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4. Pediatrics MCQs

Practice Set 173 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 3441

Topic: 4. Pediatrics

A 14-year-old obese boy presents with progressive bowing of his left leg. Radiographs reveal a severe varus deformity centered at the proximal tibia, with medial physeal widening and an open proximal tibial physis. What is the most appropriate initial management?

. Bracing with a custom knee-ankle-foot orthosis
. High tibial osteotomy with rigid internal fixation
. Guided growth via lateral tension band plating
. Tibial plateau elevation osteotomy
. Proximal fibular epiphysiodesis

Correct Answer & Explanation

. Guided growth via lateral tension band plating

Explanation

In adolescent Blount disease with open physes and sufficient remaining growth potential, guided growth (hemiepiphysiodesis) using lateral tension band plating is the preferred initial minimally invasive treatment to gradually correct the varus deformity.

Question 3442

Topic: Pediatric Hip

A 13-year-old boy undergoes in-situ percutaneous pinning of a stable slipped capital femoral epiphysis (SCFE) on the left side. Which of the following is considered an absolute indication for prophylactic pinning of the asymptomatic contralateral right hip?

. Patient age > 14 years at presentation
. Presence of an underlying endocrine disorder (e.g., hypothyroidism)
. Severe obesity (BMI > 99th percentile)
. Male gender
. Severe slip angle (> 60 degrees) on the symptomatic left side

Correct Answer & Explanation

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

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly recommended for patients with an underlying endocrine disorder (such as hypothyroidism or renal osteodystrophy) or a history of radiation therapy, as their risk of eventual bilateral involvement approaches 100%.

Question 3443

Topic: 4. Pediatrics
A 13-year-old girl twists her ankle while playing soccer and sustains a Salter-Harris III fracture of the anterolateral distal tibia. Which ligamentous structure transmits the avulsion force responsible for this specific fracture pattern?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A Tillaux fracture is an avulsion of the anterolateral epiphysis of the distal tibia (Salter-Harris III). It is caused by tension from the anterior inferior tibiofibular ligament (AITFL) during an external rotation injury, typically occurring as the medial physis has already closed.

Question 3444

Topic: Pediatric Hip

A 3-month-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). At her 2-week follow-up, she is noted to have decreased active knee extension on the affected side. What is the most appropriate next step in management?

. Continue the harness and observe
. Stop the harness temporarily and observe for neurologic recovery
. Loosen the posterior straps of the harness
. Perform a closed reduction and spica casting
. Switch to a rigid abduction orthosis

Correct Answer & Explanation

. Stop the harness temporarily and observe for neurologic recovery

Explanation

Decreased active knee extension in a Pavlik harness indicates femoral nerve palsy due to excessive hyperflexion. The harness must be discontinued temporarily until neurologic function returns to prevent permanent damage.

Question 3445

Topic: Pediatric Hip

A 12-year-old obese boy presents with left thigh pain and a limp. Radiographs confirm a stable left slipped capital femoral epiphysis (SCFE). Which of the following is an absolute indication for prophylactic pinning of the contralateral right hip?

. Patient age younger than 10 years
. Presence of an endocrine disorder such as hypothyroidism
. Body Mass Index > 35
. Closure of the triradiate cartilage
. Presentation with a stable slip

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with endocrine or metabolic disorders, as well as in patients presenting prior to age 10 or those undergoing radiation therapy. Obesity is a risk factor but not an absolute indication.

Question 3446

Topic: Pediatric Hip
In the evaluation of a 7-year-old boy with Legg-Calvé-Perthes disease, which of the following is the most significant prognostic radiographic factor according to the Herring classification?
. Extent of medial metaphyseal cysts
. Presence of the Gage sign
. Height of the lateral pillar of the capital femoral epiphysis
. Subchondral radiolucency (crescent sign)
. Degree of coxa magna

Correct Answer & Explanation

. Height of the lateral pillar of the capital femoral epiphysis

Explanation

The Herring (lateral pillar) classification assesses the height of the lateral aspect of the capital femoral epiphysis during the fragmentation phase. It is widely considered the most reliable prognostic indicator for long-term hip outcome in Legg-Calvé-Perthes disease.

Question 3447

Topic: Pediatric Lower Extremity

A 4-year-old boy with a history of idiopathic clubfoot treated successfully with the Ponseti method presents with a relapsed deformity. He walks with dynamic supination of the foot during the swing phase. Passive range of motion is full, and the foot is completely correctable. What is the most appropriate surgical management?

