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4. Pediatrics MCQs

Practice Set 11 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 201

Topic: 4. Pediatrics

A 4-year-old boy with spastic diplegic cerebral palsy undergoes routine radiographic screening of his hips. The Reimers migration percentage is calculated to be 45%. What does this value indicate, and what is the generally recommended orthopedic management?

. Normal finding; clinical observation
. Hip subluxation; prophylactic soft tissue release and varus derotational osteotomy (VDRO)
. Complete dislocation; salvage pelvic osteotomy
. Hip dysplasia; immediate application of a Pavlik harness
. Impending spinal imbalance; neuromuscular scoliosis screening

Correct Answer & Explanation

. Hip subluxation; prophylactic soft tissue release and varus derotational osteotomy (VDRO)

Explanation

A Reimers migration index greater than 33% indicates significant hip subluxation in a child with cerebral palsy. A migration percentage of 45% typically mandates surgical intervention, such as VDRO, to prevent complete dislocation.

Question 202

Topic: 4. Pediatrics

A 9-year-old boy sustained a fracture to his distal radius physis. One year later, radiographs

reveal a central physeal bar occupying 25% of the cross-sectional area. He has an estimated 3 cm of growth remaining. What is the most appropriate surgical treatment?

. Complete distal radius epiphysiodesis
. Observation only with serial radiographs
. Physeal bar resection and interposition of a fat graft or cranioplast
. Distal radius osteotomy without bar resection
. Ulnar shortening osteotomy alone

Correct Answer & Explanation

. Physeal bar resection and interposition of a fat graft or cranioplast

Explanation

For a physeal bar occupying less than 50% of the cross-sectional area in a patient with more than 2 years (or 2 cm) of growth remaining, bar resection with interposition material (fat, wax, or cranioplast) is indicated to restore growth potential.

Question 203

Topic: 4. Pediatrics
An 18-month-old boy is brought to the clinic with severe bowing of the legs. Radiographs show an abrupt varus angulation at the proximal medial tibia with a distinct metaphyseal beak. He is diagnosed with infantile Blount's disease. Which of the following Langenskiöld stages denotes the formation of a bony bar across the physis, making spontaneous resolution highly unlikely?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage VI

Correct Answer & Explanation

. Stage IV

Explanation

Langenskiöld Stage IV is characterized by the development of a bony bar across the medial physis, creating an irreversible tether. At this stage, surgical intervention with corrective osteotomy is mandated.

Question 204

Topic: 4. Pediatrics
A 12-year-old boy presents with right ankle pain after a severe inversion and external rotation injury. Radiographs show a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. What is the most likely diagnosis?
. Juvenile Tillaux fracture
. Triplane fracture
. Pilon fracture
. Maisonneuve fracture
. Bosworth fracture

Correct Answer & Explanation

. Juvenile Tillaux fracture

Explanation

The juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs due to avulsion by the anterior inferior tibiofibular ligament during external rotation, as this is the last portion of the physis to close.

Question 205

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp of 3 months' duration. Radiographs demonstrate sclerosis and fragmentation of the femoral head. Measurement reveals the lateral pillar height is 60% of normal. What is the appropriate Herring classification?
. Herring A
. Herring B
. Herring C
. Catterall I
. Salter-Thompson A

Correct Answer & Explanation

. Herring B

Explanation

The Herring (lateral pillar) classification for Legg-Calvé-Perthes disease is based on the height of the lateral pillar of the femoral head on the AP radiograph. A height of >50% but <100% indicates Herring B, whereas less than 50% indicates Herring C.

Question 206

Topic: 4. Pediatrics

An 18-month-old presents with unilateral in-toeing. Physical examination reveals a rigid medial deviation of the forefoot with a completely normal, flexible hindfoot. What is the most likely diagnosis?

. Idiopathic Clubfoot
. Metatarsus adductus
. Skewfoot
. Calcaneovalgus foot
. Congenital vertical talus

Correct Answer & Explanation

. Metatarsus adductus

Explanation

Metatarsus adductus presents with medial deviation of the forefoot with a normal, flexible hindfoot. While most resolve spontaneously, rigid cases in older toddlers may require serial casting.

