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2. Trauma MCQs

Practice Set 555 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 11081

Topic: 2. Trauma

A 28-year-old male develops severe foot pain and tense swelling following a severe crush injury. Compartment syndrome of the foot is suspected. Among the nine recognized fascial compartments of the foot, the calcaneal compartment contains which of the following vital structures?

. Abductor hallucis and medial plantar nerve
. Quadratus plantae and lateral plantar nerve
. Flexor digitorum brevis and medial plantar nerve
. Adductor hallucis and deep plantar arch
. First lumbrical and digital nerve

Correct Answer & Explanation

. Abductor hallucis and medial plantar nerve

Explanation

The calcaneal compartment is located in the hindfoot and contains the quadratus plantae muscle and the lateral plantar nerve. It communicates directly with the deep posterior compartment of the leg.

Question 11082

Topic: 2. Trauma

According to the Lauge-Hansen classification of ankle fractures, a Supination-External Rotation (SER) mechanism predictably injures structures in a sequential order. What represents Stage 3 of this injury pattern?

. Rupture of the anterior inferior tibiofibular ligament (AITFL)
. Short oblique or spiral fracture of the lateral malleolus
. Rupture of the posterior inferior tibiofibular ligament (PITFL) or fracture of the posterior malleolus
. Transverse fracture of the medial malleolus or deltoid ligament rupture
. Vertical fracture of the medial malleolus

Correct Answer & Explanation

. Rupture of the anterior inferior tibiofibular ligament (AITFL)

Explanation

The SER sequence is: Stage 1 (AITFL rupture), Stage 2 (spiral/oblique fibula fracture), Stage 3 (PITFL rupture or posterior malleolus fracture), and Stage 4 (deltoid rupture or medial malleolus fracture).

Question 11083

Topic: 2. Trauma

A 24-year-old sprinter presents with acute plantar first MTP joint pain after forcefully pushing off the starting blocks. Radiographs reveal a radiolucency through the tibial sesamoid. Which of the following radiographic characteristics best distinguishes an acute sesamoid fracture from a congenital bipartite sesamoid?

. Smooth, sclerotic margins
. Irregular, sharp, radiolucent line without sclerotic edges
. Transverse orientation of the radiolucency
. Bilateral occurrence on comparison views
. Summation of the two fragments is larger than a single normal sesamoid

Correct Answer & Explanation

. Smooth, sclerotic margins

Explanation

An acute sesamoid fracture typically presents with an irregular, sharp radiolucent line without sclerotic margins. In contrast, a bipartite sesamoid generally has smooth, corticated (sclerotic) edges and is often bilateral.

Question 11084

Topic: 2. Trauma

A 40-year-old construction worker falls from a height and sustains a severely displaced, joint-depressed calcaneus fracture. The surgeon elects to perform an open reduction and internal fixation via an extensile lateral approach. Which of the following is the most common postoperative complication associated with this specific surgical approach?

. Sural nerve transection
. Wound edge necrosis and dehiscence
. Peroneal tendon dislocation
. Nonunion of the calcaneal body
. Flexor hallucis longus tethering

Correct Answer & Explanation

. Sural nerve transection

Explanation

Wound edge necrosis and dehiscence at the apex of the flap is the most common complication of the extensile lateral approach to the calcaneus, occurring in up to 10-25% of cases. Careful soft tissue handling, subperiosteal dissection, and utilizing a 'no-touch' technique are critical to minimizing this risk.

Question 11085

Topic: 2. Trauma

A 21-year-old collegiate soccer player sustains a twisting injury to his foot and is diagnosed with an acute diaphyseal/metaphyseal junction fracture of the fifth metatarsal (Zone 2, Jones fracture). Given his desire to return to elite-level sports, what is the gold standard of treatment?

. Strict non-weight bearing in a short leg cast for 6 weeks
. Percutaneous intramedullary screw fixation
. Excision of the proximal fragment and peroneus brevis advancement
. Open reduction and internal fixation with a dynamic compression plate
. Tension band wiring

Correct Answer & Explanation

. Strict non-weight bearing in a short leg cast for 6 weeks

Explanation

Zone 2 fractures (Jones fractures) occur in a vascular watershed area and have a high risk of delayed union or nonunion. In competitive athletes, early percutaneous intramedullary screw fixation is the gold standard to expedite return to play and reduce nonunion risk.

