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4. Pediatrics MCQs

Practice Set 136 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 2701

Topic: Pediatric Hip

A 9-year-old female presents with bilateral Slipped Capital Femoral Epiphysis (SCFE). She is in the 10th percentile for height and weight.

Which of the following laboratory investigations is most indicated for this patient?

. Hemoglobin A1c
. Free T4 and TSH
. Serum calcium and phosphate
. Growth hormone levels
. Serum parathyroid hormone

Correct Answer & Explanation

. Hemoglobin A1c

Explanation

Patients presenting with SCFE under the age of 10 years or with bilateral disease have a high incidence of underlying endocrine disorders, most commonly hypothyroidism. TSH and Free T4 are the primary screening tests indicated.

Question 2702

Topic: Pediatric Hip

A 14-year-old male is unable to bear weight on his right leg after a minor fall. Radiographs demonstrate a severe, acute unstable SCFE. What is the primary advantage of the modified Dunn procedure via a surgical dislocation approach compared to in-situ pinning for this patient?

. It completely eliminates the risk of avascular necrosis
. It has a significantly shorter operative time
. It allows anatomical reduction while directly visualizing and protecting the retinacular vessels
. It avoids the need for an extensive capsulotomy
. It allows for earlier return to full contact sports

Correct Answer & Explanation

. It completely eliminates the risk of avascular necrosis

Explanation

The modified Dunn procedure involves a surgical hip dislocation to anatomically reduce the slipped epiphysis. Its main advantage is the direct visualization and protection of the posterior retinacular vessels, though it is technically demanding and AVN risk remains.

Question 2703

Topic: Pediatric Hip

An 11-year-old boy undergoes in-situ pinning for a symptomatic left SCFE. Which of the following is the strongest clinical indication for prophylactic pinning of the asymptomatic right hip?

. A modified Southwick angle of 40 degrees on the left
. Patient age over 14 years
. Underlying diagnosis of renal osteodystrophy
. Obese body habitus
. Male sex

Correct Answer & Explanation

. A modified Southwick angle of 40 degrees on the left

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with underlying endocrine or metabolic disorders (such as renal osteodystrophy or hypothyroidism) because their risk of developing a subsequent contralateral slip is exceedingly high.

Question 2704

Topic: Pediatric Hip

A 14-year-old male treated with in-situ pinning for a stable SCFE 6 months ago now presents with severe hip stiffness and worsening pain. Radiographs reveal global joint space narrowing to 2 mm. What is the most likely cause of this complication?

. Undiagnosed hypothyroidism
. Unrecognized hardware penetration into the joint space
. Avascular necrosis of the femoral head
. Secondary femoroacetabular impingement
. Subacute septic arthritis

Correct Answer & Explanation

. Undiagnosed hypothyroidism

Explanation

Chondrolysis presents with severe stiffness and diffuse joint space narrowing (< 3 mm). The most common iatrogenic cause is unrecognized pin penetration into the articular space during SCFE fixation.

Question 2705

Topic: Pediatric Hip

A 12-year-old female presents with hip pain for 3 weeks but is able to ambulate into the clinic with a mild limp.

According to the Loder classification, what is her approximate risk of developing avascular necrosis (AVN) following in-situ pinning?

. Less than 5%
. 10 to 15%
. 25 to 30%
. 45 to 50%
. Greater than 75%

Correct Answer & Explanation

. Less than 5%

Explanation

The Loder classification divides SCFE into stable (patient can bear weight) and unstable (unable to bear weight). A stable SCFE carries a very low risk of AVN, historically less than 5%.

Question 2706

Topic: Pediatric Hip

A 13-year-old male presents with vague knee pain. An AP pelvis radiograph is obtained. Which of the following radiographic signs strongly indicates a subtle SCFE?

. Intersection of the lateral epiphysis by Klein's line
. The entire epiphysis falling lateral to Klein's line
. Klein's line passing superior to the epiphysis without intersecting it
. Symmetric widening of the teardrop distance bilaterally
. An increased lateral center-edge angle of Wiberg

Correct Answer & Explanation

. Intersection of the lateral epiphysis by Klein's line

Explanation

Klein's line is drawn along the superior margin of the femoral neck on an AP radiograph. In a normal hip, it intersects the lateral portion of the epiphysis. Trethowan's sign in SCFE occurs when the line passes completely superior to the epiphysis.

Question 2707

Topic: 4. Pediatrics

A 6-week-old female infant is brought to the clinic for a routine check-up. She was born via cesarean section for a breech presentation. Clinical examination reveals symmetrical thigh creases and negative Barlow and Ortolani maneuvers. What is the most appropriate next step in management?

