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4. Pediatrics MCQs

Practice Set 161 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 3201

Topic: 4. Pediatrics
A 6-year-old boy sustains a widely displaced, extension-type supracondylar humerus fracture. In the emergency department, his hand is pale, pulseless, and cool. Following urgent closed reduction and percutaneous pinning, the hand becomes pink and warm with brisk capillary refill (<2 seconds), but the radial pulse remains absent. What is the most appropriate next step in management?
. Immediate vascular exploration
. Angiography of the upper extremity
. Removal of the pins and transition to open reduction
. Observation and admission for close neurovascular monitoring
. Prophylactic fasciotomy of the forearm

Correct Answer & Explanation

. Observation and admission for close neurovascular monitoring

Explanation

The management of a 'pink, pulseless' hand following the reduction of a pediatric supracondylar humerus fracture is observation. Because the hand is well-perfused (warm, pink, brisk capillary refill), collateral circulation is adequate. The radial pulse typically returns over hours to weeks as vasospasm resolves. Vascular exploration is only indicated for a persistently 'white, pulseless' hand after adequate reduction.

Question 3202

Topic: Pediatric Hip
An 8-year-old boy presents with a limp and right hip pain for 3 months. Radiographs reveal fragmentation of the right capital femoral epiphysis consistent with Legg-Calvé-Perthes disease. The lateral pillar height is evaluated and found to be 40% of the normal contralateral side. Based on the Herring Lateral Pillar Classification, what is the prognosis and recommended treatment?
. Group A; symptomatic treatment and observation as outcomes are universally excellent
. Group B; symptomatic treatment and observation as surgery offers no benefit
. Group B; proximal femoral or pelvic osteotomy to improve outcomes
. Group C; proximal femoral or pelvic osteotomy has not been shown to significantly alter the final radiographic outcome
. Group C; immediate total hip arthroplasty due to inevitable joint destruction

Correct Answer & Explanation

. Group C; proximal femoral or pelvic osteotomy has not been shown to significantly alter the final radiographic outcome

Explanation

According to the Herring Lateral Pillar Classification, a lateral pillar height <50% places the hip in Group C. The prospective multicenter study by Herring et al. demonstrated that for Group C hips, surgical containment (osteotomy) does not significantly improve the final Stulberg radiographic outcome compared to non-operative treatment, as these hips tend to have poor results regardless of intervention. In contrast, children >8 years old with Group B or B/C border hips benefit significantly from surgical containment.

Question 3203

Topic: 4. Pediatrics

A 9-month-old male infant with a known mutation in the FGFR3 gene presents for routine evaluation. The parents report increased irritability, poor head control, and recent episodes of apnea during sleep. On physical examination, the child has generalized hypotonia but demonstrates hyperreflexia and sustained ankle clonus. Which of the following is the most critical diagnostic study to perform next?

. Radiographs of the thoracolumbar spine
. MRI of the brain and cervicomedullary junction
. Polysomnography (Sleep study) alone
. Computed tomography of the lumbar spine
. Genetic karyotyping to rule out secondary syndromes

Correct Answer & Explanation

. MRI of the brain and cervicomedullary junction

Explanation

The child has achondroplasia (due to an FGFR3 mutation). Infants with achondroplasia are at high risk for foramen magnum stenosis, which can lead to life-threatening cervicomedullary compression. Symptoms of upper motor neuron compression include hypotonia, hyperreflexia, sleep apnea, and potentially sudden death. MRI of the brain and cervicomedullary junction is the modality of choice to evaluate the severity of stenosis and the presence of cord signal changes, dictating the need for urgent suboccipital decompression.

Question 3204

Topic: Pediatric Hip

A 12-year-old boy with a body mass index (BMI) in the 99th percentile undergoes uneventful in situ single-screw fixation for a stable right slipped capital femoral epiphysis (SCFE). The parents inquire about the necessity of prophylactic fixation for the asymptomatic left hip. Which of the following patient factors most strongly supports proceeding with prophylactic pinning of the contralateral hip?

. Chronological age of 12 years
. Open triradiate cartilage
. A measured slip angle of 40 degrees on the right
. Male sex
. The chronicity of the right-sided slip symptoms prior to presentation

Correct Answer & Explanation

. Open triradiate cartilage

Explanation

The decision to perform prophylactic pinning of the contralateral hip in SCFE is based on the risk of a subsequent slip. An open triradiate cartilage (or a modified Oxford bone age score of 16 or lower) is one of the strongest radiographic predictors for a future contralateral slip. Other significant risk factors include endocrine disorders (e.g., hypothyroidism), renal osteodystrophy, history of radiation therapy, and younger age (typically boys < 10-12 years or girls < 10 years). While obesity is a risk factor for SCFE generally, the biologic immaturity indicated by an open triradiate cartilage is a more specific and potent indicator for prophylactic fixation.

