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4. Pediatrics MCQs

Practice Set 69 of 334

This practice set contains high-yield board review questions covering key concepts in 4. Pediatrics. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1361

Topic: 4. Pediatrics

In the context of Ilizarov distraction osteogenesis, what is the primary biological purpose of the 'latency period' following the corticotomy?

. To allow the hematoma to resolve and prevent infection
. To allow mesenchymal stem cells to populate the gap and initiate early angiogenesis
. To permit early cortical bridging before distraction begins
. To allow the periosteum to rigidly fuse to the surrounding muscle
. To prevent premature consolidation of the osteotomy

Correct Answer & Explanation

. To allow mesenchymal stem cells to populate the gap and initiate early angiogenesis

Explanation

The latency period (typically 5-10 days) allows a hematoma to form and mesenchymal stem cells/angiogenesis to organize within the corticotomy gap, laying the foundation for the fibrovascular bridge needed for successful regenerate bone formation.

Question 1362

Topic: 4. Pediatrics

According to Ilizarov principles of distraction osteogenesis, what is the optimal rate and rhythm for bone transport or lengthening?

. 0.25 mm/day divided into 1 increment
. 1.0 mm/day divided into 4 increments
. 2.0 mm/day divided into 2 increments
. 0.5 mm/day divided into 6 increments
. 1.5 mm/day divided into 1 increment

Correct Answer & Explanation

. 1.0 mm/day divided into 4 increments

Explanation

The classic Ilizarov protocol recommends a rate of 1.0 mm per day, divided into four increments of 0.25 mm. This rhythm balances the risk of premature consolidation with the risk of poor regenerate bone formation.

Question 1363

Topic: 4. Pediatrics

A 4-year-old child with progressive infantile Blount's disease is scheduled for a proximal tibial osteotomy. To adequately address the classic components of this deformity and minimize recurrence, the osteotomy must correct varus angulation, and what other typical deformities?

. External rotation and recurvatum
. External rotation and procurvatum
. Internal rotation and procurvatum
. Internal rotation and recurvatum
. Pure varus only

Correct Answer & Explanation

. Internal rotation and procurvatum

Explanation

Infantile Blount's disease is a three-dimensional deformity characterized by proximal tibial varus, internal tibial torsion, and procurvatum (flexion deformity of the proximal tibia).

Question 1364

Topic: 4. Pediatrics

During an Ilizarov tibial lengthening procedure, radiographs at 4 weeks show premature consolidation of the regenerate bone. Which of the following technical errors is the most likely cause of this complication?

. Thermal necrosis during corticotomy
. Distraction rate of 2 mm per day
. Excessive instability of the external fixator
. Latency period of 14 days
. Failure to perform a fibular osteotomy

Correct Answer & Explanation

. Latency period of 14 days

Explanation

A prolonged latency period (e.g., 14 days) or a distraction rate that is too slow can allow the corticotomy site to heal prematurely before adequate length is achieved, leading to premature consolidation.

Question 1365

Topic: 4. Pediatrics

Which of the following is the primary biomechanical advantage of using a hexapod circular external fixator (e.g., Taylor Spatial Frame) compared to a traditional Ilizarov frame for complex deformity correction?

. It does not require transfixing wires.
. It allows simultaneous correction of all six degrees of freedom via a virtual hinge.
. It accelerates the biological rate of bone regeneration.
. It completely eliminates the risk of pin tract infections.
. It allows for weight-bearing immediately after corticotomy, unlike traditional frames.

Correct Answer & Explanation

. It allows simultaneous correction of all six degrees of freedom via a virtual hinge.

Explanation

Hexapod frames utilize a computer program to calculate strut adjustments, allowing simultaneous correction of translation, angulation, and rotation (six degrees of freedom) without physically changing the frame hinges.

Question 1366

Topic: 4. Pediatrics

According to Ilizarov's principles of distraction osteogenesis, what is the optimal rate and rhythm of distraction to promote high-quality regenerate bone while protecting soft tissues?

