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4. Pediatrics MCQs

Practice Set 102 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 2021

Topic: 4. Pediatrics

A 5-year-old female presents with progressive bowing of her left leg. She has a history of prematurity and has been diagnosed with hypophosphatemic rickets (X-linked dominant). She has been on oral phosphate and calcitriol supplementation for 2 years, but her bowing deformity has worsened. Radiographs demonstrate severe genu varum deformity with widening and fraying of the physeal plates.

What is the MOST appropriate surgical management for her worsening deformity?

. Continued medical management with adjustment of vitamin D and phosphate doses.
. Placement of a guided growth plate (hemi-epiphysiodesis) on the medial side of the distal femur and proximal tibia.
. Acute corrective osteotomy with internal fixation.
. External fixator application for gradual correction.
. Amputation due to progressive and severe deformity.

Correct Answer & Explanation

. Placement of a guided growth plate (hemi-epiphysiodesis) on the medial side of the distal femur and proximal tibia.

Explanation

The image shows a bowed long bone, consistent with rickets. The patient has hypophosphatemic rickets with progressive genu varum despite medical management. In children with active growth plates and significant angular deformities, surgical correction is often required when medical management fails to prevent deformity progression.For progressive angular deformities in skeletally immature children, guided growth techniques (also known as 'tethering' or 'hemi-epiphysiodesis') are the preferred method. This involves placing a plate and screws (e.g., tension band plating or 8-plate) on theconvexside of the deformity. In genu varum (bow-leg), this means plating the medial side of the distal femur and/or proximal tibia. This slows growth on the medial side, allowing the lateral side to catch up, thereby gradually correcting the deformity over time. This avoids acute osteotomies, which carry higher risks of neurovascular injury, compartment syndrome, and recurrence, especially in patients with metabolic bone disease.Rationale for options:A. Continued medical management alone is insufficient as the deformity is worsening despite 2 years of treatment. While medical management is crucial, it may not prevent all deformities, and surgical intervention is needed for established angular deformities.B. Placement of a guided growth plate (hemi-epiphysiodesis) on the medial side of the distal femur and proximal tibia is the most appropriate surgical intervention for progressive genu varum in a growing child with rickets, allowing for gradual, physiological correction. This is the correct answer.C. Acute corrective osteotomy with internal fixation is an option for older children or severe, fixed deformities, but it is more invasive and carries higher risks (recurrence, neurovascular injury) compared to guided growth in a young, growing child, especially with underlying metabolic bone disease.D. External fixator application for gradual correction (e.g., Ilizarov) is effective but generally reserved for very severe, multiplanar deformities, or limb lengthening, and is more cumbersome than guided growth for simple angular correction.E. Amputation is a salvage procedure for severe, irreversible conditions, not indicated here.

Question 2022

Topic: 4. Pediatrics

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the parents report the infant has stopped kicking the affected leg. On examination, the knee is held in flexion, and the infant demonstrates absent active knee extension, though passive motion is full and pain-free. What is the most appropriate next step in management?

. Continue harness with no modifications
. Adjust the anterior strap to increase hip flexion
. Discontinue the harness and observe for spontaneous recovery
. Switch immediately to a rigid abduction orthosis
. Perform closed reduction and spica casting

Correct Answer & Explanation

. Discontinue the harness and observe for spontaneous recovery

Explanation

This infant is presenting with a femoral nerve palsy, a known complication of treating DDH with a Pavlik harness, typically caused by excessive hip flexion (hyperflexion >120 degrees). The compression of the femoral nerve against the inguinal ligament leads to temporary neuropraxia. The most appropriate next step is to discontinue the harness and observe; recovery is generally spontaneous within a few days to weeks. Once recovered, alternative treatment or a modified harness protocol can be initiated. Continuing the harness or increasing flexion would exacerbate the palsy.

Question 2023

Topic: Pediatric Hip

A 13-year-old obese male presents with a 3-week history of left thigh pain and a limp. Examination reveals obligate external rotation upon flexing the left hip. Radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE). During in situ single-screw fixation, to minimize the risk of avascular necrosis (AVN), the screw should ideally be positioned in which quadrant of the femoral head?

