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4. Pediatrics MCQs

Practice Set 25 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 481

Topic: 4. Pediatrics

A mutation in type II collagen is responsible for all of the following conditions except:

. Stickler syndrome
. Spondyloepiphyseal dysplasia congenita
. Kniest syndrome
. Strudwick dysplasia
. Achondroplasia

Correct Answer & Explanation

. Achondroplasia

Explanation

Type II collagen is largely found in hyaline cartilage. All of the dysplasias, with the exception of achondroplasia, have significant abnormalities of articular cartilage. Achondroplasia results from a defect in fibroblast growth factor receptor protein.

Question 482

Topic: 4. Pediatrics

Which of the following conditions is least commonly seen in patients with congenital dislocation of the patella:

. Fibrosis of the vastus lateralis
. C ontracture of the iliotibial band
. Hypoplasia of the vastus medialis
. Enlarged patella
. Flexion contracture

Correct Answer & Explanation

. C ontracture of the iliotibial band

Explanation

Congenital dislocation of the patella is present from birth and diagnosed in childhood. It is not reducible with the knee in extension. Essential elements include contracture of the iliotibial band, vastus lateralis, hypoplasia of the vastus medialis, lateral insertion of the patellar tendon, decreased size of the patella, flexion contracture and valgus alignment of the knee, and hypoplasia of the patellar sulcus. Operative treatment is usually successful, and the success rate is increased with early surgery.

Question 483

Topic: 4. Pediatrics

The surgical reconstruction of a congenitally dislocated patella includes all of the following elements except:

. Advancement of the vastus medialis insertion
. Lengthening or release of the iliotibial band
. Lengthening or release of the biceps femoris muscle
. Lateral capsular release
. Lateral transfer of the patellar tendon insertion

Correct Answer & Explanation

. Lengthening or release of the biceps femoris muscle

Explanation

The surgical reconstruction of a congenitally dislocated patella includes lengthening or release of the lateral capsule, lengthening or release of the iliotibial band, lengthening or release of the biceps femoris muscle, distal advancement or imbrication of the patellar tendon, and sometimes a rectus femoris lengthening. Semitendinosus transfer to the patella may also be added. The lateral insertion of the patellar tendon may be transferred medially.

Question 484

Topic: 4. Pediatrics
Which of the following radiographic parameters is most appropriately used to assess the status of the hip in a growing child with cerebral palsy?
. The Stulberg rating
. The migration index of Reimer
. The alpha and beta angle of Graf
. Klein's line
. The Hilgenreiner-epiphyseal angle

Correct Answer & Explanation

. The migration index of Reimer

Explanation

The migration index (of Reimer) is the percentage of the femoral head outside of the acetabulum. This radiographic parameter tracks the progress of the hip in patients with cerebral palsy because the femoral head may gradually migrate out. The other parameters refer to radiographic assessments of other hip disorders: The Stulberg rating is used in patients with healed Perthes' disease. The alpha and beta angles of Graf provide ultrasonic assessment of patients with developmental hip dysplasia. Klein's line is used in early detection of slipped capital femoral epiphysis. The Hilgenreiner-epiphyseal angle is used in developmental coxa vara.

Question 485

Topic: Pediatric Hip
A 12-year-old overweight boy presents with sudden onset of severe groin pain and inability to bear weight on his right leg after a minor fall. Radiographs demonstrate a displaced capital femoral epiphysis. He had 3 weeks of mild antecedent thigh aching. Which of the following best characterizes his condition and associated risk?
. Stable SCFE with low risk of avascular necrosis
. Unstable SCFE with high risk of avascular necrosis
. Stable SCFE with high risk of chondrolysis
. Unstable SCFE with low risk of avascular necrosis
. Legg-Calvé-Perthes disease with high risk of coxa magna

Correct Answer & Explanation

. Unstable SCFE with high risk of avascular necrosis

Explanation

The inability to bear weight makes this an unstable slipped capital femoral epiphysis (SCFE) according to the Loder classification. Unstable SCFE has a significantly higher risk of avascular necrosis (AVN), historically up to 47%, compared to stable SCFE.

Question 486

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. According to the Herring lateral pillar classification, which radiographic finding defines a Group C hip?
. No lucency in the lateral pillar
. Greater than 50% of lateral pillar height maintained
. Less than 50% of lateral pillar height maintained
. Complete resorption of the medial pillar
. Subchondral fracture extending into the lateral pillar

Correct Answer & Explanation

. Less than 50% of lateral pillar height maintained

Explanation

In the Herring lateral pillar classification, Group C is defined by the maintenance of less than 50% of the original lateral pillar height. This group carries the poorest prognosis for subsequent hip deformity and osteoarthritis.

