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2. Trauma MCQs

Practice Set 291 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 5801

Topic: 2. Trauma

A 22-year-old male presents with wrist pain after a fall. Radiographs reveal a displaced fracture through the proximal pole of the scaphoid. Why does this specific fracture pattern carry a significantly high risk of nonunion and avascular necrosis?

. The scaphoid lacks a periosteal blood supply completely.
. The primary blood supply enters distally and flows retrograde.
. The volar carpal branch supplies only the proximal pole.
. The proximal pole consists exclusively of avascular cartilage.
. It is always associated with complete scapholunate ligament tears.

Correct Answer & Explanation

. The primary blood supply enters distally and flows retrograde.

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters at the distal pole and perfuses the bone in a retrograde fashion. Fractures at the proximal pole isolate the fragment from this retrograde flow, drastically increasing AVN risk.

Question 5802

Topic: 2. Trauma

A 35-year-old male sustains a closed, highly comminuted tibial pilon fracture (OTA 43C) with marked soft tissue swelling and fracture blisters circumferentially. What is the optimal initial operative management?

. Immediate ORIF with dual anatomic plating
. Immediate intramedullary nailing
. Application of a short leg cast
. Primary tibiotalar arthrodesis
. Spanning external fixation with delayed definitive ORIF

Correct Answer & Explanation

. Spanning external fixation with delayed definitive ORIF

Explanation

Severe pilon fractures with significant soft tissue compromise are best managed with a "span, scan, and plan" protocol. Temporary spanning external fixation allows the precarious soft tissue envelope to heal prior to definitive open reduction and internal fixation.

Question 5803

Topic: 2. Trauma
A 40-year-old farmer sustains an open tibial shaft fracture in a barnyard with massive soft tissue stripping and bone loss (Gustilo-Anderson IIIB). According to advanced trauma guidelines, which intravenous antibiotic regimen is most appropriate upon initial presentation?
. Cefazolin alone
. Ceftriaxone alone
. Cefazolin and Gentamicin
. Cefazolin, Gentamicin, and Penicillin
. Vancomycin and Piperacillin-Tazobactam

Correct Answer & Explanation

. Cefazolin, Gentamicin, and Penicillin

Explanation

For Gustilo IIIB fractures, gram-positive and gram-negative coverage (like a first-generation cephalosporin and an aminoglycoside) is standard. In environments heavily contaminated with soil or feces (barnyard), Penicillin is added to specifically cover Clostridium species and prevent gas gangrene.

Question 5804

Topic: 2. Trauma

A 20-year-old elite collegiate basketball player develops lateral foot pain. Radiographs show a non-displaced transverse fracture at the metaphyseal-diaphyseal junction of the 5th metatarsal (Zone 2). To ensure the quickest and most reliable return to sport, what is the recommended treatment?

. Hard-soled shoe weight-bearing as tolerated for 4 weeks
. Short leg non-weight-bearing cast for 8 weeks
. Excision of the proximal bone fragment
. Intramedullary screw fixation
. Extracorporeal shockwave therapy

Correct Answer & Explanation

. Intramedullary screw fixation

Explanation

Zone 2 fractures (Jones fractures) occur in a vascular watershed area and have a high rate of nonunion. In competitive athletes, early intramedullary screw fixation is the standard of care to accelerate healing and prevent delayed union or refracture.

Question 5805

Topic: 2. Trauma
A 50-year-old male sustains a lateral tibial plateau fracture. CT demonstrates a purely central articular depression with a completely intact lateral cortical rim (Schatzker Type III). What is the preferred surgical approach for elevating the joint surface?
. Extensile anterolateral arthrotomy with submeniscal exposure
. Posterior midline approach with neurovascular mobilization
. Medial approach with placement of an anti-glide plate
. Creation of a metaphyseal cortical window for bone tamping
. Application of a circular fine-wire external fixator

Correct Answer & Explanation

. Creation of a metaphyseal cortical window for bone tamping

Explanation

In a Schatzker Type III pure depression fracture, the lateral cortex is intact. The joint surface is best elevated by creating a small cortical window in the metaphysis, using a bone tamp to push the depressed fragment superiorly, followed by bone grafting and raft screw fixation.

