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2. Trauma MCQs

Practice Set 16 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 301

Topic: 2. Trauma

Which of the following conditions is not part of the differential diagnosis of a valgus knee in a 4-year-old child:

. Physiologic valgus
. Prior proximal metaphyseal fracture
. Multiple exostoses
. C hondroectodermal dysplasia
. Infantile Blount disease

Correct Answer & Explanation

. Infantile Blount disease

Explanation

Physiologic valgus, prior proximal metaphyseal fracture, multiple exostoses, and chondroectodermal dysplasia produce valgus. Infantile Blount disease produces varus.

Question 302

Topic: Lower Extremity Trauma

A 10-year-old girl has a leg length discrepancy. Using the multiplier method, her projected discrepancy at skeletal maturity is calculated to be 3.5 cm. Assuming a normal, stable hip and knee, what is the most appropriate surgical management?

. Contralateral distal femoral epiphysiodesis
. Ipsilateral acute lengthening with an external fixator
. Ipsilateral gradual lengthening with an intramedullary nail at age 10
. Contralateral proximal tibial acute shortening
. Observation and a 3.5 cm shoe lift for life

Correct Answer & Explanation

. Contralateral distal femoral epiphysiodesis

Explanation

Projected leg length discrepancies between 2.0 and 5.0 cm at maturity are typically best managed with a properly timed contralateral epiphysiodesis to halt growth on the longer leg.

Question 303

Topic: 2. Trauma

A 6-year-old falls on an outstretched hand and sustains a completely displaced, extension-type supracondylar humerus fracture. The hand is pink but the radial pulse is non-palpable. After closed reduction and percutaneous pinning, the hand remains pink and well-perfused, but the pulse is still absent. What is the most appropriate next step?

. Immediate open vascular exploration
. Administration of intra-arterial vasodilators
. Observation and admission for 24-48 hours
. Remove the pins and re-reduce the fracture
. Perform a prophylactic forearm fasciotomy

Correct Answer & Explanation

. Observation and admission for 24-48 hours

Explanation

In a "pink, pulseless" hand following reduction of a supracondylar fracture, collateral circulation is sufficient for perfusion. The standard of care is close observation and hospital admission, as the palpable pulse typically returns within 24 to 48 hours.

Question 304

Topic: 2. Trauma
A 5-year-old child sustains a minimally displaced (<2 mm) lateral condyle fracture of the humerus. It is treated conservatively. At the 4-month follow-up, the fracture shows established nonunion. What is the most common long-term complication of a nonunion of the lateral humeral condyle?
. Cubitus varus
. Tardy ulnar nerve palsy
. Radial nerve palsy
. Avascular necrosis of the trochlea
. Premature closure of the medial epicondyle

Correct Answer & Explanation

. Tardy ulnar nerve palsy

Explanation

Nonunion of a lateral condyle fracture often leads to a progressive cubitus valgus deformity as the medial side continues to grow. Over time, this valgus stretching causes a tardy ulnar nerve palsy.

Question 305

Topic: 2. Trauma
A patient sustains a transverse fracture of the sacrum through the central canal (Denis Zone III). Which of the following is the most likely neurological complication associated with this specific zone of injury?
. Unilateral L5 weakness
. Bowel and bladder dysfunction
. Isolated S1 sensory loss
. Isolated L4 motor weakness
. Lateral femoral cutaneous nerve palsy

Correct Answer & Explanation

. Bowel and bladder dysfunction

Explanation

Denis Zone III fractures involve the central sacral canal. They carry the highest risk of neurologic injury (up to 57%), predominantly presenting as saddle anesthesia, sexual dysfunction, and bowel/bladder dysfunction.

Question 306

Topic: 2. Trauma

What is the approximate risk of growth disturbance of distal radial Salter II fractures:

. 50%
. 25%
. 15%
. 5%
. 1%

Correct Answer & Explanation

. 1%

Explanation

Although distal radial physeal fractures are common, growth disturbance is rare with a 1% occurence. Growth disturbance poses a challenge for follow- up, but physicians should at least mention the risk to patients.