. Anterior-superior
. Anterior-inferior
. Posterior-superior
. Posterior-inferior
. Directly in the fovea capitis

Correct Answer & Explanation

. Posterior-inferior

Explanation

In the treatment of SCFE, the femoral head typically slips posterior and inferior relative to the femoral neck. To avoid joint penetration and to stay away from the vulnerable blood supply entering the superior-posterior capsule (retinacular vessels from the medial femoral circumflex artery), the starting point on the lateral femur is anterior, and the screw trajectory aims for the center of the epiphysis, typically ending up in the posterior-inferior quadrant of the head. Placing screws in the anterior-superior quadrant has the highest risk of unrecognized joint penetration and AVN.

Question 2024

Topic: Pediatric Lower Extremity

In the Ponseti method for the treatment of idiopathic clubfoot, a specific sequence of deformity correction is strictly followed to avoid creating a midfoot breach (rocker-bottom deformity). Which of the following represents the correct sequential order of correction?

. Cavus, Adduction, Varus, Equinus (CAVE)
. Equinus, Varus, Adduction, Cavus (EVAC)
. Varus, Equinus, Cavus, Adduction (VECA)
. Adduction, Cavus, Equinus, Varus (ACEV)
. Cavus, Equinus, Varus, Adduction (CEVA)

Correct Answer & Explanation

. Cavus, Equinus, Varus, Adduction (CEVA)

Explanation

The Ponseti method dictates a very specific sequence for the manipulation and casting of idiopathic clubfoot, easily remembered by the acronym CAVE: Cavus (corrected first by elevating the first ray to align the forefoot with the hindfoot), Adduction (abducting the forefoot around the talar head), Varus (the heel varus corrects passively as the forefoot is abducted), and finally Equinus (which often requires a percutaneous Achilles tenotomy as the final step).

Question 2025

Topic: Pediatric Hip

A 12-year-old obese male presents with chronic left groin pain and an obligatory slip into external rotation with passive hip flexion. Radiograph of the hip is shown.

Which of the following represents the strongest indication for prophylactic in situ pinning of the contralateral, asymptomatic hip in a patient with a Slipped Capital Femoral Epiphysis (SCFE)?

. Underlying endocrine disorder
. Age greater than 14 years
. Male gender
. Weight greater than the 99th percentile

Correct Answer & Explanation

. Underlying endocrine disorder

Explanation

The strongest indications for prophylactic pinning of the contralateral hip in a patient with SCFE include an underlying endocrine disorder (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy), prior radiation therapy, or age less than 10 years. Endocrine disorders carry a significantly higher risk of bilateral involvement compared to idiopathic SCFE.

Question 2026

Topic: 4. Pediatrics

A 10-year-old boy sustains a Salter-Harris II fracture of the distal femur. Despite an anatomic closed reduction and casting, the patient develops a significant leg length discrepancy 2 years later. Which of the following is the approximate historical rate of physeal growth arrest associated with distal femoral physeal fractures?

. 5%
. 15%
. 50%
. 90%

Correct Answer & Explanation

. 50%

Explanation

Distal femoral physeal fractures carry a notoriously high risk of premature physeal closure and growth arrest, historically reported to be around 40-50%, even with seemingly anatomic reduction. This is due to the highly undulating anatomy of the distal femoral physis, which sustains significant sheer force during injury.

Question 2027

Topic: Pediatric Hip

A 4-week-old female infant is currently undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up appointment, the mother notes that the infant has stopped kicking her left leg, and the knee rests in a persistently extended position. What is the most likely iatrogenic cause of this finding?

. The harness is adjusted with excessive hip abduction
. The harness is adjusted with excessive hip flexion
. An acute superior dislocation of the hip
. Ischemic necrosis of the proximal femoral epiphysis

Correct Answer & Explanation

. The harness is adjusted with excessive hip flexion

Explanation

The clinical picture describes a femoral nerve palsy, a known complication of Pavlik harness treatment. It is caused by hyperflexion of the hip (usually >120 degrees), which compresses the femoral nerve against the inguinal ligament. This results in decreased quadriceps function (absence of kicking and an extended resting knee). Treatment involves loosening the anterior straps to decrease hip flexion. Excessive abduction, by contrast, is associated with avascular necrosis of the femoral head.

Question 2028

Topic: Pediatric Hip

A 12-year-old boy presents with a left-sided slipped capital femoral epiphysis (SCFE). He is noticeably short for his age and has a documented history of hypothyroidism. What is the most appropriate management regarding his completely asymptomatic, radiographically normal contralateral right hip?

. Observation until closure of the right proximal femoral physis.
. Prophylactic in situ pinning of the right hip due to his endocrine abnormality.
. Prophylactic right proximal femoral varus osteotomy.
. Spica cast immobilization for 6 weeks.
. Wait for symptoms to develop before initiating treatment on the right hip.

