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4. Pediatrics MCQs

Practice Set 107 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 2121

Topic: Pediatric Hip

Which of the following is considered the strongest indication for prophylactic in situ pinning of the contralateral hip in a patient presenting with a unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. Age greater than 14 years in males
. Obesity with a BMI greater than the 95th percentile
. Presence of an underlying endocrine disorder
. Acute-on-chronic slip presentation
. Severe initial slip angle greater than 50 degrees

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with an underlying endocrine disorder (e.g., hypothyroidism, renal osteodystrophy, or growth hormone therapy) due to a near 100% risk of developing bilateral SCFE. Routine prophylactic pinning in idiopathic cases remains controversial but is less indicated than in endocrine-related SCFE.

Question 2122

Topic: 4. Pediatrics
A patient diagnosed with Osteogenesis Imperfecta Type I, the most common and mildest form of the disease, has a genetic mutation that predominantly results in which of the following?
. Decreased quantitative production of structurally normal Type I collagen
. Production of severely structurally abnormal Type I collagen
. A defect in osteoclast carbonic anhydrase II
. An activating mutation in the FGFR3 receptor
. A defect in the RUNX2 transcription factor

Correct Answer & Explanation

. Decreased quantitative production of structurally normal Type I collagen

Explanation

Osteogenesis Imperfecta (OI) Type I is typically caused by a null allele mutation resulting in haploinsufficiency—a decreased amount of structurally normal Type I collagen. In contrast, the more severe forms (OI Types II, III, and IV) typically involve structural (qualitative) mutations, such as glycine substitutions in the collagen chains, which disrupt triple helix formation.

Question 2123

Topic: Pediatric Hip

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

. A 13-year-old male with a body mass index (BMI) in the 85th percentile
. A 14-year-old female with an acute-on-chronic slip
. A 10-year-old male with hypothyroidism
. A 15-year-old male with a severe slip (Southwick angle >60 degrees)
. A 12-year-old female with an isolated slip and closed triradiate cartilage

Correct Answer & Explanation

. A 10-year-old male with hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism) due to the high risk of bilateral involvement. It is also considered in patients presenting at a very young age (males <12, females <10) or those undergoing prior radiation therapy.

Question 2124

Topic: Pediatric Lower Extremity

When applying the Ponseti method for the correction of idiopathic congenital talipes equinovarus (clubfoot), which of the following represents the correct sequence of deformity correction?

. Equinus, Varus, Adductus, Cavus
. Cavus, Adductus, Varus, Equinus
. Adductus, Varus, Cavus, Equinus
. Varus, Cavus, Adductus, Equinus
. Cavus, Equinus, Adductus, Varus

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method corrects the deformities of clubfoot in a specific sequence, remembered by the acronym CAVE: Cavus (corrected by elevating the first ray to supinate the forefoot), Adductus, Varus, and finally Equinus. Equinus is corrected last, often requiring a percutaneous Achilles tenotomy once the foot is abducted to about 60 degrees.

Question 2125

Topic: Pediatric Hip

In evaluating an AP pelvis radiograph of a 6-month-old female for Developmental Dysplasia of the Hip (DDH), you draw Hilgenreiner's line and Perkin's line. In a normal, properly developing hip, the ossific nucleus of the femoral head should be located in which quadrant formed by these intersecting lines?

. Superomedial
. Superolateral
. Inferomedial
. Inferolateral
. Directly on the intersection

Correct Answer & Explanation

. Inferomedial

Explanation

On an AP pelvis radiograph, Hilgenreiner's line is drawn horizontally through the triradiate cartilages, and Perkin's line is drawn perpendicular to it at the lateral margin of the ossified acetabulum. In a normal hip, the femoral head ossific nucleus (or the medial beak of the metaphysis if unossified) should lie in the inferomedial quadrant. A subluxated or dislocated hip typically lies in the superolateral quadrant.