Question 3205

Topic: 4. Pediatrics

A 5-year-old boy sustains a completely displaced, extension-type supracondylar fracture of the humerus. On initial evaluation, his hand is pink and warm, but the radial pulse is not palpable. Neurologic examination reveals an inability to actively flex the interphalangeal joint of the thumb. The patient undergoes urgent closed reduction and percutaneous pinning in the operating room. Postoperatively, the hand remains well-perfused, pink, and warm, with a capillary refill time of less than 2 seconds, but the radial pulse remains non-palpable by Doppler. What is the most appropriate next step in management?

. Immediate open exploration of the brachial artery
. Noninvasive vascular studies followed by urgent CT angiography
. Observation and close clinical monitoring of neurovascular status
. Immediate removal of the pins and transition to open reduction
. Administration of intra-arterial vasodilators to relieve vasospasm

Correct Answer & Explanation

. Observation and close clinical monitoring of neurovascular status

Explanation

The clinical scenario describes a 'pulseless, pink' hand following closed reduction and percutaneous pinning (CRPP) of a supracondylar humerus fracture, accompanied by an anterior interosseous nerve (AIN) palsy (indicated by the inability to flex the IP joint of the thumb). The AIN is the most commonly injured nerve in extension-type supracondylar fractures. Current AAOS guidelines and pediatric orthopaedic consensus dictate that if the hand remains pink and well-perfused (capillary refill < 2 seconds, warm) after anatomic reduction and stabilization, the most appropriate management is observation and close clinical monitoring. Arterial exploration is indicated for a 'pulseless, white' (ischemic) hand that does not improve after fracture reduction.

Question 3206

Topic: Pediatric Hip

An infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). During a routine follow-up evaluation, the parents report that the child has stopped kicking the affected leg. On physical examination, the affected knee is held in extension and there is an absence of active quadriceps contraction. This specific complication is most directly caused by which of the following positioning errors within the harness?

. Excessive abduction of the hip
. Inadequate abduction of the hip
. Excessive flexion of the hip
. Inadequate flexion of the hip
. Excessive internal rotation of the hip

Correct Answer & Explanation

. Inadequate flexion of the hip

Explanation

Femoral nerve palsy is a well-documented complication of Pavlik harness treatment for DDH, typically presenting as an inability to actively extend the knee or a decrease in spontaneous kicking on the affected side. It is caused by hyperflexion of the hips, which compresses the femoral nerve against the inguinal ligament. Management involves adjusting the anterior straps to decrease hip flexion, which almost universally results in spontaneous resolution of the nerve palsy within a few days to weeks. Conversely, excessive abduction in the harness increases the risk of avascular necrosis (AVN) of the femoral head.

Question 3207

Topic: Pediatric Hip
An 8.5-year-old boy presents with a 4-month history of a painless limp. Radiographs demonstrate Legg-Calvé-Perthes disease in the fragmentation stage. Analysis of the anteroposterior pelvis radiograph shows that the lateral pillar of the affected capital femoral epiphysis maintains 60% of its normal height. Based on the Herring lateral pillar classification and prospective multicenter data, which of the following statements most accurately reflects the current consensus on his management and prognosis?
. Nonoperative management with bracing provides superior outcomes compared to surgery due to his advanced age.
. Surgical containment yields significantly better radiographic outcomes compared to nonoperative treatment.
. Surgical containment is contraindicated due to the severity of lateral pillar collapse.
. He is classified as Lateral Pillar Group C, and outcomes are uniformly excellent without intervention.
. He is classified as Lateral Pillar Group A, and should be treated with immediate prophylactic pinning.

Correct Answer & Explanation

. Surgical containment yields significantly better radiographic outcomes compared to nonoperative treatment.

Explanation

According to the Herring lateral pillar classification for Legg-Calvé-Perthes disease, a femoral head that maintains >50% of its lateral pillar height is classified as Group B. The prospective multicenter study by Herring et al. demonstrated that for children older than 8 years of age at the time of disease onset with Group B or Group B/C border involvement, surgical containment (e.g., femoral varus osteotomy or pelvic osteotomy) results in significantly better long-term radiographic outcomes (measured by the Stulberg classification) compared to nonoperative management. Patients under age 8 with Group B generally have favorable outcomes regardless of treatment, whereas Group C patients over age 8 often have poor outcomes despite surgical intervention.