. Posteromedial release
. Complete subtalar release
. Tibialis anterior tendon transfer to the lateral cuneiform
. Split tibialis posterior tendon transfer
. Achilles tendon lengthening alone

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic supination in a relapsed clubfoot that is passively correctable is best treated with a full transfer of the tibialis anterior tendon to the lateral cuneiform. This procedure balances the muscular forces of the foot and prevents further relapse.

Question 3448

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand is pink but the radial pulse is not palpable. Capillary refill is less than 2 seconds. What is the most appropriate next step?

. Immediate exploration of the brachial artery
. Release of the anterior compartment of the forearm
. Removal of the pins and open reduction
. Observation and close clinical monitoring
. Administration of intravenous heparin

Correct Answer & Explanation

. Observation and close clinical monitoring

Explanation

A "pink, pulseless" hand after reduction and pinning of a supracondylar humerus fracture with good perfusion (capillary refill <2 seconds) should be closely observed. Vascular exploration is indicated only if the hand becomes pale and poorly perfused.

Question 3449

Topic: 4. Pediatrics

An 18-month-old child presents with a limp, low-grade fever, and refusal to bear weight on the right leg. Blood cultures are negative, but a joint aspirate is positive for Kingella kingae. What is the most common route of entry for this organism?

. Skin abrasion
. Oropharyngeal mucosa
. Gastrointestinal tract
. Genitourinary tract
. Transplacental transfer

Correct Answer & Explanation

. Oropharyngeal mucosa

Explanation

Kingella kingae is a fastidious Gram-negative organism recognized as a leading cause of pediatric osteoarticular infections in children under 4. It typically colonizes the oropharynx and enters the bloodstream through the respiratory mucosa.

Question 3450

Topic: 4. Pediatrics
An 8-year-old obese boy with Blount's disease presents with a significant varus deformity of the left knee. Radiographs reveal a Langenskiöld stage IV depression of the medial tibial plateau. Which of the following procedures is most appropriate?
. Bracing with a knee-ankle-foot orthosis (KAFO)
. Medial hemi-epiphysiodesis
. Proximal tibial corrective osteotomy with elevation of the medial plateau
. Guided growth of the lateral proximal tibia
. Distal femoral valgus osteotomy

Correct Answer & Explanation

. Proximal tibial corrective osteotomy with elevation of the medial plateau

Explanation

In late-onset or advanced infantile Blount's disease (Langenskiöld stage IV-VI), there is significant depression of the medial plateau and physeal bony bridging. Corrective osteotomy with intra-articular elevation of the medial plateau is required to restore joint congruity.

Question 3451

Topic: 4. Pediatrics
According to international hip surveillance guidelines for children with cerebral palsy, which patient demographic requires the most frequent radiographic monitoring for hip displacement?
. GMFCS Level I, age 10
. GMFCS Level II, age 12
. GMFCS Level V, age 4
. Hemiplegic CP, age 8
. GMFCS Level III, post-varus derotational osteotomy (VDRO)

Correct Answer & Explanation

. GMFCS Level V, age 4

Explanation

Children with cerebral palsy classified as GMFCS Levels IV and V are at the highest risk for progressive hip displacement and dislocation. They require regular clinical and radiographic screening starting at an early age.

Question 3452

Topic: 4. Pediatrics
A 2-year-old boy presents with anterolateral bowing of the tibia and a pseudoarthrosis. He has 8 café-au-lait spots and axillary freckling. What is the underlying genetic anomaly associated with this condition?
. Mutation in the FGFR3 gene
. Mutation in the COL1A1 gene
. Mutation in the NF1 gene
. Mutation in the COMP gene
. Mutation in the RUNX2 gene

Correct Answer & Explanation

. Mutation in the NF1 gene

Explanation

Congenital pseudarthrosis of the tibia with anterolateral bowing is highly associated with Neurofibromatosis Type 1 (NF1), which is caused by a mutation in the NF1 gene on chromosome 17. The patient's cutaneous findings confirm the diagnosis.

Question 3453

Topic: Pediatric Hip

A 13-year-old boy undergoes in-situ percutaneous pinning for an unstable slipped capital femoral epiphysis (SCFE). At 6 months post-op, he develops severe hip stiffness, pain, and joint space narrowing on radiographs. The hardware does not penetrate the joint. What is the most likely diagnosis?

. Avascular necrosis (AVN)
. Chondrolysis
. Septic arthritis
. Hardware failure
. Unrecognized contralateral SCFE

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a devastating complication of SCFE, characterized by acute loss of articular cartilage, joint space narrowing, and severe stiffness. It can occur idiopathically, especially in severe or unstable slips, even without hardware penetration.

Question 3454

Topic: Pediatric Lower Extremity

A newborn is evaluated for a short lower extremity. Radiographs show a very short femur, an absent proximal femur, and no hip joint articulation. According to the Aitken classification, which class does this represent?