Question 2126

Topic: Pediatric Hip

An infant being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness is noted by the parents to have decreased spontaneous movement of the right leg. On examination, the infant has an absent active knee extension but intact sensation over the leg. Which of the following nerve palsies is the most likely cause?

. Obturator nerve palsy
. Sciatic nerve palsy
. Femoral nerve palsy
. Superior gluteal nerve palsy
. Genitofemoral nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically resulting from hyperflexion of the hips, which compresses the femoral nerve against the inguinal ligament. It manifests as decreased active quadriceps function (absent knee extension). The treatment is modifying the harness to decrease flexion or temporarily discontinuing it.

Question 2127

Topic: Pediatric Hip

A 10-year-old boy presents with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following patient profiles represents the strongest absolute indication for prophylactic percutaneous pinning of the contralateral, asymptomatic hip?

. A 12-year-old boy with a BMI in the 99th percentile
. A 10-year-old boy with Down syndrome
. A 14-year-old boy with a family history of SCFE
. An 11-year-old boy with previously diagnosed primary hypothyroidism
. A 9-year-old girl with early-onset menarche

Correct Answer & Explanation

. An 11-year-old boy with previously diagnosed primary hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is universally recommended in patients with underlying endocrinopathies (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency) or prior pelvic radiation therapy, as their risk of bilateral involvement approaches 100%. While obesity and young age are risk factors, endocrine disorders are the strongest indication.

Question 2128

Topic: 4. Pediatrics

A 12-year-old obese male presents with a left-sided stable slipped capital femoral epiphysis (SCFE). Prophylactic in situ pinning of the asymptomatic right hip is most strongly indicated if the patient has a history of which of the following underlying conditions?

. Down syndrome
. Hypothyroidism
. Type 1 diabetes mellitus
. Marfan syndrome
. Achondroplasia

Correct Answer & Explanation

. Hypothyroidism

Explanation

Prophylactic pinning of the contralateral, unaffected hip in SCFE is controversial for idiopathic cases but is strongly indicated in patients with underlying endocrine or metabolic disorders (such as hypothyroidism, renal osteodystrophy, or panhypopituitarism) due to a very high risk (up to 100% in some series) of bilateral involvement.

Question 2129

Topic: 4. Pediatrics
A 4-year-old girl is diagnosed with Langenskiöld stage III infantile Blount's disease. Her metaphyseal-diaphyseal angle (Drennan's angle) is 22 degrees, and clinical bowing is progressive. What is the most appropriate management?
. Observation and annual radiographs
. Knee-ankle-foot orthosis (KAFO) bracing
. Proximal tibial corrective osteotomy
. Medial proximal tibial epiphysiodesis
. Lateral proximal tibial hemiepiphysiodesis

Correct Answer & Explanation

. Proximal tibial corrective osteotomy

Explanation

For infantile Blount's disease presenting at age 4 or older with Langenskiöld stage III or higher, bracing is generally ineffective and observation will lead to progressive deformity and physeal damage. Proximal tibial corrective osteotomy is the treatment of choice to restore mechanical alignment and relieve pathologic compression on the medial physis.

Question 2130

Topic: Pediatric Hip

The Salter innominate osteotomy is a surgical procedure used for the treatment of developmental dysplasia of the hip (DDH) to redirect the acetabulum and improve anterior and lateral coverage. Where is the functional hinge point of rotation for this specific osteotomy?

. Sacroiliac joint
. Symphysis pubis
. Triradiate cartilage
. Ischial spine
. Acetabular teardrop

Correct Answer & Explanation

. Symphysis pubis

Explanation

The Salter osteotomy is a complete, single-cut trans-iliac osteotomy extending from the sciatic notch to the anterior inferior iliac spine (AIIS). The distal segment (acetabulum) is rotated anteriorly, laterally, and inferiorly, hinging on the symphysis pubis.