Question 5806

Topic: 2. Trauma

A surgeon is comparing two different fixation constructs for a distal femur fracture: a locking plate and a standard dynamic compression plate (DCP). Which biomechanical property is most enhanced by the locking plate design, leading to improved stability in osteoporotic bone?

. Axial stiffness
. Torsional stiffness
. Screw pullout strength
. Interfragmentary motion
. Plate contourability

Correct Answer & Explanation

. Screw pullout strength

Explanation

Locking plates provide angular stability, meaning the screw heads lock into the plate, creating a fixed-angle construct. This effectively transforms the screw-plate interface into a rigid unit, making the construct behave more like an internal fixator rather than a compression device. This design significantly enhances screw pullout strength, particularly critical in osteoporotic bone where the bone-screw interface strength is compromised. While locking plates also offer good axial and torsional stability and reduce interfragmentary motion, their primary advantage in osteoporotic bone stems from their superior screw purchase and resistance to pullout due to the fixed-angle design. Plate contourability is generally less than DCPs for locking plates, as over-contouring can lead to screw divergence.

Question 5807

Topic: 2. Trauma

The primary blood supply to the diaphysis of a long bone, particularly in adults, is typically derived from which of the following?

. Metaphyseal arteries
. Epiphyseal arteries
. Periosteal arteries
. Nutrient artery
. Articular arterial networks

Correct Answer & Explanation

. Nutrient artery

Explanation

The blood supply to long bones is complex. The nutrient artery, which typically enters the diaphysis through a nutrient foramen, is the principal supplier to the bone marrow, inner two-thirds of the cortical bone, and part of the metaphysis. The periosteal arteries, originating from surrounding musculature, supply the outer one-third of the cortical bone. The metaphyseal and epiphyseal arteries supply those respective regions, often forming anastomotic networks. In adults, especially with intact periosteum, the nutrient artery remains dominant for the diaphysis, although the periosteal supply becomes more critical in situations like stripping of the periosteum or after intramedullary reaming.

Question 5808

Topic: 2. Trauma

Intramedullary nails are favored for diaphyseal long bone fractures due to their load-sharing capabilities. This load-sharing characteristic primarily reduces which biomechanical phenomenon at the fracture site compared to plate fixation?

. Torsional stiffness
. Bending stiffness
. Stress concentration
. Stress shielding
. Interfragmentary motion

Correct Answer & Explanation

. Stress shielding

Explanation

Stress shielding occurs when an implant carries a disproportionately high amount of the load, thereby reducing the stress experienced by the adjacent bone. Bone adapts to stress (Wolff's Law), so reduced stress can lead to bone loss (osteopenia). Intramedullary nails are load-sharing devices because they are placed within the medullary canal, closer to the mechanical axis of the bone. This central placement allows them to share axial loads more effectively with the bone than eccentrically placed plates. By distributing load more naturally, intramedullary nails minimize stress shielding of the bone cortex, which is beneficial for bone remodeling and long-term bone quality. While they influence bending and torsional stiffness, the primary advantage for bone physiology is reduced stress shielding.

Question 5809

Topic: Pelvic & Acetabular Trauma

The articular cartilage in a healthy synovial joint is primarily a type of:

. Elastic cartilage
. Fibrocartilage
. Hyaline cartilage
. Calcified cartilage
. Reticular cartilage

Correct Answer & Explanation

. Hyaline cartilage

Explanation

Articular cartilage, which covers the ends of bones in synovial joints, is a specialized form of hyaline cartilage. Hyaline cartilage is characterized by a matrix rich in Type II collagen and aggrecan, providing a smooth, resilient, and low-friction surface crucial for joint movement. It lacks blood vessels, nerves, and lymphatic vessels, relying on synovial fluid for nutrition. Fibrocartilage, found in menisci, intervertebral discs, and pubic symphysis, has a higher proportion of Type I collagen and is more resistant to tensile forces. Elastic cartilage is found in the ear and epiglottis.

