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4. Pediatrics MCQs

Practice Set 311 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 6201

Topic: 4. Pediatrics

A child diagnosed with Sprengel's deformity is being evaluated. The surgeon should be vigilant in screening for which of the following frequently associated conditions?

. Osteogenesis imperfecta
. Klippel-Feil syndrome
. Marfan syndrome
. Neurofibromatosis type 1
. Achondroplasia

Correct Answer & Explanation

. Klippel-Feil syndrome

Explanation

Sprengel's deformity is highly associated with Klippel-Feil syndrome, congenital scoliosis, and fused cervical ribs. Up to one-third of patients with Klippel-Feil syndrome have an associated Sprengel's deformity.

Question 6202

Topic: Pediatric Hip

In a Slipped Capital Femoral Epiphysis (SCFE), the epiphysis remains in the acetabulum while the femoral neck displaces. In which direction does the femoral neck typically displace relative to the epiphysis?

. Anteriorly and superiorly
. Posterly and inferiorly
. Anteriorly and inferiorly
. Posterly and superiorly
. Medially and inferiorly

Correct Answer & Explanation

. Anteriorly and superiorly

Explanation

In SCFE, the femoral neck displaces anteriorly and superiorly relative to the epiphysis. This altered anatomy creates the characteristic varus and retroverted morphology of the proximal femur.

Question 6203

Topic: Pediatric Hip

A 13-year-old boy with a BMI in the 99th percentile undergoes pinning for a left-sided SCFE. The right hip is asymptomatic and has normal radiographs. When discussing prophylactic pinning of the right hip, the parents ask about the risk of a contralateral slip if observed. What is the approximate risk of developing a contralateral SCFE in this patient?

. 5-10%
. 15-20%
. 30-40%
. 60-70%
. Greater than 90%

Correct Answer & Explanation

. 30-40%

Explanation

The general risk of a contralateral slip is roughly 30-40%, though it may be higher in specific populations like those with severe obesity or younger age at onset. Prophylactic pinning is strongly considered in highly obese or unreliable patients.

Question 6204

Topic: 4. Pediatrics

What is the primary histological zone of the physis where the mechanical failure occurs in a slipped capital femoral epiphysis?

. Zone of resting cartilage
. Zone of proliferation
. Zone of hypertrophy
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Zone of hypertrophy

Explanation

In SCFE, the mechanical failure through the physis typically occurs in the zone of hypertrophy. This is largely due to weakening from increased shear stress, often exacerbated by endocrine imbalances or obesity.

Question 6205

Topic: Pediatric Hip

A 25-year-old male presents with groin pain exacerbated by hip flexion and internal rotation. He has a history of a mild slipped capital femoral epiphysis treated with in situ pinning at age 13. What is the most likely mechanism of his current pain?

. Pincer impingement from acetabular retroversion
. Cam impingement from the prominent anterior-superior femoral metaphysis
. Subtrochanteric hardware failure
. Late-onset avascular necrosis
. Chondrolysis

Correct Answer & Explanation

. Cam impingement from the prominent anterior-superior femoral metaphysis

Explanation

Healing of a SCFE in situ leaves a residual anterior-superior metaphyseal prominence. This acts as a classic cam lesion, causing anterior femoroacetabular impingement against the acetabulum during hip flexion and internal rotation.

Question 6206

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department with severe left groin pain after a minor fall. He is completely unable to bear weight on the left leg, even with the assistance of crutches. Radiographs confirm a severe left slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is the most significant prognostic implication of this patient's presentation?

. A 100% risk of bilateral involvement within 1 year
. A high risk (up to 50%) of developing avascular necrosis (AVN)
. A guaranteed requirement for a subtrochanteric osteotomy
. A high risk of developing chondrolysis directly related to the slip severity
. A negligible risk of premature osteoarthritis

Correct Answer & Explanation

. A high risk (up to 50%) of developing avascular necrosis (AVN)

Explanation

The Loder classification defines an unstable SCFE as the inability to bear weight, with or without crutches. Unstable slips have a significantly higher rate of AVN (up to 50%), whereas stable slips have a nearly 0% AVN rate.

Question 6207

Topic: 4. Pediatrics

Sprengel's deformity is an arrest in the normal embryonic descent of the scapula. Which of the following conditions is most commonly associated with this anomaly?

. Neurofibromatosis type 1
. Achondroplasia
. Klippel-Feil syndrome
. Osteogenesis imperfecta
. Marfan syndrome

Correct Answer & Explanation

. Klippel-Feil syndrome

Explanation

Klippel-Feil syndrome (congenital cervical fusion) is heavily associated with Sprengel's deformity, occurring in up to one-third of cases. Other common associations include congenital scoliosis and absent/fused ribs.