. Reassurance and follow-up at 6 months
. AP radiograph of the pelvis
. Ultrasound of the hips
. Application of a Pavlik harness
. CT scan of the pelvis

Correct Answer & Explanation

. Reassurance and follow-up at 6 months

Explanation

Infants with a history of breech presentation have a higher risk of DDH and should undergo ultrasound screening at 4 to 6 weeks of age, even with a normal clinical examination.

Question 2708

Topic: 4. Pediatrics

A 4-month-old infant with developmental dysplasia of the hip has been treated in a Pavlik harness for 3 weeks. The parents report that the child has stopped kicking the left leg. On examination, the knee lacks active extension but has normal sensation. What is the most likely cause?

. Unrecognized hip dislocation
. Sciatic nerve palsy
. Obturator nerve palsy
. Femoral nerve palsy
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Unrecognized hip dislocation

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically resulting from hyperflexion of the hips. Management involves removing the harness or adjusting the flexion straps.

Question 2709

Topic: 4. Pediatrics

A 14-year-old boy with a BMI in the 95th percentile presents with 3 weeks of vague left knee pain and a slight limp. He is able to bear weight on the affected limb. Radiographs show a widened and irregular left capital femoral physis with a posterior and inferior slip. What is the most appropriate treatment?

. Spica cast immobilization
. Closed reduction and internal fixation with a single screw
. In situ fixation with a single cannulated screw
. Open reduction and internal fixation via surgical dislocation
. Proximal femoral osteotomy

Correct Answer & Explanation

. Spica cast immobilization

Explanation

This is a stable slipped capital femoral epiphysis (SCFE). The standard of care is in situ fixation with a single cannulated screw placed in the center of the epiphysis.

Question 2710

Topic: Pediatric Hip

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

. Age 14 years in a male
. Body mass index (BMI) > 30
. Renal osteodystrophy
. Mild slip angle on the affected side
. Acute presentation of the affected side

Correct Answer & Explanation

. Age 14 years in a male

Explanation

Prophylactic pinning of the contralateral hip is generally recommended for patients with endocrine or metabolic disorders (like renal osteodystrophy or hypothyroidism), prior radiation therapy, or age < 10 years.

Question 2711

Topic: Pediatric Hip

A 9-year-old boy presents with an acute, unstable slipped capital femoral epiphysis (SCFE) after a minor fall. He is unable to bear weight. Which of the following complications is most highly associated with this specific type of SCFE compared to a stable SCFE?

. Chondrolysis
. Osteomyelitis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (FAI)
. Leg length discrepancy

Correct Answer & Explanation

. Chondrolysis

Explanation

Unstable SCFE (defined as the inability to bear weight) has a significantly higher rate of avascular necrosis (up to 50%) compared to stable SCFE.

Question 2712

Topic: Pediatric Hip

A 12-month-old girl is noted to have a painless limp. Examination reveals a positive Galeazzi sign and asymmetric thigh folds. Radiographs demonstrate a superolaterally displaced right femoral head with an acetabular index of 40 degrees. What is the most appropriate initial management?

. Pavlik harness
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Varus derotational osteotomy of the proximal femur
. Reassurance and follow-up

Correct Answer & Explanation

. Pavlik harness

Explanation

In a child aged 6 to 18 months with DDH, the initial treatment of choice is typically closed reduction and spica casting. A Pavlik harness is generally ineffective after 6 months of age.

Question 2713

Topic: Pediatric Hip

During the surgical treatment of a slipped capital femoral epiphysis (SCFE) with in situ pinning, the surgeon must be careful to avoid joint penetration. Which complication is most directly associated with unrecognized pin penetration into the hip joint?

. Avascular necrosis
. Chondrolysis
. Subtrochanteric fracture
. Femoroacetabular impingement
. Slipped capital femoral epiphysis of the contralateral hip

Correct Answer & Explanation

. Avascular necrosis

Explanation

Unrecognized pin penetration during in situ fixation of SCFE is classically associated with chondrolysis, leading to severe stiffness and joint space narrowing.

Question 2714

Topic: Pediatric Hip
A 3-week-old male infant undergoes ultrasound screening for developmental dysplasia of the hip (DDH). The alpha angle is measured at 40 degrees. According to the Graf classification, what does this alpha angle indicate?
. A normal, mature hip
. Physiologic immaturity
. Subluxation with structural deficiency
. An irreducible dislocation
. A normal variant requiring no treatment

Correct Answer & Explanation

. Subluxation with structural deficiency

Explanation

In the Graf classification, an alpha angle of less than 43 degrees (Type III) indicates a subluxated hip with poor bony roof coverage. This structural deficiency requires immediate treatment.

