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2. Trauma MCQs

Practice Set 494 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 9861

Topic: 2. Trauma
A 30-year-old male sustains a Gustilo-Anderson Type IIIC open tibial shaft fracture after being struck by a vehicle. He presents with significant soft tissue loss, exposed bone, and a non-viable dorsalis pedis artery requiring vascular repair. After initial debridement, external fixation, and vascular reconstruction, what is the most appropriate next step in the reconstructive ladder for definitive soft tissue coverage and fracture management?
. Delayed primary closure and intramedullary nailing.
. Local rotation flap and plate fixation.
. Free tissue transfer (e.g., free fibula flap) and intramedullary nailing.
. Split-thickness skin graft and circular external fixation.
. Amputation due to the severity of the injury.

Correct Answer & Explanation

. Free tissue transfer (e.g., free fibula flap) and intramedullary nailing.

Explanation

A Gustilo-Anderson Type IIIC open tibial fracture is characterized by extensive soft tissue damage and a major arterial injury requiring repair, making it one of the most severe open fractures. After initial damage control (debridement, external fixation, vascular repair), definitive soft tissue coverage and fracture stabilization are paramount. Given the significant soft tissue loss and exposed bone, a simple delayed primary closure (Option A) or split-thickness skin graft (Option D) is insufficient. Local rotation flaps (Option B) may be considered if sufficient healthy surrounding tissue is available, but for large defects and exposed bone, especially after vascular repair, a free tissue transfer (free flap) (Option C) is often necessary. A free fibula flap or a large muscle flap (e.g., latissimus dorsi) can provide robust, vascularized tissue for coverage and, in the case of the fibula, bone for reconstruction, allowing for definitive fracture fixation (e.g., intramedullary nailing) once soft tissue coverage is achieved. Amputation (Option E) is a last resort, usually for unsalvageable limbs. The reconstructive ladder principle guides this decision-making, and free tissue transfer is high on the ladder for complex defects.

Question 9862

Topic: 2. Trauma
A patient sustained a high-velocity rifle wound to the proximal tibia, resulting in a Gustilo-Anderson Type IIIB open fracture with significant bone loss and compromised soft tissue, but no major neurovascular injury. What is the primary initial goal of surgical management for this complex injury?
. Immediate definitive reconstruction of bone and soft tissue
. Aggressive debridement of all devitalized tissue and fracture stabilization
. Application of external fixation for temporary stability and delayed wound closure
. Antibiotic administration and serial wound checks for infection
. Primary closure of the wound over the fracture site

Correct Answer & Explanation

. Aggressive debridement of all devitalized tissue and fracture stabilization

Explanation

For a high-velocity, Gustilo-Anderson Type IIIB open fracture, the primary initial surgical goal is aggressive and thorough debridement of all devitalized bone and soft tissue to minimize the risk of infection. Following debridement, fracture stabilization (typically with external fixation as a temporary measure) is performed. Definitive bone and soft tissue reconstruction is usually staged, not immediate. While antibiotic administration is crucial, it's adjunctive to surgical debridement. Primary wound closure is contraindicated due to high infection risk in Type IIIB injuries. The immediate focus is on converting a contaminated wound to a clean, stable environment.

Question 9863

Topic: 2. Trauma

A 45-year-old patient sustains a terrible triad injury of the elbow (posterior dislocation, radial head fracture, coronoid fracture). Following successful open reduction and internal fixation of all components, post-operative radiographs show good alignment and stable fixation. What is the most critical aspect of the early post-operative rehabilitation protocol to optimize the outcome and prevent stiffness?

. Complete immobilization in a long arm cast for a minimum of 6 weeks
. Early protected range of motion (ROM) initiated within the first week
. Immediate full weight-bearing and strengthening exercises
. Dynamic splinting to achieve full extension within 2 weeks
. Continuous passive motion (CPM) for 24 hours a day

Correct Answer & Explanation

. Early protected range of motion (ROM) initiated within the first week

Explanation

For a terrible triad injury of the elbow, once stability is achieved surgically, early protected range of motion (ROM) is critical. Prolonged immobilization significantly increases the risk of severe elbow stiffness, which is a common complication. Motion should ideally be initiated within the first week, often in a hinged brace with controlled arcs of motion to protect the repairs. Complete immobilization for 6 weeks would lead to severe stiffness. Immediate full weight-bearing and strengthening are too aggressive. Dynamic splinting may be used later to address specific motion deficits, not as an immediate primary approach. CPM is not universally favored over active-assisted ROM, and 24-hour CPM is excessive.

