar body

Explanation

The Hawkins sign is a subchondral radiolucent band seen in the talar dome on the AP or mortise radiograph, typically appearing 6 to 8 weeks after injury. It represents subchondral osteopenia secondary to regional hyperemia. The presence of this hyperemia confirms that the vascular supply to the talar body is intact, thereby serving as a positive prognostic indicator that avascular necrosis (AVN) will not develop.

Question 8440

Topic: 2. Trauma
A 24-year-old male is involved in a high-speed motor vehicle collision resulting in a closed, comminuted midshaft tibia fracture. He is admitted and treated with a reamed intramedullary nail. Twelve hours postoperatively, he complains of severe leg pain requiring increasing doses of IV opioids. Passive stretch of his toes elicits excruciating pain. The physician decides to measure compartment pressures. Which of the following is the most accepted threshold for diagnosing acute compartment syndrome and proceeding with fasciotomy?
. Absolute compartment pressure greater than 20 mm Hg
. Absolute compartment pressure greater than 25 mm Hg
. Delta pressure (diastolic blood pressure minus compartment pressure) less than 30 mm Hg
. Delta pressure (mean arterial pressure minus compartment pressure) less than 40 mm Hg
. Absolute compartment pressure greater than diastolic blood pressure

Correct Answer & Explanation

. Delta pressure (diastolic blood pressure minus compartment pressure) less than 30 mm Hg

Explanation

The diagnosis of acute compartment syndrome is primarily clinical, but objective measurement is crucial in equivocal cases or in obtunded patients. The delta pressure (ΔP) is the most reliable parameter, calculated as Diastolic Blood Pressure minus Compartment Pressure. A delta pressure of less than 30 mm Hg suggests inadequate tissue perfusion and is the universally accepted threshold for emergent fasciotomy.

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