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4. Pediatrics MCQs

Practice Set 166 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 3301

Topic: Pediatric Hip

A 9-year-old boy presents with left knee pain and an obligatory external rotation of the left lower extremity with hip flexion. Radiographs demonstrate a severe, chronic slipped capital femoral epiphysis (SCFE) on the left. The patient's medical history is significant for chronic kidney disease and secondary hyperparathyroidism. Following in situ pinning of the left hip, what is the most appropriate management for the asymptomatic right hip?

. Observation with serial radiographs every 6 months
. Prophylactic in situ percutaneous pinning
. Prophylactic Imhauser osteotomy
. Surgical hip dislocation and prophylactic relative neck lengthening
. Spica casting

Correct Answer & Explanation

. Prophylactic in situ percutaneous pinning

Explanation

The patient has a known endocrinopathy/metabolic disorder (renal osteodystrophy with secondary hyperparathyroidism), which places him at an exceptionally high risk for developing a contralateral slipped capital femoral epiphysis (SCFE). Prophylactic prophylactic in situ percutaneous pinning of the contralateral hip is strongly indicated in patients with underlying endocrinopathies, radiation therapy history, and in very young patients (typically less than 10 years old) presenting with a unilateral SCFE. Observation is appropriate for older, idiopathic cases, but not for this high-risk patient.

Question 3302

Topic: 4. Pediatrics

A 6-week-old female infant is undergoing treatment with a Pavlik harness for a dislocated right hip (developmental dysplasia of the hip). During a follow-up visit after 1 week, the parents report that the infant is no longer extending her right knee spontaneously. On examination, the knee extension is absent, and the patellar reflex is diminished. This complication is most likely the result of which of the following positioning errors in the harness?

. Excessive hip abduction
. Excessive hip flexion
. Inadequate hip flexion
. Excessive hip adduction
. Inadequate hip abduction

Correct Answer & Explanation

. Excessive hip flexion

Explanation

The clinical presentation describes a femoral nerve palsy, which is the most common nerve palsy associated with the use of a Pavlik harness. It is caused by excessive hyperflexion of the hip. The appropriate management is to temporarily remove the harness or adjust the anterior straps to decrease the amount of flexion until the nerve palsy resolves. In contrast, excessive hip abduction in the harness places the hip at high risk for avascular necrosis (AVN) of the femoral head.

Question 3303

Topic: 4. Pediatrics

An 18-month-old girl presents with bilateral genu varum. Standing full-length lower extremity radiographs reveal a metaphyseal-diaphyseal angle (Drennan's angle) of 18 degrees bilaterally, along with beaking of the medial proximal tibial metaphysis. What is the most appropriate initial management?

. Reassurance and observation for spontaneous resolution
. Bilateral proximal tibial valgus-producing osteotomies
. Bilateral knee-ankle-foot orthoses (KAFOs)
. Bilateral lateral eight-plate hemiepiphysiodesis
. High-dose Vitamin D supplementation

Correct Answer & Explanation

. Bilateral knee-ankle-foot orthoses (KAFOs)

Explanation

The patient's clinical and radiographic presentation is consistent with infantile Blount's disease (tibia vara). A metaphyseal-diaphyseal angle (Drennan's angle) greater than 16 degrees has a high predictive value for true infantile Blount's disease rather than physiologic bowing. For a child under the age of 3 with Blount's disease (typically stages I and II), the standard initial treatment is bracing with Knee-Ankle-Foot Orthoses (KAFOs) worn during weight-bearing. Surgical intervention (osteotomy or guided growth) is reserved for older children, those who fail bracing, or those presenting with more advanced Langenskiold stages.

Question 3304

Topic: 4. Pediatrics

A 7-year-old boy with spastic quadriplegic cerebral palsy (GMFCS Level IV) is evaluated during a routine hip surveillance clinic. Anteroposterior pelvis radiographs demonstrate a migration percentage of 55% in the right hip, with breaking of Shenton's line. The hip is reducible on physical examination. What is the most appropriate surgical intervention?