Question 487

Topic: Pediatric Lower Extremity

A 10-year-old boy presents with anterior knee pain and a high-riding patella after forcefully jumping during a basketball game. Radiographs show a small bony fragment distal to the inferior pole of the patella. What is the most likely diagnosis?

. Osgood-Schlatter disease
. Sinding-Larsen-Johansson syndrome
. Patellar sleeve fracture
. Tibial tubercle avulsion fracture
. Bipartite patella

Correct Answer & Explanation

. Patellar sleeve fracture

Explanation

A patellar sleeve fracture is a chondrous or osteochondrous avulsion of the inferior pole of the patella seen in skeletally immature patients. A high-riding patella (patella alta) distinguishes it from Sinding-Larsen-Johansson syndrome, which is an overuse apophysitis without disruption of the extensor mechanism.

Question 488

Topic: 4. Pediatrics

During evaluation of a newborn, the orthopedic surgeon notes bilateral hyperextended knees. The diagnosis of congenital dislocation of the knee (CDK) is made. The infant also has positive Ortolani signs bilaterally. What is the most appropriate management sequence?

. Treat the hips with a Pavlik harness first, then address the knees
. Treat the knees first with serial casting, then address the hips
. Perform open reduction of the hips immediately, then cast the knees
. Perform simultaneous open reduction of knees and hips
. Observe the knees for spontaneous resolution while treating hips

Correct Answer & Explanation

. Treat the knees first with serial casting, then address the hips

Explanation

In patients with congenital dislocation of the knee and concomitant developmental dysplasia of the hip (DDH), the knee deformity must be addressed first. Correcting the knee allows the necessary flexion required to safely treat the hips with a Pavlik harness.

Question 489

Topic: 4. Pediatrics

A 14-year-old female basketball player tears her anterior cruciate ligament (ACL). She has wide open physes. Which surgical technique carries the highest risk of causing a growth arrest with subsequent angular deformity or limb length discrepancy?

. Iliotibial band physeal-sparing reconstruction
. All-epiphyseal reconstruction
. Transphyseal reconstruction with a 10 mm bone-patellar tendon-bone graft
. Transphyseal reconstruction with a soft tissue hamstring graft
. Non-operative physical therapy until skeletal maturity

Correct Answer & Explanation

. Transphyseal reconstruction with a soft tissue hamstring graft

Explanation

Using a bone plug across an open physis significantly increases the risk of premature physeal closure. Soft-tissue grafts or completely physeal-sparing techniques are preferred in patients with significant remaining growth to avoid growth arrest.

Question 490

Topic: Pediatric Hip
A 6-year-old child presents with a painless limp. Examination reveals limited abduction and internal rotation of the hip. Radiographs show increased radiodensity and fragmentation of the capital femoral epiphysis. What is the primary goal of treatment for this condition?
. Immediate fusion of the hip joint
. Containment of the femoral head within the acetabulum
. Prophylactic pinning of the contralateral hip
. Eradication of infection with antibiotics
. Surgical excision of the fragmented epiphysis

Correct Answer & Explanation

. Containment of the femoral head within the acetabulum

Explanation

The diagnosis is Legg-Calvé-Perthes disease. The primary goal of treatment is containment of the femoral head within the acetabulum during the fragmentation and reossification phases to ensure it heals spherically and to prevent late osteoarthritis.

Question 491

Topic: Pediatric Hip

A 12-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor fall. Radiographs demonstrate a severe right slipped capital femoral epiphysis (SCFE). Which of the following complications is he at the highest risk for developing compared to a patient who can bear weight?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoroacetabular impingement (FAI)
. Premature osteoarthritis
. Leg length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The inability to bear weight defines an unstable SCFE, which carries a significantly higher risk of avascular necrosis (up to 50%) compared to a stable SCFE. Urgent or semi-urgent in-situ pinning is required.

Question 492

Topic: Pediatric Hip

In patients presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is the strongest indication for prophylactic pinning of the contralateral hip?

. Age greater than 14 years in males
. Presentation with an unstable slip
. Presence of endocrine or metabolic disorders
. High body mass index (>95th percentile) alone
. Severity of the initial slip angle (>50 degrees)

Correct Answer & Explanation

. Presence of endocrine or metabolic disorders

Explanation

Patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) or undergoing radiation therapy have a very high risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is strongly recommended in these populations regardless of age.

Question 493

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). What is the risk of excessive hyperflexion of the hips while in the harness?

. Femoral nerve palsy
. Avascular necrosis of the femoral head
. Inferior dislocation of the hip
. Acetabular dysplasia
. Sciatic nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Excessive hyperflexion (>120 degrees) in a Pavlik harness risks femoral nerve palsy. Excessive abduction increases the risk of avascular necrosis of the femoral head.

