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4. Pediatrics MCQs

Practice Set 14 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 261

Topic: 4. Pediatrics

During computerized gait analysis of a child with spastic diplegic cerebral palsy, the kinematic data reveals excessive knee flexion during the stance phase (crouch gait). Which of the following interventions is most likely to exacerbate this specific gait abnormality?

. Distal femoral extension osteotomy
. Hamstring lengthening
. Patellar tendon advancement
. Achilles tendon lengthening
. Rectus femoris transfer

Correct Answer & Explanation

. Achilles tendon lengthening

Explanation

Achilles tendon lengthening weakens the calf muscles (plantarflexors). The plantarflexor-knee extension couple is crucial for maintaining knee extension during stance, so weakening it exacerbates crouch gait.

Question 262

Topic: Pediatric Hip

A 13-year-old obese boy underwent in situ pinning for a stable slipped capital femoral epiphysis (SCFE) 6 months ago. He now complains of progressive hip stiffness and pain. Radiographs reveal a narrowed joint space with periarticular osteopenia. What is the most likely cause of this complication?

. Avascular necrosis (AVN)
. Implant failure
. Chondrolysis
. Septic arthritis
. Femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a known complication of SCFE characterized by progressive joint space narrowing and stiffness. It is strongly associated with unrecognized pin penetration into the joint space.

Question 263

Topic: 4. Pediatrics

A newborn with a myelomeningocele at the L4 level is evaluated in the nursery. What is the most likely hip pathology expected in this patient over time?

. Progressive coxa vara
. Paralytic hip dislocation secondary to muscle imbalance
. Spontaneous resolution of neonatal dysplasia
. Severe fixed abduction contractures
. Bilateral rigid cam impingement

Correct Answer & Explanation

. Paralytic hip dislocation secondary to muscle imbalance

Explanation

Patients with an L4 motor level have intact hip flexors and adductors but lack strong hip extensors and abductors. This unopposed muscle action frequently leads to paralytic hip subluxation and dislocation.

Question 264

Topic: 4. Pediatrics

Which of the following patients with Cerebral Palsy is the most ideal candidate for Selective Dorsal Rhizotomy (SDR)?

. A 10-year-old with dyskinetic CP and severe athetosis
. A 5-year-old with spastic diplegia, good selective motor control, and independent ambulation
. A 14-year-old with spastic quadriplegia and fixed joint contractures
. A 3-year-old with hypotonic CP and global developmental delay
. A 7-year-old with spastic hemiplegia and dystonia

Correct Answer & Explanation

. A 5-year-old with spastic diplegia, good selective motor control, and independent ambulation

Explanation

The ideal candidate for SDR is a child aged 3 to 8 years with spastic diplegia, good cognition, minimal fixed contractures, and good underlying selective motor control. It is generally contraindicated in dyskinetic or dystonic CP.

Question 265

Topic: Pediatric Hip

A 3-year-old girl is diagnosed with a neglected unilateral developmental dysplasia of the hip (DDH).

The femoral head is dislocated superiorly. What is the most appropriate surgical management?

. Closed reduction and spica casting
. Open reduction with adductor tenotomy alone
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy
. Pavlik harness application
. Proximal femoral focal deficiency reconstruction

Correct Answer & Explanation

. Open reduction, femoral shortening osteotomy, and pelvic osteotomy

Explanation

In children over 2 to 3 years old with a high dislocation, open reduction typically requires a concurrent femoral shortening osteotomy to reduce pressure on the femoral head and a pelvic osteotomy for adequate acetabular coverage.

Question 266

Topic: Pediatric Hip

In a patient diagnosed with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is an absolute indication for prophylactic pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Presentation with a stable slip
. Presence of an endocrine disorder such as hypothyroidism
. Obesity with a BMI in the 90th percentile
. Family history of SCFE

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Endocrine disorders (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency) significantly increase the risk of bilateral SCFE. Prophylactic pinning of the contralateral hip is highly recommended in these cases.

Question 267

Topic: 4. Pediatrics
According to consensus guidelines for hip surveillance in children with cerebral palsy, at what Gross Motor Function Classification System (GMFCS) level is the risk of hip displacement the highest, necessitating the most frequent radiographic screening?
. GMFCS Level I
. GMFCS Level II
. GMFCS Level III
. GMFCS Level IV
. GMFCS Level V

Correct Answer & Explanation

. GMFCS Level V

Explanation

The risk of hip displacement in CP is directly proportional to the severity of neurologic involvement. Children at GMFCS Level V have the highest risk (approaching 90%) and require the most frequent radiographic surveillance.

