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4. Pediatrics MCQs

Practice Set 87 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 1721

Topic: 4. Pediatrics

According to the Ponseti method for the treatment of idiopathic congenital talipes equinovarus, what is the correct sequential order of deformity correction?

. Equinus, Varus, Adductus, Cavus
. Cavus, Varus, Equinus, Adductus
. Cavus, Adductus, Varus, Equinus
. Adductus, Cavus, Equinus, Varus
. Varus, Cavus, Adductus, Equinus

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The mnemonic CAVE dictates the sequential correction of clubfoot deformity in the Ponseti method: Cavus (corrected by elevating the first ray), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy).

Question 1722

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from monkey bars and sustains an extension-type supracondylar humerus fracture. Radiographs show a Gartland Type III pattern with posteromedial displacement of the distal fragment. Which peripheral nerve is at the greatest risk of injury in this specific displacement pattern?
. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

Posteromedial displacement of the distal fragment causes the proximal metaphyseal fragment to spike anterolaterally, placing the radial nerve at the highest risk of injury. Posterolateral displacement endangers the median nerve (or AIN).

Question 1723

Topic: 4. Pediatrics

A 19-year-old male sustains a posterior sternoclavicular dislocation during a rugby match. The orthopedic surgeon plans an open reduction. During preoperative planning, the surgeon recalls that the medial clavicle physis is typically the last primary ossification center to fuse in the human body. This may mean the injury is a physeal fracture rather than a true dislocation. At what age does the medial clavicular physis typically fuse?

. 14 to 16 years
. 18 to 20 years
. 23 to 25 years
. 28 to 30 years
. 32 to 35 years

Correct Answer & Explanation

. 23 to 25 years

Explanation

The medial clavicle physis is the last growth plate in the body to fuse. Ossification begins around age 18, and complete fusion does not occur until 23 to 25 years of age. Therefore, apparent sternoclavicular dislocations in patients under 25 are frequently Salter-Harris physeal fractures.

Question 1724

Topic: Pediatric Lower Extremity

During the Ponseti method for treating idiopathic clubfoot, a specific sequence of deformity correction must be strictly followed. Which of the following components of the deformity is corrected last?

. Midfoot cavus
. Forefoot adductus
. Hindfoot varus
. Ankle equinus
. Tibial internal torsion

Correct Answer & Explanation

. Ankle equinus

Explanation

The Ponseti method corrects clubfoot in the sequence of CAVE: Cavus, Adductus, Varus, and finally Equinus. Equinus is addressed last, often requiring a percutaneous Achilles tenotomy.

Question 1725

Topic: Pediatric Lower Extremity
A 55-year-old woman presents with chronic, insidious midfoot pain and a progressive flatfoot. Radiographs demonstrate a comma-shaped deformity of the tarsal navicular with lateral subluxation of the talar head and dorsal fragmentation. What is the most likely diagnosis?
. Köhler disease
. Freiberg's infraction
. Sever's disease
. Müller-Weiss disease
. Charcot neuroarthropathy

Correct Answer & Explanation

. Müller-Weiss disease

Explanation

Müller-Weiss disease is spontaneous osteonecrosis of the tarsal navicular in adults, presenting with midfoot pain, a characteristic comma-shaped navicular, and lateral talar subluxation. Köhler disease is navicular osteonecrosis but occurs in young children.

Question 1726

Topic: 4. Pediatrics
A 12-year-old boy who has had a 1-month history of right thigh pain and a limp reports worsening of the pain after a fall, and he can no longer walk or bear weight on the involved extremity. Radiographs of the pelvis reveal a slipped capital femoral epiphysis with moderate to severe displacement. While positioning the patient on the fracture table for screw fixation, partial reduction of the slip is achieved. No further reduction maneuvers are attempted, and the epiphysis is stabilized with a single cannulated screw. What complication is most likely to develop following this procedure?
. Infection
. Chondrolysis
. Nonunion
. Osteonecrosis
. Epiphyseal arrest

Correct Answer & Explanation

. Osteonecrosis

Explanation

This is an unstable slipped capital femoral epiphysis. Reduction of an unstable slip often occurs unintentionally with induction of anesthesia and positioning of the patient for surgery. The rate of satisfactory results is lower primarily because of a much higher incidence of osteonecrosis following internal fixation of an unstable slip.