Question 494

Topic: Pediatric Hip

In evaluating a 7-year-old child with Legg-Calve-Perthes disease, the Herring Lateral Pillar Classification is used to determine prognosis. Which radiographic view and stage of the disease are most appropriate for applying this classification?

. Frog-leg lateral view during the initial stage
. Anteroposterior (AP) pelvis during the fragmentation stage
. Frog-leg lateral view during the reossification stage
. Anteroposterior (AP) pelvis during the initial stage
. Dunn view during the fragmentation stage

Correct Answer & Explanation

. Anteroposterior (AP) pelvis during the fragmentation stage

Explanation

The Herring Lateral Pillar Classification assesses the height of the lateral pillar of the femoral head and is best applied on an AP radiograph during the fragmentation stage of the disease. This stage provides the most accurate prognostic information regarding final femoral head sphericity.

Question 495

Topic: 4. Pediatrics

A 3-year-old girl is evaluated for worsening bilateral genu varum. Standing radiographs show a sharp varus angulation at the proximal medial tibial metaphysis with beaking and an epiphyseal-metaphyseal angle of 22 degrees. What is the most appropriate initial treatment?

. Reassurance and annual follow-up
. Knee-ankle-foot orthoses (KAFOs)
. Proximal tibial valgus osteotomy
. Guided growth with tension band plates
. Lateral distal femoral hemiepiphysiodesis

Correct Answer & Explanation

. Knee-ankle-foot orthoses (KAFOs)

Explanation

The patient has infantile Blount disease, indicated by progressive varus and an epiphyseal-metaphyseal (Drennan) angle >16 degrees. For children under age 3-4 with early-stage infantile Blount disease, KAFOs are the recommended initial treatment.

Question 496

Topic: 4. Pediatrics

An 18-month-old child presents with anterolateral bowing of the left tibia. Radiographs show medullary sclerosis and a narrow, dysplastic tibial diaphysis. What is the most commonly associated systemic condition?

. Achondroplasia
. Osteogenesis imperfecta
. Neurofibromatosis type 1
. Marfan syndrome
. McCune-Albright syndrome

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Anterolateral bowing of the tibia is the hallmark precursor to congenital pseudarthrosis of the tibia. Over 50% of these cases are associated with Neurofibromatosis type 1 (NF1).

Question 497

Topic: Pediatric Lower Extremity

During the Ponseti casting technique for the treatment of idiopathic clubfoot, what is the correct order of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The acronym CAVE dictates the sequence of clubfoot correction in the Ponseti method: Cavus (corrected by supinating the forefoot to align with the hindfoot), Adductus, Varus, and finally Equinus (often requiring a percutaneous Achilles tenotomy).

Question 498

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, you notice the infant has decreased active knee extension on the affected side. Which of the following is the most appropriate next step?

. Immediate open reduction
. Switching to a spica cast
. Adjusting the harness to decrease hip flexion
. Obtaining an MRI of the lumbar spine
. Performing an ultrasound of the hip

Correct Answer & Explanation

. Adjusting the harness to decrease hip flexion

Explanation

Decreased active knee extension indicates a femoral nerve palsy, a known complication of excessive hyperflexion in a Pavlik harness. The harness should be discontinued or adjusted to decrease hip flexion. Observation is typically sufficient as it generally resolves spontaneously.

Question 499

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute-on-chronic left groin pain and inability to bear weight. Radiographs show a severe slipped capital femoral epiphysis (SCFE). Which of the following factors most significantly increases his risk of avascular necrosis (AVN)?

. Degree of posterior slip angle > 50 degrees
. Age of the patient > 14 years
. Bilateral involvement
. Inability to bear weight on the affected limb
. Concomitant endocrine abnormalities

Correct Answer & Explanation

. Inability to bear weight on the affected limb

Explanation

The inability to bear weight defines an unstable SCFE, which carries a much higher risk of avascular necrosis (up to 50%) compared to a stable SCFE. Severity of the slip is less predictive of AVN than the stability of the physis.

Question 500

Topic: Pediatric Hip

In the evaluation of a 6-year-old boy with Legg-Calve-Perthes disease, which of the following radiographic classifications is most prognostic for long-term hip joint congruency?

. Catterall classification
. Lateral pillar (Herring) classification
. Salter-Thompson classification
. Stulberg classification
. Reimer's migration index

Correct Answer & Explanation

. Lateral pillar (Herring) classification

Explanation

The lateral pillar (Herring) classification is considered the most reliable prognostic indicator for long-term outcomes in Perthes disease. It assesses the height of the lateral pillar of the capital femoral epiphysis during the fragmentation phase. The Stulberg classification assesses the final outcome at skeletal maturity, not initial prognosis.

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