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4. Pediatrics MCQs

Practice Set 318 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 6341

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs reveal fragmentation of the femoral head with the lateral pillar maintaining exactly 40% of its original height. According to the Herring lateral pillar classification, what is the most appropriate grade and the associated long-term prognosis for joint congruency if treated non-operatively?
. Group C; poor prognosis with a high risk of an aspherical femoral head and early osteoarthritis.
. Group A; minimal risk of aspherical femoral head.
. Group B; favorable prognosis if the patient is over 8 years old.
. Group B; predictable remodeling into a spherical head regardless of age.
. Group B/C; guarded prognosis requiring immediate total hip arthroplasty.

Correct Answer & Explanation

. Group B; favorable prognosis if the patient is over 8 years old.

Explanation

In the Herring classification, Group C involves >50% loss of lateral pillar height (maintaining <50%). This group has a universally poor prognosis with a high risk of developing an aspherical femoral head and early osteoarthritis, often requiring surgical containment.

Question 6342

Topic: 4. Pediatrics

A 6-year-old girl with spastic quadriplegic cerebral palsy (GMFCS Level V) is evaluated during a routine surveillance clinic. An AP pelvis radiograph demonstrates a Reimers migration percentage of 45% in the right hip. She has no pain, but hip abduction is limited to 20 degrees bilaterally. What is the most appropriate management?

. Observation and repeat radiographs in 1 year
. Bilateral adductor tenotomies alone
. Right hip open reduction, femoral varus derotational osteotomy (VDRO), and pelvic osteotomy
. Right total hip arthroplasty
. Botulinum toxin injections to the adductors and hamstrings

Correct Answer & Explanation

. Right hip open reduction, femoral varus derotational osteotomy (VDRO), and pelvic osteotomy

Explanation

A Reimers migration percentage >40% in a child with CP typically requires bony reconstruction to stabilize the hip and prevent painful dislocation. This consists of a femoral varus derotational osteotomy (VDRO) combined with a pelvic osteotomy (e.g., Dega or San Diego), as soft tissue releases alone are insufficient.

Question 6343

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department unable to bear weight on his left leg after minor trauma. Radiographs show a severe left slipped capital femoral epiphysis (SCFE). He is diagnosed with an unstable SCFE. Which of the following factors is most strongly associated with the development of osteonecrosis (AVN) in this patient?

. Degree of epiphyseal displacement on the lateral radiograph
. Presence of an unstable slip (inability to bear weight)
. Prompt prophylactic pinning of the contralateral hip
. The patient's body mass index (BMI) > 95th percentile
. Concomitant endocrine abnormalities

Correct Answer & Explanation

. Presence of an unstable slip (inability to bear weight)

Explanation

The primary risk factor for osteonecrosis (AVN) in SCFE is the clinical stability of the slip. Unstable slips (defined by the inability to bear weight even with crutches) have an AVN rate of up to 47%, compared to nearly 0% in stable slips.

Question 6344

Topic: Pediatric Hip

An 18-month-old girl presents with a painless limp and leg length discrepancy. Pelvic radiographs reveal a completely dislocated left hip with an acetabular index of 40 degrees and a broken Shenton's line. Which of the following represents the most appropriate surgical approach for this patient?

. Closed reduction and spica casting
. Open reduction alone
. Open reduction, capsulorrhaphy, and pelvic osteotomy
. Femoral varus derotational osteotomy (VDRO) alone
. Pavlik harness application

Correct Answer & Explanation

. Open reduction, capsulorrhaphy, and pelvic osteotomy

Explanation

In a child over 18 months of age with developmental dysplasia of the hip, closed reduction is rarely successful. The standard of care is an open reduction and capsulorrhaphy, frequently combined with a pelvic osteotomy (e.g., Salter) to address residual acetabular dysplasia.

Question 6345

Topic: 4. Pediatrics

A 14-year-old elite baseball pitcher presents with dominant shoulder pain that worsens with throwing. Radiographs reveal widening and irregularity of the proximal humeral physis. Range of motion testing shows increased external rotation and decreased internal rotation compared to the contralateral side. What is the most appropriate initial management for this condition?

