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4. Pediatrics MCQs

Practice Set 322 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 6421

Topic: Pediatric Hip

A 12-year-old obese male presents with acute-on-chronic hip pain and inability to bear weight. Radiographs show a severe slipped capital femoral epiphysis (SCFE). Intraoperatively, a capsulotomy is performed before pinning. What is the primary rationale for this capsulotomy?

. To improve visualization of the physis for pin placement
. To decrease intracapsular pressure and potentially lower the risk of avascular necrosis (AVN)
. To facilitate an open reduction of the epiphysis
. To remove loose bodies from the joint space
. To allow placement of an intra-articular drain

Correct Answer & Explanation

. To decrease intracapsular pressure and potentially lower the risk of avascular necrosis (AVN)

Explanation

In unstable SCFE, an acute hemarthrosis significantly elevates intracapsular pressure, compromising retinacular vessel flow. A capsulotomy decompresses this hematoma, theoretically restoring blood flow and lowering the high risk of AVN.

Question 6422

Topic: 4. Pediatrics
You are evaluating a 2-year-old with infantile tibia vara (Blount's disease). During radiographic follow-up, which finding according to the Langenskiöld classification indicates an irreversible physeal injury that typically requires surgical intervention?
. Stage I (irregular metaphyseal beak)
. Stage II (sharp depression of the medial metaphysis)
. Stage III (step-off at the metaphysis)
. Stage IV (narrow bony bridge across the medial physis)
. Stage V (cleft in the epiphysis)

Correct Answer & Explanation

. Stage IV (narrow bony bridge across the medial physis)

Explanation

Langenskiöld Stage IV is defined by the formation of a physeal bar (bony bridge) across the medial metaphysis and epiphysis. This arrests medial growth, requiring surgical intervention such as bar excision or osteotomy to prevent worsening deformity.

Question 6423

Topic: Pediatric Hip

An infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report the infant is not kicking the affected leg. Examination reveals lack of knee extension. Which of the following harness adjustments is required?

. Increase the flexion of the anterior straps
. Decrease the flexion of the anterior straps
. Increase the abduction of the posterior straps
. Decrease the abduction of the posterior straps
. Discontinue the harness immediately for 4 weeks

Correct Answer & Explanation

. Decrease the flexion of the anterior straps

Explanation

Femoral nerve palsy is a known complication of excessive hip flexion in a Pavlik harness. The appropriate management is to decrease the flexion of the anterior straps and observe for clinical recovery.

Question 6424

Topic: 4. Pediatrics
A 4-year-old girl with severe infantile Blount's disease undergoes a proximal tibial osteotomy. During preoperative planning, you note Langenskiöld stage V changes. What additional procedure is most commonly required in this stage compared to stage II?
. Fibular shortening osteotomy
. Medial tibial plateau elevation
. Lateral hemiepiphysiodesis
. Application of a guided growth plate
. Gastrocnemius release

Correct Answer & Explanation

. Medial tibial plateau elevation

Explanation

Langenskiöld stage V and VI infantile Blount's disease typically involves severe depression of the medial tibial plateau and often a physeal bar. Medial tibial plateau elevation combined with a corrective osteotomy is required to restore joint congruity.

Question 6425

Topic: Pediatric Hip

A 13-year-old obese male presents to the ED with a 2-day history of severe left hip pain and inability to bear weight. Radiographs demonstrate a Slipped Capital Femoral Epiphysis (SCFE). Which of the following factors best defines this as an 'unstable' SCFE?

. Slip angle greater than 50 degrees
. Presence of an effusion on ultrasound
. Inability to ambulate with or without crutches
. Duration of symptoms less than 3 weeks
. Open triradiate cartilage

Correct Answer & Explanation

. Inability to ambulate with or without crutches

Explanation

The Loder classification defines unstable SCFE as the patient's inability to bear weight on the affected limb, even with the use of crutches. Unstable SCFEs have a significantly higher risk of avascular necrosis.

Question 6426

Topic: Pediatric Lower Extremity

When applying the Ponseti method for the treatment of idiopathic clubfoot, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method systematically corrects deformities in the CAVE sequence: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus (often requiring a percutaneous Achilles tenotomy).

Question 6427

Topic: 4. Pediatrics

In a 5-year-old child with spastic quadriplegic cerebral palsy, routine radiographic surveillance shows a Reimers migration percentage of 45% in the left hip. The child is symptomatic with limited hip abduction. Which of the following interventions is most appropriate?

. Observation with repeat radiographs in 1 year
. Isolated botulinum toxin injection to the adductors
. Adductor longus release and varus derotational osteotomy (VDRO)
. Total hip arthroplasty
. Salter innominate osteotomy alone

Correct Answer & Explanation

. Adductor longus release and varus derotational osteotomy (VDRO)

Explanation

A Reimers migration index greater than 40% in a child with cerebral palsy indicates progressive hip subluxation that typically requires bony reconstruction. Soft tissue release combined with a varus derotational osteotomy (VDRO) and possible pelvic osteotomy is the standard of care.