Question 11086

Topic: Lower Extremity Trauma

A 22-year-old skier experiences a sudden 'popping' sensation behind his lateral malleolus after forced dorsiflexion and eversion of his ankle. Examination reveals tenderness and visible swelling over the peroneal tendons, which subluxate anteriorly with active eversion. Which of the following is the most common anatomic variant of the superior peroneal retinaculum (SPR) injury in this condition?

. Midsubstance transverse tear of the SPR
. Periosteal avulsion of the SPR from the lateral aspect of the distal fibula
. Avulsion of the SPR from its calcaneal insertion
. Concomitant tear of the inferior extensor retinaculum
. Intratendinous longitudinal split of the peroneus longus tendon

Correct Answer & Explanation

. Midsubstance transverse tear of the SPR

Explanation

Acute peroneal tendon dislocation is typically caused by failure of the superior peroneal retinaculum (SPR). The most common mechanism of SPR failure is a periosteal avulsion from its attachment on the posterolateral distal fibula, sometimes creating a 'fleck sign' on radiographs.

Question 11087

Topic: 2. Trauma

According to the Lauge-Hansen classification system, what is the typical progression of osseous and ligamentous injury in a Supination-External Rotation (SER) ankle fracture?

. AITFL -> Short oblique/spiral fibula fracture -> PITFL/posterior malleolus -> Deltoid/medial malleolus
. Medial malleolus -> AITFL -> Short oblique fibula fracture -> PITFL
. Deltoid ligament -> Transverse fibula fracture -> AITFL -> PITFL
. Transverse fibula fracture -> AITFL -> Deltoid ligament -> PITFL
. PITFL -> Short oblique fibula fracture -> AITFL -> Deltoid ligament

Correct Answer & Explanation

. AITFL -> Short oblique/spiral fibula fracture -> PITFL/posterior malleolus -> Deltoid/medial malleolus

Explanation

The Lauge-Hansen SER mechanism follows a sequential pattern: Stage 1 is the anterior inferior tibiofibular ligament (AITFL), Stage 2 is a spiral/oblique fracture of the lateral malleolus, Stage 3 is the posterior inferior tibiofibular ligament (PITFL) or posterior malleolus, and Stage 4 is the deltoid ligament or medial malleolus.

Question 11088

Topic: 2. Trauma

A 78-year-old female presents with a periprosthetic femur fracture around a cemented polished taper slip stem, 10 years post-op. Radiographs show a spiral fracture extending to the distal tip of the stem. The stem cement mantle is debonded and the implant has subsided, but the proximal femoral bone stock remains robust. What is the Vancouver classification and the recommended standard of care?

. Vancouver B1; ORIF with a lateral locking plate and cerclage cables
. Vancouver B2; Revision to a long uncemented porous-coated or fluted tapered stem
. Vancouver B2; Revision to a long cemented stem with impaction grafting
. Vancouver B3; Proximal femoral replacement
. Vancouver C; ORIF with overlapping plates

Correct Answer & Explanation

. Vancouver B1; ORIF with a lateral locking plate and cerclage cables

Explanation

This is a Vancouver B2 fracture: fracture around the stem (B), loose implant (2), with adequate proximal bone stock. The standard of care for Vancouver B2 fractures is revision arthroplasty using a long uncemented diaphyseal engaging stem (extensively porous-coated or fluted tapered), bypassing the most distal fracture line by at least two cortical diameters. B1 fractures (well-fixed stem) are treated with ORIF. B3 fractures (loose stem, poor bone stock) require proximal femoral replacement.

Question 11089

Topic: Pelvic & Acetabular Trauma

A 65-year-old female with long-standing rheumatoid arthritis presents with progressive hip pain. Radiographs demonstrate severe protrusio acetabuli with the femoral head migrated medially past the Kohler line. During THA, which of the following is the most appropriate technique to reconstruct the acetabulum and restore biomechanics?

. Use of a jumbo uncemented cup to fill the entire uncontained defect
. Placement of the acetabular component at the current, medially migrated center of rotation
. Impaction of morselized cancellous bone graft medially followed by a standard hemispherical cup
. Resection of the anterior column to lateralize the acetabular cup
. Use of a constrained tripolar liner to prevent medial subluxation

Correct Answer & Explanation

. Use of a jumbo uncemented cup to fill the entire uncontained defect

Explanation

In protrusio acetabuli, the center of rotation is pathologically medialized. The goal of surgery is to restore the anatomic center of rotation laterally to its native position. This is best achieved by impacting morselized cancellous bone graft into the medial defect to lateralize the standard hemispherical cup, preventing further medial migration.

