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2. Trauma MCQs

Practice Set 393 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 7841

Topic: Lower Extremity Trauma

Histological analysis of articular cartilage from a patient with early osteoarthritis reveals duplication of a specific boundary layer. What is the normal functional significance of the tidemark in articular cartilage?

. It represents the primary vascular supply to the chondrocytes
. It is the boundary separating the superficial and middle zones of uncalcified cartilage
. It divides the uncalcified articular cartilage from the calcified cartilage
. It anchors the menisci to the tibial plateau
. It provides the primary source of stem cells for cartilage repair

Correct Answer & Explanation

. It represents the primary vascular supply to the chondrocytes

Explanation

The tidemark is a distinct histological line that demarcates the transition between the deep zone of uncalcified articular cartilage and the underlying calcified cartilage. Duplication or advancement of the tidemark is a hallmark of osteoarthritis.

Question 7842

Topic: Upper Extremity Trauma

A 22-year-old rugby player sustains an acromioclavicular (AC) joint separation. During surgical reconstruction, the surgeon reconstructs the coracoclavicular (CC) ligaments. Which of the following accurately describes the anatomy of the native CC ligaments?

. The conoid ligament inserts anterolaterally on the clavicle.
. The trapezoid ligament inserts posteromedially on the clavicle.
. The conoid ligament is the primary restraint to superior translation of the clavicle.
. The trapezoid ligament is the primary restraint to inferior translation of the clavicle.
. The conoid and trapezoid ligaments merge to form a single insertion on the acromion.

Correct Answer & Explanation

. The conoid ligament inserts anterolaterally on the clavicle.

Explanation

The conoid ligament inserts posteromedially on the clavicle and is the primary restraint to superior clavicular translation. The trapezoid ligament inserts anterolaterally and primarily resists axial compression of the AC joint.

Question 7843

Topic: 2. Trauma

During a posterior approach to the knee for a displaced medial tibial plateau fracture, the surgeon dissects meticulously through the popliteal fossa. What is the correct anatomical sequence of the primary neurovascular structures encountered from superficial (posterior) to deep (anterior)?

. Popliteal artery -> popliteal vein -> tibial nerve
. Tibial nerve -> popliteal vein -> popliteal artery
. Popliteal vein -> tibial nerve -> popliteal artery
. Tibial nerve -> popliteal artery -> popliteal vein
. Popliteal artery -> tibial nerve -> popliteal vein

Correct Answer & Explanation

. Popliteal artery -> popliteal vein -> tibial nerve

Explanation

In the popliteal fossa, the structures from superficial to deep are the tibial nerve, popliteal vein, and popliteal artery. The popliteal artery is the deepest structure, lying directly against the posterior joint capsule and femur.

Question 7844

Topic: 2. Trauma

During a lateral extensile approach for open reduction and internal fixation of a calcaneus fracture, the sural nerve is at risk. What is the usual anatomic course of the sural nerve at the level of the lateral malleolus?

. Anterior to the lateral malleolus, alongside the great saphenous vein
. Posterior to the lateral malleolus, alongside the small saphenous vein
. Anterior to the lateral malleolus, alongside the small saphenous vein
. Posterior to the lateral malleolus, alongside the great saphenous vein
. Directly superficial to the lateral malleolus

Correct Answer & Explanation

. Anterior to the lateral malleolus, alongside the great saphenous vein

Explanation

The sural nerve courses posterior to the lateral malleolus in close association with the small (short) saphenous vein. It provides sensation to the lateral aspect of the hindfoot and midfoot.

Question 7845

Topic: 2. Trauma

A 22-year-old male sustains a scaphoid waist fracture. The proximal pole is highly susceptible to avascular necrosis due to its retrograde blood flow. Which vessel is the primary source of blood supply to the scaphoid?