Question 9864

Topic: 2. Trauma

A patient with a Young-Burgess Type APC-II pelvic ring injury presents with hemodynamic instability despite initial fluid resuscitation. Clinical examination reveals signs of ongoing hemorrhage. What is the most critical immediate intervention following initial stabilization with a pelvic binder/external fixation?

. Emergent internal fixation of the anterior and posterior pelvic ring
. Diagnostic peritoneal lavage to assess for intra-abdominal bleeding
. Angiography with embolization of bleeding vessels
. Transfer to the operating room for exploratory laparotomy
. Massive transfusion protocol initiation

Correct Answer & Explanation

. Angiography with embolization of bleeding vessels

Explanation

For a hemodynamically unstable patient with an APC-II pelvic ring injury (which indicates significant disruption of the anterior ring, often with posterior ligamentous injury) despite initial resuscitation and pelvic stabilization (binder/external fixation), ongoing hemorrhage is typically from venous plexus or arterial sources. Angiography with embolization is the most critical immediate intervention to control arterial bleeding, which is a major contributor to hemodynamic instability in pelvic fractures. While massive transfusion protocol will be initiated and exploratory laparotomy might be considered for intra-abdominal organ injury (less common in APC-II than open book), controlling the pelvic vascular bleed via angiography is paramount. Emergent internal fixation is a definitive step, but not for initial hemorrhage control. Diagnostic peritoneal lavage is less sensitive for retroperitoneal hemorrhage and not the primary method for identifying the source of instability in a pelvic fracture.

Question 9865

Topic: 2. Trauma

A patient sustains a high-energy trauma resulting in an open tibial fracture with significant muscle damage and a large soft tissue defect. During the healing process, what is the primary role of satellite cells in skeletal muscle repair and regeneration?

. Synthesizing new collagen to form scar tissue
. Differentiating into fibroblasts to enhance wound contraction
. Acting as quiescent adult stem cells that activate, proliferate, and differentiate into new myofibers
. Secreting growth factors that inhibit angiogenesis
. Regulating bone marrow stromal cell activity

Correct Answer & Explanation

. Acting as quiescent adult stem cells that activate, proliferate, and differentiate into new myofibers

Explanation

Satellite cells are quiescent, undifferentiated myogenic precursor cells located between the sarcolemma and the basal lamina of mature muscle fibers. In response to muscle injury, these cells become activated, proliferate, and then differentiate into myoblasts. These myoblasts fuse to form new myofibers or fuse with existing damaged myofibers, thereby contributing to muscle repair and regeneration. They are the primary source of new muscle cells following injury. Fibroblasts, not satellite cells, are primarily responsible for collagen synthesis and scar tissue formation, though some satellite cells can adopt a fibrotic fate in severe chronic injury. They do not inhibit angiogenesis nor directly regulate bone marrow stromal cells.

Question 9866

Topic: 2. Trauma

Considering the principles of fracture fixation, what is the primary biomechanical advantage of using a dynamic compression plate (DCP) over a non-locking plate for diaphyseal long bone fractures?

. The DCP promotes secondary bone healing through micromotion at the fracture site.
. The DCP maintains an absolute rigid fixation, eliminating all motion and promoting primary bone healing.
. The DCP provides angular stability, which is crucial for comminuted fractures.
. The DCP allows for controlled compression across the fracture site as screws are tightened, enhancing stability and reducing interfragmentary gap.
. The DCP minimizes stress shielding by having a lower modulus of elasticity.

Correct Answer & Explanation

. The DCP allows for controlled compression across the fracture site as screws are tightened, enhancing stability and reducing interfragmentary gap.

Explanation

The primary biomechanical advantage of a dynamic compression plate (DCP) is its ability to generate and maintain axial compression across the fracture site. This is achieved through the design of its screw holes, which are eccentrically drilled, allowing the screw head to slide down an inclined plane as it is tightened, pulling the bone fragment towards the plate and creating compression at the fracture interface. This compression enhances stability, reduces the interfragmentary gap, and promotes primary bone healing. While it aims for rigid fixation, 'eliminating all motion' is an ideal that is hard to achieve, and some micromotion can still occur. It does not primarily provide angular stability (that's locking plates). It does not necessarily promote secondary healing through micromotion; it aims for rigid fixation for primary healing. It typically uses steel or titanium, which have higher moduli than bone, thus causing stress shielding.

Question 9867

Topic: 2. Trauma

A patient experiences significant disuse muscle atrophy after prolonged immobilization following a fracture. Which molecular pathway is primarily activated in skeletal muscle during disuse to promote protein degradation?