. 0.25 mm per day in a single adjustment
. 1.0 mm per day in a single adjustment
. 1.0 mm per day divided into four 0.25 mm adjustments
. 2.0 mm per day divided into two 1.0 mm adjustments
. 1.5 mm per day divided into six 0.25 mm adjustments

Correct Answer & Explanation

. 1.0 mm per day divided into four 0.25 mm adjustments

Explanation

Ilizarov demonstrated that a distraction rate of 1.0 mm per day is optimal. Dividing this into multiple smaller increments (e.g., four 0.25 mm increments) provides a smoother environment for regenerate formation and less soft tissue tension.

Question 1367

Topic: Pediatric Upper Extremity & Spine

A 7-year-old male presents to the emergency department after falling from monkey bars onto an outstretched right hand. Clinical examination reveals marked diffuse swelling over the right elbow, predominantly on the lateral aspect, with significant tenderness over the lateral epicondyle. Active and passive range of motion are severely restricted and painful. Initial standard AP and lateral radiographs are equivocal for the extent of displacement and articular involvement of a suspected lateral condyle fracture. Given the high clinical suspicion, an additional radiograph is obtained, as shown below:

Which of the following statements best describes the utility of this specific radiographic view in this clinical scenario?

. It is primarily used to assess for supracondylar humerus fractures and associated neurovascular compromise.
. It provides a clearer view of the olecranon fossa, aiding in the diagnosis of olecranon fractures.
. It places the lateral condyle in profile, removing superimposition of the radial head and ulna, and is highly sensitive for detecting subtle displacement.
. It is the preferred view for evaluating medial epicondyle avulsion fractures and assessing ulnar nerve entrapment.
. It is most useful for identifying subtle radial head subluxation or dislocation in pediatric patients.

Correct Answer & Explanation

. It places the lateral condyle in profile, removing superimposition of the radial head and ulna, and is highly sensitive for detecting subtle displacement.

Explanation

Correct Answer: CThe image provided is an internal oblique radiograph of the elbow. As detailed in the teaching case, this view is crucial in pediatric elbow trauma, particularly for assessing lateral condyle fractures. It is obtained by internally rotating the arm 45 degrees, which places the lateral condyle in profile and removes the superimposition of the ulna and radial head. This specific projection is highly sensitive for detecting gap formation at the posterior aspect of the lateral metaphysis, often the first sign of displacement, and unequivocally demonstrates the true extent of the fracture line and any subtle displacement or rotation that might be missed on standard AP and lateral projections.Option A is incorrect:While supracondylar fractures are common, this view is not primarily for their assessment or neurovascular compromise, which is a clinical finding.Option B is incorrect:The internal oblique view is not specifically designed to visualize the olecranon fossa or diagnose olecranon fractures.Option D is incorrect:Medial epicondyle fractures are best assessed on standard AP and lateral views, sometimes with an external oblique view, but not typically the internal oblique. Ulnar nerve entrapment is a clinical diagnosis.Option E is incorrect:Radial head subluxation (nursemaid's elbow) is a clinical diagnosis, and while radial head dislocations can be seen on standard views, the internal oblique is not the primary view for this assessment.

Question 1368

Topic: 4. Pediatrics
A 7-year-old male presents with a lateral condyle fracture of the humerus, confirmed on internal oblique radiographs. The fracture line extends from the lateral metaphysis, through the physis, and into the articular surface. The fracture fragment includes the entire capitellum and a portion of the lateral trochlear ridge. Based on the provided case information, which of the following classifications best describes this fracture type and its implications?
. Milch Type I, indicating the fracture line courses lateral to the trochlear groove, preserving elbow stability.
. Milch Type II, indicating the fracture line extends into the apex of the trochlear groove, destabilizing the forearm.
. Salter-Harris Type II, characterized by a fracture through the physis and metaphysis, sparing the epiphysis.
. Salter-Harris Type III, characterized by a fracture through the physis and epiphysis, sparing the metaphysis.
. Salter-Harris Type IV, characterized by a fracture extending through the metaphysis, physis, and epiphysis (articular surface).

Correct Answer & Explanation

. Salter-Harris Type IV, characterized by a fracture extending through the metaphysis, physis, and epiphysis (articular surface).

Explanation

The fracture line extends from the lateral metaphysis, through the physis, and into the articular surface. This definition matches Salter-Harris Type IV, which involves the metaphysis, physis, and epiphysis (articular surface).