. Volar carpal branch of the radial artery
. Dorsal carpal branch of the radial artery
. Anterior interosseous artery
. Ulnar artery via the deep palmar arch
. Deep palmar branch of the ulnar artery

Correct Answer & Explanation

. Volar carpal branch of the radial artery

Explanation

The dorsal carpal branch of the radial artery provides the dominant blood supply to the scaphoid, entering at the distal pole and flowing in a retrograde fashion. This anatomy explains the high risk of nonunion and avascular necrosis in proximal pole fractures.

Question 7846

Topic: Upper Extremity Trauma

Historically, the anterior circumflex humeral artery was considered the primary blood supply to the humeral head. Based on modern quantitative cadaveric perfusion studies, which vessel is now recognized as providing the predominant blood supply to the articular segment of the proximal humerus?

. Anterior circumflex humeral artery
. Posterior circumflex humeral artery
. Thoracoacromial artery
. Profunda brachii artery
. Suprascapular artery

Correct Answer & Explanation

. Anterior circumflex humeral artery

Explanation

Recent anatomical and perfusion studies have demonstrated that the posterior circumflex humeral artery provides the dominant blood supply (approximately 64%) to the humeral head, challenging older literature.

Question 7847

Topic: 2. Trauma

A trauma surgeon is placing an S1 iliosacral screw for a vertically unstable pelvic fracture. If the guidewire is placed too anteriorly and breaches the anterior cortex of the sacral ala, which nerve root is most directly at risk of injury?

. L4 nerve root
. L5 nerve root
. S1 nerve root
. S2 nerve root
. Pudendal nerve

Correct Answer & Explanation

. L4 nerve root

Explanation

The L5 nerve root descends anteriorly across the sacral ala to join the lumbosacral trunk. An anteriorly misplaced S1 iliosacral screw directly threatens this nerve root.

Question 7848

Topic: Upper Extremity Trauma

A 35-year-old male sustains a Type III acromioclavicular (AC) joint separation requiring surgical reconstruction. To accurately recreate the coracoclavicular ligaments, the surgeon must identify their native footprints. What is the average distance from the distal end of the clavicle to the conoid and trapezoid tuberosities, respectively?

. 15 mm and 25 mm
. 25 mm and 15 mm
. 45 mm and 30 mm
. 30 mm and 45 mm
. 50 mm and 20 mm

Correct Answer & Explanation

. 15 mm and 25 mm

Explanation

The conoid tuberosity is located approximately 45 mm medial to the distal clavicle, while the trapezoid tuberosity is more lateral, at roughly 30 mm. Anatomic reconstruction relies on accurate placement of these drill holes.

Question 7849

Topic: 2. Trauma

When placing an iliosacral screw for a zone 1 sacral fracture, the surgeon must stay within the 'alar safe zone.' An errant guidewire placed anteriorly through the sacral ala primarily endangers which neural structure?

. L4 nerve root
. L5 nerve root
. S1 nerve root
. S2 nerve root
. Pudendal nerve

Correct Answer & Explanation

. L4 nerve root

Explanation

The L5 nerve root courses directly anterior to the sacral ala as it descends to join the sacral plexus. An anterior cortical breach during iliosacral screw placement places the L5 root at high risk for injury.

Question 7850

Topic: 2. Trauma

A 28-year-old male polytrauma patient presents with bilateral closed femoral shaft fractures, a pulmonary contusion, and an isolated head injury (GCS 10). Initial arterial blood gas reveals a pH of 7.2, and serum lactate is 4.8 mmol/L. His blood pressure is 95/60 mmHg after 2 liters of crystalloid. What is the most appropriate initial orthopedic management of his femoral fractures?

. Bilateral reamed intramedullary nailing
. Damage control orthopedics with bilateral spanning external fixators
. Bilateral unreamed intramedullary nailing
. Open reduction and internal fixation with locking plates
. Skeletal traction and delayed definitive fixation

Correct Answer & Explanation

. Bilateral reamed intramedullary nailing

Explanation

This patient is hemodynamically marginal and under-resuscitated with elevated lactate, indicating a 'borderline' or 'in extremis' status. Damage control orthopedics (external fixation) is prioritized to minimize the second hit from systemic inflammatory response syndrome (SIRS) caused by early total care (ETC).

