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4. Pediatrics MCQs

Practice Set 238 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 4741

Topic: Pediatric Lower Extremity

An infant with bilateral idiopathic clubfeet is undergoing Ponseti casting. After three casts, the treating physician notices the foot has become severely plantarflexed, the midfoot is deeply creased with a transverse plantar crease, and the heel is slipping out of the cast. What is the most appropriate modification to the standard Ponseti technique for this 'atypical' clubfoot?

. Proceed directly to a posteromedial release
. Perform a percutaneous Achilles tenotomy immediately, regardless of hindfoot varus
. Remove the cast, immobilize the knee in 110 degrees of flexion, and correct cavus and equinus simultaneously
. Apply a short leg cast to focus purely on forefoot abduction
. Transition to the French functional taping method

Correct Answer & Explanation

. Proceed directly to a posteromedial release

Explanation

An 'atypical' or complex clubfoot is characterized by a short, stubby foot, severe plantar flexion, a deep transverse plantar crease, and a tendency for the cast to slip. The Ponseti method must be modified: the knee is flexed to 110 degrees to prevent cast slippage, and equinus and varus are corrected simultaneously rather than sequentially.

Question 4742

Topic: 4. Pediatrics

A 5-year-old girl is noted to have a highly elevated, hypoplastic left scapula. Physical examination reveals limited shoulder abduction. Radiographs demonstrate an osseous connection between the superomedial angle of the scapula and the cervical spine. Which of the following is most strongly associated with this condition?

. Radial longitudinal deficiency
. Cervical spine anomalies (Klippel-Feil syndrome)
. Neurofibromatosis type 1
. Developmental dysplasia of the hip
. Proximal focal femoral deficiency

Correct Answer & Explanation

. Radial longitudinal deficiency

Explanation

The clinical picture describes Sprengel deformity (congenital elevation of the scapula). The osseous connection is an omovertebral bone, present in approximately 30% of cases. Sprengel deformity is highly associated with Klippel-Feil syndrome (congenital fusion of the cervical spine), as well as congenital scoliosis and renal anomalies.

Question 4743

Topic: Pediatric Upper Extremity & Spine
A newborn is evaluated for an absent right thumb and a radially deviated right wrist. Radiographs confirm complete absence of the radius. Which of the following diagnostic tests is most critical to perform next to rule out a potentially fatal associated condition?
. Renal ultrasound
. Echocardiogram
. Chromosomal breakage analysis
. Complete blood count with smear
. Cranial ultrasound

Correct Answer & Explanation

. Chromosomal breakage analysis

Explanation

Radial longitudinal deficiency with an absent thumb is strongly associated with Fanconi anemia, Holt-Oram syndrome, and VACTERL. Fanconi anemia involves fatal aplastic anemia if undiagnosed, and chromosomal breakage analysis (using diepoxybutane) is the definitive screening test. TAR syndrome typically presents with a preserved thumb.

Question 4744

Topic: Pediatric Hip

A 6-week-old female with a completely dislocated left hip (Graf Type IV) is placed in a Pavlik harness. After 4 weeks of compliant, full-time wear, ultrasound demonstrates the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Adjust the anterior straps to increase hip flexion past 120 degrees
. Discontinue the Pavlik harness and transition to a rigid abduction orthosis or consider closed reduction
. Proceed immediately to a Salter innominate osteotomy
. Perform an adductor tenotomy and reapply the Pavlik harness

Correct Answer & Explanation

. Continue the Pavlik harness for an additional 4 weeks

Explanation

If a Pavlik harness fails to reduce a dislocated hip after 3 to 4 weeks, it must be discontinued to prevent 'Pavlik harness disease' (erosion and damage to the posterior acetabular wall). The next step is transitioning to a rigid abduction orthosis (e.g., Rhino Cruiser or Ilfeld brace) or proceeding directly to a closed reduction and spica casting.

Question 4745

Topic: 4. Pediatrics

A 2-year-old child presents with significant leg length discrepancy, anteromedial bowing of the right tibia, and an equinovalgus foot. Radiographs reveal partial absence of the right fibula. Which of the following anomalies is most commonly associated with this condition?

. Anterior cruciate ligament (ACL) deficiency
. Avascular necrosis of the talus
. Sprengel deformity
. Congenital radioulnar synostosis
. Posterior cruciate ligament (PCL) deficiency

Correct Answer & Explanation

. Anterior cruciate ligament (ACL) deficiency

Explanation

Fibular hemimelia is the most common congenital long bone deficiency. It is highly associated with anteromedial tibial bowing, absent lateral rays of the foot, tarsal coalition, ball-and-socket ankle joint, and hypoplasia of the lateral femoral condyle resulting in ACL and/or PCL deficiency (ACL deficiency being extremely common).