Question 3208

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip. At the 2-week follow-up, the parents report the infant is no longer kicking her right leg. Examination reveals decreased active knee extension on the right, but normal sensation. What is the most appropriate next step in management?

. Proceed to closed reduction and spica casting
. Remove the harness temporarily and observe
. Adjust the posterior straps to increase hip abduction
. Adjust the anterior straps to increase hip flexion
. Obtain an urgent MRI of the lumbar spine

Correct Answer & Explanation

. Remove the harness temporarily and observe

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically resulting from hyperflexion of the hip due to overly tight anterior straps. The harness should be temporarily removed or adjusted; the palsy almost always resolves spontaneously.

Question 3209

Topic: 4. Pediatrics

In the Ponseti method for the treatment of idiopathic congenital talipes equinovarus (clubfoot), what is the correct sequential order of deformity correction?

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

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

The Ponseti method dictates correction in the mnemonic sequence CAVE: Cavus, Adductus, Varus, and finally Equinus. Correcting the cavus first by elevating the first ray provides a solid foundation to correct the remaining deformities.

Question 3210

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy presents with a completely displaced, extension-type supracondylar humerus fracture. On examination, the hand is pink and warm, but the radial pulse is absent. After urgent closed reduction and percutaneous pinning, the hand remains pink and warm, but the pulse remains absent. What is the most appropriate next step?

. Immediate open exploration of the brachial artery
. Perform a CT angiogram of the upper extremity
. Remove the pins and attempt a second closed reduction
. Admit for 24-48 hours of observation with serial vascular checks
. Administer intravenous heparin and discharge home

Correct Answer & Explanation

. Admit for 24-48 hours of observation with serial vascular checks

Explanation

A "pulseless, pink" hand after reduction and pinning of a supracondylar fracture indicates adequate collateral circulation. Observation is the standard of care, as most radial pulses return within 24 to 48 hours without needing surgical exploration.

Question 3211

Topic: Pediatric Hip

A 13-year-old obese boy presents with acute-on-chronic hip pain and an inability to bear weight. Radiographs confirm a Slipped Capital Femoral Epiphysis (SCFE). He undergoes urgent in situ percutaneous pinning. Which of the following complications is most highly associated with this specific preoperative presentation?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoral nerve palsy
. Slipped capital femoral epiphysis of the contralateral hip
. Hardware failure

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The inability to bear weight defines an unstable SCFE, which carries a significantly higher risk of avascular necrosis (AVN) of the femoral head compared to stable SCFE. Urgent decompression and fixation are often advocated to mitigate this risk.

Question 3212

Topic: 4. Pediatrics
A 14-year-old boy sustains a twisting ankle injury resulting in a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following best describes the anatomical basis for this specific fracture pattern?
. Avulsion by the anterior talofibular ligament
. Asymmetric closure of the distal tibial physis starting centrally and medially
. Asymmetric closure of the distal tibial physis starting anterolaterally
. Avulsion by the calcaneofibular ligament
. Premature closure of the distal fibular physis

Correct Answer & Explanation

. Asymmetric closure of the distal tibial physis starting anterolaterally

Explanation

A Tillaux fracture occurs because the distal tibial physis closes in a predictable sequence: central, medial, then lateral. The anterolateral portion remains open longest, making it susceptible to avulsion by the anterior inferior tibiofibular ligament (AITFL).

Question 3213

Topic: 4. Pediatrics

A 5-year-old child with spastic quadriplegic cerebral palsy (GMFCS level V) undergoes routine hip surveillance. An AP pelvis radiograph demonstrates a Reimers migration percentage of 45% bilaterally. What is the most appropriate definitive management?

. Observation with repeat radiographs in 1 year
. Botulinum toxin injections to the adductors
. Bilateral isolated adductor tenotomies
. Bilateral varus derotational osteotomies (VDRO) with or without pelvic osteotomies
. Bilateral proximal femoral resections (Girdlestone procedure)

Correct Answer & Explanation

. Bilateral varus derotational osteotomies (VDRO) with or without pelvic osteotomies

Explanation

In children with cerebral palsy, a Reimers migration percentage greater than 40% indicates significant subluxation with high risk of dislocation. Bony reconstruction with a VDRO is necessary, as soft tissue releases alone are no longer sufficient.