. Immediate percutaneous pinning of the proximal humerus
. Physical therapy focusing on aggressive internal rotation stretching immediately
. Complete cessation of throwing for 3 months followed by a progressive throwing program
. Corticosteroid injection into the subacromial space
. Arthroscopic labral repair

Correct Answer & Explanation

. Complete cessation of throwing for 3 months followed by a progressive throwing program

Explanation

"Little League Shoulder" is a stress fracture of the proximal humeral physis caused by repetitive rotational torque. The cornerstone of treatment is absolute rest from throwing, typically for 3 months until clinically and radiographically healed, followed by a structured return-to-throwing program.

Question 6346

Topic: 4. Pediatrics
A 5-year-old child presents with a severe limp and a 3 cm limb length discrepancy. History reveals a prolonged NICU stay for sepsis as a neonate. Radiographs show complete absence of the femoral head and neck with proximal migration of the femoral shaft. This severe deformity is a known sequela of delayed treatment for which of the following?
. Developmental dysplasia of the hip
. Legg-Calvé-Perthes disease
. Slipped capital femoral epiphysis
. Neonatal septic coxitis
. Proximal focal femoral deficiency

Correct Answer & Explanation

. Neonatal septic coxitis

Explanation

Neonatal septic coxitis can rapidly and completely destroy the unossified cartilaginous femoral head due to proteolytic enzymes. Delayed diagnosis often results in permanent loss of the proximal femur, classified as Tomich type IV sequelae.

Question 6347

Topic: Pediatric Hip

A 2-week-old neonate is brought to the emergency department for irritability and decreased spontaneous movement of the right lower extremity. Ultrasound reveals a significant hip effusion.

What is the most appropriate next step in management?

. Intravenous antibiotics and observation
. Closed reduction and spica casting
. MRI of the pelvis with and without contrast
. Urgent joint aspiration and surgical drainage
. Pavlik harness application

Correct Answer & Explanation

. Urgent joint aspiration and surgical drainage

Explanation

The neonate presents with pseudoparalysis and an effusion, highly suspicious for septic coxitis. Urgent aspiration and surgical drainage (arthrotomy) are required to prevent catastrophic destruction of the cartilaginous femoral head.

Question 6348

Topic: Pediatric Hip

A 3-week-old neonate presents with fever, irritability, and decreased spontaneous movement of the right lower extremity. Clinical examination reveals pain upon passive range of motion of the right hip. Ultrasound shows a joint effusion. What is the most appropriate next step in management?

. Intravenous antibiotics and close observation
. MRI of the right hip with contrast
. Ultrasound-guided hip aspiration and urgent surgical drainage
. Closed reduction and spica casting
. Pavlik harness application

Correct Answer & Explanation

. Ultrasound-guided hip aspiration and urgent surgical drainage

Explanation

Septic coxitis in a neonate is an orthopedic emergency presenting as pseudoparalysis. Immediate ultrasound-guided aspiration followed by urgent surgical debridement is required to prevent rapid femoral head destruction.

Question 6349

Topic: 4. Pediatrics

A 4-year-old child presents with a severe limp and limb length discrepancy. His mother reports he had a severe febrile illness requiring an operation on his hip shortly after birth. Radiographs show a completely absent femoral head and neck with proximal migration of the femoral shaft. What was the most likely diagnosis during the neonatal period?

. Developmental dysplasia of the hip
. Legg-Calve-Perthes disease
. Slipped capital femoral epiphysis
. Neonatal septic coxitis
. Proximal focal femoral deficiency

Correct Answer & Explanation

. Neonatal septic coxitis

Explanation

Delay in diagnosis and treatment of neonatal septic arthritis of the hip (septic coxitis) leads to rapid destruction of the cartilaginous femoral head by proteolytic enzymes. This results in severe, permanent deformity and joint subluxation.