Question 1369

Topic: 4. Pediatrics

A 7-year-old patient undergoes open reduction and internal fixation for a displaced lateral condyle fracture. Postoperatively, the patient is placed in a long arm splint. Three weeks later, radiographs show early callus formation and maintenance of reduction. The pins are removed. Which of the following instructions is most appropriate for the immediate post-pin removal rehabilitation phase?

. Begin passive stretching exercises with a physical therapist to regain full extension quickly.
. Start active range of motion exercises, avoiding passive stretching or aggressive physical therapy.
. Continue strict immobilization in a cast for another 3 weeks to ensure complete bony union.
. Initiate weight-bearing activities on the affected arm to promote bone healing.
. Return to contact sports and high-impact activities immediately to prevent stiffness.

Correct Answer & Explanation

. Start active range of motion exercises, avoiding passive stretching or aggressive physical therapy.

Explanation

Correct Answer: BThe teaching case explicitly states the postoperative rehabilitation protocol: 'Following pin removal, the patient may begin active range of motion exercises. It is critical to emphasizeactivemotion only. Passive stretching or aggressive physical therapy is strictly contraindicated in the pediatric elbow, as it increases the risk of joint stiffness, heterotopic ossification, and myositis ossificans.' This approach protects the healing fracture while allowing for gradual restoration of motion.Option A is incorrect:Passive stretching is strictly contraindicated due to the risk of complications like joint stiffness, heterotopic ossification, and myositis ossificans.Option C is incorrect:Immobilization is typically for 3-4 weeks. If callus formation is evident and reduction maintained, pins are removed, and active motion is initiated. Prolonged strict immobilization can lead to stiffness.Option D is incorrect:Weight-bearing activities are not appropriate immediately after pin removal and before complete bony remodeling, which takes longer.Option E is incorrect:Return to contact sports and high-impact activities is generally restricted for 10 to 12 weeks post-injury to allow for complete bony remodeling, not immediately after pin removal.

Question 1370

Topic: 4. Pediatrics

During open reduction and internal fixation of a pediatric lateral condyle fracture, the surgeon has achieved anatomic reduction of the fracture fragment, as shown in the intraoperative image. The next critical step is to secure this reduction. Which of the following fixation strategies is generally considered the most biomechanically stable for this injury?

. A single smooth K-wire placed perpendicular to the fracture line.
. Two or three parallel smooth K-wires achieving unicortical purchase.
. Two or three divergent smooth K-wires achieving bicortical purchase.
. A single cannulated screw placed across the physis for compression.
. Absorbable sutures to repair the periosteum and hold the reduction.

Correct Answer & Explanation

. Two or three divergent smooth K-wires achieving bicortical purchase.

Explanation

Correct Answer: CThe teaching case states: 'Definitive fixation is typically achieved using two or three smooth K-wires (1.6 mm or 2.0 mm, depending on patient age). The most biomechanically stable configuration utilizes divergent pins. The first pin is directed from the lateral condyle, across the fracture site, engaging the medial cortex of the distal humerus. The second pin is directed more proximally up the lateral column. Parallel pins are also acceptable provided they achieve bicortical purchase.' Therefore, two or three divergent smooth K-wires achieving bicortical purchase is the most biomechanically stable configuration.Option A is incorrect:A single K-wire is generally insufficient for stable fixation of a displaced fracture.Option B is incorrect:While parallel pins are acceptable, divergent pins offer superior torsional stability. Unicortical purchase is less stable than bicortical.Option D is incorrect:Cannulated screws may be used in older children, but theymust not cross an open physisto avoid premature growth arrest. A 5-year-old has an open physis.Option E is incorrect:Absorbable sutures are used to repair the capsule and extensor aponeurosis, but they do not provide sufficient bony fixation for a displaced fracture.

Question 1371

Topic: 4. Pediatrics

Which of the following statements accurately reflects a key principle in the management of pediatric lateral condyle fractures, as emphasized by the provided teaching case and current guidelines?

. The Milch Type I classification is more clinically relevant for treatment algorithms than the Jakob classification.
. Aggressive passive stretching is encouraged postoperatively to prevent joint stiffness and achieve full extension rapidly.
. The best treatment for an established lateral condyle nonunion is always aggressive late open reduction and internal fixation with bone grafting.
. Anatomic reduction is paramount, and the morbidity of a small lateral incision for ORIF is generally outweighed by the consequences of a malreduced joint.
. Cannulated screw fixation is the preferred method for all pediatric lateral condyle fractures, regardless of patient age or physeal status.

