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4. Pediatrics MCQs

Practice Set 16 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 301

Topic: Pediatric Hip
A 6-year-old boy with Legg-Calvé-Perthes disease is evaluated. According to the Herring lateral pillar classification, a Type C rating signifies which of the following?
. No involvement of the lateral pillar
. Less than 50% loss of lateral pillar height
. Greater than 50% loss of lateral pillar height
. Complete extrusion of the femoral head laterally
. Presence of a metaphyseal cyst (Gage sign)

Correct Answer & Explanation

. Greater than 50% loss of lateral pillar height

Explanation

The Herring classification assesses the height of the lateral pillar of the femoral head. Type C indicates greater than 50% collapse of the lateral pillar height, which correlates with a poor clinical and radiographic prognosis.

Question 302

Topic: Pediatric Lower Extremity

A 13-year-old male athlete presents with localized pain, swelling, and tenderness over the tibial tubercle, which worsens with jumping. He is diagnosed with Osgood-Schlatter disease. What is the primary underlying pathology?

. Degeneration of the patellar tendon
. Traction apophysitis of the tibial tubercle
. Avascular necrosis of the inferior pole of the patella
. Osteochondral defect of the tibial plateau
. Bursitis of the superficial infrapatellar bursa

Correct Answer & Explanation

. Traction apophysitis of the tibial tubercle

Explanation

Osgood-Schlatter disease is an overuse injury caused by repetitive microtrauma and traction from the patellar tendon on the unossified tibial tubercle apophysis, leading to a traction apophysitis.

Question 303

Topic: 4. Pediatrics

A 1-year-old child is diagnosed with congenital anterolateral bowing of the tibia. Radiographs demonstrate medullary sclerosis and early cystic changes at the apex of the bow. If left untreated, what is the most likely natural history of this condition?

. Spontaneous remodeling by age 5
. Progression to congenital pseudarthrosis of the tibia
. Malignant transformation to osteosarcoma
. Development of an isolated leg length discrepancy without fracture
. Progression to a severe equinovarus deformity

Correct Answer & Explanation

. Progression to congenital pseudarthrosis of the tibia

Explanation

Congenital anterolateral bowing of the tibia is strongly associated with Neurofibromatosis Type 1. The natural history of this specific directional bowing, unlike posteromedial bowing, is progression to fracture and recalcitrant congenital pseudarthrosis.

Question 304

Topic: 4. Pediatrics

Which of the following describes the proper sizing technique for selecting titanium elastic nails (TENs) for a pediatric femur fracture?

. Two nails, each 20% of the narrowest diaphyseal diameter
. Two nails, each 40% of the narrowest diaphyseal diameter
. Two nails, each 60% of the narrowest diaphyseal diameter
. One nail that fills 80% of the isthmus
. Three nails, each 30% of the narrowest diaphyseal diameter

Correct Answer & Explanation

. Two nails, each 40% of the narrowest diaphyseal diameter

Explanation

For optimal biomechanical stability, two nails of the same diameter should be used, with each nail being approximately 40% of the narrowest diaphyseal diameter, thus filling 80% of the canal.

Question 305

Topic: 4. Pediatrics

A 10-year-old boy sustains a Delbet Type II (transcervical) femoral neck fracture. Following closed reduction and percutaneous pinning, the parents should be counseled that the child is at highest risk for which of the following complications?

. Nonunion
. Avascular necrosis (AVN)
. Chondrolysis
. Premature physeal closure
. Infection

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Avascular necrosis is the most devastating and common complication of pediatric femoral neck fractures. The risk is strongly associated with the Delbet classification, being highest in Type I and Type II fractures.

Question 306

Topic: 4. Pediatrics

During the insertion of a rigid intramedullary nail for an adolescent femur fracture, the surgeon inadvertently uses a starting point at the tip of the greater trochanter instead of lateral to it. What growth disturbance is most likely to occur?

. Coxa vara
. Coxa valga
. Genu valgum
. Femoral retroversion
. Premature closure of the distal femoral physis

Correct Answer & Explanation

. Coxa valga

Explanation

Damage to the greater trochanteric apophysis from a tip starting point can cause premature arrest of the apophysis. Continued growth of the capital femoral epiphysis then leads to a relative coxa valga deformity.

Question 307

Topic: 4. Pediatrics

What is the primary rationale for pre-bending titanium elastic nails (TENs) prior to insertion in a pediatric femur fracture?

