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4. Pediatrics MCQs

Practice Set 112 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 2221

Topic: 4. Pediatrics

In the Ponseti method for the treatment of congenital idiopathic clubfoot, what is the proper sequence of deformity correction during the serial casting phase?

. Equinus, Varus, Adduction, Cavus
. Cavus, Adduction, Varus, Equinus
. Adduction, Cavus, Varus, Equinus
. Cavus, Varus, Adduction, Equinus
. Equinus, Cavus, Adduction, Varus

Correct Answer & Explanation

. Cavus, Adduction, Varus, Equinus

Explanation

The correct sequence of correction in the Ponseti method follows the acronym CAVE: Cavus (corrected first by supinating the forefoot to align it with the hindfoot), Adduction, Varus, and lastly Equinus. The equinus is corrected last and often requires a percutaneous Achilles tenotomy to achieve full dorsiflexion.

Question 2222

Topic: Pediatric Hip

A 12-year-old boy undergoes in situ pinning for a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral, currently asymptomatic hip?

. Patient age over 14 years at presentation
. Female gender
. Presence of an endocrinopathy such as hypothyroidism
. Body Mass Index > 95th percentile
. Severe slip angle (> 60 degrees) on the affected side

Correct Answer & Explanation

. Presence of an endocrinopathy such as hypothyroidism

Explanation

Patients with underlying endocrinopathies (such as hypothyroidism, growth hormone deficiency, or renal osteodystrophy) have an exceptionally high risk (up to 100% in some series) of developing bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly indicated in this population. Age < 10 or > 16 is also a relative indication, but endocrinopathy is the strongest.

Question 2223

Topic: Pediatric Hip

In Legg-Calve-Perthes disease, which of the following is considered the most significant and reliable prognostic factor regarding the long-term development of premature osteoarthritis?

. Age at the clinical onset of symptoms
. Gender of the patient
. Duration of the initial fragmentation stage
. Presence of a metaphyseal cyst on radiographs
. Degree of early joint effusion

Correct Answer & Explanation

. Age at the clinical onset of symptoms

Explanation

Age at clinical onset is the most consistently reported prognostic factor in Legg-Calve-Perthes disease. Children who develop the disease at a younger age (especially <6 years) have a significantly better prognosis for remodeling the femoral head and a lower risk of premature osteoarthritis, as they have more remaining growth potential.

Question 2224

Topic: Pediatric Hip

An 18-month-old girl is evaluated for developmental dysplasia of the hip (DDH). An anteroposterior pelvic radiograph is obtained. Which of the following radiographic parameters is the most reliable metric to evaluate acetabular coverage/dysplasia at this specific age?

. Alpha angle
. Center-edge angle of Wiberg
. Reimers migration percentage
. Acetabular index
. Southwick angle

Correct Answer & Explanation

. Acetabular index

Explanation

The acetabular index (or Tonnis angle) is the standard radiographic measure of acetabular roof inclination and dysplasia in children from birth up to approximately 5 to 8 years of age. Wiberg's center-edge angle is used for older children when the femoral head center can be accurately identified. The alpha angle is an ultrasound metric for infants (<6 months).

Question 2225

Topic: Pediatric Hip

Which of the following is considered an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic hip in a patient diagnosed with a unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. Male gender, age 14 years old
. Female gender, age 12 years old
. Presence of an underlying endocrinopathy (e.g., hypothyroidism or renal osteodystrophy)
. Obesity with a BMI greater than the 95th percentile
. Radiographic evidence of a severe slip angle (>50 degrees) in the ipsilateral hip

Correct Answer & Explanation

. Presence of an underlying endocrinopathy (e.g., hypothyroidism or renal osteodystrophy)

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended and considered essentially absolute in patients with underlying metabolic or endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy), as their risk of bilateral disease can approach 100%. Other relative indications include young age (e.g., modified Oxford bone age score), prior radiation therapy, and inability to follow up, but endocrinopathy remains the strongest indication.