. Class A
. Class B
. Class C
. Class D
. Class E

Correct Answer & Explanation

. Class D

Explanation

In Aitken Class D Proximal Focal Femoral Deficiency (PFFD), both the acetabulum and the proximal femur are severely dysplastic or absent. There is no bony connection between the femur and the pelvis.

Question 3455

Topic: 4. Pediatrics
A 14-year-old boy sustains an ankle injury while skateboarding. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the deforming force mechanism and involved structure?
. Supination-adduction, calcaneofibular ligament
. External rotation, anterior inferior tibiofibular ligament (AITFL)
. Plantarflexion, posterior talofibular ligament
. Pronation-abduction, deltoid ligament
. Internal rotation, superficial peroneal nerve

Correct Answer & Explanation

. External rotation, anterior inferior tibiofibular ligament (AITFL)

Explanation

A Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs due to an external rotation force avulsing the anterior inferior tibiofibular ligament (AITFL) from its attachment, as the medial physis closes before the lateral physis.

Question 3456

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute onset of right hip pain and inability to bear weight after tripping. Radiographs confirm a slipped capital femoral epiphysis (SCFE). He is completely unable to ambulate even with crutches. What is the most common severe complication directly associated with the unstable nature of this specific diagnosis?

. Chondrolysis
. Avascular necrosis of the femoral head
. Septic arthritis
. Femoral neck nonunion
. Early-onset osteoarthritis

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

This patient has an unstable SCFE, defined clinically by the inability to bear weight even with crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN) compared to stable SCFE, with rates historically reported up to 50%.

Question 3457

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced, extension-type supracondylar humerus fracture. Upon arrival, his hand is pink but pulseless, and he has a dense anterior interosseous nerve (AIN) palsy. Following closed reduction and percutaneous pinning, the hand remains pink and pulseless. What is the most appropriate next step in management?

. Immediate vascular exploration
. Close observation and admission for 24-48 hours
. Removal of pins and re-reduction of the fracture
. Emergent color duplex ultrasonography
. Open reduction and internal fixation

Correct Answer & Explanation

. Close observation and admission for 24-48 hours

Explanation

A 'pink, pulseless hand' after a satisfactory reduction and pinning of a supracondylar humerus fracture should be admitted and observed closely. Vascular exploration is generally indicated only if the hand is poorly perfused (white and pulseless) after reduction.

Question 3458

Topic: Pediatric Hip

An 18-month-old girl presents with a limp. Clinical examination and pelvic radiographs reveal an untreated, dislocated right hip with a dysplastic acetabulum consistent with developmental dysplasia of the hip (DDH). What is the most appropriate initial management for this patient?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction, pelvic osteotomy, and spica casting
. Proximal femoral varus derotation osteotomy
. Observation and physical therapy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In children aged 6 to 18 months with untreated DDH, the standard first-line treatment is typically an attempt at closed reduction and spica casting under general anesthesia. Open reduction is reserved for cases where a stable and concentric closed reduction cannot be achieved.

Question 3459

Topic: Pediatric Lower Extremity

A 4-week-old infant with an idiopathic clubfoot has undergone four weekly casts using the Ponseti method. The midfoot cavus, adductus, and heel varus are now fully corrected. However, ankle dorsiflexion is limited to 5 degrees of plantarflexion. What is the most appropriate next step in treatment?

. Two additional weeks of serial casting
. Percutaneous Achilles tenotomy
. Comprehensive posteromedial release
. Transfer of the anterior tibial tendon
. Immediate application of a foot abduction orthosis

Correct Answer & Explanation

. Percutaneous Achilles tenotomy

Explanation

According to the Ponseti method, once the midfoot deformities (cavus, adductus, varus) are fully corrected, residual equinus is addressed with a percutaneous Achilles tenotomy. This is typically required in over 80% of idiopathic clubfoot cases.

Question 3460

Topic: Pediatric Hip

A 9-year-old boy is diagnosed with Legg-Calve-Perthes disease. Pelvic radiographs demonstrate that more than 50% of the lateral pillar of the femoral head has collapsed. According to the Herring lateral pillar classification, what group does this represent and what is the expected outcome?

. Group B, favorable outcome
. Group B, poor outcome
. Group C, favorable outcome
. Group C, poor outcome
. Group A, favorable outcome

Correct Answer & Explanation

. Group C, poor outcome

Explanation

Herring Group C is characterized by greater than 50% loss of lateral pillar height. In children over the age of 8, Group C presentation is strongly associated with a poor long-term clinical and radiographic outcome regardless of the treatment modality.

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