Question 11090

Topic: 2. Trauma

A 35-year-old farmer sustains an open tibia fracture highly contaminated with soil and farm debris. According to classical evidence-based guidelines, which antibiotic regimen is most appropriate for initial management?

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

Correct Answer & Explanation

. First-generation cephalosporin alone

Explanation

For severe open fractures occurring in an agricultural setting (highly contaminated with soil/feces), there is a significant risk for clostridial infection (gas gangrene). The standard empiric antibiotic regimen includes a first-generation cephalosporin (for Gram-positives), an aminoglycoside (for Gram-negatives), and high-dose penicillin (specifically to cover anaerobes like Clostridium).

Question 11091

Topic: 2. Trauma

When evaluating a patient for suspected acute compartment syndrome of the lower leg, which of the following objective pressure measurements is generally accepted as an absolute indication to perform a fasciotomy?

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

Correct Answer & Explanation

. Absolute compartment pressure > 20 mmHg

Explanation

A Delta P (Diastolic blood pressure minus intra-compartmental pressure) of less than 30 mmHg is the most reliable threshold for diagnosing acute compartment syndrome and is an absolute indication for emergency fasciotomy. Using an absolute pressure threshold alone is less reliable due to physiologic variability in systemic blood pressure.

Question 11092

Topic: Pelvic & Acetabular Trauma

What is the optimal anatomic location for the application of a circumferential pelvic binder in a hemodynamically unstable trauma patient with a suspected anteroposterior compression ('open book') pelvic ring injury?

. At the level of the iliac crests
. Centered over the greater trochanters
. Midway between the iliac crests and the umbilicus
. At the level of the anterior superior iliac spines (ASIS)
. Distal to the lesser trochanters

Correct Answer & Explanation

. At the level of the iliac crests

Explanation

A pelvic binder should be centered precisely over the greater trochanters (the level of the pubic symphysis) to effectively close the pelvic ring and reduce pelvic volume. Placement higher up, such as over the iliac crests or ASIS, is a common error and can be less effective or even paradoxically open the pelvis further.

Question 11093

Topic: 2. Trauma

According to Perren's strain theory of fracture healing, primary (osteonal) bone healing without callus formation requires absolute stability. This biological process can only occur when the strain at the fracture site is:

. Less than 2%
. Between 2% and 10%
. Between 10% and 30%
. Greater than 30%
. Exactly 100%

Correct Answer & Explanation

. Less than 2%

Explanation

Perren's strain theory dictates the type of tissue that can form in a fracture gap based on deformation (strain). Primary bone healing (direct remodeling via cutting cones without intermediate callus) requires absolute stability, defined as strain less than 2%. Strain between 2% and 10% permits secondary bone healing (callus formation). Strain above 10% prevents bone formation and leads to fibrous nonunion.

Question 11094

Topic: 2. Trauma
A 24-year-old male is admitted with a closed, highly comminuted tibial shaft fracture. He is complaining of pain out of proportion to the injury. Which of the following absolute intracompartmental pressure criteria is the most reliable threshold for diagnosing acute compartment syndrome and indicating urgent 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
. Diastolic blood pressure minus compartment pressure < 45 mm Hg
. Mean arterial pressure minus compartment pressure < 45 mm Hg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mm Hg

Explanation

The Delta P (ΔP) threshold is considered the most reliable objective measure for acute compartment syndrome. It is calculated as the Diastolic Blood Pressure minus the Intracompartmental Pressure. A ΔP of less than 30 mm Hg indicates critically impaired capillary perfusion and is an absolute indication for emergency fasciotomy. Absolute pressure alone (e.g., >30 mm Hg) is less reliable due to variations in baseline blood pressure.

Question 11095

Topic: 2. Trauma

When utilizing a fully threaded screw as a lag screw to achieve interfragmentary compression across a fracture site, what defines the 'working length' of the screw?