Correct Answer & Explanation

. Prophylactic in situ pinning of the right hip due to his endocrine abnormality.

Explanation

Patients with underlying endocrine or metabolic disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) have a significantly higher risk of developing a contralateral SCFE (often reported near 100% in some series). Therefore, prophylactic in situ pinning of the unaffected hip is strongly indicated in this population.

Question 2029

Topic: 4. Pediatrics
A 2.5-year-old boy presents with progressive bilateral genu varum and an asymmetric waddling gait. Standing long-leg radiographs demonstrate medial metaphyseal beaking and a metaphyseal-diaphyseal angle (MDA) of 20 degrees bilaterally. What is the most appropriate initial management?
. Reassurance and observation as this represents physiologic bowing.
. Prescribe bilateral knee-ankle-foot orthoses (KAFOs) for daytime and nighttime use.
. Bilateral proximal tibial valgus osteotomies.
. Epiphysiodesis of the lateral proximal tibial physes.
. Vitamin D supplementation for suspected nutritional rickets.

Correct Answer & Explanation

. Prescribe bilateral knee-ankle-foot orthoses (KAFOs) for daytime and nighttime use.

Explanation

This presentation describes infantile Blount's disease (tibia vara), characterized by a disordered endochondral ossification of the medial proximal tibial physis. An MDA > 16 degrees strongly predicts progression rather than spontaneous resolution (physiologic bowing usually has an MDA < 11 degrees). In a child under the age of 3 to 4 with early-stage disease (Langenskiรถld I or II), the treatment of choice is a trial of bracing with KAFOs to unload the medial compartment.

Question 2030

Topic: 4. Pediatrics

A 9-year-old boy whose weight is in the 95th percentile presents with groin pain and an obligatory external rotation of the hip with passive flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Given the patient's age, which of the following underlying conditions should be investigated?

. Hyperthyroidism
. Hypothyroidism
. Hyperparathyroidism
. Achondroplasia
. Marfan syndrome

Correct Answer & Explanation

. Hypothyroidism

Explanation

SCFE typically occurs in boys aged 12-16. Presentation in children under 10 years of age or with bilateral involvement strongly suggests an underlying endocrine disorder, most commonly hypothyroidism.

Question 2031

Topic: 4. Pediatrics
A 6-year-old child sustains a severely displaced Type III supracondylar humerus fracture. Upon arrival, the hand is pink but pulseless. After closed reduction and percutaneous pinning, the hand remains pink and pulseless. Doppler ultrasound confirms biphasic signals in the palmar arch. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. Administration of intra-arterial vasodilators
. Observation and admission for serial neurovascular checks
. Removal of pins and open reduction
. Fasciotomy of the forearm

Correct Answer & Explanation

. Observation and admission for serial neurovascular checks

Explanation

A "pink and pulseless" hand with confirmed distal Doppler flow after reduction of a pediatric supracondylar humerus fracture should be observed closely. Surgical exploration is indicated if the hand is white/ischemic or if perfusion is lost after reduction.

Question 2032

Topic: Pediatric Hip

A 12-year-old boy undergoes in situ single screw fixation for a stable slipped capital femoral epiphysis (SCFE). Over the next 6 months, he develops severe hip stiffness, pain, and a concentric loss of joint space on radiographs. This complication is most strongly associated with which intraoperative error?

. Placement of the screw in the anterior half of the epiphysis
. Failure to use a second screw for rotational stability
. Unrecognized intra-articular penetration by the hardware
. Over-reduction of the slip prior to pinning
. Starting the screw superior to the lesser trochanter

Correct Answer & Explanation

. Unrecognized intra-articular penetration by the hardware

Explanation

Chondrolysis is characterized by progressive joint stiffness and narrowing of the joint space. It is most commonly associated with unrecognized intra-articular penetration of the pins or screws during fixation of a SCFE.

Question 2033

Topic: Pediatric Lower Extremity

When initiating the Ponseti method of serial casting for an infant born with idiopathic talipes equinovarus (clubfoot), what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method follows the CAVE sequence: Cavus (corrected by elevating the first ray), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy).

Question 2034

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 35 presents with left groin pain and an obligate external rotation of the hip with flexion. Radiographs show a severe left slipped capital femoral epiphysis (SCFE). When considering prophylactic pinning of the contralateral asymptomatic right hip, which of the following represents the strongest indication?