Question 207

Topic: Pediatric Hip

A 13-year-old obese boy presents with right knee pain and a limp. On examination, obligate external rotation of the right hip is noted during passive flexion.

What is the most appropriate initial treatment?

. In situ single screw fixation
. Bilateral spica casting
. Open reduction and internal fixation
. Proximal femoral osteotomy
. Observation and physical therapy

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The clinical presentation is classic for a slipped capital femoral epiphysis (SCFE). The gold standard treatment for a stable SCFE is in situ fixation with a single cannulated screw to prevent further slippage.

Question 208

Topic: Pediatric Lower Extremity

A newborn is diagnosed with severe idiopathic clubfoot. The pediatric orthopedic surgeon begins treatment using the Ponseti method. According to this protocol, which deformity must be corrected first?

. Equinus
. Varus
. Adductus
. Cavus
. Supination

Correct Answer & Explanation

. Cavus

Explanation

In the Ponseti method, the sequence of correction follows the mnemonic CAVE (Cavus, Adductus, Varus, Equinus). Cavus is corrected first by supinating the forefoot and elevating the first ray to align it with the hindfoot.

Question 209

Topic: Pediatric Hip

A 4-year-old girl is evaluated for a persistent limp. Radiographs demonstrate late-presenting developmental dysplasia of the hip (DDH) with a fully dislocated femoral head.

What is the most appropriate definitive management?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction with pelvic and femoral osteotomies
. Traction followed by bracing
. Femoral head resection

Correct Answer & Explanation

. Open reduction with pelvic and femoral osteotomies

Explanation

In a child older than 2-3 years, conservative measures and closed reduction are highly likely to fail. Open reduction combined with pelvic (to correct acetabular dysplasia) and femoral (to correct excessive anteversion) osteotomies is typically required.

Question 210

Topic: 4. Pediatrics

A pediatric patient presents with anterolateral bowing of the tibia that progresses to a spontaneous fracture. Which of the following systemic conditions is most strongly associated with this finding?

. Neurofibromatosis type 1
. Achondroplasia
. Osteogenesis imperfecta
. Ehlers-Danlos syndrome
. Marfan syndrome

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Congenital pseudarthrosis of the tibia (CPT) typically presents as anterolateral bowing that eventually fractures and fails to heal. It is strongly associated with Neurofibromatosis type 1 (NF1) in up to 50% of cases.

Question 211

Topic: 4. Pediatrics

A 12-year-old competitive gymnast complains of chronic, bilateral dorsal wrist pain. Radiographs reveal widening of the distal radial physis and cystic changes.

What is the most appropriate initial management?

. Surgical fixation
. Corticosteroid injection
. Rest from weight-bearing activities
. Ulnar lengthening osteotomy
. Radial closing wedge osteotomy

Correct Answer & Explanation

. Rest from weight-bearing activities

Explanation

'Gymnast wrist' is a stress injury to the distal radial physis caused by repetitive compressive loading. The primary treatment is complete rest and cessation of upper extremity weight-bearing activities until symptoms and radiographic abnormalities resolve.

Question 212

Topic: 4. Pediatrics

A 7-year-old is undergoing evaluation for a suspected physeal bar across the distal femur following a previous fracture.

Which imaging modality is considered the gold standard to accurately map the size, geometry, and location of the bar?

. CT scan with 3D reconstruction
. Dynamic Ultrasound
. Technetium-99m bone scan
. MRI with gradient-echo sequences
. Standard weight-bearing radiographs

Correct Answer & Explanation

. MRI with gradient-echo sequences

Explanation

MRI, particularly using fat-suppressed or gradient-echo sequences, is the best modality for evaluating the physis. It allows for accurate 3D mapping of the uncalcified cartilage and the exact extent of the bony bridge.

Question 213

Topic: 4. Pediatrics

When considering the surgical resection of a post-traumatic physeal bar, what is the generally accepted maximum percentage of cross-sectional physeal area involvement that still permits successful resection?

. 10%
. 25%
. 50%
. 75%
. 90%

Correct Answer & Explanation

. 50%

Explanation

Resection of a physeal bar (epiphysiodesis takedown) is generally indicated only if it involves less than 50% of the cross-sectional area of the physis. The patient must also have at least 2 years or 2 cm of remaining growth.