Question 268

Topic: Pediatric Hip

A 6-week-old female infant is placed in a Pavlik harness for a dislocated left hip (Ortolani positive). After 3 weeks of strict full-time harness wear, ultrasound shows the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for another 3 weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)
. Perform an open reduction immediately
. Abandon the harness and perform closed reduction with spica casting
. Perform a varus derotational osteotomy

Correct Answer & Explanation

. Abandon the harness and perform closed reduction with spica casting

Explanation

Failure to reduce a dislocated hip after 3 weeks in a Pavlik harness is an indication to abandon the harness to prevent 'Pavlik harness disease' (posterior acetabular wear). The next step is typically closed reduction and spica casting under anesthesia.

Question 269

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 confirm a severe, unstable slipped capital femoral epiphysis (SCFE). Which blood supply to the femoral head is most at risk of injury in this acute, unstable scenario?

. Artery of the ligamentum teres
. Descending branch of the lateral circumflex femoral artery
. Ascending cervical branches of the medial circumflex femoral artery
. Inferior gluteal artery
. Pudendal artery

Correct Answer & Explanation

. Ascending cervical branches of the medial circumflex femoral artery

Explanation

The medial circumflex femoral artery (MCFA) provides the primary blood supply to the femoral head via its ascending cervical branches. In an unstable SCFE, these extraosseous vessels are tethered and highly susceptible to rupture or occlusion, leading to osteonecrosis.

Question 270

Topic: Pediatric Lower Extremity

In the Ponseti method for treating idiopathic clubfoot, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The CAVE mnemonic dictates the order of correction in the Ponseti method: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus (usually requiring a percutaneous Achilles tenotomy).

Question 271

Topic: 4. Pediatrics

A 4-year-old girl with blue sclerae, dentinogenesis imperfecta, and multiple prior long bone fractures is diagnosed with osteogenesis imperfecta. This condition is most commonly caused by a mutation affecting which of the following?

. Type II collagen
. Type I collagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)
. Core binding factor alpha 1 (CBFA1)

Correct Answer & Explanation

. Type I collagen

Explanation

Osteogenesis imperfecta is primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode the chains of Type I collagen. This leads to brittle bones, blue sclerae, and hearing loss.

Question 272

Topic: Pediatric Hip

According to the Herring Lateral Pillar classification for Legg-Calve-Perthes disease, a hip in which the lateral pillar maintains between 50% and 100% of its original height is classified as:

. Type A
. Type B
. Type B/C border
. Type C
. Type D

Correct Answer & Explanation

. Type C

Explanation

In the Herring classification, Type A has no lateral pillar involvement. Type B maintains >50% lateral pillar height. Type C has <50% height maintained, portending a worse prognosis.

Question 273

Topic: 4. Pediatrics

A 4-year-old girl with cerebral palsy (GMFCS Level IV) undergoes routine radiographic hip surveillance. The AP pelvis radiograph demonstrates a Reimers' migration percentage of 45%. What is the most appropriate next step in management?

. Observation and repeat radiograph in 1 year
. Botulinum toxin injection to hip adductors
. Adductor and iliopsoas tenotomies
. Varus derotational osteotomy (VDRO) with pelvic osteotomy
. Proximal femoral resection (Castle procedure)

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) with pelvic osteotomy

Explanation

In CP patients, a migration percentage >40-50% generally warrants bony reconstructive surgery (VDRO and pelvic osteotomy) to prevent dislocation. Soft tissue releases alone are insufficient for migration >40%.

Question 274

Topic: Pediatric Hip

A 12-year-old boy weighing 90 kg presents with acute on chronic left knee and groin pain. He is unable to bear weight. Radiographs show a posterior and inferior displacement of the proximal femoral epiphysis. What is the most serious complication associated with the appropriate initial surgical treatment of this condition?