. Adductor tenotomy and psoas release alone
. Botulinum toxin injection into the adductors and hamstrings
. Varus derotational osteotomy (VDRO) and pelvic osteotomy
. Hip arthrodesis
. Proximal femoral resection (Castle procedure)

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) and pelvic osteotomy

Explanation

In children with cerebral palsy, a migration percentage (Reimer's index) greater than 40-50% indicates significant hip subluxation that is unlikely to respond to soft-tissue releases alone. Bony reconstruction is indicated to provide a stable, concentric reduction and prevent progression to a painful, dislocated hip. The standard reconstructive procedure involves a varus derotational osteotomy (VDRO) of the proximal femur to correct coxa valga and excessive anteversion, combined with a pelvic osteotomy (e.g., Dega or San Diego) to correct the acetabular dysplasia. Soft-tissue releases alone are reserved for migration percentages less than 30-40% in younger children (typically <4-5 years old).

Question 3305

Topic: 4. Pediatrics

An orthopaedic surgeon is treating a 2-week-old infant with idiopathic congenital clubfoot using the Ponseti method. When applying the first cast to correct the cavus deformity, which specific manipulative maneuver is required?

. Pronating the forefoot to align with the hindfoot
. Elevating the first metatarsal to supinate the forefoot
. Depressing the first metatarsal to plantarflex the medial column
. Abducting the midfoot with counter-pressure on the cuboid
. Plantarflexing the ankle to relax the Achilles tendon

Correct Answer & Explanation

. Elevating the first metatarsal to supinate the forefoot

Explanation

In the Ponseti method of clubfoot casting, the deformities are corrected in a specific sequence (CAVE: Cavus, Adductus, Varus, Equinus). The cavus deformity is driven by a pronated forefoot relative to the hindfoot. To correct the cavus, the first metatarsal must be elevated, which effectively supinates the forefoot to align it properly with the hindfoot. Once the forefoot is supinated and the cavus is corrected in the first cast, subsequent casts will focus on abducting the foot around the fixed talar head.

Question 3306

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a Gartland type III extension-type supracondylar humerus fracture. On initial evaluation in the emergency department, the hand is pink and warm with brisk capillary refill, but the radial pulse is not palpable. After emergent closed reduction and percutaneous pinning in the operating room, the fracture is anatomically aligned, but the radial pulse remains absent. The hand remains warm and pink. What is the most appropriate next step in management?
. Immediate open exploration of the brachial artery
. Observation with continuous clinical monitoring
. CT angiography of the upper extremity
. Removal of the pins and transition to a long arm cast
. Prophylactic forearm fasciotomies

Correct Answer & Explanation

. Observation with continuous clinical monitoring

Explanation

The management of a 'pulseless, pink hand' following a supracondylar humerus fracture involves urgent closed reduction and percutaneous pinning (CRPP) to restore anatomy and potentially release a kinked or entrapped brachial artery. If the hand remains pink and well-perfused (capillary refill <2 seconds) after anatomic reduction and stabilization, despite an absent palpable pulse, the standard of care is observation and continuous monitoring. Many of these hands have adequate collateral circulation. Open exploration of the brachial artery is indicated if the hand becomes or remains 'pulseless and white' (ischemic) after reduction.

Question 3307

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease of the right hip. Which of the following radiographic findings is considered the most significant poor prognostic indicator, predictive of a poor long-term outcome (Stulberg class IV or V)?
. Crescent sign indicating a subchondral fracture
. Intact lateral pillar maintaining >50% of its height
. Lateral subluxation of the femoral head with hinge abduction
. Increased medial joint space
. Appearance of a metaphyseal cyst

Correct Answer & Explanation

. Lateral subluxation of the femoral head with hinge abduction

Explanation

In Legg-Calvé-Perthes disease, lateral subluxation of the femoral head out of the acetabulum leads to hinge abduction, where the extruded, enlarged femoral head impinges on the lateral acetabular margin during abduction. This causes severe mechanical damage, failure of the head to remodel concentrically, and a poor long-term outcome (Stulberg IV or V). An intact lateral pillar (>50% height, Herring A or B) is a good prognostic sign. The crescent sign and metaphyseal cysts are diagnostic and part of the staging but are not the primary drivers of mechanical failure compared to loss of containment and lateral subluxation.

