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2. Trauma MCQs

Practice Set 417 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 8321

Topic: 2. Trauma

A 50-year-old male is involved in a high-speed MVC. Pelvic radiographs and CT demonstrate a fracture involving both the anterior and posterior columns of the acetabulum. On the obturator oblique plain radiograph, a prominent "spur sign" is identified. This radiographic sign represents:

. The intact portion of the ilium attached to the axial skeleton
. The medially displaced quadrilateral surface
. An avulsion fracture of the ischial spine
. A displaced fragment of the superior pubic ramus
. The posterior column attached to the femoral head

Correct Answer & Explanation

. The intact portion of the ilium attached to the axial skeleton

Explanation

The "spur sign" on an obturator oblique radiograph is pathognomonic for an associated both-column acetabular fracture. It represents the lowest margin of the intact, unfractured superior ilium (which remains anatomically attached to the axial skeleton via the sacroiliac joint) protruding posteriorly relative to the medially displaced articular segments of the acetabulum.

Question 8322

Topic: 2. Trauma
A 42-year-old man sustains a severe closed pelvic fracture following a motorcycle collision. Clinical examination reveals a large, fluctuant area over the greater trochanter with intact, but hypoesthetic overlying skin. Aspiration yields serosanguineous fluid. Which of the following best describes the pathophysiology of this specific soft-tissue injury?
. Direct crush injury to the muscle fibers leading to extensive myonecrosis
. Shearing forces that separate the subcutaneous fat from the underlying deep fascia
. Rupture of the tensor fasciae latae muscle belly with associated hematoma
. Intramuscular hematoma secondary to a torn superior gluteal artery
. Lymphatic disruption due to a full-thickness deep fascial tear

Correct Answer & Explanation

. Shearing forces that separate the subcutaneous fat from the underlying deep fascia

Explanation

The scenario describes a Morel-Lavallée lesion, a closed degloving injury. It is caused by traumatic shearing forces that separate the subcutaneous tissue from the underlying deep fascia. This separation shears the trans-fascial perforating vessels, leading to an accumulation of hemolymphatic fluid, blood, and necrotic fat in the newly created potential space. Hypoesthesia is common due to shearing of the cutaneous nerves.

Question 8323

Topic: 2. Trauma

A 28-year-old man sustains a closed midshaft tibia fracture. Four hours post-injury, he complains of severe leg pain that is unresponsive to opioids. His blood pressure is 110/65 mmHg. Intracompartmental pressures are measured: anterior 42 mmHg, lateral 38 mmHg, deep posterior 45 mmHg, and superficial posterior 30 mmHg. What is the most appropriate management based on the objective data?

. Observation and elevate the leg above the level of the heart
. Application of a bivalved short leg cast
. Immediate four-compartment fasciotomy
. Bivalve the splint and re-evaluate pressures in 4 hours
. Administer intravenous mannitol and hypertonic saline

Correct Answer & Explanation

. Immediate four-compartment fasciotomy

Explanation

Delta pressure is calculated as the Diastolic Blood Pressure minus the highest intracompartmental pressure. In this case, 65 mmHg - 45 mmHg = 20 mmHg. A delta pressure of 30 mmHg or less is widely accepted as an absolute indication for emergency four-compartment fasciotomy to prevent irreversible muscle and nerve ischemia associated with acute compartment syndrome.

Question 8324

Topic: 2. Trauma

A 22-year-old man sustains a low-velocity gunshot wound to the distal thigh. Radiographs demonstrate a comminuted distal femur fracture and a retained bullet lodged within the knee joint space. The entry wound is 1 cm, clean, without massive soft-tissue destruction. What is the most appropriate initial management regarding the retained bullet?

. Observation and internal fixation of the femur
. Intra-articular bullet retrieval and joint irrigation
. Systemic lead chelation therapy followed by definitive fixation
. Extensile debridement of the bullet entry tract down to the bone
. Primary arthrodesis of the knee joint

Correct Answer & Explanation

. Intra-articular bullet retrieval and joint irrigation

Explanation

Retained bullets within a synovial joint space must be surgically removed. Synovial fluid dissolves the lead over time, which can lead to systemic lead toxicity (plumbism) as well as severe intra-articular third-body wear and mechanical cartilage damage. Extensile debridement of low-velocity entry tracts is generally not required unless heavily contaminated.