Question 1727

Topic: 4. Pediatrics
A 6-year-old boy sustains a Gartland type III supracondylar humerus fracture. Upon arrival, his hand is pale and pulseless. He is immediately taken to the operating room, where closed reduction and percutaneous pinning are successfully performed. Following fixation, the hand becomes warm and pink with a capillary refill time of less than 2 seconds, but the radial pulse remains absent on palpation and Doppler ultrasound. What is the most appropriate next step in management?
. Immediate open exploration of the brachial artery via an anterior approach
. Immediate CT angiogram of the upper extremity
. Removal of the pins and hyperflexion of the elbow to restore the pulse
. Observation and inpatient admission with serial vascular checks
. Intra-arterial infusion of vasodilators and heparin

Correct Answer & Explanation

. Observation and inpatient admission with serial vascular checks

Explanation

The 'pink, pulseless hand' following reduction and pinning of a pediatric supracondylar humerus fracture is a well-known clinical scenario. Current pediatric orthopaedic consensus and AAOS guidelines strongly recommend observation as long as the hand is well-perfused (warm, pink, capillary refill <2 seconds). Collateral circulation is robust in children, and the radial pulse often returns within days to weeks as vasospasm resolves. Emergent vascular exploration is reserved for hands that remain cold, white, and poorly perfused after reduction.

Question 1728

Topic: 4. Pediatrics
A 5-year-old child sustains a Gartland type III supracondylar humerus fracture. The hand is pink but lacks a palpable radial pulse. Following closed reduction and percutaneous pinning, the hand remains well-perfused (pink) with brisk capillary refill, but the radial pulse remains absent. What is the next best step in management?
. Immediate open vascular exploration
. Observation and hospital admission for close clinical monitoring
. Immediate removal of pins and conversion to open reduction
. Emergent formal arteriography
. Prophylactic fasciotomy of the volar forearm

Correct Answer & Explanation

. Observation and hospital admission for close clinical monitoring

Explanation

For a 'pink, pulseless' hand following stable reduction and pinning of a pediatric supracondylar humerus fracture, current guidelines recommend observation and close clinical monitoring. The collateral circulation around the elbow is typically sufficient to maintain viability.

Question 1729

Topic: 4. Pediatrics

A 6-year-old boy presents with a completely displaced, extension-type supracondylar humerus fracture. His hand is pink and warm, but the radial pulse is absent. After closed reduction and percutaneous pinning, the hand remains well-perfused with excellent capillary refill, but the radial pulse is still non-palpable. What is the next most appropriate step in management?

. Immediate exploration of the brachial artery
. CT angiography of the upper extremity
. Close clinical observation and admission for 24-48 hours
. Removal of pins and open reduction
. Prophylactic fasciotomy of the forearm

Correct Answer & Explanation

. Close clinical observation and admission for 24-48 hours

Explanation

In a 'pulseless, pink' hand following an adequate and stable reduction of a pediatric supracondylar humerus fracture, the standard of care is close clinical observation. Collateral circulation is sufficient to maintain viability, and the pulse typically returns within a few days to weeks.

Question 1730

Topic: 4. Pediatrics

A 6-year-old boy presents with a displaced extension-type supracondylar humerus fracture. On initial examination, the hand is pink and well-perfused, but the radial pulse is absent. After closed reduction and percutaneous pinning, the radial pulse remains absent, but the hand remains pink with a capillary refill time of less than 2 seconds. What is the most appropriate next step in management?

. Immediate open exploration of the brachial artery
. Perform a brachial arteriogram
. Remove the pins and attempt an open reduction
. Admit for close observation and neurovascular checks
. Perform a sympathetic block to relieve vasospasm

Correct Answer & Explanation

. Admit for close observation and neurovascular checks

Explanation

A 'pink, pulseless' hand following reduction and pinning of a pediatric supracondylar humerus fracture is indicative of adequate collateral circulation despite probable brachial artery spasm, kinking, or entrapment. Current AAOS and POSNA guidelines recommend admission for close observation (typically 24-48 hours) as long as the hand remains well-perfused (warm, pink, capillary refill <2 seconds). Immediate exploration is reserved for a 'white, pulseless' hand (dysvascular) that does not improve after reduction.