Question 3214

Topic: Pediatric Hip
In the management of Legg-Calvé-Perthes disease, the Herring Lateral Pillar Classification is most accurately assessed and clinically useful during which stage of the disease?
. Initial stage
. Early fragmentation stage
. Late fragmentation stage
. Reossification stage
. Healed stage

Correct Answer & Explanation

. Early fragmentation stage

Explanation

The Herring Lateral Pillar Classification evaluates the height of the lateral pillar of the femoral head and is the most reliable prognostic indicator. It is most accurately applied during the early to late fragmentation stage of the disease.

Question 3215

Topic: 4. Pediatrics

Prophylactic in situ pinning of the contralateral, asymptomatic hip in a patient with a unilateral Slipped Capital Femoral Epiphysis (SCFE) is most strongly indicated if the patient has a history of which of the following underlying conditions?

. Down syndrome
. Morbid obesity
. Hypothyroidism
. Attention-deficit/hyperactivity disorder
. Achondroplasia

Correct Answer & Explanation

. Hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is highly recommended for patients with endocrine disorders such as hypothyroidism or panhypopituitarism. These underlying systemic conditions dramatically increase the risk of a subsequent bilateral SCFE.

Question 3216

Topic: Pediatric Lower Extremity

An infant is born with idiopathic clubfoot. The treating surgeon begins Ponseti casting. What specific technical maneuver dictates the correct treatment of the cavus deformity in the application of the first cast?

. Plantarflexion of the first ray and pronation of the forefoot
. Dorsiflexion of the first ray and pronation of the forefoot
. Eversion of the hindfoot
. Dorsiflexion of the entire forefoot
. Dorsiflexion of the first ray and supination of the forefoot

Correct Answer & Explanation

. Dorsiflexion of the first ray and supination of the forefoot

Explanation

The first step in the Ponseti method (CAVE) corrects the cavus by elevating (dorsiflexing) the first ray to align the forefoot with the hindfoot, effectively supinating the forefoot. This unlocks the transverse tarsal joint allowing subsequent abduction.

Question 3217

Topic: Pediatric Hip

A 6-week-old infant is placed in a Pavlik harness for Developmental Dysplasia of the Hip (DDH). At the 2-week follow-up, the mother reports the infant is not extending the knee on the affected side. On examination, the quadriceps muscle is flaccid. What is the most appropriate next step in management?

. Remove the harness temporarily until quadriceps function returns
. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to decrease hip abduction
. Proceed immediately to closed reduction and spica casting
. Proceed immediately to open reduction

Correct Answer & Explanation

. Remove the harness temporarily until quadriceps function returns

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hip. The appropriate management is to remove the harness temporarily or significantly decrease hip flexion until clinical resolution of the nerve palsy occurs.

Question 3218

Topic: Pediatric Hip

A 12-year-old boy presents with left hip pain and an obligatory external rotation of the hip during active flexion. He is diagnosed with a stable slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

. Male sex
. Age greater than 14 years
. Underlying endocrine disorder
. African American race
. Symptom duration greater than 6 months

Correct Answer & Explanation

. Underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) due to the substantially increased risk of bilateral involvement.

Question 3219

Topic: Pediatric Hip
An 8-year-old boy presents with a painful limp of insidious onset. Radiographs demonstrate changes consistent with Legg-Calvé-Perthes disease. According to the Herring lateral pillar classification, what specific radiographic finding characterizes a Group B hip?
. Greater than 50% of the lateral pillar height is maintained
. No involvement of the lateral pillar
. Less than 50% of the lateral pillar height is maintained
. Complete collapse of the lateral pillar
. Extrusion of the femoral head lateral to the acetabular margin

Correct Answer & Explanation

. Less than 50% of the lateral pillar height is maintained

Explanation

In the Herring lateral pillar classification, Group A has no lateral pillar involvement, Group B maintains >50% of the original lateral pillar height, and Group C has <50% of the height maintained. This classification is heavily used for determining prognosis.

Question 3220

Topic: Pediatric Lower Extremity

An infant with a severe, rigid, idiopathic clubfoot is treated with the Ponseti casting method. To prevent recurrence and effectively correct the deformity, what is the correct anatomical sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method sequentially corrects clubfoot deformities in the specific order of Cavus, Adductus, Varus, and finally Equinus (remembered by the acronym CAVE). Equinus is corrected last, typically requiring a percutaneous Achilles tenotomy.

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