Question 7851

Topic: 2. Trauma

A 30-year-old female sustains a Pauwels type III (vertically oriented) femoral neck fracture. Which of the following internal fixation constructs provides the most biomechanically stable fixation to prevent shear displacement and varus collapse?

. Three parallel cancellous screws
. Dynamic hip screw (sliding hip screw) with an anti-rotation screw
. Standard cephalomedullary nail
. Proximal femoral locking plate
. Two parallel fully threaded cortical screws

Correct Answer & Explanation

. Three parallel cancellous screws

Explanation

Pauwels III fractures experience high shear forces that typically lead to varus collapse and nonunion if fixed with parallel screws alone. A fixed-angle device such as a dynamic hip screw with a derotational screw provides superior biomechanical resistance to shear forces in young adults.

Question 7852

Topic: 2. Trauma

In a hemodynamically unstable polytrauma patient with an anterior-posterior compression (APC III) pelvic ring injury, a pelvic binder must be applied. To maximize mechanical advantage and effectively reduce pelvic volume, the binder should be centered directly over which of the following anatomic structures?

. Iliac crests
. Greater trochanters
. Symphysis pubis
. Anterior superior iliac spines
. Umbilicus

Correct Answer & Explanation

. Iliac crests

Explanation

Pelvic binders should be placed at the level of the greater trochanters to directly compress the pelvic ring and reduce the symphyseal diastasis effectively. Placement over the iliac crests is incorrect and can paradoxically widen the true pelvis.

Question 7853

Topic: 2. Trauma

A 35-year-old male sustains a high-energy Gustilo-Anderson type IIIB open tibia fracture with massive periosteal stripping and gross contamination from a farming accident. According to recent trauma guidelines, what is the most appropriate initial empiric antibiotic regimen?

. First-generation cephalosporin alone
. First-generation cephalosporin and an aminoglycoside
. Ceftriaxone alone or a first-generation cephalosporin with an aminoglycoside
. Vancomycin and Piperacillin-Tazobactam
. Penicillin G and Clindamycin

Correct Answer & Explanation

. First-generation cephalosporin alone

Explanation

Current EAST guidelines recommend broad Gram-negative and Gram-positive coverage for type III open fractures, typically achieved with Ceftriaxone or a combination of Cefazolin and Gentamicin. High-dose Penicillin is historically added for farm injuries (Clostridium), but modern broad-spectrum regimens often suffice.

Question 7854

Topic: 2. Trauma

A 22-year-old male with an isolated closed femoral shaft fracture develops confusion, tachypnea, and a petechial rash on his chest 48 hours post-injury. Which of the following interventions has been proven to be most effective in preventing this specific syndrome?

. Prophylactic administration of corticosteroids
. Early operative stabilization of the fracture
. Placement of an inferior vena cava (IVC) filter
. Prophylactic therapeutic heparinization
. Hyperbaric oxygen therapy

Correct Answer & Explanation

. Prophylactic administration of corticosteroids

Explanation

This patient has classic Fat Embolism Syndrome (FES). The most effective prophylactic measure against FES in patients with long bone fractures is early definitive surgical stabilization, ideally within the first 24 hours.

Question 7855

Topic: 2. Trauma

A 45-year-old male sustains a subtrochanteric fracture of the femur. Radiographs demonstrate the classic deformity of the proximal fragment, which is flexed, abducted, and externally rotated. Which muscle is primarily responsible for the flexion deformity of the proximal fragment?

. Gluteus medius
. Gluteus maximus
. Iliopsoas
. Short external rotators
. Adductor magnus

Correct Answer & Explanation

. Gluteus medius

Explanation

In a subtrochanteric femur fracture, the iliopsoas muscle pulls the proximal fragment into flexion. The gluteus medius and minimus pull it into abduction, while the short external rotators pull it into external rotation.