Question 8325

Topic: 2. Trauma

A 19-year-old motorcyclist is thrown from his bike. He presents with a completely flail, pulseless left upper extremity. Radiographs reveal lateral displacement of the left scapula by 3 cm compared to the right, a displaced clavicle fracture, and acromioclavicular joint disruption. Which of the following injuries is most strongly associated with this clinical picture?

. Complete brachial plexus avulsion
. Esophageal rupture
. Tracheobronchial tear
. Atlanto-occipital dissociation
. Subclavian vein thrombosis

Correct Answer & Explanation

. Complete brachial plexus avulsion

Explanation

The patient has sustained a scapulothoracic dissociation, characterized by lateral displacement of the scapula, clavicle fracture or AC/SC joint disruption, and severe soft tissue injury. It is considered a closed, traumatic forequarter amputation and is frequently associated with complete brachial plexus avulsions (up to 80-90%) and severe subclavian/axillary vascular injuries. The limb is often neurologically flail and may require early amputation.

Question 8326

Topic: 2. Trauma
A 45-year-old construction worker sustains an open tibial shaft fracture with a 6 cm laceration, significant periosteal stripping, and exposed bone, but adequate soft tissue for coverage without requiring a flap (Gustilo-Anderson IIIA). Which of the following interventions is the most critical factor in preventing deep infection in this patient?
. Time to definitive soft-tissue closure
. Time to administration of systemic antibiotics
. Use of high-pressure pulsatile lavage during debridement
. Immediate application of a circular external fixator
. Prophylactic use of local antibiotic-impregnated cement beads

Correct Answer & Explanation

. Time to administration of systemic antibiotics

Explanation

Early administration of systemic antibiotics (ideally within 1 hour of injury) is the single most critical and strongly evidence-based factor in reducing the risk of infection in open fractures. High-pressure lavage is no longer recommended due to the risk of driving debris and bacteria deeper into tissues or causing further soft-tissue damage (as demonstrated in the FLOW trial).

Question 8327

Topic: 2. Trauma
A 25-year-old male falls from a height of 15 feet, sustaining a vertically oriented, displaced intracapsular femoral neck fracture (Pauwels type III). What biomechanical force is most responsible for the high rate of internal fixation failure in this specific fracture pattern?
. Compressive forces across the fracture site
. Shear forces at the fracture site
. Rotational forces around the femoral shaft axis
. Tensile forces on the anterior hip capsule
. Bending forces in the sagittal plane

Correct Answer & Explanation

. Shear forces at the fracture site

Explanation

Pauwels type III femoral neck fractures have a vertical fracture line (angle > 50 degrees to the horizontal). This vertical orientation subjects the fracture to profoundly high shear forces and varus instability during weight-bearing. This leads to a significantly higher rate of fixation failure, nonunion, and osteonecrosis compared to more horizontally oriented fractures (Pauwels I), which experience primarily stable compressive forces.

Question 8328

Topic: 2. Trauma

A 76-year-old woman with a well-functioning cruciate-retaining (CR) total knee arthroplasty (TKA) falls and sustains a displaced supracondylar femur fracture (Lewis-Rorabeck Type II). Radiographs demonstrate a closed fracture with the distal component ending 1 cm superior to the intact, well-fixed femoral component. Which of the following is the most appropriate surgical treatment?

. Revision to a distal femoral replacement
. Retrograde intramedullary nailing
. Open reduction and internal fixation with a lateral locking plate
. Application of a hinged knee brace and weight-bearing as tolerated
. Revision to a constrained condylar knee (CCK) prosthesis

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locking plate

Explanation

For a periprosthetic distal femur fracture above a well-fixed femoral component (Lewis-Rorabeck Type II), lateral locked plating is the standard of care. A cruciate-retaining (CR) TKA femoral component typically lacks an intercondylar box or sufficient intercondylar notch space to permit the insertion of a standard retrograde intramedullary nail. Distal femoral replacement is reserved for loose components, severe comminution in the elderly, or exceedingly poor bone stock.

