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4. Pediatrics MCQs

Practice Set 17 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 321

Topic: 4. Pediatrics
A newborn infant presents with a knee complication. The patient's knee hyperextends to 30° and flexes to 30°. The neurovascular examination is normal, and the patient's hips are stable. No other skeletal complications are found. Radiographs show a line along the axis of the tibia intersecting the ossific nucleus of the distal femur, signaling significant hyperextension. Recommended treatment includes:
. Observation
. Serial casting
. Pavlik harness
. Prone skin traction to gradually flex the leg
. Open reduction of the knee with V-Y plasty

Correct Answer & Explanation

. Observation

Explanation

This patient has a hyperextensible, but not dislocated, knee. In the radiograph, the line along the axis of the tibia would intersect the femur anterior to the ossific nucleus if the patient's knee were dislocated. Hyperextensible knee is an in utero complication and resolves without treatment.

Question 322

Topic: 4. Pediatrics
Which of the following methods of treatment has the lowest success rate in treating patients with congenital pseudarthrosis of the tibia:
. Electromagnetic stimulation
. Vascularized fibula graft
. Ilizarov's method
. Intramedullary (IM) rod fixation and bone graft
. Ilizarov's method over an intramuscular rod

Correct Answer & Explanation

. Electromagnetic stimulation

Explanation

Electromagnetic stimulation has the lowest success rate in treating patients with congenital pseudarthrosis of the tibia. Vascularized fibula graft, Ilizarov's method, IM rod fixation and bone graft, and Ilizarov's method over an intramuscular rod have similar success rates.

Question 323

Topic: 4. Pediatrics
This is a radiograph of a patient with myelomeningocele. At which of the following levels is the lesion located?
. L1
. L2
. L4
. L5
. S1

Correct Answer & Explanation

. L4

Explanation

This patient has active quadriceps (which are innervated through L2-L4) and adductors (which are innervated through L1-L3). Because the patient's knees are slightly hyperextended there is no hamstring function. The patient's right foot has some dorsiflexion. The lesion is rated as L4. However, the patient's right side may be rated as L3.

Question 324

Topic: 4. Pediatrics
An 8-year-old girl with myelomeningocele has sustained warmth and swelling of her leg for 2 weeks. She does not recall any trauma. She has had a temperature of 101° on several occasions. Her radiograph (Slide) is shown below. The most likely diagnosis is:
. Osteomyelitis of the tibia
. Fracture of the distal tibia
. Deep venous thrombosis
. Ewing's tumor
. Osteogenic sarcoma

Correct Answer & Explanation

. Fracture of the distal tibia

Explanation

This patient has a Salter 1 physeal fracture of the distal tibia, which was probably caused by stress that remained unrecognized due to the patient's lack of pain. Patients with spina bifida experience extensive periosteal reaction because they do not get early immobilization.

Question 325

Topic: 4. Pediatrics

This radiograph (Slide) shows a 5-year-old boy with an L4 myelomeningocele. He can ambulate with a walker. Recommended treatment includes:

. Observation
. Abduction bracing
. Bilateral adductor tenotomy
. Bilateral adductor tenotomy and femoral osteotomy
. Bilateral adductor tenotomy, femoral and iliac osteotomy

Correct Answer & Explanation

. Observation

Explanation

This patient has symmetrical high, longstanding dislocations. Because his level is L4, he has no abductor function. The patient has multiple contraindications to surgery, including current symmetry, lack of abduction power, young age, and an inability to walk without a walker. His ability to walk would likely be hindered by surgery.

Question 326

Topic: 4. Pediatrics
The first radiograph (Slide 1) shows the pelvis of a patient with L3 myelomeningocele at 9 years old. The second radiograph (Slide 2) shows the pelvis of the same patient taken 2 years later. Which of the following factors most likely contributed to the change in the patient's pelvis?
. Increased standing activity in therapy
. Excessive sitting
. Adductor tenotomy
. Chiari's malformation
. Tethered cord

Correct Answer & Explanation

. Tethered cord

Explanation

Note that the radiograph in Slide 1 shows normal hip joints, and the radiograph in Slide 2, which was taken 2 years later, shows symmetric dislocation. This patient has a tethered cord. The tethered cord caused increased spasticity, resulting in the spontaneous dislocation of the patient's hips during the 2 years between the time the two radiographs were taken.