Question 2131

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother notes that the infant is no longer actively extending the knee on the treated side. What is the most likely cause of this complication?

. Excessive hip flexion causing femoral nerve palsy
. Excessive hip abduction causing obturator nerve palsy
. Excessive hip adduction causing sciatic nerve palsy
. Excessive hip flexion causing sciatic nerve palsy
. Excessive hip abduction causing avascular necrosis

Correct Answer & Explanation

. Excessive hip flexion causing femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, most commonly caused by excessive hip flexion, which stretches or compresses the femoral nerve. It presents as an inability to actively extend the knee. The treatment is to temporarily loosen the anterior straps to decrease hip flexion. Excessive hip abduction, on the other hand, puts the hip at increased risk for avascular necrosis (AVN) of the femoral head.

Question 2132

Topic: Pediatric Upper Extremity & Spine
A 6-year-old child arrives at the trauma bay with a severely displaced Gartland type III supracondylar humerus fracture. On initial assessment, the hand is pulseless and pale. Following prompt closed reduction and percutaneous pinning in the operating room, the radial pulse remains unpalpable, but the hand becomes warm, pink, and has a capillary refill of 2 seconds. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. CT angiography of the upper extremity
. Removal of pins and open reduction
. Observation and hospital admission for serial neurovascular checks
. Administration of intra-arterial vasodilators

Correct Answer & Explanation

. Observation and hospital admission for serial neurovascular checks

Explanation

In the setting of a supracondylar humerus fracture, if the hand is 'pulseless but pink' (perfused via collateral circulation) following an adequate reduction and stabilization, the standard of care is close observation and hospital admission. Immediate vascular exploration is indicated if the hand remains 'pulseless and pale' (ischemic) despite reduction.

Question 2133

Topic: Pediatric Hip

According to the Loder classification system, which of the following is the defining clinical characteristic of an 'unstable' slipped capital femoral epiphysis (SCFE)?

. Slip angle greater than 50 degrees on the lateral radiograph
. Presence of a significant hip joint effusion on ultrasound
. Inability of the patient to ambulate, even with the use of crutches
. Duration of prodromal hip or knee symptoms less than 3 weeks
. Radiographic evidence of severe physeal widening and metaphyseal blanching

Correct Answer & Explanation

. Inability of the patient to ambulate, even with the use of crutches

Explanation

The Loder classification divides SCFE into stable and unstable based entirely on clinical presentation. An 'unstable' SCFE is defined by the patient's inability to ambulate, either with or without crutches. This distinction is highly prognostic; unstable SCFE carries a much higher risk of avascular necrosis (AVN) of the femoral head (up to nearly 50%) compared to stable SCFE (near 0%).

Question 2134

Topic: Pediatric Hip

A 12-year-old male presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the left hip. Radiographs of the right hip are completely normal. Which of the following conditions represents an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic right hip?

. Obesity with BMI > 95th percentile
. Hypothyroidism
. Male gender
. African American ethnicity
. Age greater than 14 years

Correct Answer & Explanation

. Hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is universally recommended for patients with endocrine disorders (such as hypothyroidism, growth hormone deficiency, or panhypopituitarism) and patients undergoing radiation therapy, due to the extremely high risk of bilateral involvement in these systemic conditions. While obesity and young age are risk factors for bilaterality, they remain relative indications depending on the surgeon's and family's shared decision-making, whereas endocrinopathies are considered strong/absolute indications.

Question 2135

Topic: Pediatric Hip

During a reconstructive pelvic osteotomy for developmental dysplasia of the hip (DDH) in a 6-year-old child, the surgeon performs an incomplete cut starting anteriorly just superior to the AIIS and extending posteriorly down to the ilioischial limb of the flexible triradiate cartilage. The osteotomy is then hinged open to decrease acetabular volume and improve anterior and lateral coverage. Which specific osteotomy was performed?