Question 4746

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvรฉ-Perthes disease. Radiographs obtained during the fragmentation phase reveal that the lateral pillar of the femoral head maintains 60% of its original height. According to the Herring Lateral Pillar Classification, what group is this, and what is the typical recommendation for a child of this age?
. Group A; symptomatic treatment and observation
. Group B; surgical containment (e.g., pelvic or femoral osteotomy)
. Group C; symptomatic treatment and observation
. Group B/C border; immediate hip arthrodesis
. Group C; surgical containment

Correct Answer & Explanation

. Group B; surgical containment (e.g., pelvic or femoral osteotomy)

Explanation

According to the Herring Lateral Pillar classification, Group A has 100% lateral pillar height, Group B maintains >50% height, and Group C has <50% height. For children aged 8 or older with Group B (or B/C border) hips, surgical containment (femoral or pelvic osteotomy) has been shown to result in significantly better spherical outcomes compared to non-operative treatment.

Question 4747

Topic: 4. Pediatrics

A 3-year-old girl presents with massive, disproportionate overgrowth of her index and middle fingers on the right hand. The fingers are stiff and deviated. Intraoperative findings reveal massive enlargement of the digital nerves with fibrofatty infiltration. A somatic mutation in which of the following genes is most strongly associated with this isolated condition?

. NF1
. PIK3CA
. FGFR3
. COL1A1
. SHOX

Correct Answer & Explanation

. NF1

Explanation

Macrodactyly (nerve territory overgrowth) is characterized by fibrofatty hyperplasia of the nerve and its surrounding tissues (most commonly the median nerve distribution). It is classified under the PIK3CA-related overgrowth spectrum (PROS) and is driven by an isolated post-zygotic somatic mutation in the PIK3CA gene.

Question 4748

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy sustains a fall on an outstretched hand and presents with a completely displaced, extension-type supracondylar humerus fracture with no cortical contact (Gartland Type III). Which of the following peripheral nerve injuries is most commonly associated with this specific fracture pattern?
. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve (AIN)
. Median nerve (excluding AIN)
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN)

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. It typically presents with weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger, resulting in an inability to make an "OK" sign.

Question 4749

Topic: 4. Pediatrics

An infant is diagnosed with idiopathic congenital talipes equinovarus (clubfoot) and is undergoing the Ponseti method of serial casting.

According to the Ponseti method, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The correct sequence of correction in the Ponseti method is C-A-V-E: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus. Equinus is often corrected at the end with a percutaneous Achilles tenotomy.

Question 4750

Topic: Pediatric Lower Extremity

A 3-year-old girl is evaluated for bilateral severe genu varum. Standing radiographs demonstrate medial beaking of the proximal tibial epiphyses.

Measurement of the metaphyseal-diaphyseal (MD) angle is obtained. Which of the following MD angle measurements most strongly supports the diagnosis of infantile Blount's disease rather than physiologic bowing?

. Greater than 5 degrees
. Greater than 9 degrees
. Greater than 11 degrees
. Greater than 16 degrees
. Less than 10 degrees

Correct Answer & Explanation

. Greater than 5 degrees

Explanation

An MD angle of greater than 16 degrees on standing AP radiographs indicates a high likelihood of progression to true infantile Blount's disease. Angles less than 10 degrees are typically associated with physiologic bowing that will spontaneously resolve.

Question 4751

Topic: 4. Pediatrics

An 18-month-old non-ambulatory child is brought to the emergency department with a spiral fracture of the left femur.

The parents state the child fell off a low sofa. What is the most critical next step in the management of this patient?

. Immediate operative fixation with flexible intramedullary nails
. Application of a Pavlik harness
. Admission, skeletal survey, and child protective services consultation
. Discharge home in a single-leg spica cast with outpatient follow-up
. Bilateral lower extremity traction

Correct Answer & Explanation

. Immediate operative fixation with flexible intramedullary nails

Explanation

Femur fractures in non-ambulatory infants, especially spiral fractures with a low-energy mechanism history, are highly suspicious for non-accidental trauma (NAT). Admission, a full skeletal survey, and a CPS consult are mandatory.

Question 4752

Topic: 4. Pediatrics

A 9-year-old girl with cerebral palsy (GMFCS Level IV) has an AP pelvic radiograph demonstrating a Reimers migration percentage of 55% in the right hip. There are early osteoarthritic changes. What is the most appropriate definitive management?

. Observation and yearly radiographs
. Isolated adductor longus tenotomy
. Varus derotational osteotomy (VDRO) of the proximal femur with pelvic osteotomy
. Total hip arthroplasty
. Botulinum toxin injection to the adductors

Correct Answer & Explanation

. Observation and yearly radiographs

Explanation

In cerebral palsy patients, a Reimers migration index >40-50% indicates significant hip subluxation requiring bony reconstructive surgery. The standard treatment is a proximal femoral varus derotational osteotomy (VDRO) combined with a pelvic osteotomy (e.g., Dega or San Diego).

Question 4753

Topic: Pediatric Hip

A 13-year-old male is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE). Prophylactic in situ pinning of the contralateral hip is being considered. Which of the following is the strongest clinical indication for prophylactic contralateral pinning?