Correct Answer & Explanation

. Anatomic reduction is paramount, and the morbidity of a small lateral incision for ORIF is generally outweighed by the consequences of a malreduced joint.

Explanation

Correct Answer: DThe teaching case strongly emphasizes the importance of anatomic reduction: 'The management of pediatric lateral condyle fractures hinges entirely on the precise measurement of displacement and the assessment of articular congruity.' And in the summary, 'Recent guidelines from the Pediatric Orthopaedic Society of North America (POSNA) emphasize the absolute necessity of anatomic reduction. While K-wire fixation remains the standard of care for the vast majority of these fractures, biomechanical studies have shown that divergent pin placement offers superior torsional stability compared to parallel pins. Furthermore, literature regarding the late management of nonunions continues to caution against aggressive late open reduction, reinforcing the principle that the best treatment for a lateral condyle nonunion is its prevention through accurate initial diagnosis and meticulous surgical execution.'Option A is incorrect:The case states, 'More clinically relevant for treatment algorithms is the Jakob classification, which evaluates the degree of displacement and the integrity of the cartilaginous articular hinge.'Option B is incorrect:The case explicitly states, 'Passive stretching or aggressive physical therapy is strictly contraindicated in the pediatric elbow, as it increases the risk of joint stiffness, heterotopic ossification, and myositis ossificans.'Option C is incorrect:The case cautions against aggressive late open reduction for nonunions due to the high risk of AVN, advocating for benign neglect in asymptomatic cases and in situ fixation for symptomatic ones.Option E is incorrect:Cannulated screw fixation is an alternative forolder children or adolescents approaching skeletal maturity, andmust not cross an open physis. K-wires are the standard for most pediatric cases.

Question 1372

Topic: 4. Pediatrics

A 35-year-old man presents with progressive weakness in his hands and numbness in his ring and small fingers. He sustained an untreated pediatric elbow fracture 30 years ago. Physical examination reveals a profound cubitus valgus deformity. Which of the following original pediatric injuries most likely led to this clinical presentation?

. Supracondylar humerus fracture
. Lateral condyle fracture
. Medial epicondyle fracture
. Radial neck fracture
. Olecranon fracture

Correct Answer & Explanation

. Lateral condyle fracture

Explanation

Nonunion of a pediatric lateral condyle fracture leads to a progressive cubitus valgus deformity. This chronic valgus stretching can ultimately result in tardy ulnar nerve palsy decades after the initial injury.

Question 1373

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from a trampoline and sustains a Gartland Type III supracondylar humerus fracture. On initial examination, the hand is pink and warm, but the radial pulse is not palpable. What is the most appropriate next step in management?
. Immediate open vascular exploration
. Emergent CT angiography
. Closed reduction and percutaneous pinning, followed by reassessment of the pulse
. Fasciotomy of the forearm
. Administration of systemic thrombolytics

Correct Answer & Explanation

. Closed reduction and percutaneous pinning, followed by reassessment of the pulse

Explanation

In a patient with a 'pulseless but pink' (well-perfused) hand following a supracondylar fracture, the first step is urgent closed reduction and percutaneous pinning. The pulse often returns after fracture reduction relieves kinking or compression of the brachial artery.

Question 1374

Topic: 4. Pediatrics

Intraoperative fluoroscopy is used to assess the reduction of a pediatric supracondylar humerus fracture. The surgeon measures Baumann's angle. Which two radiographic lines form this angle, and what does it assess?

. The line parallel to the longitudinal axis of the humerus and the line along the physeal line of the lateral condyle; it assesses coronal alignment (varus/valgus)
. The anterior humeral line and the radiocapitellar line; it assesses sagittal alignment (flexion/extension)
. The line along the long axis of the ulna and the long axis of the humerus; it assesses rotational alignment
. The line along the medial epicondyle and the trochlea; it assesses length restoration
. The anterior humeral line and the posterior humeral line; it assesses translation

Correct Answer & Explanation

. The line parallel to the longitudinal axis of the humerus and the line along the physeal line of the lateral condyle; it assesses coronal alignment (varus/valgus)

Explanation

Baumann's angle is measured on the AP radiograph by the intersection of a line parallel to the longitudinal axis of the humerus and a line drawn along the physeal line of the lateral condyle. It is critical for assessing coronal alignment and preventing cubitus varus.