. To prevent nail migration through the skin
. To allow the nails to cross each other outside the fracture site
. To establish three-point fixation within the medullary canal
. To facilitate easier removal
. To bypass the distal femoral physis safely

Correct Answer & Explanation

. To establish three-point fixation within the medullary canal

Explanation

Pre-bending the nails ensures they apex at the fracture site, providing tension against the endosteum. This three-point bending biomechanics is essential for rotational and angular stability.

Question 308

Topic: 4. Pediatrics

A 9-year-old boy weighing 40 kg sustains a comminuted, length-unstable subtrochanteric femur fracture after a fall.

Which of the following fixation methods is most appropriate to maintain length and alignment?

. Spica casting
. Titanium elastic nails
. Submuscular bridge plating
. Rigid antegrade piriformis-entry intramedullary nail
. Pavlik harness

Correct Answer & Explanation

. Submuscular bridge plating

Explanation

Submuscular bridge plating is ideal for length-unstable, comminuted, or subtrochanteric pediatric femur fractures. Flexible nails lack rotational and length stability in comminuted patterns, and piriformis entry nails risk AVN.

Question 309

Topic: Pediatric Hip

An obese 13-year-old boy presents with left knee pain and an obligatory external rotation of the left hip during flexion. Which of the following is the most appropriate initial imaging step?

. MRI of the left knee
. AP and frog-leg lateral radiographs of the pelvis
. Ultrasound of the left hip
. CT scan of the left femur
. Bone scan of the lower extremities

Correct Answer & Explanation

. AP and frog-leg lateral radiographs of the pelvis

Explanation

This is the classic presentation of a slipped capital femoral epiphysis (SCFE), which commonly presents with referred knee pain and obligatory external rotation upon hip flexion. AP and frog-leg lateral pelvis radiographs are required for diagnosis.

Question 310

Topic: Pediatric Hip

During in-situ pinning of a slipped capital femoral epiphysis (SCFE), an unrecognized intra-articular pin penetration into the anterosuperior quadrant of the femoral head most commonly leads to:

. Avascular necrosis
. Chondrolysis
. Femoroacetabular impingement
. Coxa vara
. Sciatic nerve injury

Correct Answer & Explanation

. Chondrolysis

Explanation

Unrecognized pin penetration into the hip joint during SCFE fixation destroys the articular cartilage, leading to severe chondrolysis. Careful fluoroscopic evaluation using the approach-withdrawal principle is required to confirm pin position.

Question 311

Topic: Pediatric Hip
In a patient diagnosed with Legg-Calvé-Perthes disease, which of the following factors is most strongly associated with a poor radiographic outcome and a spherical mismatch at skeletal maturity?
. Age at presentation of 5 years
. Catterall group I classification
. Intact lateral pillar (Herring A)
. Age at presentation over 8 years
. Presence of an ossific nucleus

Correct Answer & Explanation

. Age at presentation over 8 years

Explanation

Age at clinical onset is the most significant prognostic factor in Legg-Calvé-Perthes disease. Children presenting at age 8 or older have less time for remodeling and generally suffer worse radiographic and clinical outcomes.

Question 312

Topic: 4. Pediatrics

A 9-month-old non-ambulatory infant presents with a spiral fracture of the femoral shaft. The parents state the child 'rolled off the bed.' What is the most appropriate next step in management alongside immobilization?

. Immediate discharge with a Pavlik harness
. Skeletal survey and child protective services consultation
. Flexible intramedullary nailing
. Metabolic bone disease workup and calcium supplementation
. MRI of the femur

Correct Answer & Explanation

. Skeletal survey and child protective services consultation

Explanation

Femur fractures in non-ambulatory infants are highly suspicious for non-accidental trauma (child abuse). A full skeletal survey and involvement of child protective services are mandatory steps in management.

Question 313

Topic: Pediatric Hip

A 4-week-old female undergoes a screening ultrasound for developmental dysplasia of the hip (DDH). The Graf alpha angle is reported as 65 degrees. What does this indicate?

. A normal, mature infant hip
. Mild dysplasia requiring a Pavlik harness
. A subluxated hip requiring closed reduction
. A completely dislocated hip
. A teratologic dislocation

Correct Answer & Explanation

. A normal, mature infant hip

Explanation

In the Graf ultrasound classification for DDH, an alpha angle greater than 60 degrees indicates a normal, mature hip (Type I). No treatment is required.

Question 314

Topic: Pediatric Hip

A newborn is diagnosed with arthrogryposis multiplex congenita and bilateral developmental dysplasia of the hip. Why is a Pavlik harness contraindicated in the management of this patient?