Question 7856

Topic: 2. Trauma

A 30-year-old male undergoes reamed intramedullary nailing for a closed tibial shaft fracture. In the PACU, he complains of severe, escalating leg pain. His blood pressure is 110/70 mmHg. Intracompartmental pressure monitoring reveals an anterior compartment pressure of 45 mmHg. What is the most appropriate management?

. Elevate the leg above heart level and closely observe
. Administer intravenous mannitol and dexamethasone
. Emergent four-compartment fasciotomy
. Remove the intramedullary nail immediately
. Perform an MRI of the lower extremity

Correct Answer & Explanation

. Elevate the leg above heart level and closely observe

Explanation

The delta pressure (diastolic blood pressure minus compartment pressure) is 70 - 45 = 25 mmHg. A delta pressure of 30 mmHg or less is an absolute indication for an emergent fasciotomy to treat acute compartment syndrome.

Question 7857

Topic: 2. Trauma

A 25-year-old male is brought in after a motorcycle crash. He has a closed left femoral shaft fracture, bilateral pulmonary contusions, and a grade III liver laceration. Current vitals: BP 85/50, HR 120, Temp 35.0 C. Arterial blood gas shows pH 7.21, Base Excess -8, and Lactate 5.2 mmol/L. What is the most appropriate management of his femur fracture?

. Reamed antegrade intramedullary nailing
. Unreamed retrograde intramedullary nailing
. External fixation
. Skeletal traction
. Plate osteosynthesis

Correct Answer & Explanation

. Reamed antegrade intramedullary nailing

Explanation

This patient is hemodynamically unstable and acidotic, meeting criteria for damage control orthopedics (DCO). Immediate external fixation minimizes additional surgical trauma while stabilizing the fracture. Definitive fixation (IM nailing) is delayed until his physiologic status improves.

Question 7858

Topic: 2. Trauma

A 34-year-old male presents with a comminuted proximal tibia fracture. He complains of pain out of proportion to the injury. Vitals: BP 110/70. Intracompartmental pressure testing reveals a pressure of 45 mm Hg in the anterior compartment. What is the most accurate indicator for four-compartment fasciotomy in this patient?

. Absolute compartment pressure > 30 mm Hg
. Delta pressure (Diastolic BP - Compartment Pressure) < 30 mm Hg
. Delta pressure (Mean Arterial Pressure - Compartment Pressure) < 30 mm Hg
. Loss of palpable dorsalis pedis pulse
. Paresthesias in the deep peroneal nerve distribution

Correct Answer & Explanation

. Absolute compartment pressure > 30 mm Hg

Explanation

The most reliable threshold for diagnosing acute compartment syndrome is a delta pressure (diastolic blood pressure minus compartment pressure) of less than 30 mm Hg. Relying on absolute pressure alone can lead to overtreatment, while pulse loss and paresthesias are late and unreliable findings.

Question 7859

Topic: 2. Trauma

A 28-year-old female sustains a severe open tibia fracture (Gustilo-Anderson Type IIIA) with heavy soil contamination after an ATV accident. She has no known drug allergies. What is the most appropriate initial intravenous antibiotic regimen?

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

Correct Answer & Explanation

. First-generation cephalosporin alone

Explanation

For highly contaminated open fractures, especially those involving soil or agricultural environments, coverage for Clostridium species is required. The standard recommendation is a first-generation cephalosporin, an aminoglycoside, and penicillin (or metronidazole) for anaerobic coverage.

Question 7860

Topic: Pelvic & Acetabular Trauma

A 50-year-old male is brought to the trauma bay after a high-speed motor vehicle collision. He is hypotensive (BP 75/40). Primary survey reveals an unstable pelvis to manual compression. A pelvic binder is ordered. What is the correct anatomic landmark for centering the pelvic binder?

. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Ischial tuberosities

Correct Answer & Explanation

. Iliac crests

Explanation

Pelvic binders must be centered over the greater trochanters to effectively reduce pelvic ring volume and control hemorrhage. Placement over the iliac crests is incorrect and can exacerbate certain fracture patterns or cause abdominal compression.

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