Question 6350

Topic: Pediatric Hip
A 2-week-old neonate presents with irritability, poor feeding, and pseudoparalysis of the left lower extremity. Examination shows pain with passive range of motion of the left hip. If left untreated, which of the following is the most likely catastrophic complication specific to this joint in this age group?
. Malignant transformation
. Slipped capital femoral epiphysis
. Complete destruction of the femoral head and neck
. Premature closure of the triradiate cartilage
. Development of Legg-Calvé-Perthes disease

Correct Answer & Explanation

. Complete destruction of the femoral head and neck

Explanation

Septic arthritis of the hip in a neonate is a surgical emergency. Delayed treatment rapidly leads to complete destruction of the cartilaginous femoral anlage (femoral head and neck) due to proteolytic enzymes and compromised intracapsular blood supply.

Question 6351

Topic: 4. Pediatrics

A 4-week-old infant is diagnosed with a delayed presentation of septic coxitis

. Which of the following is the most devastating, yet common, complication of delayed surgical decompression in this specific age group?

. Development of an osteoid osteoma
. Capital femoral epiphysis destruction
. Sciatic nerve palsy
. Overgrowth of the affected limb
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Capital femoral epiphysis destruction

Explanation

Septic arthritis of the hip in infants is a surgical emergency. Delayed decompression leads to rapid proteolytic destruction of the largely cartilaginous capital femoral epiphysis, causing irreversible joint damage and catastrophic growth disturbances.

Question 6352

Topic: 4. Pediatrics

After successful correction of idiopathic genu valgum with a tension band plate (guided growth), what is the most significant risk factor for rebound deformity after implant removal?

. Patient age less than 10 years
. Male sex
. Overcorrection
. Concomitant sagittal plane deformity
. Implant type (stainless steel vs. titanium)

Correct Answer & Explanation

. Patient age less than 10 years

Explanation

Younger age (especially girls <10 and boys <12) and significant remaining skeletal growth are the primary risk factors for rebound deformity following implant removal. Close monitoring until skeletal maturity is required.

Question 6353

Topic: 4. Pediatrics
Which of the following is an absolute contraindication to tension band plating (guided growth) for infantile Blount disease?
. Age over 4 years
. Bilateral involvement
. Langenskiöld stage VI
. Obesity (BMI > 95th percentile)
. Concomitant internal tibial torsion

Correct Answer & Explanation

. Langenskiöld stage VI

Explanation

Langenskiöld stages V and VI involve physeal bar formation, meaning the medial physis is closed or severely tethered. Guided growth relies on an open, functional physis and will fail if a physeal bar is present.

Question 6354

Topic: Pediatric Lower Extremity

In a patient with Aitken Class A proximal focal femoral deficiency (PFFD), what is the most typical associated lower extremity anomaly?

. Tibial hemimelia
. Fibular hemimelia
. Tarsal coalition
. Congenital vertical talus
. Developmental dysplasia of the hip

Correct Answer & Explanation

. Fibular hemimelia

Explanation

PFFD is highly associated with fibular hemimelia, occurring in up to 70-80% of cases. These patients also frequently present with ACL deficiency and lateral ray foot deficiencies.

Question 6355

Topic: 4. Pediatrics

During Ilizarov distraction osteogenesis, radiographs are taken.

If the regenerate bone appears cystic and thin, what modification to the distraction protocol is most appropriate?

. Increase the distraction rate
. Decrease the distraction rate
. Maintain the current rate and add electrical stimulation
. Administer systemic corticosteroids
. Remove the frame and apply a long-leg cast

Correct Answer & Explanation

. Decrease the distraction rate

Explanation

Poor, cystic, or sparse regenerate bone indicates that osteogenesis is not keeping pace with the mechanical distraction. The rate of distraction should be decreased to allow bone mineralization to catch up.

Question 6356

Topic: 4. Pediatrics

What is the most common cause of tension band plate screw breakage during guided growth for angular deformity correction?