Question 307

Topic: 2. Trauma

Which of the following fracture situations would be most appropriate for internal fixation vs. attempted closed reduction:

. A 7-year-old girl with 35° angulation of greenstick radius and ulna fracture
. A 7-year-old boy with 35° angulation of complete radius and ulna fracture
. A 9-year-old girl with 30° angulation of complete radius and ulna fracture
. A 12-year-old boy with 25° angulation of complete radius and ulna fracture
. A 15-year-old girl with 25° angulation of complete radius and ulna fracture

Correct Answer & Explanation

. A 15-year-old girl with 25° angulation of complete radius and ulna fracture

Explanation

Remodeling potential is significantly decreased at skeletal maturity. The first four scenarios represent skeletally immature patients. The 15-year-old girl should be treated like an adult to achieve the most acceptable result. All other patients deserve an attempt at closed reduction.

Question 308

Topic: 2. Trauma

A 6-year-old boy with osteogenesis imperfecta has had three fractures of his proximal femur resulting in progressive bowing, which has now reached 70°. He has pain in his thigh and a sclerotic stress line at the apex of the bow. The best treatment is:

. C losed osteoclasis and spica cast
. Osteoclasis and external fixator
. Osteotomy and plate fixation
. Osteotomy and internal fixation with an expandable rod
. Observation

Correct Answer & Explanation

. Osteotomy and internal fixation with an expandable rod

Explanation

As bowing becomes greater, the likelihood of a re-fracture increases. The presence of a lucent sclerotic line and pain increases the risk of re-fracture. Intramedullary fixation is preferred to plate fixation because plate fixation increases the risk of stress risers. Expandable rods that bridge the entire bone from one epiphysis to the other are the best treatment for excessive bowing. Examples include the Bailey Dubow or the Fassier rods.

Question 309

Topic: 2. Trauma

Non-viral gene delivery using naked plasmid DNA is being evaluated for fracture healing. What is the main limitation of this technique compared to viral vectors?

. High risk of insertional mutagenesis
. Severe local inflammatory response
. Low transfection efficiency
. Inability to carry genes larger than 2 kb
. Strict requirement for dividing target cells

Correct Answer & Explanation

. Low transfection efficiency

Explanation

Naked plasmid DNA delivery has the advantages of safety and low immunogenicity but suffers from very low transfection efficiency and transient gene expression. It typically requires physical methods like electroporation to improve cellular uptake.

Question 310

Topic: 2. Trauma

To understand the global genetic changes occurring during fracture nonunion, researchers isolate mRNA from the fracture site to compare expression levels of thousands of genes simultaneously. Which technology is best suited for this analysis?

. Sanger sequencing
. Enzyme-linked immunosorbent assay (ELISA)
. Western blotting
. DNA microarray analysis
. Immunohistochemistry

Correct Answer & Explanation

. DNA microarray analysis

Explanation

DNA microarrays allow for the simultaneous measurement of the expression levels of thousands of genes (transcriptomics). This provides a global view of gene expression changes in tissues like a fracture callus.

Question 311

Topic: 2. Trauma

An experimental model utilizes a naked plasmid vector injected directly into an osteoporotic fracture site to induce localized bone formation. This represents which type of gene delivery system?

. Non-viral in vivo
. Viral ex vivo
. Non-viral ex vivo
. Retroviral ex vivo
. Lentiviral in vivo

Correct Answer & Explanation

. Non-viral in vivo

Explanation

Directly injecting a plasmid (which lacks viral components) into a living subject is a non-viral, in vivo method of gene delivery. While simpler and safer, it often suffers from lower transfection efficiency compared to viral vectors.

Question 312

Topic: 2. Trauma

Fractures that have a high specificity for child abuse include all of the following except:

. C orner fractures
. Rib fractures
. Scapular fractures
. Sternal fractures
. Spiral femur fractures

Correct Answer & Explanation

. Spiral femur fractures

Explanation

Even though a spiral pattern suggests a rotational force, spiral fractures of the femur are not specific for abuse. All of the other patterns are highly specific although not absolutely diagnostic.

Question 313

Topic: 2. Trauma
Among children with nonossifying fibromas, a risk of pathologic fracture exists mainly when a lesion exceeds what minimum percentage of a bone's diameter?
. 10%
. 25%
. 33%
. 50%
. 75%

Correct Answer & Explanation

. 50%

Explanation

In a series from the Mayo clinic, all pathologic fractures associated with nonossifying fibromas in the lower extremity occurred in lesions larger than 50% of the transverse diameter.

Question 314

Topic: 2. Trauma

Which of the following fracture patterns carries the highest specificity for non-accidental trauma (child abuse) in an infant?