. mTOR signaling pathway
. Insulin-like growth factor 1 (IGF-1) pathway
. Ubiquitin-proteasome system (UPS)
. Satellite cell activation pathway
. Glycolytic pathway

Correct Answer & Explanation

. Ubiquitin-proteasome system (UPS)

Explanation

The ubiquitin-proteasome system (UPS) is the primary intracellular proteolytic pathway responsible for the degradation of most muscle proteins during disuse atrophy. Key ubiquitin ligases, such as MuRF1 (Muscle RING-finger protein 1) and MAFbx/Atrogin-1, are upregulated during atrophy and tag proteins with ubiquitin, targeting them for degradation by the 26S proteasome. The mTOR (mammalian target of rapamycin) and IGF-1 pathways are typically involved in protein synthesis and muscle growth/hypertrophy. Satellite cell activation is involved in muscle repair and regeneration. The glycolytic pathway is for energy production, not protein degradation.

Question 9868

Topic: 2. Trauma

The development of non-union in long bone fractures, despite adequate reduction and fixation, is a complex biological problem. Which of the following conditions is most directly associated with a high risk of developing an 'atrophic' non-union?

. Excessive interfragmentary motion leading to hypertrophic callus.
. Severe comminution and significant bone loss at the fracture site.
. An underlying inflammatory arthropathy with elevated cytokine levels.
. Systemic infection with Gram-positive bacteria.
. Early weight-bearing with stable internal fixation.

Correct Answer & Explanation

. Severe comminution and significant bone loss at the fracture site.

Explanation

Atrophic non-union is characterized by a lack of biological activity at the fracture site, with minimal callus formation. This type of non-union typically results from inadequate biology, such as poor vascularity, severe soft tissue injury, or significant bone loss/gaps. When there is severe comminution and significant bone loss, the biological environment is severely compromised (lack of osteoprogenitor cells, growth factors, and often vascular supply), leading to an atrophic non-union. Option B is correct. Option A describes a hypertrophic non-union, which is biologically active but fails to unite due to excessive motion. Option C is a systemic factor, but less directly linked to the atrophic vs. hypertrophic distinction in the context of the fracture site's local biology. Option D would lead to an infected non-union, a separate category. Option E would generally promote healing with stable fixation, though premature excessive weight-bearing could lead to fixation failure, not directly an atrophic non-union.

Question 9869

Topic: 2. Trauma

A research group is investigating advanced fracture fixation techniques to optimize biological healing. They are particularly interested in techniques that promote stable vascularity and intramembranous bone formation. Which of the following fracture fixation principles would be most conducive to facilitating early intramembranous healing?

. Rigid absolute stability provided by lag screws and compression plates.
. Flexible fixation with controlled micromotion, typical of external fixators.
. Intramedullary nailing providing relative stability and preserving periosteal blood supply.
. Dynamic compression plating with minimal periosteal stripping.
. Bone grafting with osteoconductive ceramic materials.

Correct Answer & Explanation

. Intramedullary nailing providing relative stability and preserving periosteal blood supply.

Explanation

Intramembranous ossification (direct bone formation without a cartilage intermediate) is typically favored by stable fixation and adequate blood supply. Intramedullary nailing, especially reamed nailing, provides relative stability (allowing for some micromotion, which can be beneficial for callus formation) while critically preserving the periosteal blood supply, which is vital for intramembranous healing. It also distributes load along the entire length of the bone. Option C is correct. Option A (absolute rigidity with compression plating) tends to promote primary bone healing, which is intramembranous but relies on direct bone-to-bone contact, not typically a robust callus. Option B (flexible fixation with external fixators) is more associated with secondary (endochondral) healing. Option D, while preserving periosteum, compression plating can often strip the periosteum locally and achieve absolute stability, pushing towards primary healing. Option E is an adjunct for improving biology but not a fixation principle.

Question 9870

Topic: 2. Trauma

Regarding the pathophysiology of acute compartment syndrome, which cellular event is the most direct cause of irreversible muscle and nerve damage?

. Increased extracellular fluid leading to tissue edema.
. Compression of small veins leading to venous congestion.
. Impaired arterial perfusion and cellular ischemia.
. Accumulation of metabolic waste products.
. Direct mechanical trauma to muscle fibers.

Correct Answer & Explanation

. Impaired arterial perfusion and cellular ischemia.

Explanation

The most direct cause of irreversible damage in acute compartment syndrome is impaired arterial perfusion leading to cellular ischemia. While increased extracellular fluid and venous congestion occur first, the critical step in the vicious cycle is when the intracompartmental pressure rises above capillary perfusion pressure. This halts arterial blood flow to the muscles and nerves, leading to hypoxia, energy depletion, and ultimately cell death (ischemia). Accumulation of metabolic waste and mechanical trauma are contributing factors or consequences, not the primary irreversible cellular event.