. Salter osteotomy
. Pemberton osteotomy
. Chiari osteotomy
. Steel triple osteotomy
. Dega osteotomy

Correct Answer & Explanation

. Pemberton osteotomy

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the flexible triradiate cartilage (specifically the ilioischial limb). It alters the morphology of the acetabulum, decreasing its volume while improving anterolateral coverage. The Salter is a complete innominate osteotomy that hinges at the pubic symphysis, redirecting the entire acetabulum without changing its volume. The Dega also hinges on the triradiate cartilage but typically relies on the central/posterior portion, commonly used for posterior coverage in neuromuscular dysplasia.

Question 2136

Topic: Pediatric Hip

In which of the following scenarios is prophylactic in situ pinning of the contralateral hip most strongly indicated in a patient presenting with an acute slipped capital femoral epiphysis (SCFE)?

. A 14-year-old male with a BMI of 25
. A 10-year-old female with primary hypothyroidism
. A 13-year-old male with a stable SCFE and a positive Klein's line on the contralateral side
. A 15-year-old male with a history of minor hip trauma
. A 12-year-old female with an acute-on-chronic SCFE pattern

Correct Answer & Explanation

. A 10-year-old female with primary hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is strongly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone supplementation) due to the high risk (up to 100% in some series) of developing bilateral SCFE. It is also considered for patients of very young age or those unable to follow up.

Question 2137

Topic: Pediatric Lower Extremity

During the Ponseti method for correcting idiopathic clubfoot, what is the final deformity to be corrected?

. Cavus
. Adductus
. Varus
. Equinus
. Internal rotation

Correct Answer & Explanation

. Cavus

Explanation

The order of correction in the Ponseti method is CAVE: Cavus (corrected first by supinating the forefoot to align with the hindfoot), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy).

Question 2138

Topic: Pediatric Hip

Prophylactic pinning of the contralateral hip in a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. A 12-year-old male with a BMI of 30
. A 10-year-old female with an idiopathic slip
. A 13-year-old female with a history of DDH
. A 14-year-old male with renal osteodystrophy
. A 15-year-old male with a sports-related acute slip

Correct Answer & Explanation

. A 14-year-old male with renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is generally recommended for patients with an underlying endocrine or metabolic disorder (such as renal osteodystrophy, hypothyroidism, or prior pelvic radiation) due to the high risk of a contralateral slip, which can approach 100% in these populations.

Question 2139

Topic: Pediatric Lower Extremity
A 4-year-old child who was successfully treated for idiopathic clubfoot with the Ponseti method presents with dynamic supination of the foot during the swing phase of gait. Passive dorsiflexion is 15 degrees. What is the most appropriate management?
. Repeat percutaneous tendo-Achilles lengthening
. Split anterior tibial tendon transfer (SPLATT)
. Full anterior tibial tendon transfer to the lateral cuneiform
. Cuboid decancellation
. Triple arthrodesis

Correct Answer & Explanation

. Full anterior tibial tendon transfer to the lateral cuneiform

Explanation

Dynamic supination in a treated clubfoot is typically due to an overpowering anterior tibial tendon relative to the evertors. The treatment of choice for a flexible foot with dynamic supination without equinus is a full transfer of the anterior tibial tendon (TATT) to the lateral cuneiform. A SPLATT is generally reserved for adult neurogenic conditions like stroke or CP.

Question 2140

Topic: Pediatric Hip

A 13-year-old boy undergoes in-situ pinning of a severe, unstable slipped capital femoral epiphysis (SCFE). Postoperatively, he has significantly decreased hip motion and pain, and radiographs reveal diffuse narrowing of the joint space. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Undiagnosed contralateral SCFE
. Septic arthritis
. Cam impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis (acute cartilage necrosis) is a serious complication of SCFE, presenting with progressive stiffness, pain, and marked joint space narrowing on radiographs. Risk factors include severe slips, unrecognized pin penetration into the joint, and spica cast immobilization.

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