Question 3308

Topic: Pediatric Hip

A 12-year-old obese boy presents with a 4-week history of left groin pain and a new inability to bear weight on the left leg for the past 48 hours. On examination, his left lower extremity is externally rotated, and attempts at hip flexion result in obligate external rotation. Radiographs demonstrate a left slipped capital femoral epiphysis (SCFE). He undergoes in situ percutaneous pinning. Which of the following factors presents the highest risk for the development of avascular necrosis (AVN) of the femoral head in this patient?

. Patient age greater than 10 years
. The duration of prodromal symptoms exceeding 3 weeks
. The inability to bear weight prior to surgical intervention
. The use of a single screw rather than double screws for fixation
. The degree of initial posterior epiphyseal displacement

Correct Answer & Explanation

. The inability to bear weight prior to surgical intervention

Explanation

The inability to bear weight with or without crutches characterizes an unstable SCFE according to the Loder classification. Unstable SCFE is the single most significant risk factor for the development of avascular necrosis (AVN), carrying an AVN rate of up to 47%, compared to nearly 0% in stable SCFE. Age, duration of prodromal symptoms, degree of slip, and use of single versus double screw fixation do not predict AVN as strongly as the stability of the slip.

Question 3309

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from the monkey bars and sustains a widely displaced, extension-type supracondylar humerus fracture.

On presentation in the emergency department, his hand is pink and warm, but the radial pulse is not palpable. He is taken emergently to the operating room. After successful closed reduction and percutaneous pinning, the hand remains pink with brisk capillary refill, but the radial pulse is still absent on Doppler ultrasound. What is the most appropriate next step in management?

. Immediate vascular exploration
. Close observation with hospital admission
. Emergent arteriography
. Removal of the pins and transition to open reduction
. Administration of systemic intravenous heparin

Correct Answer & Explanation

. Close observation with hospital admission

Explanation

The management of a 'pulseless, pink hand' after a supracondylar humerus fracture reduction is close clinical observation. As long as the hand remains well-perfused (warm, pink, capillary refill < 2 seconds), adequate collateral circulation is present. Vascular exploration is indicated only if the hand becomes dysvascular (white, cold, prolonged capillary refill) after reduction, or if there is a loss of a previously palpable pulse following reduction.

Question 3310

Topic: 4. Pediatrics
A 4-year-old boy with a history of idiopathic clubfoot, initially treated successfully with the Ponseti method, presents to the clinic with his parents who report he is 'walking on the outside of his foot'. Gait analysis reveals a dynamic supination deformity during the swing phase. Physical examination shows his ankle passively dorsiflexes to 15 degrees beyond neutral with the knee extended. What is the most appropriate surgical management for this relapse?
. Repeat percutaneous Achilles tenotomy
. Split anterior tibial tendon transfer (SPLATT)
. Full anterior tibial tendon transfer to the lateral cuneiform
. Calcaneocuboid joint arthrodesis
. Posteromedial soft tissue release

Correct Answer & Explanation

. Full anterior tibial tendon transfer to the lateral cuneiform

Explanation

Dynamic supination during the swing phase in a patient with a relapsed Ponseti-treated clubfoot is typically caused by an overpowering tibialis anterior muscle. The gold standard treatment, provided there is adequate passive ankle dorsiflexion, is a full transfer of the tibialis anterior tendon to the lateral cuneiform. A split transfer (SPLATT) is generally reserved for patients with spasticity (e.g., cerebral palsy) to avoid overcorrection. Repeat Achilles tenotomy is not indicated since passive dorsiflexion is well preserved (15 degrees).