Question 2226

Topic: 4. Pediatrics
A 13-year-old female sustains a juvenile Tillaux fracture of the ankle. What is the characteristic mechanism of injury and the specific anatomic structure responsible for the avulsion?
. Avulsion of the anterolateral distal tibial epiphysis by the Anterior Inferior Tibiofibular Ligament (AITFL) due to an external rotation force
. Impaction of the talus into the central tibial plafond due to axial loading
. Avulsion of the medial malleolus by the deep deltoid ligament due to an eversion force
. Shear fracture of the posterior malleolus by the Posterior Inferior Tibiofibular Ligament (PITFL) due to hyperflexion
. Avulsion of the posterolateral tibial epiphysis by the PITFL due to an internal rotation force

Correct Answer & Explanation

. Avulsion of the anterolateral distal tibial epiphysis by the Anterior Inferior Tibiofibular Ligament (AITFL) due to an external rotation force

Explanation

A juvenile Tillaux fracture is a Salter-Harris type III fracture of the anterolateral portion of the distal tibial epiphysis. It occurs during early adolescence when the medial and central aspects of the distal tibial physis have closed, but the anterolateral portion remains open. An external rotation force causes the Anterior Inferiotibiofibular Ligament (AITFL) to avulse the unfused anterolateral epiphysis.

Question 2227

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. During a follow-up visit, the parents report that the infant is no longer kicking the right leg. On examination, the right knee is extended, and there is an absence of active knee extension. Which of the following adjustments to the Pavlik harness is required?

. Loosen the anterior straps
. Tighten the anterior straps
. Loosen the posterior straps
. Tighten the posterior straps
. Discontinue the harness completely

Correct Answer & Explanation

. Loosen the anterior straps

Explanation

The infant presents with femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The anterior straps control the degree of hip flexion. Loosening the anterior straps reduces hyperflexion, which typically relieves the compression on the femoral nerve, leading to spontaneous recovery.

Question 2228

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in situ single-screw fixation for a mild, stable slipped capital femoral epiphysis (SCFE). During follow-up, he demonstrates limited hip internal rotation and pain with combined flexion, adduction, and internal rotation. Which of the following is the most likely long-term complication explaining his symptoms?

. Avascular necrosis of the femoral head
. Chondrolysis
. Femoroacetabular impingement (FAI)
. Slipped capital femoral epiphysis of the contralateral hip
. Nonunion of the physis

Correct Answer & Explanation

. Femoroacetabular impingement (FAI)

Explanation

Following in situ fixation of a SCFE, the residual prominent anterior metaphysis can abut the anterior acetabular rim during hip flexion and internal rotation. This biomechanical mismatch leads to cam-type femoroacetabular impingement (FAI), causing pain and restricted range of motion. AVN and chondrolysis are less common in mild, stable slips treated with a single screw.

Question 2229

Topic: Pediatric Hip

A 12-year-old obese boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE). Intraoperatively, an intracapsular hematoma is evacuated. What is the primary blood supply to the femoral head that is at greatest risk of injury in this condition?

. Ascending branch of the medial femoral circumflex artery
. Lateral epiphyseal artery
. Medial epiphyseal artery
. Artery of the ligamentum teres
. Inferior gluteal artery

Correct Answer & Explanation

. Lateral epiphyseal artery

Explanation

The lateral epiphyseal artery is the terminal branch of the medial femoral circumflex artery (MFCA) and provides the predominant blood supply to the femoral head in children and adolescents. It is uniquely vulnerable to stretching, kinking, or tearing in SCFE, which can result in avascular necrosis (AVN).

Question 2230

Topic: 4. Pediatrics

A 10-year-old boy (Tanner stage I) sustains an acute ACL tear. A physeal-sparing ACL reconstruction is planned using an iliotibial band autograft (MacIntosh procedure). Which of the following best describes the anatomical routing of the graft to minimize physeal injury?

. Trans-epiphyseal femoral and trans-epiphyseal tibial tunnels
. Over-the-top femoral position and deep to the anterior horn of the medial meniscus
. Through a central trans-physeal tibial tunnel and an over-the-top femoral routing
. Over-the-top femoral routing and under the anterior intermeniscal ligament on the tibia
. Over-the-top femoral position and superficial to the tibial tuberosity apophysis

Correct Answer & Explanation

. Over-the-top femoral routing and under the anterior intermeniscal ligament on the tibia

Explanation

In prepubescent children (Tanner stage I or II) with significant remaining growth, a fully physeal-sparing technique is often indicated. The modified MacIntosh (or Kocher) technique involves routing the IT band graft 'over-the-top' of the lateral femoral condyle (avoiding a femoral tunnel) and under the intermeniscal ligament (avoiding a tibial tunnel), suturing it to the tibial periosteum.