. Male sex
. Obesity (BMI > 95th percentile)
. Concomitant endocrine disorder (e.g., hypothyroidism)
. Mild initial slip angle
. Age greater than 14 years

Correct Answer & Explanation

. Male sex

Explanation

Endocrine disorders (such as hypothyroidism, growth hormone deficiency, or renal osteodystrophy) dramatically increase the risk of a contralateral slip in SCFE patients. Prophylactic pinning of the unaffected hip is highly recommended in these populations.

Question 4754

Topic: Pediatric Hip

A 3-month-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During follow-up, the mother notes the child is no longer actively kicking or extending the affected knee. Sensation appears intact. Which nerve is most likely compressed due to improper harness positioning?

. Obturator nerve
. Sciatic nerve
. Femoral nerve
. Superior gluteal nerve
. Lateral femoral cutaneous nerve

Correct Answer & Explanation

. Obturator nerve

Explanation

Femoral nerve palsy in a Pavlik harness is typically caused by excessive hip hyperflexion. It presents as an inability to actively extend the knee. The harness should be loosened or temporarily removed until function returns.

Question 4755

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calve-Perthes disease. Radiographs reveal more than 50% loss of lateral pillar height. Which of the following factors at the time of presentation is the most reliable predictor of long-term prognosis?

. Gender of the patient
. Body Mass Index (BMI)
. Age at the onset of disease
. Bilateral vs. unilateral involvement
. History of preceding trauma

Correct Answer & Explanation

. Gender of the patient

Explanation

Age at clinical onset is one of the most critical prognostic factors in Legg-Calve-Perthes disease. Children who develop the disease after age 8 generally have a worse prognosis due to having less remaining time for remodeling before skeletal maturity.

Question 4756

Topic: 4. Pediatrics
A 14-year-old boy twisted his ankle while skateboarding. Anteroposterior radiographs show a Salter-Harris type III fracture of the anterolateral aspect of the distal tibial epiphysis. Avulsion by which of the following ligaments causes this specific fracture pattern?
. Anterior talofibular ligament (ATFL)
. Posterior inferior tibiofibular ligament (PITFL)
. Anterior inferior tibiofibular ligament (AITFL)
. 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 tibial epiphysis. It is caused by an avulsion force from the anterior inferior tibiofibular ligament (AITFL) as the medial physis closes earlier than the lateral side in adolescents.

Question 4757

Topic: 4. Pediatrics
An adolescent sustains a triplane fracture of the distal tibia following an external rotation injury. Radiographically, the fracture appears as a Salter-Harris Type III on the AP view and a Salter-Harris Type II on the lateral view. What is the overall Salter-Harris classification of a standard triplane fracture?
. Salter-Harris Type I
. Salter-Harris Type II
. Salter-Harris Type III
. Salter-Harris Type IV
. Salter-Harris Type V

Correct Answer & Explanation

. Salter-Harris Type IV

Explanation

A triplane fracture crosses the epiphysis, physis, and metaphysis, making it a Salter-Harris Type IV fracture by definition. It occurs during the transitional phase of distal tibial physeal closure.

Question 4758

Topic: 4. Pediatrics

A 9-month-old infant is brought in for an abnormal leg shape. Examination reveals anterolateral bowing of the left tibia. Radiographs demonstrate diaphyseal narrowing and sclerosis at the apex of the bow. This condition is most strongly associated with which underlying genetic disorder?

. Osteogenesis Imperfecta
. Achondroplasia
. Neurofibromatosis Type 1
. Marfan Syndrome
. Cleidocranial Dysplasia

Correct Answer & Explanation

. Osteogenesis Imperfecta

Explanation

Anterolateral bowing of the tibia is the hallmark precursor to Congenital Pseudarthrosis of the Tibia (CPT). It is strongly associated with Neurofibromatosis Type 1 (NF1), which is present in over 50% of these patients.

Question 4759

Topic: Pediatric Hip

A 14-year-old boy presents with an unstable slipped capital femoral epiphysis (SCFE) and undergoes open reduction and internal fixation via a surgical hip dislocation approach. To minimize the risk of osteonecrosis, preserving the blood supply to the epiphysis is critical. Which vessel provides the primary blood supply to the femoral head in this patient?

. Obturator artery via the ligamentum teres
. Deep branch of the medial femoral circumflex artery
. Descending branch of the lateral femoral circumflex artery
. Inferior gluteal artery

Correct Answer & Explanation

. Obturator artery via the ligamentum teres

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head in adolescents. Protection of this retinacular vessel is critical during surgical hip dislocation for SCFE.

Question 4760

Topic: Pediatric Lower Extremity

A 2-week-old infant is undergoing serial casting for idiopathic clubfoot using the Ponseti method. What is the correct sequence of deformity correction in this technique?

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

Correct Answer & Explanation

. Equinus, Varus, Adductus, Cavus

Explanation

The Ponseti method corrects deformities in the CAVE sequence: Cavus, Adductus, Varus, and finally Equinus. The cavus is corrected first by supinating the forefoot to align it with the hindfoot.

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