Question 3311

Topic: 4. Pediatrics

A 7-year-old child with spastic quadriplegic cerebral palsy is evaluated for progressive bilateral hip subluxation. His Gross Motor Function Classification System (GMFCS) level is V. Anteroposterior pelvis radiographs show a Reimers migration percentage of 55% bilaterally. There are no degenerative changes of the femoral head or acetabulum. What is the most appropriate treatment to achieve durable hip stability?

. Bilateral adductor and iliopsoas tenotomies
. Bilateral varus derotational proximal femoral osteotomies (VDRO) with pelvic osteotomies
. Proximal femoral resection (Castle procedure)
. Continued observation with semi-annual radiographs
. Botulinum toxin A injections to the hip adductors

Correct Answer & Explanation

. Bilateral varus derotational proximal femoral osteotomies (VDRO) with pelvic osteotomies

Explanation

In a child with cerebral palsy and a hip migration percentage > 50%, soft tissue releases alone (e.g., adductor/iliopsoas tenotomies) are highly likely to fail. Bony reconstruction with a varus derotational osteotomy (VDRO) of the proximal femur, typically combined with a pelvic osteotomy (e.g., Dega or San Diego), is the standard of care to achieve stable, concentric reduction. Salvage procedures like the Castle procedure are reserved for painful, chronically dislocated hips with severe articular damage.

Question 3312

Topic: Pediatric Hip

A 6-month-old girl with a dislocated left hip is brought to the operating room for a closed reduction and spica casting. An intraoperative arthrogram is performed to assess the adequacy of reduction.

On the arthrogram, the surgeon identifies a radiolucent block traversing the inferior aspect of the acetabulum, preventing concentric seating of the femoral head. Which of the following anatomical structures is most likely causing this specific block to reduction?

. Inverted limbus
. Hypertrophied pulvinar
. Transverse acetabular ligament
. Ligamentum teres
. Iliopsoas tendon

Correct Answer & Explanation

. Transverse acetabular ligament

Explanation

The transverse acetabular ligament is located at the inferior aspect of the acetabulum and, when hypertrophied or contracted, presents as an inferior block to reduction on an arthrogram in developmental dysplasia of the hip (DDH). The inverted limbus presents as a superior/lateral block. The ligamentum teres and pulvinar present as medial blocks within the cotyloid fossa. The iliopsoas tendon causes an hourglass constriction of the joint capsule extra-articularly.

Question 3313

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease of the right hip. Anteroposterior and frog-leg lateral radiographs taken during the fragmentation stage demonstrate a >50% depression of the lateral pillar height of the capital femoral epiphysis. According to the Herring lateral pillar classification, what is his classification and the expected clinical prognosis?
. Lateral Pillar A; Excellent prognosis without surgical intervention
. Lateral Pillar B; Good prognosis with containment surgery
. Lateral Pillar B/C border; Variable prognosis depending on age
. Lateral Pillar C; Poor prognosis, with a high risk of developing an aspherical femoral head
. Lateral Pillar C; Excellent prognosis if treated aggressively with a Petrie cast

Correct Answer & Explanation

. Lateral Pillar C; Poor prognosis, with a high risk of developing an aspherical femoral head

Explanation

The Herring lateral pillar classification evaluates the height of the lateral portion of the femoral head during the fragmentation stage. A loss of >50% of the lateral pillar height is classified as Herring Group C. Patients with Group C disease, particularly those 8 years of age or older at the onset of symptoms, generally have a poor prognosis characterized by an aspherical femoral head, coxa magna, and early onset of degenerative joint disease, regardless of the treatment applied.