Question 2231

Topic: Pediatric Upper Extremity & Spine

In adolescent idiopathic scoliosis (AIS), curve progression is a primary concern guiding treatment. Based on natural history studies, which of the following patients has the highest statistical risk of curve progression?

. A 15-year-old female, Risser 4, with a 35-degree curve
. A 13-year-old male, Risser 2, with a 25-degree curve
. A 12-year-old female, Risser 0, with a 25-degree curve
. A 14-year-old female, Risser 3, with a 20-degree curve
. A 16-year-old male, Risser 5, with a 45-degree curve

Correct Answer & Explanation

. A 12-year-old female, Risser 0, with a 25-degree curve

Explanation

The risk of curve progression in AIS is highest in patients who are female, have a lower Risser stage (indicating significant remaining skeletal growth), and present with larger initial curves (>20 degrees) before skeletal maturity. A 12-year-old female at Risser 0 with a 25-degree curve has a progression risk exceeding 60-80%.

Question 2232

Topic: Pediatric Lower Extremity

The Ponseti method is the internationally recognized gold standard for the conservative management of idiopathic clubfoot (talipes equinovarus). What is the correct sequence of deformity correction during serial casting in this technique?

. Cavus, Adductus, Varus, Equinus (CAVE)
. Equinus, Varus, Adductus, Cavus (EVAC)
. Cavus, Varus, Equinus, Adductus (CVEA)
. Adductus, Varus, Cavus, Equinus (AVCE)
. Varus, Cavus, Adductus, Equinus (VCAE)

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus (CAVE)

Explanation

The Ponseti method sequentially corrects the deformities of clubfoot using the acronym CAVE: first Cavus (by elevating the first ray to align the forefoot with the midfoot), then Adductus and Varus (simultaneously by abducting the midfoot around the talar head), and finally Equinus (usually requiring a percutaneous Achilles tenotomy).

Question 2233

Topic: Pediatric Hip

A 12-year-old obese male presents with a slipped capital femoral epiphysis (SCFE). Which of the following best describes the anatomical direction of the epiphyseal displacement relative to the metaphysis?

. Anterior and superior
. Anterior and inferior
. Posterior and superior
. Posterior and inferior
. Lateral and inferior

Correct Answer & Explanation

. Posterior and inferior

Explanation

In SCFE, the epiphysis actually remains relatively housed in the acetabulum while the femoral neck (metaphysis) displaces anteriorly and superiorly. Therefore, relative to the metaphysis, the epiphysis slips posteriorly and inferiorly.

Question 2234

Topic: Pediatric Hip

A 4-month-old female is diagnosed with developmental dysplasia of the hip (DDH) and treated with a Pavlik harness. Two weeks later, the parents report she has stopped kicking her right leg. Examination reveals an inability to actively extend the knee. This complication is most directly related to which improper fitting of the harness?

. Excessive abduction
. Inadequate abduction
. Excessive hip flexion
. Inadequate hip flexion
. Constriction of the chest strap

Correct Answer & Explanation

. Excessive hip flexion

Explanation

The patient has a femoral nerve palsy, a known complication of the Pavlik harness. It is caused by excessive hip flexion, which stretches or compresses the femoral nerve against the inguinal ligament. By contrast, excessive abduction is associated with avascular necrosis (AVN) of the femoral head.

Question 2235

Topic: Pediatric Hip

In Legg-Calve-Perthes disease, the lateral pillar classification of Herring is optimally assessed during which phase of the disease process?

. Initial (avascular) stage
. Early fragmentation stage
. Late fragmentation stage
. Reossification stage
. Residual stage

Correct Answer & Explanation

. Early fragmentation stage

Explanation

The Herring lateral pillar classification is ideally applied during the early fragmentation stage of Legg-Calve-Perthes disease. This provides the most accurate prognostication based on the maintenance of the height of the lateral pillar of the capital femoral epiphysis.