Question 9871

Topic: 2. Trauma

A 22-year-old man sustains a proximal pole fracture of the scaphoid. The high risk of avascular necrosis in this region is due to the retrograde blood supply primarily derived from which of the following vessels?

. Palmar carpal branch of the radial artery
. Dorsal carpal branch of the radial artery
. Superficial palmar arch
. Deep palmar arch
. Anterior interosseous artery

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

The primary blood supply to the scaphoid (supplying 70-80% of the bone, including the entire proximal pole) is from the dorsal carpal branch of the radial artery. It enters the scaphoid at the dorsal ridge distally and flows in a retrograde fashion proximally, making proximal pole fractures highly susceptible to nonunion and avascular necrosis.

Question 9872

Topic: 2. Trauma

A 6-month-old infant is evaluated for multiple fractures with no clear history of trauma. Radiographs show multiple healing fractures of different ages, osteopenia, and wormian bones in the skull. Which of the following clinical findings would most strongly support a diagnosis of Osteogenesis Imperfecta over non-accidental trauma?

. Posterior rib fractures
. Metaphyseal corner fractures
. Blue sclerae and dentinogenesis imperfecta
. Subdural hematoma
. Retinal hemorrhages

Correct Answer & Explanation

. Blue sclerae and dentinogenesis imperfecta

Explanation

Blue sclerae and dentinogenesis imperfecta are classic systemic manifestations of Osteogenesis Imperfecta (OI) caused by defective Type I collagen, which is present in sclera and dentin. Posterior rib fractures, metaphyseal corner fractures (classic metaphyseal lesions), subdural hematomas, and retinal hemorrhages are highly specific indicators of non-accidental trauma (child abuse).

Question 9873

Topic: 2. Trauma

A 5-year-old boy with Osteogenesis Imperfecta (OI) presents with bowing of the bilateral femurs.

He undergoes placement of telescoping intramedullary rods (Fassier-Duval). What is the most common mechanical complication associated with this specific type of implant?

. Infection
. Nonunion of the osteotomy site
. Proximal migration of the female component
. Fat embolism syndrome
. Failure of the rod to elongate with growth

Correct Answer & Explanation

. Failure of the rod to elongate with growth

Explanation

The most common complication of telescoping rods in growing children with OI is failure of the rod to elongate (telescope) with growth. This often leads to the bone growing past the tip of the rod, resulting in a new fracture or recurrent deformity.

Question 9874

Topic: 2. Trauma

A 6-month-old infant presents to the ED with a spiral fracture of the femur. The parents, who both have normal physical exams, claim the infant rolled off a low bed. Radiographs reveal the femur fracture and multiple classic metaphyseal lesions (corner fractures) of the distal tibias. Which of the following strongly supports non-accidental trauma rather than Osteogenesis Imperfecta?

. The presence of a spiral femur fracture
. The presence of classic metaphyseal lesions
. A family history of recurrent fractures
. Osteopenia on radiographs
. Wormian bones on skull radiographs

Correct Answer & Explanation

. The presence of classic metaphyseal lesions

Explanation

Classic metaphyseal lesions (CMLs), or corner fractures, are highly specific for non-accidental trauma (NAT) and are caused by shearing forces. They are not characteristic of Osteogenesis Imperfecta, which typically presents with diaphyseal fractures.

Question 9875

Topic: 2. Trauma

Children with Spinal Muscular Atrophy have a high incidence of fragility fractures. Which of the following principles should strictly guide the orthopedic management of a femur fracture in a non-ambulatory SMA patient?

. Prolonged cast immobilization to ensure complete remodeling
. Strict avoidance of any surgical fixation due to anesthesia risks
. Minimal immobilization and rapid return to baseline seating/function
. Immediate use of rigid external fixation for all long bone fractures
. Mandatory 6-week bed rest protocol

Correct Answer & Explanation

. Minimal immobilization and rapid return to baseline seating/function

Explanation

In SMA patients, prolonged immobilization rapidly exacerbates muscle atrophy and disuse osteopenia, worsening their functional baseline. Fractures should be managed with minimal immobilization (e.g., well-padded splints) and early mobilization back to their wheelchair.

Question 9876

Topic: 2. Trauma

A 3-year-old child is being evaluated for multiple fractures. The differential diagnosis includes Osteogenesis Imperfecta (OI) and Non-Accidental Trauma (NAT). Which of the following radiographic findings is highly specific for NAT and NOT typically seen in OI?