Question 8329

Topic: 2. Trauma
In the initial ATLS resuscitation of a hemodynamically unstable patient with an anteroposterior compression (APC) III pelvic ring injury, what is the correct anatomical landmark for the optimal placement of a circumferential pelvic binder?
. The anterior superior iliac spines
. The greater trochanters
. The iliac crests
. The umbilicus
. The pubic symphysis and sacral promontory

Correct Answer & Explanation

. The greater trochanters

Explanation

A pelvic binder or sheet must be centered directly over the greater trochanters to effectively reduce the pelvic volume and stabilize the fracture via indirect compression of the pelvic ring. Placing the binder too high (e.g., over the iliac crests or abdomen) is a common error that fails to close the pelvic ring adequately and can paradoxically increase bleeding or limit diaphragmatic excursion.

Question 8330

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the emergency department after a high-speed motor vehicle collision. He is hypotensive with a blood pressure of 75/40 mmHg. A pelvic binder is immediately applied. The FAST exam is negative. An anteroposterior pelvic radiograph shows an anteroposterior compression (APC) type III injury with a widened pubic symphysis (>3 cm) and disrupted sacroiliac joints. Despite ongoing fluid and blood resuscitation, the patient remains hemodynamically unstable. What is the most appropriate next step in management?
. CT scan of the abdomen and pelvis with intravenous contrast
. Exploratory laparotomy with retroperitoneal packing
. Immediate open reduction and internal fixation of the anterior pelvic ring
. Preperitoneal pelvic packing and/or pelvic angiography
. Removal of the pelvic binder and application of a supra-acetabular external fixator

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angiography

Explanation

In a hemodynamically unstable patient with an unstable pelvic ring injury and a negative FAST exam, the source of bleeding is predominantly retroperitoneal, typically from the venous plexus or arterial branches of the internal iliac system. Once a pelvic binder has been applied to reduce pelvic volume, if the patient remains hemodynamically unstable, ATLS and AAOS guidelines recommend either preperitoneal pelvic packing or pelvic angiography with embolization. A CT scan is contraindicated in a hemodynamically unstable patient.

Question 8331

Topic: 2. Trauma
A 28-year-old female sustains a displaced, highly vertical (Pauwels type III) femoral neck fracture after falling from a horse. Which of the following internal fixation constructs provides the greatest biomechanical stability for this specific fracture pattern?
. Three parallel cannulated screws in an inverted triangle configuration
. A sliding hip screw (fixed-angle device) with a supplemental anti-rotation screw
. Three parallel fully threaded screws in a standard triangle configuration
. A cephalomedullary nail with a single lag screw
. Two divergent partially threaded cancellous screws

Correct Answer & Explanation

. A sliding hip screw (fixed-angle device) with a supplemental anti-rotation screw

Explanation

Pauwels type III femoral neck fractures are characterized by a highly vertical fracture line (angle >50 degrees), which subjects the fracture to significant shear forces rather than compressive forces. Biomechanical studies have consistently shown that fixed-angle constructs, specifically a sliding hip screw combined with an anti-rotation (derotation) screw, provide superior stability, higher load-to-failure, and better resistance to shear compared to multiple parallel cannulated screws in young adults with vertical femoral neck fractures.

Question 8332

Topic: 2. Trauma

A 45-year-old man sustains an open fracture of the proximal third of the tibia, resulting in a 6 x 6 cm anterior soft-tissue defect with exposed bone lacking periosteum. After serial debridements and adequate skeletal stabilization, there is no evidence of infection, but the bone remains exposed. Which of the following soft-tissue coverage options is the most appropriate definitive management?

. Soleus rotational flap
. Medial gastrocnemius rotational flap
. Reverse sural artery fasciocutaneous flap
. Split-thickness skin graft directly over the exposed tibia
. Latissimus dorsi free flap

Correct Answer & Explanation

. Medial gastrocnemius rotational flap

Explanation

The lower extremity is traditionally divided into thirds for the purpose of soft-tissue coverage planning over exposed bone. The proximal third of the tibia is most reliably covered by a medial (or lateral) gastrocnemius rotational muscle flap. The middle third is typically covered by a soleus muscle flap. The distal third generally lacks adequate local muscle bulk and requires a free tissue transfer (such as an anterolateral thigh or latissimus dorsi free flap) or local fasciocutaneous flaps (like the reverse sural flap) for smaller defects. A split-thickness skin graft will not survive on bare cortical bone devoid of periosteum.

Question 8333

Topic: 2. Trauma

A 32-year-old man underwent unreamed intramedullary nailing of a closed diaphyseal tibia fracture. He was discharged on postoperative day 3. Six months later, he complains of pain in the calf and the development of severe clawing of his lesser toes (flexion at the PIP and DIP joints). He notes the deformity worsens when his ankle is passively dorsiflexed. Ischemic contracture of which of the following compartments is the most likely cause of this deformity?