Question 2236

Topic: Pediatric Hip

In a patient presenting with a Slipped Capital Femoral Epiphysis (SCFE), which of the following is the most significant prognostic clinical factor for the subsequent development of avascular necrosis (AVN) of the femoral head?

. The degree of the slip angle on the frog-leg lateral radiograph.
. The patient's chronologic age at the time of presentation.
. The patient's ability to bear weight on the affected extremity at presentation.
. The specific method of surgical fixation utilized.
. The duration of symptoms prior to the definitive diagnosis.

Correct Answer & Explanation

. The patient's ability to bear weight on the affected extremity at presentation.

Explanation

The stability of the SCFE, defined clinically by the patient's ability to bear weight (with or without crutches), is the most critical prognostic factor for the development of AVN. Unstable SCFEs (inability to bear weight) have a much higher rate of AVN (up to 20-50%) compared to stable SCFEs (nearly 0%).

Question 2237

Topic: Pediatric Hip

A 3-month-old female with Developmental Dysplasia of the Hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report that the infant is no longer kicking her right leg. Examination reveals decreased active extension of the right knee. What adjustment to the harness is required to address this specific complication?

. Decrease the flexion of the anterior strap.
. Increase the flexion of the anterior strap.
. Decrease the abduction of the posterior strap.
. Increase the abduction of the posterior strap.
. Discontinue the harness and transition immediately to a rigid hip spica cast.

Correct Answer & Explanation

. Decrease the flexion of the anterior strap.

Explanation

The clinical scenario describes a femoral nerve palsy, a known complication of the Pavlik harness caused by excessive hyperflexion of the hip. The femoral nerve becomes compressed against the anterior pelvis. The management is to decrease the tension on the anterior strap to reduce the degree of hip flexion, which usually allows the palsy to resolve.

Question 2238

Topic: Pediatric Hip

In the management of Slipped Capital Femoral Epiphysis (SCFE), prophylactic in situ pinning of the contralateral hip is most strongly indicated in a patient presenting with which of the following underlying characteristics?

. Hypothyroidism
. Obesity (>95th percentile)
. Male gender
. Age greater than 14 years at presentation
. African American descent

Correct Answer & Explanation

. Age greater than 14 years at presentation

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with underlying endocrinopathies (e.g., hypothyroidism, renal osteodystrophy, growth hormone deficiency) and in those presenting at a particularly young age (girls <10, boys <12) due to the significantly elevated risk of developing a subsequent contralateral slip.

Question 2239

Topic: Pediatric Hip
A 6-week-old female infant is evaluated for Developmental Dysplasia of the Hip (DDH). Coronal ultrasound demonstrates an alpha angle of 48 degrees and a beta angle of 65 degrees. According to Graf's classification and standard clinical guidelines, what is the most appropriate initial management?
. Observation and repeat ultrasound in 4 weeks
. Application of a Pavlik harness
. Closed reduction and spica casting under anesthesia
. Open reduction and capsulorrhaphy
. Varus derotational osteotomy

Correct Answer & Explanation

. Application of a Pavlik harness

Explanation

An alpha angle of < 60 degrees (in this case, 48 degrees) indicates a shallow, dysplastic acetabulum (Graf Type III or worse). The gold standard initial treatment for a child under 6 months of age with a dysplastic, subluxated, or reducible dislocated hip is the application of a Pavlik harness to maintain flexion and abduction, promoting physiologic remodeling of the acetabulum.

Question 2240

Topic: Pediatric Hip

Prophylactic in situ pinning of the contralateral asymptomatic hip in a patient with a Slipped Capital Femoral Epiphysis (SCFE) is most strongly indicated in which of the following clinical profiles?

. A 14-year-old boy with a normal body mass index
. A 12-year-old boy with renal osteodystrophy
. A 13-year-old girl with an acute-on-chronic SCFE
. A 15-year-old boy who sustained a mechanical fall
. A 10-year-old girl with a completely normal endocrine workup

Correct Answer & Explanation

. A 12-year-old boy with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is strongly recommended in patients with endocrine or metabolic disorders (such as renal osteodystrophy, hypothyroidism, or panhypopituitarism) due to the exceptionally high rate of bilateral involvement (up to 100% in some metabolic conditions). It is also commonly considered in patients presenting at a very young age (< 10 years).

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