Question 1375

Topic: Pediatric Upper Extremity & Spine
A 4-year-old girl is evaluated for elbow pain after a fall. Radiographs demonstrate a supracondylar humerus fracture. The anterior humeral line passes anterior to the capitellum, but the posterior humeral cortex remains intact. According to the Gartland classification, what type of fracture is this?
. Type I
. Type II
. Type III
. Type IV
. Flexion Type

Correct Answer & Explanation

. Type II

Explanation

A Gartland Type II supracondylar humerus fracture is defined as an extended and displaced fracture with an intact posterior cortical hinge. The anterior humeral line characteristically passes anterior to the middle third of the capitellum.

Question 1376

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from the monkey bars and sustains an extension-type Gartland Type III supracondylar humerus fracture. Upon physical examination, which of the following nerve injuries is most likely to be identified?
. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve
. Musculocutaneous nerve
. Posterior interosseous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. It is a motor branch of the median nerve, and injury typically presents as an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (the 'OK' sign).

Question 1377

Topic: 4. Pediatrics

A 5-year-old girl sustains a severely displaced supracondylar humerus fracture. After successful closed reduction and percutaneous pinning in the operating room, her hand remains pink with brisk capillary refill, but the radial pulse is nonpalpable. What is the most appropriate next step in management?

. Immediate open vascular exploration
. Perform a CT angiogram
. Remove the percutaneous pins and re-reduce the fracture
. Observation with close inpatient monitoring
. Fasciotomy of the forearm

Correct Answer & Explanation

. Observation with close inpatient monitoring

Explanation

A 'pink, pulseless' hand following reduction and pinning of a pediatric supracondylar humerus fracture indicates adequate collateral perfusion. The standard of care is close inpatient observation, as the pulse often returns within a few days without surgical intervention.

Question 1378

Topic: 4. Pediatrics

A 12-year-old boy suffers a posterior elbow dislocation. Following closed reduction, a radiograph is obtained. Which of the following is considered an absolute indication for operative intervention in a pediatric medial epicondyle fracture?

. Displacement of 3 millimeters
. Presence of an ulnar nerve neurapraxia
. Incarceration of the medial epicondyle fragment within the joint
. High-level competitive overhead throwing athlete
. Associated nondisplaced radial neck fracture

Correct Answer & Explanation

. Incarceration of the medial epicondyle fragment within the joint

Explanation

Incarceration of the medial epicondyle fragment within the ulnohumeral joint after a dislocation is an absolute indication for surgical extraction and fixation. Displacement >5 mm and high-level throwing demands are relative indications.

Question 1379

Topic: 4. Pediatrics

Which of the following is the most common late deformity resulting from a malunited pediatric supracondylar humerus fracture?

. Cubitus valgus
. Cubitus varus
. Genu recurvatum
. Elbow flexion contracture
. Radioulnar synostosis

Correct Answer & Explanation

. Cubitus varus

Explanation

Cubitus varus (gunstock deformity) is the most common deformity following a malunited supracondylar humerus fracture. It is primarily a cosmetic issue rather than a functional impairment and results from coronal plane tilt and rotation.

Question 1380

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents to the emergency department after falling from a trampoline. Radiographs reveal a Gartland Type III supracondylar humerus fracture. The distal fragment is displaced posterolaterally. Based on this specific displacement pattern, which of the following nerve deficits is most likely to be present on examination?
. Inability to extend the metacarpophalangeal joints of the fingers
. Decreased sensation over the dorsal first web space
. Inability to cross the index and middle fingers
. Inability to flex the interphalangeal joint of the thumb
. Inability to flex the distal interphalangeal joint of the small finger

Correct Answer & Explanation

. Inability to flex the interphalangeal joint of the thumb

Explanation

In a posterolaterally displaced extension-type supracondylar humerus fracture, the proximal fragment is driven anteromedially, placing the anterior interosseous nerve (AIN) and median nerve at highest risk. AIN palsy presents as the inability to flex the IP joint of the thumb and the DIP joint of the index finger (positive OK sign).

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