Question 3314

Topic: 4. Pediatrics
A 7-year-old child with spastic quadriplegic cerebral palsy (GMFCS level IV) presents with progressive bilateral hip displacement. Recent radiographs show a migration percentage of 55% bilaterally with increased femoral anteversion and coxa valga, but no significant degenerative joint changes. She has painful hips and difficulty with perineal care. What is the most appropriate surgical management?
. Bilateral adductor longus and psoas tenotomies
. Bilateral Varus Derotational Osteotomies (VDRO) with pelvic osteotomies
. Bilateral proximal femoral resection (Castle procedure)
. Bilateral total hip arthroplasty
. Observation and optimization of baclofen therapy

Correct Answer & Explanation

. Bilateral Varus Derotational Osteotomies (VDRO) with pelvic osteotomies

Explanation

For children with cerebral palsy (particularly GMFCS levels III-V) presenting with a migration percentage greater than 40-50%, bony reconstruction is the gold standard. A Varus Derotational Osteotomy (VDRO) corrects the abnormal femoral anteversion and coxa valga. A concomitant pelvic osteotomy (such as a Dega or San Diego procedure) is typically required to address the associated acetabular dysplasia and provide adequate anterolateral coverage. Soft tissue release alone is inadequate for a migration percentage > 40%. Proximal femoral resection is a salvage procedure reserved for painful, chronic, non-reconstructable, dislocated hips.

Question 3315

Topic: 4. Pediatrics
A 30-month-old girl is evaluated for bilateral severe bowing of her legs. She has a BMI in the 95th percentile and achieved independent ambulation at 10 months of age. Radiographs reveal a varus deformity centered at the proximal tibia with metaphyseal beaking. Langenskiöld stage II changes are present. What is the most appropriate initial management?
. Reassurance and observation for spontaneous resolution
. Knee-Ankle-Foot Orthosis (KAFO) bracing
. Proximal tibial valgus-producing osteotomy
. Guided growth with tension band plates (eight-plates)
. Lateral proximal tibial epiphysiodesis

Correct Answer & Explanation

. Knee-Ankle-Foot Orthosis (KAFO) bracing

Explanation

This patient has infantile Blount disease (tibia vara), characterized by a varus deformity at the proximal tibia, early walking, obesity, and metaphyseal beaking. For a child under 3 years of age with Langenskiöld stage I or II disease, a trial of bracing with a Knee-Ankle-Foot Orthosis (KAFO) is the recommended first-line treatment. Surgical intervention (proximal tibial osteotomy) is indicated if bracing fails, if the child is over 4 years of age at presentation, or if they present with Langenskiöld stage III or higher.

Question 3316

Topic: 4. Pediatrics

A 5-year-old boy sustains a widely displaced, extension-type supracondylar humerus fracture. On presentation, his hand is pink and warm, but the radial pulse is absent.

The patient undergoes emergent closed reduction and percutaneous pinning. Postoperatively, the hand remains well-perfused with brisk capillary refill (under 2 seconds) and normal oxygen saturation, but the radial pulse remains absent. What is the most appropriate next step in management?

. Immediate vascular exploration of the brachial artery
. CT angiography of the affected upper extremity
. Removal of pins and transition to open reduction
. Observation and hospital admission for close monitoring
. Immediate administration of intravenous heparin

Correct Answer & Explanation

. Observation and hospital admission for close monitoring

Explanation

The management of a 'pink, pulseless' hand following closed reduction and percutaneous pinning of a pediatric supracondylar humerus fracture is close observation. Assuming the hand has excellent perfusion (warm, brisk capillary refill, good pulse oximetry waveform), the collateral circulation is sufficient to maintain viability. Vascular exploration is indicated for a 'white, pulseless' (dysvascular) hand that does not improve after fracture reduction.

Question 3317

Topic: Pediatric Hip

A 13-year-old boy with a BMI of 38 presents to the emergency department unable to bear weight on his left leg after stumbling on a step. Radiographs confirm a severe, displaced slipped capital femoral epiphysis (SCFE). He is unable to walk even with crutches. Which of the following complications is most specifically associated with this patient's acute presentation compared to a patient who is able to bear weight?