. The entire length of the screw from head to tip
. The length of the threaded portion engaged in the far cortex
. The distance between the screw head and the near cortex
. The segment of the screw between the near cortex and the far cortex
. The distance from the under-surface of the screw head to the first thread engaged in the far cortex

Correct Answer & Explanation

. The entire length of the screw from head to tip

Explanation

The working length of a lag screw is the central unengaged portion of the screw that acts under tension to generate compression. It is precisely defined as the distance between the under-surface of the screw head (which is buttressed against the near cortex) and the first thread of the screw that purchases the far cortex. A longer working length allows the screw to function more like an elastic spring, maintaining compression even if slight bone resorption occurs.

Question 11096

Topic: 2. Trauma

A 28-year-old man sustains a closed tibial shaft fracture. Which of the following clinical findings is the most sensitive early indicator of evolving acute compartment syndrome?

. Absence of a palpable dorsalis pedis pulse
. Capillary refill greater than 3 seconds
. Pain with passive stretch of the involved muscles
. Paresthesia in the first dorsal webspace
. Palpable tense compartments on physical exam

Correct Answer & Explanation

. Absence of a palpable dorsalis pedis pulse

Explanation

Pain out of proportion to the injury, particularly with passive stretching of the muscles in the affected compartment, is generally considered the most sensitive and earliest clinical sign of compartment syndrome. Pulselessness and pallor are late, unreliable signs that indicate severe ischemia.

Question 11097

Topic: 2. Trauma
A 25-year-old man sustains a displaced, basicervical femoral neck fracture (Pauwels type III). During open reduction and internal fixation, what is the biomechanical advantage of using a sliding hip screw with a derotation screw over three parallel cancellous screws?
. Greater preservation of the femoral head blood supply
. Superior resistance to vertical shear forces
. Decreased risk of avascular necrosis
. Shorter operative time
. Less soft tissue dissection

Correct Answer & Explanation

. Superior resistance to vertical shear forces

Explanation

Pauwels type III fractures are characterized by a vertical fracture line that experiences high shear forces rather than compressive forces. A fixed-angle device like a sliding hip screw provides superior biomechanical resistance to these vertical shear forces compared to multiple parallel cancellous screws.

Question 11098

Topic: 2. Trauma

In a polytrauma patient, which of the following markers is the most reliable indicator of adequate physiological resuscitation allowing for safe conversion from external fixation to definitive intramedullary nailing (Early Total Care)?

. Hemoglobin greater than 10 g/dL
. Urine output of 0.5 mL/kg/hr
. Serum lactate less than 2.5 mmol/L
. Systolic blood pressure greater than 100 mmHg
. Arterial pH of 7.25

Correct Answer & Explanation

. Hemoglobin greater than 10 g/dL

Explanation

Serum lactate clearance to less than 2.5 mmol/L and normalization of base deficit are the most reliable indicators of adequate tissue perfusion. Operating on an under-resuscitated patient risks a "second hit" phenomenon, leading to ARDS and multiorgan failure.

Question 11099

Topic: 2. Trauma

Which of the following findings is the most reliable early clinical indicator for diagnosing acute compartment syndrome in an awake polytrauma patient?

. Absent distal pulses
. Paresthesias in the affected limb
. Pain out of proportion to the injury and exacerbated by passive stretch
. Tense compartments upon palpation
. Pallor of the distal extremity

Correct Answer & Explanation

. Absent distal pulses

Explanation

Pain out of proportion to the apparent injury, specifically exacerbated by passive stretch of the muscles within the involved compartment, is the most sensitive early clinical sign. Pulselessness and pallor are late, unreliable signs that indicate irreversible ischemia.

Question 11100

Topic: 2. Trauma

A patient with a 10-year history of alendronate therapy presents with thigh pain and a subtrochanteric femur fracture. Which radiographic feature is classic for an atypical femur fracture (AFF) associated with this medication?

. Medial cortical spiking
. Lateral cortical thickening (beaking) with a transverse or short oblique fracture line
. Spiral fracture pattern with severe comminution
. Extensive florid periosteal reaction mimicking osteomyelitis
. Multiple permeative lytic lesions surrounding the fracture site

Correct Answer & Explanation

. Medial cortical spiking

Explanation

Atypical femur fractures associated with prolonged bisphosphonate use characteristically present in the subtrochanteric or diaphyseal region with localized lateral cortical thickening (beaking). The fracture line is typically transverse or short oblique, and minimally comminuted.

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