Question 5810

Topic: 2. Trauma
In the Gustilo-Anderson classification system for open fractures, what is the key differentiating factor between a Type II and a Type IIIA fracture?
. Size of the skin wound
. Degree of contamination
. Extent of periosteal stripping
. Amount of soft tissue coverage
. Presence of neurovascular injury

Correct Answer & Explanation

. Amount of soft tissue coverage

Explanation

The Gustilo-Anderson classification is crucial for guiding management of open fractures. Type II fractures have moderate soft tissue damage and a wound greater than 1 cm in length, with minimal periosteal stripping. Type IIIA fractures are characterized by extensive soft tissue damage, regardless of wound size, but crucially, there is adequate soft tissue coverage of the bone. This implies that while the soft tissue injury is significant and typically involves high-energy trauma, it doesn't necessitate a regional or free flap for closure, distinguishing it from Type IIIB where bone exposure requires such intervention. Therefore, the extent of soft tissue damage impacting the viability for coverage is the primary discriminator between Type II (moderate damage) and Type IIIA (extensive damage, but still with adequate coverage).

Question 5811

Topic: 2. Trauma
Following major orthopedic trauma (e.g., polytrauma), the acute phase response involves a systemic release of various mediators. Which cytokine is considered a primary pro-inflammatory mediator released immediately after trauma, contributing to the systemic inflammatory response syndrome (SIRS)?
. Interleukin-10 (IL-10)
. Transforming growth factor-beta (TGF-β)
. Tumor necrosis factor-alpha (TNF-α)
. Interleukin-4 (IL-4)
. Erythropoietin

Correct Answer & Explanation

. Tumor necrosis factor-alpha (TNF-α)

Explanation

Major orthopedic trauma triggers a complex systemic inflammatory response, often termed the acute phase response or systemic inflammatory response syndrome (SIRS). Key pro-inflammatory cytokines, such as Tumor Necrosis Factor-alpha (TNF-α), Interleukin-1 (IL-1), and Interleukin-6 (IL-6), are rapidly released by activated immune cells (e.g., macrophages, neutrophils) and injured tissues. These cytokines mediate many of the systemic effects of trauma, including fever, leukocytosis, acute phase protein production, and metabolic changes. IL-10 and TGF-β are generally anti-inflammatory or regulatory cytokines that appear later to modulate the response. IL-4 is associated with allergic reactions and parasitic infections. Erythropoietin stimulates red blood cell production.

Question 5812

Topic: 2. Trauma

When applying a standard stainless steel plate for fracture fixation, modifying the dimensions of the plate alters its mechanical properties. The bending stiffness of the plate is proportional to which of the following?

. The square of its width
. The cube of its width
. The square of its thickness
. The cube of its thickness
. The inverse of its length

Correct Answer & Explanation

. The cube of its thickness

Explanation

The area moment of inertia for a rectangular plate is (base x height^3)/12. Therefore, the bending stiffness is linearly proportional to the width (base) and proportional to the cube of its thickness (height).

Question 5813

Topic: 2. Trauma

A 28-year-old male undergoes intramedullary nailing for a closed tibial shaft fracture. Twelve hours postoperatively, he complains of severe leg pain out of proportion to the injury, requiring escalating doses of opioids. Pain is exacerbated by passive dorsiflexion of the toes. His diastolic blood pressure is 75 mmHg and intracompartmental pressure of the anterior compartment is measured at 48 mmHg. What is the most appropriate management?

. Elevate the leg above heart level and observe
. Administer intravenous mannitol
. Immediate four-compartment fasciotomy
. Bivalve the cast and reassess in 2 hours
. Obtain an urgent duplex ultrasound to rule out DVT

Correct Answer & Explanation

. Immediate four-compartment fasciotomy

Explanation

This patient has acute compartment syndrome, indicated by pain out of proportion, pain on passive stretch, and a delta pressure (diastolic BP minus compartment pressure) of less than 30 mmHg (75 - 48 = 27 mmHg). Immediate four-compartment fasciotomy is the definitive treatment.

Question 5814

Topic: 2. Trauma

A 25-year-old motorcyclist sustains a vertically unstable (Tile C) pelvic ring injury. Cranial migration of the hemipelvis is primarily driven by which muscle?

. Rectus abdominis
. Quadratus lumborum
. Psoas major
. Gluteus maximus
. Piriformis

Correct Answer & Explanation

. Quadratus lumborum

Explanation

Quadratus lumborum provides the primary deforming force causing vertical migration in unstable pelvic fractures. It originates on the iliac crest and pulls the hemipelvis proximally.