Question 6428

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the mother notes the infant has stopped kicking her right leg, and clinical examination reveals decreased active knee extension on that side. Which of the following harness adjustments should have been avoided to prevent this complication?

. Excessive hip flexion
. Excessive hip abduction
. Inadequate hip flexion
. Inadequate hip abduction
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Excessive hip flexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy characterized by decreased active knee extension. Excessive hip abduction risks avascular necrosis (AVN) of the femoral head.

Question 6429

Topic: 4. Pediatrics

A 3-year-old overweight boy presents with progressive bilateral genu varum. Standing radiographs demonstrate an abrupt varus angulation at the proximal medial tibial metaphysis with a metaphyseal-diaphyseal angle (MDA) of 18 degrees. What is the most appropriate management?

. Reassurance and annual follow-up
. Prescription of knee-ankle-foot orthoses (KAFOs)
. Guided growth via lateral tension band plating
. Proximal tibial valgus osteotomies
. Medial epiphysiodesis

Correct Answer & Explanation

. Prescription of knee-ankle-foot orthoses (KAFOs)

Explanation

This child has infantile Blount disease, as indicated by age, risk factors, and an MDA greater than 16 degrees. For children under 3-4 years of age with early-stage infantile Blount disease (Langenskiold Stage I or II), bracing with KAFOs is the first-line treatment.

Question 6430

Topic: Pediatric Hip

A 10-year-old girl is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following patient profiles represents the strongest indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. A patient with BMI > 95th percentile
. A patient with primary hypothyroidism
. A patient with a family history of SCFE
. A patient with advanced skeletal maturity
. A male patient with traumatic SCFE onset

Correct Answer & Explanation

. A patient with primary hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or prior pelvic radiation. These patients have a significantly higher risk of developing bilateral SCFE.

Question 6431

Topic: 4. Pediatrics

When constructing a circular external fixator (Ilizarov) for tibial lengthening, which of the following modifications most significantly increases the axial stiffness of the construct?

. Increasing the distance between the rings
. Decreasing the tension on the transfixing wires from 130 kg to 90 kg
. Decreasing the ring diameter
. Using single-level half-pins instead of tensioned wires
. Crossing the wires at a 30-degree angle rather than a 90-degree angle

Correct Answer & Explanation

. Decreasing the ring diameter

Explanation

Axial stiffness in a circular frame is most significantly increased by decreasing the ring diameter (keeping the bone as central as possible), increasing wire diameter, and increasing wire tension. Wires crossed at 90 degrees provide greater stability than those intersecting at acute angles.

Question 6432

Topic: Pediatric Lower Extremity

During the Ponseti casting treatment for a rigid idiopathic clubfoot in a 4-week-old infant, the midfoot has been fully abducted. The heel varus has resolved, and the forefoot is abducted to 70 degrees. However, ankle dorsiflexion remains at -10 degrees. What is the correct next step in management?

. Percutaneous Achilles tenotomy
. Tibialis anterior transfer
. Posterior capsulotomy of the ankle
. Cuboid decancellation
. Continued casting to stretch the Achilles tendon

Correct Answer & Explanation

. Percutaneous Achilles tenotomy

Explanation

In the Ponseti method (CAVE: Cavus, Adductus, Varus, Equinus), heel varus corrects simultaneously with forefoot abduction. Once forefoot abduction reaches 60-70 degrees, equinus is the final deformity addressed, typically requiring a percutaneous Achilles tenotomy.

Question 6433

Topic: Pediatric Hip

Which of the following pediatric patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) has the strongest indication for prophylactic in situ pinning of the contralateral hip?

. A 13-year-old boy with a BMI in the 95th percentile
. A 10-year-old girl with primary hypothyroidism
. A 14-year-old boy with a history of minor trauma
. A 12-year-old boy with a family history of SCFE
. An 11-year-old girl with a stable SCFE and normal endocrine labs

Correct Answer & Explanation

. A 10-year-old girl with primary hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly indicated in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) due to an exceedingly high risk of bilateral involvement. It is also highly recommended in children presenting at a young age (<10 years).

Question 6434

Topic: Pediatric Lower Extremity

A 2-year-old girl presents with bilateral bowing of the lower extremities.

Radiographs show medial beaking of the proximal tibial metaphysis. Which radiographic measurement is most reliable in differentiating infantile Blount's disease from physiologic genu varum?

. Tibiofemoral angle
. Mechanical axis deviation
. Metaphyseal-diaphyseal angle (Drennan's angle)
. Epiphyseal-metaphyseal angle
. Anatomic axis angle

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle (Drennan's angle)

Explanation

Drennan's metaphyseal-diaphyseal angle (MDA) is critical in distinguishing infantile Blount's disease from physiologic bowing. An MDA greater than 16 degrees is highly predictive of Blount's disease and disease progression.