. Deep surgical site infection
. Using oversized plates for the patient's age
. Using titanium instead of stainless steel implants
. Screws placed perfectly parallel to the physis
. Delayed implant removal after maximal correction is achieved

Correct Answer & Explanation

. Delayed implant removal after maximal correction is achieved

Explanation

If guided growth plates are left in place long after the deformity has corrected, continued physeal growth generates massive forces. This can eventually lead to screw bending or breakage, necessitating timely removal or exchange.

Question 6357

Topic: 4. Pediatrics

A 4-year-old girl is diagnosed with unilateral infantile Blount disease (Langenskiold stage II). Which of the following is the most appropriate rationale for utilizing a tension band plate (guided growth) on the proximal lateral tibia?

. It stimulates medial physeal growth through the Delpech principle.
. It corrects the deformity by harnessing the Hueter-Volkmann principle.
. It allows immediate full weight-bearing by locking the perichondrial ring.
. It prevents premature physeal closure by distracting the lateral physis.
. It induces a compensatory rotational osteotomy over time.

Correct Answer & Explanation

. It corrects the deformity by harnessing the Hueter-Volkmann principle.

Explanation

Guided growth utilizes a tension band plate to compress the lateral physis, relying on the Hueter-Volkmann principle where increased compressive forces inhibit physeal growth. This allows the relatively normal medial physis to 'catch up' and correct the varus deformity.

Question 6358

Topic: 4. Pediatrics

A 13-year-old girl undergoes tension band plating for idiopathic genu valgum. Following successful correction to a neutral mechanical axis, the plates are removed. What is the most common complication observed in the first two years post-removal?

. Physeal arrest resulting in a limb length discrepancy.
. Progressive genu varum.
. Rebound valgus deformity.
. Pathologic fracture through the screw holes.
. Septic arthritis of the knee.

Correct Answer & Explanation

. Rebound valgus deformity.

Explanation

Rebound deformity (recurrence of the original deformity) is the most common complication after hardware removal following guided growth, particularly in younger children with significant remaining growth. For this reason, some surgeons slightly overcorrect the deformity prior to removal.

Question 6359

Topic: 4. Pediatrics

A 7-year-old child successfully undergoes medial hemiepiphysiodesis of the distal femur and proximal tibia using tension-band plates for genu valgum. The plates are removed upon achieving neutral alignment. Which of the following underlying diagnoses is associated with the highest rate of "rebound deformity" requiring repeat intervention?

. Idiopathic genu valgum
. Achondroplasia
. Multiple hereditary exostoses
. X-linked hypophosphatemic rickets
. Post-traumatic physeal arrest

Correct Answer & Explanation

. X-linked hypophosphatemic rickets

Explanation

Patients with metabolic bone diseases, particularly X-linked hypophosphatemic rickets, have a significantly higher rate of rebound angular deformity after hardware removal in guided growth compared to idiopathic cases. Consequently, some surgeons recommend leaving the implants in place or intentionally overcorrecting these patients.

Question 6360

Topic: 4. Pediatrics
A 10-year-old obese male presents with severe left genu varum. Radiographs reveal depression of the medial tibial plateau, a physeal step-off, and an epiphyseal-metaphyseal angle of 25 degrees. This is consistent with Langenskiöld Stage V Blount disease. What is the most appropriate definitive management?
. Medial tension-band plate hemiepiphysiodesis.
. Bracing with a knee-ankle-foot orthosis (KAFO).
. Proximal tibial valgus-producing osteotomy alone.
. Hemi-plateau elevation, physeal bar resection, and a metaphyseal valgus osteotomy.
. Lateral closing wedge high tibial osteotomy.

Correct Answer & Explanation

. Hemi-plateau elevation, physeal bar resection, and a metaphyseal valgus osteotomy.

Explanation

In late-onset or severe infantile Blount disease (Langenskiöld Stage V or VI), a complete bony bridge (physeal bar) has formed across the medial physis. Management requires physeal bar resection, elevation of the depressed medial plateau, and a metaphyseal osteotomy to correct the mechanical axis.

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