. High risk of severe skin ulceration
. High failure rate and risk of iatrogenic contractures or fractures
. High risk of sudden infant death syndrome
. Inability to properly size the harness
. Spontaneous resolution is expected

Correct Answer & Explanation

. High failure rate and risk of iatrogenic contractures or fractures

Explanation

The Pavlik harness relies on active spontaneous movement to achieve and maintain reduction. In teratologic dislocations (like arthrogryposis), the hips are rigid, leading to extremely high failure rates and risks of iatrogenic fractures or skin necrosis.

Question 315

Topic: 4. Pediatrics

A 10-year-old boy sustains a Salter-Harris type II fracture of the distal femur. What is the most common long-term complication specifically associated with this injury?

. Nonunion
. Avascular necrosis of the femoral condyles
. Leg length discrepancy and angular deformity
. Popliteal artery occlusion
. Peroneal nerve palsy

Correct Answer & Explanation

. Leg length discrepancy and angular deformity

Explanation

The distal femoral physis accounts for 70% of femoral growth and 37% of overall lower extremity growth. Fractures here have a high rate of physeal arrest, leading to significant leg length discrepancies and angular deformities.

Question 316

Topic: Pediatric Hip

In which of the following patients presenting with a unilateral slipped capital femoral epiphysis (SCFE) is prophylactic pinning of the contralateral hip most strongly indicated?

. A 12-year-old boy with a BMI in the 90th percentile
. A 10-year-old girl with renal osteodystrophy
. A 14-year-old boy with a history of minor trauma
. A 13-year-old boy with an acute-on-chronic slip
. An 11-year-old girl with isolated hip pain for 2 weeks

Correct Answer & Explanation

. A 10-year-old girl with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated for patients with underlying metabolic or endocrine disorders (e.g., renal osteodystrophy, hypothyroidism) due to the extremely high risk of bilateral involvement.

Question 317

Topic: Pediatric Hip

A 5-year-old boy presents for examination. He is diagnosed with developmental dysplasia of the hip. Recommended treatment includes:

. Closed reduction and cast application
. Traction, closed reduction, and cast
. Femoral osteotomy and closed reduction
. Open reduction and iliac osteotomy
. Open reduction, femoral osteotomy, and iliac osteotomy

Correct Answer & Explanation

. Open reduction, femoral osteotomy, and iliac osteotomy

Explanation

At age 5, traction or closed reduction is not likely to produce a stable joint. Femoral shortening is indicated to reduce pressure, reducing the likelihood of avascular necrosis or redislocation. The most likely option to produce a stable joint is open reduction with femoral and iliac osteotomy.

Question 318

Topic: 4. Pediatrics

The radiograph (Slide) of a 16-month-old toddler is presented. Which diagnosis is most appropriate:

. Proximal focal femoral deficiency
. C ongenital coxa valga
. Traumatic hip dislocation
. Developmental dysplasia of the hip
. Femoral retroversion

Correct Answer & Explanation

. Developmental dysplasia of the hip

Explanation

This patient has developmental dysplasia of the hip. The femoral head is delayed in ossifying because of lower contact pressure and the femur is anteverted, not retroverted.

Question 319

Topic: 4. Pediatrics

Which of the following is true regarding ability to remodel after a displaced pediatric pelvic fracture:

. The pelvis will remodel if the patient is younger than 11 years old.
. The pelvis will remodel if the patient is younger than 8 years old.
. The pelvis will remodel if triradiate cartilages are open.
. The pelvis will remodel if the patient is premenarchal.
. No significant remodeling is seen at any age.

Correct Answer & Explanation

. No significant remodeling is seen at any age.

Explanation

In pediatric pelvic fractures healing with asymmetry, no significant remodeling is seen at any age.

Question 320

Topic: Pediatric Hip

This radiograph (Slide) shows an 11-month-old girl with a Tonnis 3 developmental dislocation of the hip. Recommended treatment includes:

. Pavlik harness
. C losed reduction and spica cast application
. Open reduction and spica cast application
. Open reduction with femoral shortening derotation osteotomy
. Open reduction with Salter osteotomy

Correct Answer & Explanation

. C losed reduction and spica cast application

Explanation

Closed reduction and spica cast application is the best treatment for this patient with a Tonnis 3 developmental dislocation of the hip. Open reduction and spica cast application introduces additional risks of infection and vascular compromise and should not be performed unless closed reduction and spica cast application fails. This patient is too old to be controlled by a Pavlik harness.

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