Question 6208

Topic: Pediatric Hip

An 8-year-old boy, whose height and weight are both below the 5th percentile, is diagnosed with bilateral slipped capital femoral epiphysis (SCFE). Given his atypical age and presentation, what is the most likely underlying etiology?

. Hypothyroidism
. Hyperparathyroidism
. Growth hormone excess
. Panhypopituitarism
. Renal osteodystrophy

Correct Answer & Explanation

. Hypothyroidism

Explanation

SCFE occurring in children less than 10 years old, over 16 years old, or with a low body weight is strongly associated with endocrine disorders. Hypothyroidism is the most common endocrine cause of an atypical SCFE.

Question 6209

Topic: Pediatric Hip

A 12-year-old boy undergoes in-situ pinning for a unilateral left slipped capital femoral epiphysis (SCFE). Which of the following is an established indication for prophylactic pinning of his asymptomatic right hip?

. A modified Oxford bone age score of 22
. Male sex
. Body mass index (BMI) > 35
. Underlying renal osteodystrophy
. A slip angle > 50 degrees on the affected side

Correct Answer & Explanation

. Underlying renal osteodystrophy

Explanation

Prophylactic prophylactic pinning of the contralateral hip is universally recommended for patients with endocrine or systemic disorders (e.g., renal osteodystrophy, hypothyroidism) or previous pelvic radiation, due to a near 100% risk of contralateral slip.

Question 6210

Topic: Pediatric Hip

Chondrolysis is a devastating complication following the treatment of slipped capital femoral epiphysis (SCFE). What is the most consistently proven modifiable risk factor for the development of chondrolysis in this setting?

. Unrecognized intra-articular penetration of surgical hardware
. The use of a double-screw construct instead of a single screw
. The initial severity of the slip angle
. Inability to bear weight prior to surgery
. Delayed diagnosis of more than 6 months

Correct Answer & Explanation

. Unrecognized intra-articular penetration of surgical hardware

Explanation

While severe slips and spica casting historically increased the risk, unrecognized intra-articular hardware penetration remains the strongest direct, modifiable iatrogenic cause of chondrolysis in SCFE treatment.

Question 6211

Topic: Pediatric Hip

On an anteroposterior (AP) pelvis radiograph of an adolescent, the "blanch sign of Steel" is noted. This finding is highly suggestive of a Slipped Capital Femoral Epiphysis (SCFE) and represents which of the following anatomic overlapping structures?

. The posterior lip of the acetabulum overlapping the anteriorly displaced epiphysis
. The medially displaced femoral metaphysis overlapping the posterior lip of the acetabulum
. The femoral neck overlapping the inferior pubic ramus
. The fovea capitis overlapping the triradiate cartilage
. The anterior column of the acetabulum overlapping the slipped epiphysis

Correct Answer & Explanation

. The medially displaced femoral metaphysis overlapping the posterior lip of the acetabulum

Explanation

The blanch sign of Steel is seen on the AP radiograph in SCFE. It appears as a crescent-shaped area of increased density (blanching) created by the superimposition of the medially and anteriorly displaced femoral metaphysis over the posterior lip of the acetabulum.

Question 6212

Topic: Pediatric Hip

A 12-year-old boy presents with an inability to bear weight on his left leg. Radiographs confirm a slipped capital femoral epiphysis (SCFE). According to the Loder classification, what is his primary complication risk compared to a patient who is able to bear weight?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (FAI)
. Early-onset osteoarthritis
. Septic arthritis

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The Loder classification differentiates SCFE into stable (able to bear weight) and unstable (unable to bear weight). Unstable SCFE carries a significantly higher risk of AVN, occurring in up to 47% of cases, compared to less than 10% in stable SCFE.

Question 6213

Topic: Pediatric Hip

In the treatment of a stable Slipped Capital Femoral Epiphysis (SCFE) with in situ percutaneous pinning, which of the following is the most significant risk factor for the development of chondrolysis?

. Unrecognized intra-articular hardware penetration
. Acute unstable slip presentation
. Patient obesity (BMI > 95th percentile)
. Concomitant untreated hypothyroidism
. The use of two screws instead of a single screw

Correct Answer & Explanation

. Unrecognized intra-articular hardware penetration

Explanation

Chondrolysis in SCFE is most strongly associated with unrecognized intra-articular pin penetration during fixation. Using fluoroscopy with the 'approach-withdraw' technique helps confirm the hardware is extra-articular.

Question 6214

Topic: Pediatric Hip

An 8-year-old child presents with a unilateral SCFE. Given his young age, an underlying endocrinopathy is suspected. Which of the following is the most common endocrine abnormality associated with the development of SCFE?