Question 327

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip has been managed in a Pavlik harness for 4 weeks with no ultrasound evidence of reduction. What is the next best step in management?

. Continue the harness for 4 more weeks
. Switch to a rigid abduction orthosis
. Perform closed reduction and spica casting
. Proceed to immediate open reduction and pelvic osteotomy
. Perform varus derotational osteotomy

Correct Answer & Explanation

. Perform closed reduction and spica casting

Explanation

If a Pavlik harness fails to achieve reduction within 3 to 4 weeks, it should be discontinued to avoid 'Pavlik harness disease' (posterior wear of the acetabulum). The next appropriate step is closed reduction and spica casting under general anesthesia.

Question 328

Topic: Pediatric Hip

A 12-year-old overweight boy presents with sudden inability to bear weight on his right leg after a minor fall. Radiographs show a slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the most significant risk associated with this specific presentation?

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

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The inability to bear weight even with crutches defines an unstable SCFE according to the Loder classification. Unstable slips carry a significantly higher risk of avascular necrosis (up to 47%) compared to stable slips.

Question 329

Topic: Pediatric Hip
In a patient with Legg-Calvé-Perthes disease, the Herring lateral pillar classification is used for prognosis. Which of the following describes a Herring Group B classification?
. No involvement of the lateral pillar
. Greater than 50% of the lateral pillar height is maintained
. Less than 50% of the lateral pillar height is maintained
. Total collapse of the epiphysis
. Extrusion of the lateral pillar beyond the acetabulum

Correct Answer & Explanation

. Greater than 50% of the lateral pillar height is maintained

Explanation

In the Herring classification, Group B indicates that the lateral pillar maintains >50% of its normal height. Group C indicates <50% height maintained, which corresponds to a worse prognosis and a higher risk of aspherical head development.

Question 330

Topic: Pediatric Lower Extremity

During the correction of idiopathic clubfoot using the Ponseti method, the deformities are addressed in a specific sequence. Which deformity is corrected last?

. Cavus
. Adductus
. Varus
. Equinus
. Internal rotation

Correct Answer & Explanation

. Equinus

Explanation

The Ponseti method corrects clubfoot deformities in the CAVE sequence: Cavus, Adductus, Varus, and finally Equinus. Correction of equinus usually requires a percutaneous Achilles tenotomy as the final step.

Question 331

Topic: Pediatric Hip

A 6-week-old female infant undergoes a screening ultrasound for developmental dysplasia of the hip (DDH). What is the minimum normal alpha angle according to the Graf classification?

. 40 degrees
. 50 degrees
. 60 degrees
. 70 degrees
. 80 degrees

Correct Answer & Explanation

. 60 degrees

Explanation

In the Graf classification for developmental dysplasia of the hip, an alpha angle of 60 degrees or greater indicates a mature, normal hip (Type I). The alpha angle measures the bony acetabular roof depth.

Question 332

Topic: 4. Pediatrics

A 4-year-old child with developmental coxa vara is being evaluated for surgical intervention. Which of the following radiographic parameters is generally accepted as an indication for a valgus producing proximal femoral osteotomy?

. Neck-shaft angle of 110 degrees
. Hilgenreiner-epiphyseal angle (HEA) greater than 60 degrees
. Presence of an inverted Y fragment
. Articulotrochanteric distance less than 10 mm
. Center-edge angle of Wiberg less than 20 degrees

Correct Answer & Explanation

. Hilgenreiner-epiphyseal angle (HEA) greater than 60 degrees

Explanation

A Hilgenreiner-epiphyseal angle (HEA) greater than 60 degrees is a classic indication for surgical correction (valgus osteotomy) in developmental coxa vara. An HEA less than 45 degrees usually resolves spontaneously or does not progress.

Question 333

Topic: 4. Pediatrics

A 7-year-old girl is diagnosed with Klippel-Feil syndrome. Because of the known systemic associations with this condition, which of the following screening tests should be routinely ordered?

. Echocardiogram
. Renal ultrasound
. Cranial MRI
. Pulmonary function tests
. Thyroid profile

Correct Answer & Explanation

. Renal ultrasound

Explanation

Klippel-Feil syndrome is defined by congenital fusion of two or more cervical vertebrae. Approximately 30% of these patients have associated genitourinary anomalies, making a screening renal ultrasound an essential step.