Question 1731

Topic: 4. Pediatrics
A 2-year-old child presents with bilateral genu varum. Standing radiographs demonstrate a metaphyseal-diaphyseal angle (MDA) of 20 degrees bilaterally. What is the most appropriate initial management?
. Observation and reassurance
. Bilateral knee-ankle-foot orthoses (KAFOs)
. Bilateral proximal tibial valgus osteotomies
. Medial hemiepiphysiodesis
. Lateral hemiepiphysiodesis

Correct Answer & Explanation

. Bilateral knee-ankle-foot orthoses (KAFOs)

Explanation

In a child under 3 years old with suspected infantile Blount's disease, a metaphyseal-diaphyseal angle (MDA or Drennan's angle) greater than 16 degrees strongly suggests true Blount's disease rather than physiologic bowing. The initial treatment for infantile Blount's disease in children under age 3 is bracing with knee-ankle-foot orthoses (KAFOs). Surgery is indicated if bracing fails or if the child presents at an older age with advanced Langenskiöld stages.

Question 1732

Topic: 4. Pediatrics

A 9-year-old girl undergoes tension band plating (guided growth) for idiopathic genu valgum. Following clinical and radiographic correction of the mechanical axis, the plates and screws are removed. She returns to the clinic 18 months later with recurrent genu valgum. What is the most likely cause of this recurrent deformity?

. Incomplete removal of the epiphyseal screws
. Iatrogenic premature physeal closure (epiphysiodesis)
. Rebound phenomenon due to rapid periosteal growth
. Undiagnosed multiple hereditary exostoses
. Reactivation of Blount's disease

Correct Answer & Explanation

. Rebound phenomenon due to rapid periosteal growth

Explanation

The 'rebound phenomenon' is a well-documented complication following implant removal in guided growth (tension band plating), particularly in younger patients with significant remaining growth potential. The physis 'rebounds' and grows at an accelerated rate, causing a recurrence of the original deformity. Some surgeons intentionally overcorrect by a few degrees to account for this expected rebound.

Question 1733

Topic: 4. Pediatrics
A 30-month-old child presents with bilateral symmetric genu varum. Radiographs reveal a metaphyseal-diaphyseal angle of 18 degrees and lateral thrust during ambulation. Which of the following is the most appropriate initial management?
. Reassurance and clinical observation
. Knee-ankle-foot orthosis (KAFO)
. Eight-plate hemiepiphysiodesis of the medial proximal tibia
. High tibial valgus osteotomy
. Guided growth of the lateral distal femur

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO)

Explanation

A metaphyseal-diaphyseal angle greater than 16 degrees strongly suggests infantile Blount's disease rather than physiologic bowing. In children under 3 years old with Langenskiöld stage I or II, full-time bracing with a KAFO is the recommended initial management.

Question 1734

Topic: 4. Pediatrics

Which of the following radiographic or clinical parameters is uniquely essential for programming a hexapod circular external fixator (e.g., Taylor Spatial Frame) but is not explicitly required for building a standard Ilizarov frame?

. The mechanical axis deviation of the extremity
. The center of rotation of angulation (CORA)
. The mounting parameters (e.g., distance from the reference ring to the origin)
. The magnitude of the angular deformity in the coronal plane
. The cross-sectional diameter of the diaphysis

Correct Answer & Explanation

. The mounting parameters (e.g., distance from the reference ring to the origin)

Explanation

Hexapod fixators utilize computer software to generate a prescription for 6-axis deformity correction. This requires precise mounting parameters, which describe the spatial relationship between the reference ring and the reference bone segment.

Question 1735

Topic: 4. Pediatrics
An 8-year-old severely obese male presents with worsening unilateral tibia vara. Radiographs reveal a depressed medial tibial plateau, profound metaphyseal beaking, and an established physeal bar (Langenskiöld stage VI). What is the most definitive surgical management?
. Guided growth with a lateral tension band plate
. High tibial opening-wedge osteotomy with gradual correction
. Physeal bar excision, medial plateau elevation, and corrective osteotomy
. Hemiepiphysiodesis of the lateral proximal tibia alone
. Application of a Taylor Spatial Frame without physeal surgery

Correct Answer & Explanation

. Physeal bar excision, medial plateau elevation, and corrective osteotomy

Explanation

In advanced infantile Blount disease (Langenskiöld stage V-VI), a bony bar crosses the physis and causes intra-articular depression. Treatment requires resection of the physeal bar, elevation of the depressed medial plateau, and a proximal tibial osteotomy to restore mechanical alignment.