. Wormian bones of the skull
. Diffuse osteopenia
. Classic metaphyseal lesions (corner fractures)
. Protrusio acetabuli
. Bowing of the long bones

Correct Answer & Explanation

. Classic metaphyseal lesions (corner fractures)

Explanation

Classic metaphyseal lesions (CMLs), also known as corner or bucket-handle fractures, are highly specific for non-accidental trauma. They are caused by torsional and tractional forces, which are not typical mechanisms for osteoporotic fractures in OI.

Question 9877

Topic: 2. Trauma
A 10-year-old boy falls off his bicycle and presents with knee hemarthrosis. Radiographs reveal a Meyers and McKeever Type II fracture of the tibial eminence. Which of the following best describes the anatomical displacement in this fracture pattern?
. A completely non-displaced fracture
. Anterior elevation of the fragment with an intact posterior hinge
. Complete displacement of the fragment without any rotation
. Complete displacement of the fragment with rotation
. A comminuted fracture of the eminence

Correct Answer & Explanation

. Anterior elevation of the fragment with an intact posterior hinge

Explanation

The Meyers and McKeever classification for tibial eminence fractures is: Type I (non-displaced), Type II (anterior elevation with an intact posterior bony hinge, resembling a 'bird's beak'), Type III (completely displaced; IIIa without rotation, IIIb with rotation), and Type IV (comminuted, added later by Zaricznyj).

Question 9878

Topic: Pelvic & Acetabular Trauma

An 18-month-old female presents with an untreated, late-diagnosed Developmental Dysplasia of the Hip (DDH). Open reduction and a pelvic osteotomy are planned to improve anterolateral acetabular coverage. Which of the following pelvic osteotomies utilizes the pubic symphysis as its primary hinge?

. Pemberton osteotomy
. Dega osteotomy
. Salter innominate osteotomy
. Chiari osteotomy
. Steel triple osteotomy

Correct Answer & Explanation

. Salter innominate osteotomy

Explanation

The Salter innominate osteotomy is a complete cut through the ilium extending to the greater sciatic notch. It redirects the entire acetabulum using the pubic symphysis as its hinge. The Pemberton osteotomy hinges on the triradiate cartilage, and the Dega osteotomy hinges on the intact posterior cortex of the ilium.

Question 9879

Topic: 2. Trauma
A 2-year-old boy presents with a completely displaced, atraumatic fracture of the middle/distal third of the tibia. Radiographs show dysplastic, tapered bone ends at the fracture site. He has 7 café-au-lait spots measuring >5mm. Which of the following is the most important surgical principle in achieving primary osseous union for this condition?
. Complete excision of the pseudarthrosis and surrounding hamartomatous periosteum.
. Placement of an intramedullary nail without the use of bone grafting.
. Utilization of an Ilizarov external fixator solely for compression of the bone ends.
. Prophylactic administration of intravenous bisphosphonates post-surgery.
. Early elective transtibial amputation to allow immediate prosthetic fitting.

Correct Answer & Explanation

. Complete excision of the pseudarthrosis and surrounding hamartomatous periosteum.

Explanation

This child has congenital pseudarthrosis of the tibia (CPT), which is strongly associated with Neurofibromatosis Type 1 (indicated by the presence of multiple café-au-lait spots). The core pathology in CPT is a thickened, hamartomatous periosteum that impairs local blood supply and osteogenesis, leading to bone resorption and nonunion. The critical first step in surgical management is the aggressive, complete excision of this diseased periosteum and the pseudarthrotic tissue. This is followed by robust stabilization (often an intramedullary rod) and bone grafting to achieve union.

Question 9880

Topic: 2. Trauma
A 5-year-old boy with Sillence Type III osteogenesis imperfecta sustains a recurrent mid-diaphyseal femur fracture. His previous fracture was treated non-operatively and healed with significant anterolateral bowing. What is the optimal surgical management for his current fracture to prevent future deformities?
. Compression plating with 3.5mm locking screws
. Monolateral external fixation
. Rigid reamed locked intramedullary nailing
. Telescoping intramedullary rodding (e.g., Fassier-Duval)
. Flexible titanium intramedullary nailing (TENs)

Correct Answer & Explanation

. Telescoping intramedullary rodding (e.g., Fassier-Duval)

Explanation

In severe osteogenesis imperfecta, telescoping intramedullary rods are the standard of care for long bone fractures and deformities. They accommodate the child's longitudinal growth while protecting the entire diaphysis from recurrent bowing and fractures.

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