Question 2715

Topic: Pediatric Hip

A 5-month-old infant is being treated with a Pavlik harness for DDH. The ultrasound at 4 weeks of treatment shows failure of reduction of the hip. What is the most appropriate next step in management?

. Continue Pavlik harness for an additional 4 weeks
. Switch to a rigid abduction orthosis (e.g., Ilfeld splint)
. Perform a closed reduction and spica casting
. Perform an open reduction and pelvic osteotomy
. Discontinue treatment and observe until skeletal maturity

Correct Answer & Explanation

. Continue Pavlik harness for an additional 4 weeks

Explanation

If a Pavlik harness fails to achieve reduction within 3 to 4 weeks, it should be discontinued to prevent "Pavlik harness disease" (abrading the posterior acetabulum). The next standard step is closed reduction and spica casting.

Question 2716

Topic: Pediatric Hip

Which of the following radiographic findings on an AP pelvis is most indicative of developmental dysplasia of the hip (DDH) in an 8-month-old child?

. Acetabular index of 15 degrees
. Femoral head ossific nucleus located in the lower inner quadrant of Perkin and Hilgenreiner lines
. Disruption of Shenton's line
. Alpha angle greater than 60 degrees
. Presence of the teardrop sign

Correct Answer & Explanation

. Acetabular index of 15 degrees

Explanation

In DDH, the femoral head typically migrates superolaterally, causing a break in Shenton's line. A normal hip has the ossific nucleus in the lower inner quadrant formed by Perkin and Hilgenreiner lines.

Question 2717

Topic: Pediatric Hip

A 6-week-old female is undergoing treatment for developmental dysplasia of the hip with a Pavlik harness. During a follow-up visit, the mother notes the child is no longer kicking her leg on the affected side. On examination, active knee extension is absent, but the hip remains well reduced. What is the most appropriate next step in management?

. Continue the harness and reassure the mother
. Adjust the anterior strap to increase hip flexion
. Remove the harness and give the family a brief holiday
. Switch to a rigid hip abduction orthosis
. Perform a closed reduction and spica casting

Correct Answer & Explanation

. Continue the harness and reassure the mother

Explanation

Absent knee extension indicates a femoral nerve palsy, the most common nerve palsy associated with the Pavlik harness. The harness should be removed temporarily to allow the nerve to recover, which usually happens within a few days to weeks.

Question 2718

Topic: 4. Pediatrics

A 5-week-old female infant undergoes hip ultrasound screening due to a breech presentation. The alpha angle is 55 degrees and the beta angle is 60 degrees. Dynamic testing demonstrates a stable hip. What is the most appropriate next step?

. Pavlik harness application
. Rigid hip abduction orthosis
. Repeat ultrasound in 4 to 6 weeks
. Closed reduction and spica casting
. MRI of the hips

Correct Answer & Explanation

. Pavlik harness application

Explanation

An alpha angle between 50 and 59 degrees at this age classifies as Graf Type IIa, indicating physiologic immaturity. Because the hip is stable, the correct management is observation and repeat ultrasound in 4 to 6 weeks to ensure normal development.

Question 2719

Topic: Pediatric Hip

An 8-year-old boy presents with an acute on chronic slipped capital femoral epiphysis. His height and weight are both at the 25th percentile for his age. Which of the following laboratory studies is most strongly indicated?

. Fasting blood glucose
. Thyroid-stimulating hormone (TSH)
. Rheumatoid factor
. HLA-B27
. Serum calcium

Correct Answer & Explanation

. Fasting blood glucose

Explanation

SCFE in atypical patients (age younger than 10, or weight below the 50th percentile) raises strong suspicion for an underlying endocrine or metabolic disorder. Hypothyroidism is a common cause, making TSH an essential screening test.

Question 2720

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department with severe right hip pain after a minor fall. He is unable to bear weight on the right leg, even with crutches. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Which of the following represents the highest risk of complication for this patient?

. Chondrolysis
. Femoroacetabular impingement
. Osteonecrosis (Avascular necrosis)
. Leg length discrepancy
. Contralateral SCFE

Correct Answer & Explanation

. Chondrolysis

Explanation

Inability to bear weight defines an unstable SCFE according to the Loder classification. Unstable SCFE carries a significantly higher risk of osteonecrosis (up to 47%) compared to stable SCFE.

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