. The patient's chronological age.
. The patient's BMI.
. A modified Oxford Bone Age score of 20.
. Open triradiate cartilage.
. The severity of the symptomatic slip.

Correct Answer & Explanation

. Open triradiate cartilage.

Explanation

Prophylactic pinning of the contralateral hip in SCFE is recommended in patients with a high risk of a future slip. Open triradiate cartilage is a strong radiographic marker of skeletal immaturity and is considered one of the most reliable predictors for a contralateral slip. A low modified Oxford bone age score (e.g., 16) also indicates immaturity, whereas a score of 20 indicates skeletal maturity.

Question 2035

Topic: Pediatric Hip



A 6-month-old female presents with a neglected developmental dysplasia of the hip (DDH). Ultrasound and plain radiographs confirm a dislocated left hip. She has never received treatment. What is the most appropriate initial management?

. Pavlik harness.
. Closed reduction and spica casting under anesthesia.
. Open reduction via an anterior approach.
. Femoral derotational osteotomy.
. Observation with serial ultrasounds.

Correct Answer & Explanation

. Closed reduction and spica casting under anesthesia.

Explanation

At 6 months of age, a Pavlik harness is generally less effective and carries a higher failure rate. The standard initial management for a 6-month-old with a dislocated hip is an examination under anesthesia, closed reduction, and spica casting. Open reduction is indicated if a concentric closed reduction cannot be achieved or if the child presents at an older age (e.g., typically >18 months).

Question 2036

Topic: 4. Pediatrics

A 13-year-old obese male presents with left hip pain and an obligatory external rotation of the hip during passive flexion. Slipped capital femoral epiphysis (SCFE) is confirmed. Prophylactic pinning of the asymptomatic contralateral hip is most strongly indicated if the patient has a concomitant diagnosis of:

. Type 2 Diabetes Mellitus
. Hypothyroidism
. Prader-Willi Syndrome
. Asthma requiring chronic steroids
. Blount's disease

Correct Answer & Explanation

. Hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with underlying endocrine or metabolic disorders (like hypothyroidism or renal osteodystrophy) due to a substantially higher risk of bilateral involvement.

Question 2037

Topic: 4. Pediatrics

Understanding the microanatomy of the physis is essential in pediatric orthopedics. In Slipped Capital Femoral Epiphysis (SCFE), the mechanical failure primarily occurs through which cellular zone of the physis?

. Reserve zone
. Proliferative zone
. Hypertrophic zone
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Hypertrophic zone

Explanation

The hypertrophic zone is the weakest layer of the physis mechanically due to an increased matrix-to-cell ratio and loss of longitudinal septa. It is the zone where failure occurs in SCFE and typical Salter-Harris type I fractures.

Question 2038

Topic: Pediatric Lower Extremity

An infant is diagnosed with idiopathic clubfoot (talipes equinovarus) and is set to undergo serial casting using the Ponseti method. What is the correct chronological sequence of deformity correction using this technique?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method follows the CAVE sequence: Cavus is corrected first by supinating the forefoot, followed by Adductus and Varus by abducting the foot around the talar head, and finally Equinus with dorsiflexion and often a percutaneous Achilles tenotomy.

Question 2039

Topic: Pediatric Hip

A 12-year-old obese male presents with left knee pain and an antalgic gait. Radiographs confirm a mild, stable slipped capital femoral epiphysis (SCFE) on the left. Which of the following is an absolute indication for prophylactic pinning of the contralateral asymptomatic hip?

. Patient age > 14 years
. Female gender
. Presence of an underlying endocrine disorder
. Initial slip angle > 50 degrees
. Body mass index > 99th percentile

Correct Answer & Explanation

. Presence of an underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy) due to the high risk of bilateral involvement. Other relative indications include young age (<10 years) and poor follow-up compliance.

Question 2040

Topic: Pediatric Upper Extremity & Spine
A 6-year-old female falls from monkey bars and sustains a Gartland type III extension-type supracondylar humerus fracture. On examination, the hand is pink and well-perfused, but the radial pulse is absent. What is the next best step in management?
. Immediate open reduction and brachial artery exploration
. Urgent closed reduction and percutaneous pinning
. CT angiography of the upper extremity
. Observation and casting in situ
. Administration of intra-arterial vasodilators

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning

Explanation

A "pulseless, pink" hand after a displaced supracondylar humerus fracture indicates adequate collateral circulation. The next best step is urgent closed reduction and percutaneous pinning, as reduction often relieves kinking of the brachial artery and restores the pulse.

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