. Chondrolysis
. Avascular necrosis (AVN)
. Leg length discrepancy
. Femoroacetabular impingement
. Infection

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The clinical picture describes an unstable slipped capital femoral epiphysis (SCFE). Unstable SCFE has a high risk of avascular necrosis (AVN), which can occur naturally or be exacerbated by surgical reduction and fixation.

Question 275

Topic: Pediatric Hip

A 6-week-old female infant is treated with a Pavlik harness for a dislocated left hip. After 3 weeks of strict harness wear, ultrasound reveals that the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for another 3 weeks
. Tighten the anterior straps to increase flexion
. Transition to a rigid abduction orthosis (e.g., Ilfeld splint)
. Perform an arthrogram, closed reduction, and spica casting
. Perform an open reduction and pelvic osteotomy

Correct Answer & Explanation

. Perform an arthrogram, closed reduction, and spica casting

Explanation

Failure to reduce a dislocated hip after 3 weeks of Pavlik harness wear is an indication to abandon the harness to avoid Pavlik harness disease (posterior acetabular wear). The next step is a closed reduction and spica casting.

Question 276

Topic: Pediatric Hip

A 13-year-old boy presents with progressive right hip pain and stiffness 6 months after in situ pinning of a stable slipped capital femoral epiphysis. Examination reveals significant restriction of all hip motions, particularly internal rotation and abduction. Radiographs show symmetric narrowing of the joint space. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Hardware failure
. Septic arthritis
. Heterotopic ossification

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is characterized by acute or insidious onset of pain, stiffness, and symmetric joint space narrowing (typically <3 mm) after SCFE. It may be associated with unrecognized screw penetration into the joint.

Question 277

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp. Radiographs reveal fragmentation and sclerosis of the proximal femoral epiphysis. According to the lateral pillar classification for Legg-Calvรฉ-Perthes disease, which radiographic finding constitutes a Group C categorization?
. No involvement of the lateral pillar
. >50% maintained height of the lateral pillar
. <50% maintained height of the lateral pillar
. Complete collapse of the medial pillar
. Subchondral fracture (crescent sign) involving <50% of the epiphysis

Correct Answer & Explanation

. <50% maintained height of the lateral pillar

Explanation

In the Herring lateral pillar classification of Perthes disease, Group C involves <50% maintenance of the lateral pillar height. This group has a poor prognosis and a higher risk of aspherical healing.

Question 278

Topic: 4. Pediatrics

A 3-year-old child with blue sclerae, dentinogenesis imperfecta, and multiple fractures with minimal trauma is evaluated. She is diagnosed with Osteogenesis Imperfecta (OI). Which molecular defect is most likely responsible?

. Mutation in the FGFR3 gene
. Mutation in the COL1A1 or COL1A2 genes
. Mutation in the COMP gene
. Mutation in the RUNX2 gene
. Mutation in the SOX9 gene

Correct Answer & Explanation

. Mutation in the COL1A1 or COL1A2 genes

Explanation

Osteogenesis Imperfecta is primarily caused by mutations in the COL1A1 or COL1A2 genes, which encode type I collagen. This leads to brittle bones, blue sclerae, and varying degrees of skeletal deformity.

Question 279

Topic: 4. Pediatrics

According to best practice guidelines for cerebral palsy hip surveillance, how frequently should a non-ambulatory 6-year-old child (GMFCS Level V) undergo radiographic screening of the hips?

. Every 6 months
. Annually
. Every 2 years
. Only if symptomatic
. At skeletal maturity

Correct Answer & Explanation

. Every 6 months

Explanation

Children with GMFCS levels IV and V are at the highest risk for hip displacement. Current surveillance guidelines recommend radiographic screening every 6 months for these patients until skeletal maturity or stabilization.

Question 280

Topic: 4. Pediatrics

A 2-year-old boy has profound hypotonia, absent deep tendon reflexes, and fine fasciculations of the tongue. He is able to sit independently but cannot pull to stand or walk. Genetic testing reveals a deletion in the SMN1 gene. What is the most likely orthopedic complication he will develop?

. Hip dysplasia
. Scoliosis
. Cavovarus foot deformity
. Slipped capital femoral epiphysis
. Tarsal coalition

Correct Answer & Explanation

. Scoliosis

Explanation

The patient has Spinal Muscular Atrophy (SMA) Type II. The most common and significant orthopedic complication in non-ambulatory SMA patients is early-onset, progressive scoliosis.

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