. Hyperparathyroidism
. Hypothyroidism
. Growth hormone deficiency
. Panhypopituitarism
. Pseudohypoparathyroidism

Correct Answer & Explanation

. Hypothyroidism

Explanation

Hypothyroidism is the most common endocrinopathy associated with SCFE. Routine screening with TSH and Free T4 is recommended for patients presenting outside the typical age range (girls <11, boys <13) or with bilateral disease.

Question 6215

Topic: Pediatric Hip

Which of the following radiographic lines is used to evaluate a suspected Slipped Capital Femoral Epiphysis (SCFE) on an anteroposterior (AP) pelvis radiograph, where an abnormal finding indicates posterior-inferior displacement of the epiphysis?

. Hilgenreiner's line
. Perkin's line
. Shenton's line
. Klein's line
. Skinner's line

Correct Answer & Explanation

. Klein's line

Explanation

Klein's line is drawn along the superior margin of the femoral neck on an AP radiograph. Normally, it should intersect the lateral portion of the capital femoral epiphysis; failure to do so (Trethowan's sign) indicates a SCFE.

Question 6216

Topic: Pediatric Hip

A 12-year-old boy presents to the emergency department unable to bear weight on his left leg after a minor twisting injury. Radiographs reveal a slipped capital femoral epiphysis (SCFE). Which of the following factors is the strongest predictor for the development of avascular necrosis (AVN) in this patient?

. Degree of epiphyseal slip angle
. Duration of prodromal symptoms
. Inability to bear weight (Loder classification)
. Patient's body mass index (BMI)
. Presence of a concomitant endocrine disorder

Correct Answer & Explanation

. Inability to bear weight (Loder classification)

Explanation

The Loder classification divides SCFE into stable (able to bear weight) and unstable (unable to bear weight) slips. Unstable slips have a significantly higher rate of avascular necrosis (up to 47%) compared to stable slips (nearly 0%). Therefore, weight-bearing status is the strongest predictor of AVN.

Question 6217

Topic: 4. Pediatrics

In a patient presenting with a slipped capital femoral epiphysis (SCFE), the mechanical failure and displacement of the epiphysis relative to the metaphysis occurs predominantly through which histologic zone of the physis?

. Reserve zone
. Proliferative zone
. Hypertrophic zone
. Primary spongiosa
. Secondary spongiosa

Correct Answer & Explanation

. Hypertrophic zone

Explanation

In SCFE, the slippage occurs through the hypertrophic zone of the physis. This zone is mechanically the weakest part of the growth plate due to an increased ratio of matrix to cells and lack of stabilizing collagen fibrils.

Question 6218

Topic: Pediatric Hip

A 14-year-old boy undergoes in-situ single-screw fixation for a stable, moderate SCFE. Six months postoperatively, he presents with worsening global hip pain and severely limited range of motion, particularly in rotation and abduction. Radiographs show joint space narrowing and subchondral irregularities without focal collapse or hardware penetration. What is the most likely diagnosis?

. Unrecognized femoral neck fracture
. Chondrolysis
. Avascular necrosis
. Septic arthritis
. Screw back-out

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a severe complication of SCFE characterized by acute narrowing of the joint space and global loss of hip motion. It is associated with severe slips, prolonged immobilization, and unrecognized hardware penetration into the joint.

Question 6219

Topic: Pediatric Hip

A 9-year-old boy with a history of panhypopituitarism currently on exogenous growth hormone therapy presents with bilateral anterior knee pain. Examination shows an obligate external rotation of the hip upon passive flexion. Which of the following is the most appropriate next step in management?

. Discontinue growth hormone therapy and obtain AP and frog-leg lateral pelvic radiographs
. Continue growth hormone therapy and obtain bilateral knee MRIs to rule out osteochondritis dissecans
. Perform bilateral prophylactic hip pinning immediately without further imaging
. Prescribe physical therapy for presumed iliotibial band syndrome
. Administer bisphosphonates for atypical osteopenia

Correct Answer & Explanation

. Discontinue growth hormone therapy and obtain AP and frog-leg lateral pelvic radiographs

Explanation

This patient's presentation of knee pain and obligate external rotation with hip flexion is highly suspicious for SCFE. Growth hormone therapy is a known risk factor for SCFE; thus, the hormone must be discontinued until the diagnosis is ruled out or treated, and proper pelvic imaging must be obtained.

Question 6220

Topic: 4. Pediatrics
A 13-year-old male skateboarder sustains an external rotation injury to his ankle. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral aspect of the distal tibia. Which of the following ligamentous structures is directly responsible for the avulsion force generating this specific fracture pattern?
. Posterior inferior tibiofibular ligament (PITFL)
. Anterior inferior tibiofibular ligament (AITFL)
. Anterior talofibular ligament (ATFL)
. Calcaneofibular ligament (CFL)
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

A Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs during late adolescence as the distal tibial physis closes from medial to lateral, allowing the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral fragment during external rotation.

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