Question 5815

Topic: 2. Trauma

A 30-year-old man sustains a closed tibial shaft fracture. Which clinical finding is the most sensitive early indicator of acute compartment syndrome?

. Absence of distal pulses
. Paresthesia in the first web space
. Pain with passive stretch of the toes
. Paralysis of the extensor hallucis longus
. Pallor of the foot

Correct Answer & Explanation

. Pain with passive stretch of the toes

Explanation

Pain out of proportion to the injury and pain with passive stretching of the affected compartment's muscles are the earliest and most sensitive clinical signs. Pulselessness and pallor are late, unreliable signs of irreversible ischemia.

Question 5816

Topic: 2. Trauma

A Schatzker IV (medial tibial plateau) fracture is notoriously associated with a high rate of which concomitant injury?

. Popliteal artery injury
. Anterior tibial artery transection
. Patellar tendon rupture
. Superficial peroneal nerve neuropraxia
. Medial meniscus root tear

Correct Answer & Explanation

. Popliteal artery injury

Explanation

Schatzker IV fractures involve the medial tibial plateau and represent high-energy trauma often associated with knee subluxation or dislocation. They carry a significantly high risk of popliteal artery injury.

Question 5817

Topic: 2. Trauma

During a two-incision fasciotomy of the lower leg for compartment syndrome, which compartment is most frequently inadequately decompressed?

. Anterior compartment
. Lateral compartment
. Superficial posterior compartment
. Deep posterior compartment
. Tibialis posterior compartment

Correct Answer & Explanation

. Deep posterior compartment

Explanation

The deep posterior compartment is the most frequently missed compartment during fasciotomies because of its deep anatomic location surrounded by dense fascia. Inadequate decompression here can lead to severe ischemic contractures of the toe flexors.

Question 5818

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay with an anteroposterior compression (APC-III) pelvic ring injury. Despite application of a pelvic binder, 2L of crystalloid, and 2 units of uncrossmatched blood, his blood pressure remains 80/50 mmHg. A FAST exam is negative. What is the most appropriate next step?
. CT scan of the abdomen and pelvis
. Pelvic packing or immediate angiography
. Exploratory laparotomy
. Definitive anterior and posterior pelvic fixation
. Removal of the pelvic binder to assess for REBOA placement

Correct Answer & Explanation

. Pelvic packing or immediate angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, retroperitoneal venous or arterial bleeding is the primary culprit. Preperitoneal pelvic packing or angiography is the most appropriate next step to achieve hemostasis.

Question 5819

Topic: 2. Trauma

A 25-year-old male with a closed tibia fracture treated with intramedullary nailing develops severe, disproportionate leg pain. Which intracompartmental pressure measurement is the most reliable threshold for performing a four-compartment fasciotomy?

. Absolute pressure greater than 20 mmHg
. Absolute pressure greater than 30 mmHg
. Diastolic blood pressure minus compartment pressure less than 30 mmHg
. Mean arterial pressure minus compartment pressure less than 40 mmHg
. Systolic blood pressure minus compartment pressure less than 50 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure less than 30 mmHg

Explanation

A delta pressure (diastolic blood pressure minus intra-compartmental pressure) of less than 30 mmHg is the most reliable clinical indicator for acute compartment syndrome. Absolute pressures alone can be misleading, especially in hypotensive trauma patients.

Question 5820

Topic: Pelvic & Acetabular Trauma

A 13-year-old obese male presents with left groin pain and obligatory external rotation of the hip during flexion. Imaging confirms a severe slipped upper femoral epiphysis (SUFE). Anatomically, what is the primary mechanism of deformity in this condition?

. Anterior and superior displacement of the epiphysis
. Anterior and superior displacement of the metaphysis
. Posterior and inferior displacement of the metaphysis
. Posterior and superior displacement of the metaphysis
. Medial and inferior displacement of the epiphysis

Correct Answer & Explanation

. Anterior and superior displacement of the metaphysis

Explanation

In SUFE, the epiphysis remains relatively secured in the acetabulum by the ligamentum teres. The deformity is actually caused by the femoral neck (metaphysis) displacing anteriorly and superiorly relative to the epiphysis.

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