. Anterior compartment
. Lateral compartment
. Superficial posterior compartment
. Deep posterior compartment
. Plantar intrinsic compartment of the foot

Correct Answer & Explanation

. Deep posterior compartment

Explanation

The patient is presenting with late sequelae of an unrecognized deep posterior compartment syndrome. The deep posterior compartment of the leg contains the flexor hallucis longus (FHL), flexor digitorum longus (FDL), and tibialis posterior muscles, as well as the tibial nerve. Ischemic contracture of the FHL and FDL tendons results in fixed flexion of the interphalangeal joints of the toes, causing a claw toe deformity. This deformity typically becomes more pronounced with ankle dorsiflexion due to the tenodesis effect on the shortened tendons.

Question 8334

Topic: 2. Trauma

A 48-year-old construction worker falls from scaffolding, sustaining a high-energy, highly comminuted closed distal tibia pilon fracture. On presentation to the emergency department, the ankle is grossly deformed, and the overlying skin is tight, shiny, and demonstrates multiple fracture blisters over the medial malleolus. What is the most appropriate initial step in the operative management?

. Immediate open reduction and internal fixation with dual-plate osteosynthesis
. Immediate primary tibiotalar arthrodesis
. Application of a joint-spanning external fixator with delayed definitive fixation
. Closed reduction and casting with delayed open reduction at 6 weeks
. Percutaneous pinning of the articular block combined with a short leg cast

Correct Answer & Explanation

. Application of a joint-spanning external fixator with delayed definitive fixation

Explanation

High-energy pilon fractures are notorious for severe surrounding soft-tissue injury. Performing immediate open reduction and internal fixation (ORIF) through swollen, compromised skin is associated with unacceptably high rates of wound dehiscence, deep infection, and hardware exposure. The current gold standard for initial management is the "span, scan, and plan" approach. This entails urgent application of a joint-spanning external fixator to restore length, alignment, and allow the soft tissues to rest. Definitive fixation is delayed (usually 10 to 21 days) until the soft-tissue envelope has sufficiently recovered, indicated by the resolution of edema and the reappearance of skin wrinkles (the "wrinkle sign").

Question 8335

Topic: 2. Trauma

A 29-year-old man undergoes open reduction and internal fixation for a displaced Hawkins type II fracture of the talar neck. At his 8-week postoperative visit, an anteroposterior radiograph of the ankle demonstrates a subchondral radiolucent band beneath the dome of the talus. What does this specific radiographic finding indicate regarding the patient's prognosis?

. It represents early avascular necrosis (AVN) of the talar body
. It indicates impending hardware failure and loss of reduction
. It demonstrates intact vascularity and indicates that AVN is highly unlikely
. It is a sign of rapidly progressive post-traumatic tibiotalar arthritis
. It suggests an indolent deep infection requiring prompt hardware removal

Correct Answer & Explanation

. It demonstrates intact vascularity and indicates that AVN is highly unlikely

Explanation

The finding described is the Hawkins sign. It appears as a subchondral radiolucent band in the talar dome on an AP (or mortise) radiograph, typically becoming visible 6 to 8 weeks following a talar neck fracture. This radiolucency represents subchondral osteopenia, which is a consequence of disuse coupled with hyperemic resorption. The presence of the Hawkins sign signifies that the talar body has an intact blood supply (or has successfully revascularized). A positive Hawkins sign is a highly reliable negative predictor for the development of avascular necrosis (AVN).

Question 8336

Topic: 2. Trauma
A 28-year-old male sustains a vertically oriented, displaced femoral neck fracture (Pauwels type III) after a fall from a height. To maximize biomechanical stability and reduce the risk of varus collapse and nonunion, which of the following internal fixation constructs is most appropriate?
. Three parallel cancellous screws in an inverted triangle configuration
. Sliding hip screw (SHS) with a derotational screw
. Two fully threaded cortical screws
. Cephalomedullary nail
. Hemiarthroplasty

Correct Answer & Explanation

. Sliding hip screw (SHS) with a derotational screw

Explanation

A sliding hip screw (SHS) provides superior biomechanical stability for vertically oriented, high-shear (Pauwels type III) femoral neck fractures compared to parallel cancellous screws. The SHS acts as a fixed-angle device that resists varus shear forces, and the addition of a derotational screw helps prevent rotation of the femoral head during lag screw insertion and physiological loading.