Question 6435

Topic: Pediatric Hip
A 6-week-old female infant born in breech presentation undergoes a screening ultrasound for developmental dysplasia of the hip (DDH). The alpha angle is reported as 45 degrees. According to Graf's classification, what is the most appropriate management?
. Reassurance and repeat ultrasound in 6 months
. Treatment with a Pavlik harness
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Use of double diapers

Correct Answer & Explanation

. Treatment with a Pavlik harness

Explanation

An alpha angle less than 60 degrees indicates a shallow acetabulum consistent with dysplasia (Graf Type IIc or III depending on the beta angle). The first-line treatment for an infant under 6 months with a dysplastic or subluxated hip is a Pavlik harness.

Question 6436

Topic: 4. Pediatrics
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the Herring Lateral Pillar classification, which of the following radiographic findings places him in Group C and predicts the poorest long-term prognosis?
. Maintenance of >50% of the lateral pillar height
. Greater than 50% collapse of the lateral pillar height
. A subchondral fracture (Crescent sign) involving >50% of the femoral head
. Extrusion of the femoral head >20% outside the acetabulum
. Premature closure of the capital femoral physis

Correct Answer & Explanation

. Greater than 50% collapse of the lateral pillar height

Explanation

The Herring Lateral Pillar classification predicts outcome based on the height of the lateral portion of the epiphysis on the AP radiograph. Group C is defined by >50% collapse (less than 50% maintained height) of the lateral pillar, which indicates a poor prognosis, particularly in children older than 8 years.

Question 6437

Topic: 4. Pediatrics

A 6-week-old infant with developmental dysplasia of the hip is being treated with a Pavlik harness. During a follow-up visit, the parents report the child has stopped actively extending the knee on the treated side. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to decrease hip abduction
. Order an urgent MRI of the lumbar spine
. Discontinue the harness temporarily or loosen the anterior straps
. Transition immediately to a rigid hip spica cast

Correct Answer & Explanation

. Discontinue the harness temporarily or loosen the anterior straps

Explanation

Active inability to extend the knee while in a Pavlik harness strongly suggests a femoral nerve palsy secondary to hyperflexion of the hip. The appropriate management is to temporarily discontinue the harness or loosen the anterior straps to relieve tension on the femoral nerve.

Question 6438

Topic: 4. Pediatrics
A 4-year-old girl presents with progressive genu varum. Radiographs demonstrate a sharp varus angulation at the proximal tibial metaphysis with a metaphyseal-diaphyseal angle of 18 degrees and profound medial physeal depression. She is diagnosed with infantile Blount's disease (Langenskiold stage III). What is the most appropriate management?
. Observation and reassurance
. Full-time use of a Knee-Ankle-Foot Orthosis (KAFO)
. Proximal tibial valgus osteotomy with concomitant fibular osteotomy
. Medial proximal tibial hemiepiphysiodesis
. Lateral proximal tibial hemiepiphysiodesis

Correct Answer & Explanation

. Proximal tibial valgus osteotomy with concomitant fibular osteotomy

Explanation

By age 4, children with stage III or higher infantile Blount's disease have a very low rate of spontaneous resolution or bracing success. A proximal tibial valgus-producing osteotomy with a fibular osteotomy is indicated to correct the deformity, unload the medial physis, and prevent further physeal damage.

Question 6439

Topic: Pediatric Hip

A 13-year-old boy with a BMI of 38 presents with a stable slipped capital femoral epiphysis (SCFE) of the left hip. Routine preoperative blood work reveals untreated hypothyroidism. After in situ pinning of the left hip, what is the most appropriate recommendation regarding the right hip?

. Observation with serial clinical exams every 6 months
. Prophylactic in situ pinning of the right hip
. Immediate bilateral spica casting
. Physical therapy for weight loss before considering any further surgery
. Pre-emptive open subcapital osteotomy of the right hip

Correct Answer & Explanation

. Prophylactic in situ pinning of the right hip

Explanation

Patients with SCFE and underlying endocrinopathies (such as hypothyroidism) or renal failure are at an exceptionally high risk for bilateral involvement. Prophylactic pinning of the contralateral hip is strongly recommended in these high-risk populations to prevent future displacement.

Question 6440

Topic: 4. Pediatrics

A 5-year-old girl is evaluated for a congenital femoral deficiency. Her current absolute femoral length discrepancy is 3 cm. Using the Paley multiplier method to estimate her discrepancy at skeletal maturity, which specific patient demographic factor is strictly required to select the correct multiplier coefficient?

. Patient's current weight
. Patient's current chronological age and gender
. Skeletal maturity assessed solely by Risser stage
. Family history of adult height
. Bone age assessed by a dedicated hand radiograph only

Correct Answer & Explanation

. Patient's current chronological age and gender

Explanation

The Paley multiplier method predicts limb length discrepancy at maturity using a specific multiplier coefficient. This coefficient is strictly determined by the patient's current chronological age and gender, assuming the discrepancy increases proportionally with normal growth.

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