Question 214

Topic: 4. Pediatrics

A 1-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip. The parents report the infant has stopped spontaneously kicking the affected leg. Ultrasound confirms the hip remains reduced. What iatrogenic complication has most likely occurred?

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

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hyperflexion of the hip pressing the nerve against the pelvis. Management involves temporary loosening or removal of the anterior straps.

Question 215

Topic: 4. Pediatrics
An 8-year-old boy was injured by a lawnmower. The resulting proximal tibial injury presented in the radiograph is classified as a:
. Salter I injury
. Salter II injury
. Salter III injury
. Salter IV injury
. Salter V injury

Correct Answer & Explanation

. Salter IV injury

Explanation

A Salter IV injury to the proximal tibia is apparent in the patient's radiograph. The fracture traverses the epiphysis, physis, and metaphysis medial to the tibial spine. No injury to the lateral portion of the plateau is present. Incidentally, the distal femoral injury is also classified as Salter IV.

Question 216

Topic: 4. Pediatrics

What is the most common cause of intoeing in children with bilateral cerebral palsy:

. Internal pelvic rotation
. Internal hip rotation
. Increased tibial torsion
. Hindfoot rotation
. Forefoot adduction

Correct Answer & Explanation

. Internal hip rotation

Explanation

The most common cause of intoeing in children with bilateral spasticity is internal hip rotation. For children with hemiplegia, the most common cause of intoeing is tibial torsion. In some patients, several causes may coexist to cause the condition.

Question 217

Topic: Pediatric Upper Extremity & Spine

Risk factors for superior mesenteric artery syndrome after adolescent idiopathic scoliosis surgery include all of the following except:

. Decreased correction of thoracic curve with preoperative bending
. Body mass index (BMI) below the 25th percentile
. Lenke lumbar modifier B or C
. Staged surgical correction
. Use of iliac crest bone graft

Correct Answer & Explanation

. Body mass index (BMI) below the 25th percentile

Explanation

Superior mesenteric artery syndrome occurs more often in patients with decreased BMI, larger and stiffer thoracic curves, lumbar apical translation of Lenke B or C , and two staged procedures.

Question 218

Topic: 4. Pediatrics

All except which of the following structural disorders often causes scoliosis and presents undiagnosed in patients:

. Marfan syndrome
. Ehlers-Danlos syndrome
. Osteogenesis imperfecta
. Loeys-Dietz syndrome
. Achondroplasia

Correct Answer & Explanation

. Achondroplasia

Explanation

Although achondroplasia causes kyphosis, it is not associated with scoliosis to a significant degree. Marfan syndrome, Ehlers- Danlos syndrome, osteogenesis imperfecta, and Loeys-Dietz syndrome (a defect in TGF-beta receptor protein) are frequently associated with scoliosis.

Question 219

Topic: 4. Pediatrics

A 3-year-old boy presents with short-limbed dwarfism, frontal bossing, and midface hypoplasia. Radiographs show narrowing of the interpedicular distances in the lumbar spine. Which of the following gene mutations is most likely responsible for this condition?

. COL1A1
. FGFR3
. COMP
. RUNX2
. COL2A1

Correct Answer & Explanation

. FGFR3

Explanation

Achondroplasia is the most common form of short-limbed dwarfism and is caused by an activating mutation in the FGFR3 gene. This mutation inhibits chondrocyte proliferation in the proliferative zone of the physis.

Question 220

Topic: 4. Pediatrics

A 10-year-old child presents with a waddling gait, joint pain, and short stature. Radiographs show delayed, irregular ossification of multiple epiphyses and a "double-layered" patella laterally. A mutation in which of the following is most commonly implicated?

. Cartilage oligomeric matrix protein (COMP)
. Fibroblast growth factor receptor 3 (FGFR3)
. Type 1 collagen (COL1A1)
. Filamin B (FLNB)
. Type 2 collagen (COL2A1)

Correct Answer & Explanation

. Cartilage oligomeric matrix protein (COMP)

Explanation

Multiple epiphyseal dysplasia (MED) is often caused by a mutation in the COMP gene. A double-layered patella on a lateral knee radiograph is a highly characteristic, pathognomonic finding for this condition.

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