Question 8337

Topic: 2. Trauma

A 32-year-old male sustains a closed comminuted midshaft tibia fracture. He is complaining of out-of-proportion pain, and physical examination reveals intact pedal pulses. His diastolic blood pressure is 70 mm Hg and his MAP is 85 mm Hg. Direct continuous pressure measurements reveal an anterior compartment pressure of 35 mm Hg, lateral 25 mm Hg, superficial posterior 20 mm Hg, and deep posterior 45 mm Hg. Which of the following is the most appropriate next step in management?

. Elevation of the limb above the level of the heart and reassessment in 2 hours
. Single-incision fasciotomy of the anterior and lateral compartments
. Two-incision four-compartment fasciotomy
. Intramedullary nailing followed by fasciotomy if pressures remain elevated
. Administration of IV mannitol

Correct Answer & Explanation

. Two-incision four-compartment fasciotomy

Explanation

The diagnosis of acute compartment syndrome is confirmed when the delta pressure (Diastolic Blood Pressure minus compartment pressure) is less than 30 mm Hg. In this patient, the deep posterior compartment delta pressure is 70 - 45 = 25 mm Hg. This is an absolute indication for emergent fasciotomy. When releasing the leg for compartment syndrome, all four compartments must be released, typically utilizing a two-incision technique.

Question 8338

Topic: 2. Trauma

A 45-year-old female presents with a complex intra-articular distal femur fracture (OTA/AO 33-C3). A CT scan reveals a coronal plane fracture of the lateral femoral condyle (Hoffa fracture). What is the most biomechanically appropriate fixation strategy for this specific coronal fragment?

. Anterior-to-posterior fully threaded cortical screws
. Posterior-to-anterior partially threaded cancellous screws positioned parallel to the fracture line
. Laterally applied locking plate alone with unicortical screws
. Anterior-to-posterior or posterior-to-anterior lag screws placed perpendicular to the fracture line
. A posterior buttress plate without interfragmentary compression

Correct Answer & Explanation

. Anterior-to-posterior or posterior-to-anterior lag screws placed perpendicular to the fracture line

Explanation

A Hoffa fracture is a coronal plane fracture of the femoral condyle. Achieving absolute stability and anatomic reduction of the articular surface is critical. This requires interfragmentary compression using lag screws directed perpendicular to the fracture line (anterior-to-posterior or posterior-to-anterior). A laterally applied locking plate alone will not adequately capture or compress a coronal fragment.

Question 8339

Topic: 2. Trauma
A 40-year-old male sustains a displaced intra-articular calcaneus fracture (Sanders type III) with significant soft tissue swelling and fracture blisters over the lateral hindfoot. If an extensile lateral approach for open reduction and internal fixation (ORIF) is planned, which of the following patient factors is the most significant predictor of postoperative wound complications?
. Age older than 40 years
. Hypertension
. Active tobacco smoking
. Obesity
. Timing of surgery within 7 days of injury

Correct Answer & Explanation

. Active tobacco smoking

Explanation

Smoking is one of the most significant risk factors for wound complications following the extensile lateral approach for calcaneus fractures. Studies have shown a markedly increased incidence of wound edge necrosis, dehiscence, and deep infection in patients who actively smoke.

Question 8340

Topic: 2. Trauma
A 25-year-old male is involved in a motor vehicle collision and sustains a Gustilo-Anderson IIIB open midshaft tibia fracture with extensive periosteal stripping and exposed bone that requires a free soft-tissue transfer. 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 in this patient?
. The presence of an open fracture
. The need for a free tissue transfer to achieve soft-tissue coverage
. Lack of plantar sensation at initial presentation
. Patient's poor socioeconomic status, lower educational level, and psychological status
. The initial use of a bridging external fixator

Correct Answer & Explanation

. Patient's poor socioeconomic status, lower educational level, and psychological status

Explanation

The landmark LEAP (Lower Extremity Assessment Project) study demonstrated that poor outcomes in severe lower extremity trauma were most closely correlated with patient characteristics such as poor socioeconomic status, lack of health insurance, lower educational level, and psychological factors (e.g., depression, self-efficacy), rather than the specific reconstructive technique, amputation vs. salvage, or initial lack of plantar sensation.

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