. Midshaft clavicle fracture
. Linear skull fracture
. Posterior rib fractures
. Spiral tibia fracture
. Buckle fracture of the distal radius

Correct Answer & Explanation

. Posterior rib fractures

Explanation

Posterior rib fractures, metaphyseal corner (bucket-handle) fractures, and scapular or spinous process fractures have the highest specificity for non-accidental trauma in infants.

Question 315

Topic: 2. Trauma

A 9-month-old non-ambulatory infant presents with a spiral fracture of the femoral shaft. What is the most appropriate next step in management?

. Perform a skeletal survey and consult child protective services
. Immediate spica casting without further imaging
. Flexible intramedullary nailing
. Pavlik harness application
. Plate osteosynthesis

Correct Answer & Explanation

. Perform a skeletal survey and consult child protective services

Explanation

Spiral femur fractures in non-ambulatory infants are highly suspicious for non-accidental trauma. A skeletal survey and child protective services consultation are mandatory.

Question 316

Topic: 2. Trauma

A 9-year-old boy presents with a pathologic fracture of the proximal humerus after a minor fall. Radiographs reveal a centrally located lytic lesion extending to the physis with a "fallen leaf" sign. What is the best initial management for the cyst?

. Immediate curettage and bone grafting
. Aspiration and injection immediately
. Observation to allow fracture healing which may resolve the cyst
. Wide resection
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Observation to allow fracture healing which may resolve the cyst

Explanation

A "fallen leaf" sign indicates a Unicameral Bone Cyst. Initial management of a pathologic fracture through a UBC is observation, as the fracture may induce spontaneous cyst healing.

Question 317

Topic: 2. Trauma

A 6-year-old girl sustains a displaced lateral condyle fracture of the humerus. Which of the following is the most common complication if this fracture is left untreated or goes on to nonunion?

. Cubitus varus
. Cubitus valgus with tardy ulnar nerve palsy
. Avascular necrosis of the trochlea
. Volkmann's ischemic contracture
. Posterior interosseous nerve palsy

Correct Answer & Explanation

. Cubitus valgus with tardy ulnar nerve palsy

Explanation

Nonunion of a lateral condyle fracture typically leads to a progressive cubitus valgus deformity. This chronic stretching can lead to a tardy ulnar nerve palsy.

Question 318

Topic: 2. Trauma
According to the Delbet classification, which type of pediatric proximal femur fracture carries the highest risk of avascular necrosis (AVN)?
. Type I (Transepiphyseal)
. Type II (Transcervical)
. Type III (Cervicotrochanteric)
. Type IV (Intertrochanteric)
. Type V (Subtrochanteric)

Correct Answer & Explanation

. Type I (Transepiphyseal)

Explanation

Delbet Type I (transepiphyseal) fractures are rare but carry the highest risk of AVN. The AVN rate approaches nearly 100% in completely displaced cases.

Question 319

Topic: 2. Trauma

An 8-year-old boy presents with sudden arm pain after throwing a baseball. Radiographs demonstrate a centrally located, lucent metaphyseal lesion in the proximal humerus with a "fallen leaf" sign.

Following fracture healing, what is the most appropriate initial management for this active lesion?

. Observation alone
. Wide en bloc resection
. Aspiration and corticosteroid injection
. Preoperative embolization and curettage
. Radiation therapy

Correct Answer & Explanation

. Aspiration and corticosteroid injection

Explanation

The "fallen leaf" sign is pathognomonic for a unicameral (simple) bone cyst. After the pathological fracture has healed, active cysts with a high risk of re-fracture are typically treated first-line with aspiration and intralesional corticosteroid or bone marrow injection.

Question 320

Topic: 2. Trauma

Which of the following radiographic fracture patterns is considered to have the highest specificity for non-accidental trauma in an infant?

. Midshaft clavicle fracture
. Linear skull fracture
. Metaphyseal corner fracture
. Spiral fracture of the femur
. Transverse fracture of the distal radius

Correct Answer & Explanation

. Metaphyseal corner fracture

Explanation

Metaphyseal corner fractures, or "bucket-handle" fractures, are highly specific for child abuse, resulting from rapid rotational or shearing forces applied to a child's limb. While spiral femur fractures are concerning in non-ambulatory infants, metaphyseal lesions carry the highest specificity.

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