Question 334

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the infant is noted to lack active knee extension on the treated side. Which of the following is the most likely cause?

. Avascular necrosis of the femoral head
. Femoral nerve palsy due to excessive hip flexion
. Obturator nerve palsy due to excessive hip abduction
. Inferior hip dislocation
. Sciatic nerve compression

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

Explanation

Hyperflexion of the hip in a Pavlik harness (typically >120 degrees) can compress the femoral nerve against the pubis, leading to femoral nerve palsy and loss of active knee extension. The harness must be adjusted to reduce flexion.

Question 335

Topic: Pediatric Hip
A 7-year-old boy is diagnosed with Legg-Calvé-Perthes disease (LCPD). Radiographs demonstrate that less than 50% of the lateral pillar height is maintained. According to the Herring classification, which type does this represent and what is the expected outcome?
. Type A, excellent outcome
. Type B, favorable outcome with conservative care
. Type C, poor outcome with early onset osteoarthritis
. Type B/C border, variable outcome
. Type D, requires immediate arthrodesis

Correct Answer & Explanation

. Type C, poor outcome with early onset osteoarthritis

Explanation

Herring Type C is defined by the lateral pillar maintaining less than 50% of its original height. This indicates severe collapse and is associated with a poor prognosis, often leading to early osteoarthritis.

Question 336

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute-on-chronic Slipped Capital Femoral Epiphysis (SCFE) and is unable to bear weight even with crutches (unstable SCFE). What is the most significant complication he is at risk for following in situ pinning?

. Chondrolysis
. Avascular necrosis (AVN)
. Infection
. Femoral shaft fracture
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Unstable SCFE carries a significantly higher risk of avascular necrosis (up to 47%) compared to stable SCFE. Urgent but careful reduction and stabilization are critical to minimize this risk.

Question 337

Topic: 4. Pediatrics
A 3-year-old girl presents with progressive bilateral bowing of the legs. Radiographs reveal a metaphyseal-diaphyseal angle (Drennan angle) of 18 degrees with early medial metaphyseal beaking. What is the most appropriate initial management?
. Observation and reassurance
. High-dose Vitamin D supplementation
. Knee-ankle-foot orthosis (KAFO) bracing
. Proximal tibial valgus osteotomy
. Guided growth (hemiepiphysiodesis)

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO) bracing

Explanation

A Drennan angle >16 degrees strongly suggests infantile Blount's disease. For a child under 3 to 4 years old in early Langenskiöld stages (I-II), KAFO bracing during weight-bearing is the standard initial treatment.

Question 338

Topic: 4. Pediatrics

In a child with spastic quadriplegic Cerebral Palsy (GMFCS Level V), hip surveillance is critical. Which radiographic threshold is generally accepted as an absolute indication for prophylactic soft tissue or bony surgical intervention to prevent dislocation?

. Reimers migration percentage > 30-40%
. Acetabular index > 20 degrees
. Neck-shaft angle < 120 degrees
. Tonnis angle > 10 degrees
. Center-edge angle of Wiberg < 25 degrees

Correct Answer & Explanation

. Reimers migration percentage > 30-40%

Explanation

A Reimers migration index >30% to 40% in a non-ambulatory child with severe CP often warrants surgical intervention (like adductor release or VDRO) due to the high risk of progressive, painful hip dislocation.

Question 339

Topic: 4. Pediatrics
A 5-year-old child with multiple fractures, blue sclerae, and dentinogenesis imperfecta is diagnosed with osteogenesis imperfecta. This condition is primarily caused by a mutation affecting the synthesis of which type of collagen?
. Type I collagen
. Type II collagen
. Type III collagen
. Type IV collagen
. Type X collagen

Correct Answer & Explanation

. Type I collagen

Explanation

Osteogenesis imperfecta is predominantly caused by mutations in the COL1A1 or COL1A2 genes, which lead to quantitative or qualitative defects in Type I collagen, the major structural protein in bone.

Question 340

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury. Radiographs show a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. What ligament is responsible for avulsing this fragment?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

This describes a juvenile Tillaux fracture. It occurs due to avulsion by the anterior inferior tibiofibular ligament (AITFL) as the distal tibial physis closes in an asymmetrical pattern (central, then medial, then lateral).

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