Question 1736

Topic: 4. Pediatrics

When utilizing the principles of distraction osteogenesis (Ilizarov method) for a tibial lengthening procedure in a healthy adult, what is the optimal latency period and rate of distraction to ensure ideal regenerate bone formation?

. 1-2 days latency; 0.25 mm/day
. 3-5 days latency; 2.0 mm/day
. 7-10 days latency; 1.0 mm/day
. 14-21 days latency; 1.0 mm/day
. 7-10 days latency; 2.5 mm/day

Correct Answer & Explanation

. 7-10 days latency; 1.0 mm/day

Explanation

Ilizarov established that a latency period of 7-10 days allows for early callus formation before distraction begins. The ideal distraction rate is 1.0 mm per day (typically divided into 0.25 mm increments four times daily) to prevent premature consolidation or poor regenerate formation.

Question 1737

Topic: Pediatric Hip

A 12-year-old obese male presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. The surgeon recommends in situ pinning of the left hip. What is the most widely accepted absolute indication for prophylactic in situ pinning of the asymptomatic, contralateral right hip?

. Severe slip angle (>60 degrees) on the affected side
. Patient age older than 14 years at presentation
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. Male gender
. High level of athletic participation

Correct Answer & Explanation

. Presence of an underlying endocrine disorder (e.g., hypothyroidism)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is universally recommended for patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or prior pelvic radiation, as their risk of developing a contralateral slip is exceedingly high (up to 100%).

Question 1738

Topic: 4. Pediatrics

A 2-year-old child presents with bilateral absent thumbs and marked radial shortening. Laboratory tests reveal pancytopenia. Chromosomal breakage testing with diepoxybutane (DEB) is strongly positive. What is the inheritance pattern and primary cellular defect associated with this condition?

. Autosomal recessive; defect in DNA interstrand cross-link repair
. Autosomal dominant; defect in fibroblast growth factor receptor 3
. X-linked recessive; defect in type 1 collagen synthesis
. Autosomal recessive; mutation in the SHH (Sonic Hedgehog) gene
. Autosomal dominant; defect in DNA mismatch repair

Correct Answer & Explanation

. Autosomal recessive; defect in DNA interstrand cross-link repair

Explanation

The patient has Fanconi anemia, which typically presents with radial longitudinal deficiency (absent thumb/radius) and aplastic anemia (pancytopenia). It is inherited in an autosomal recessive pattern and is characterized by a failure in DNA interstrand cross-link repair. Diagnosis is confirmed by increased chromosomal breakage after exposure to clastogenic agents like DEB.

Question 1739

Topic: 4. Pediatrics

A 4-month-old infant is noted to have a hairy patch and a sacral dimple above the gluteal crease. MRI confirms a thickened filum terminale and a conus medullaris terminating at the L4 level. What is the specific embryological defect primarily responsible for this tethered cord syndrome?

. Failure of primary neurulation
. Failure of secondary neurulation and retrogressive differentiation
. Premature disjunction of the cutaneous ectoderm
. Persistence of the neurenteric canal
. Failure of notochordal formation

Correct Answer & Explanation

. Failure of secondary neurulation and retrogressive differentiation

Explanation

The development of the lower sacral and coccygeal segments of the spinal cord occurs via secondary neurulation. During the subsequent phase of retrogressive differentiation, the terminal portion of the neural tube undergoes atrophy to form the filum terminale, allowing the conus medullaris to ascend. Failure of this process leads to a thickened filum terminale and a low-lying, tethered conus medullaris. Primary neurulation defects result in open defects like myelomeningocele.

Question 1740

Topic: Pediatric Upper Extremity & Spine

According to the Lenke classification for adolescent idiopathic scoliosis, a curve is considered structurally significant and should be included in the fusion construct if the Cobb angle fails to reduce below what threshold on side-bending radiographs?

. 15 degrees
. 20 degrees
. 25 degrees
. 30 degrees
. 35 degrees

Correct Answer & Explanation

. 25 degrees

Explanation

In the Lenke classification system, a minor curve is considered structural if it does not bend down to less than 25 degrees on lateral side-bending radiographs. Structural curves must be included in the final fusion construct to maintain overall coronal balance.

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