. Chondrolysis
. Avascular necrosis (AVN)
. Progressive slip
. Contralateral SCFE
. Premature hip osteoarthritis

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

This patient has an unstable SCFE, defined by the Loder classification as the inability to bear weight, even with crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (AVN), ranging from 20% to 50%, compared to stable SCFE, where the risk of AVN is near 0%. The precarious blood supply to the capital femoral epiphysis (mainly the lateral epiphyseal vessels) is acutely disrupted or kinked in an unstable slip.

Question 3318

Topic: Pediatric Hip

A 3-year-old girl is evaluated for a painless limp and leg length discrepancy. Examination reveals a positive Galeazzi sign and asymmetric thigh folds. Anteroposterior pelvis radiograph shows a dislocated right hip with significant acetabular dysplasia, a false acetabulum, and increased femoral anteversion. What is the most appropriate definitive surgical intervention?

. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction and femoral varus derotational osteotomy (VDRO)
. Open reduction, femoral VDRO, and pelvic osteotomy
. Pelvic osteotomy (Salter) alone

Correct Answer & Explanation

. Open reduction, femoral VDRO, and pelvic osteotomy

Explanation

In a child older than 2 to 3 years presenting with a late, untreated Developmental Dysplasia of the Hip (DDH), the hip is typically high-riding with adaptive changes including significant acetabular dysplasia and increased femoral anteversion. Comprehensive surgical reconstruction is required. This involves an open reduction to clear obstacles to reduction, a femoral shortening and varus derotational osteotomy (VDRO) to reduce pressure on the joint (reducing AVN risk) and correct version, and a pelvic osteotomy (e.g., Pemberton, Dega, or Salter) to address the acetabular dysplasia.

Question 3319

Topic: 4. Pediatrics
A 4-year-old boy who was successfully treated for an idiopathic right clubfoot as an infant using the Ponseti method now presents with a relapsed deformity. His parents note recurrent intoeing and that he walks on the lateral border of the foot. Physical examination shows dynamic supination of the foot during the swing phase of gait and fixed equinus of 10 degrees. What is the most appropriate treatment strategy?
. Serial casting followed by transfer of the anterior tibial tendon (ATTT)
. Split anterior tibial tendon transfer (SPLATT) alone
. Extensive posteromedial release
. Lateral column shortening osteotomy
. Triple arthrodesis

Correct Answer & Explanation

. Serial casting followed by transfer of the anterior tibial tendon (ATTT)

Explanation

Relapse in Ponseti-treated clubfoot often presents with dynamic supination and recurrent equinus. For a child over 2.5 to 3 years of age, the standard of care for a symptomatic relapse involving dynamic supination is repeat serial casting to correct any fixed deformities (restoring passive dorsiflexion and abduction), followed by a transfer of the anterior tibial tendon (ATTT) to the third cuneiform. This balances the foot dynamically and prevents further relapse. Extensive posteromedial release is largely historic and leads to a stiff, painful foot.

Question 3320

Topic: 4. Pediatrics
A 6-year-old boy with Osteogenesis Imperfecta (OI) type III presents with progressive anterolateral bowing of bilateral femurs, causing pain and difficulty with ambulation. He has a history of multiple low-energy fractures. What is the preferred surgical intervention to address the severe long bone deformities and minimize the risk of recurrent fractures?
. Unilateral external fixation for gradual deformity correction
. Multi-level corrective osteotomies and telescopic intramedullary rodding
. Multi-level corrective osteotomies and dynamic compression plating
. Closed osteoclasis and prolonged spica casting
. Non-operative management with intravenous bisphosphonates alone

Correct Answer & Explanation

. Multi-level corrective osteotomies and telescopic intramedullary rodding

Explanation

The standard of care for addressing severe long bone deformity in patients with severe Osteogenesis Imperfecta (Type III) is the Sofield-Millar procedure. This involves making multiple osteotomies to straighten the bone, followed by internal fixation using an intramedullary device. In growing children, telescopic intramedullary rods (e.g., Fassier-Duval rods) are preferred because they elongate with bone growth, providing continuous internal splinting and significantly reducing the risk of recurrent deformity and fracture. Plating creates stress risers at the ends of the plates in osteopenic bone.

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