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4. Pediatrics MCQs

Practice Set 37 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 721

Topic: Pediatric Lower Extremity

Equinovarus positioning of the foot is normal during which stage of embryonic life:

. No stage
. Eighth to tenth week
. Thirteenth to fifteenth week
. Seventeenth to nineteenth week
. Twentieth to twenty-third week

Correct Answer & Explanation

. Eighth to tenth week

Explanation

As the foot matures, it passes through a normal stage when it resembles a clubfoot in the eighth to tenth week. After this, the foot normally corrects itself.

Question 722

Topic: 4. Pediatrics

Which of the following is a similarity between congenital pseudarthrosis of the clavicle and congenital pseudarthrosis of the tibia:

. Both are common in neurofibromatosis
. Both are common in cleidocranial dysplasia
. Both have a low rate of union after treatment with autograft unless it is vascularized
. Both are more common on the left side
. Both may present with tapered, atrophic bone ends at the pseudarthrosis

Correct Answer & Explanation

. Both may present with tapered, atrophic bone ends at the pseudarthrosis

Explanation

Congenital pseudarthrosis of the clavicle and tibia may present in infants with a gap between two tapered, atrophic bone ends. However, they are dissimilar in other respects. Pseudarthrosis of the clavicle is seen almost exclusively on the right side, while that of the tibia is seen on either side. Pseudarthrosis of the clavicle may be seen in cleidocranial dysostosis, although tibial pseudarthrosis is not. Pseudarthrosis of the clavicle has a high rate of union with simple bone graft, while that of the tibia does not. One-half of patients with pseudarthrosis of the tibia have neurofibromatosis, while this is almost never seen in congenital pseudarthrosis of the clavicle.

Question 723

Topic: Pediatric Hip

Of all slipped capital femoral epiphyses, which percentage is unstable:

. 5%
. 15%
. 25%
. 35%
. 50%

Correct Answer & Explanation

. 5%

Explanation

Unstable slipped capital femoral epiphysis places the patient at a high risk of avascular necrosis (up to 47%). Fortunately, it comprises only about 5% of all slips.

Question 724

Topic: 4. Pediatrics

A 5-year-old child is bitten by a tick. Which of the following has been shown to aid in management:

. Prompt tick removal
. Immediate treatment with doxycycline
. Immediate treatment with amoxicillin
. Prompt ELISA testing
. Steroid administration

Correct Answer & Explanation

. Prompt tick removal

Explanation

Prompt tick removal is recommended because Lyme disease is more likely if the tick is attached for more than 24 hours. Immediate antibiotic administration is not recommended because the incidence of Lyme disease is low after any single tick bite and treatment is equally effective once the disease is diagnosed. Doxycycline is not recommended in children younger than 8 years old because of dental discoloration. Immediate testing for antibodies (ELISA) is not useful because antibodies do not rise for at least several weeks. Steroids are not recommended in this setting.

Question 725

Topic: 4. Pediatrics

The effects of pediatric orthopedic conditions in later adulthood commonly determine treatment choices for children. At what threshold does limb length discrepancy increase the energy cost of walking in older adults:

. 2 cm
. 3 cm
. 4 cm
. 5 cm
. No such effect has been proven at any discrepancy.

Correct Answer & Explanation

. 2 cm

Explanation

A limb length discrepancy of as little as 2 cm has shown to increase perceived exertion as well as oxygen consumption in older adults.

Question 726

Topic: 4. Pediatrics

A 5-year-old child presents with a pulseless, pink hand following a displaced supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand remains pink but pulseless. What is the next most appropriate step in management?

. Observation and hospital admission
. Immediate vascular exploration
. Doppler ultrasound of the brachial artery
. Removal of pins and open reduction
. Perform a prophylactic forearm fasciotomy

Correct Answer & Explanation

. Observation and hospital admission

Explanation

A pulseless, pink hand after reduction of a pediatric supracondylar humerus fracture indicates adequate collateral circulation and is generally managed with observation. Immediate vascular exploration is reserved for a hand that remains pulseless and pale despite reduction.

Question 727

Topic: Pediatric Hip

An overweight 13-year-old boy presents with left knee pain and a limp. Examination reveals obligate external rotation of the hip during passive flexion. Following diagnosis of a stable slipped capital femoral epiphysis (SCFE), what is the most appropriate surgical treatment?

. Closed reduction and spica casting
. Open reduction and internal fixation with multiple pins
. In situ fixation with a single cannulated screw
. Proximal femoral corrective osteotomy
. Core decompression of the femoral head

Correct Answer & Explanation

. In situ fixation with a single cannulated screw

Explanation

The gold standard treatment for a stable slipped capital femoral epiphysis is in situ pinning with a single cannulated screw placed in the center of the epiphysis. Attempts at closed reduction significantly increase the risk of avascular necrosis.

Question 728

Topic: Pediatric Hip

Which of the following is an absolute indication for prophylactic in situ fixation of the contralateral hip in a patient with a unilateral Slipped Capital Femoral Epiphysis (SCFE)?

. Age greater than 14 years
. Female gender
. Underlying endocrine disorder
. Body Mass Index greater than 35
. Grade I slip severity

Correct Answer & Explanation

. Underlying endocrine disorder

Explanation

Patients with underlying endocrine disorders (such as hypothyroidism), prior radiation, or renal failure have an exceptionally high risk of contralateral slip. In these populations, prophylactic pinning of the unaffected hip is strongly recommended.

Question 729

Topic: 4. Pediatrics

A 6-year-old child presents with a widely displaced extension-type supracondylar fracture of the humerus. Which nerve is most commonly injured in this specific fracture pattern?

. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN) is the most frequently injured nerve in extension-type pediatric supracondylar humerus fractures. Its motor function is tested clinically by asking the patient to make an "OK" sign.

Question 730

Topic: Pediatric Hip

A 6-month-old infant is diagnosed with developmental dysplasia of the hip (DDH) that has failed Pavlik harness treatment. An ultrasound confirms persistent dislocation. What is the next most appropriate step in management?

. Continue Pavlik harness for 6 more weeks
. Closed reduction and spica casting
. Open reduction and femoral osteotomy
. Pelvic osteotomy (Salter)
. Observation until walking age

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

After failure of a Pavlik harness, or if diagnosed between 6 and 18 months of age, closed reduction under general anesthesia followed by spica casting is the standard next step in DDH management.

Question 731

Topic: 4. Pediatrics

An 8-year-old boy is diagnosed with Legg-Calve-Perthes disease. Which of the following radiographic findings is recognized as a "head-at-risk" sign according to Catterall?

. Medial subluxation of the femoral head
. Medial calcification
. Metaphyseal cysts
. Sclerosis of the proximal femoral metaphysis
. Premature closure of the greater trochanteric physis

Correct Answer & Explanation

. Metaphyseal cysts

Explanation

Catterall's "head-at-risk" signs indicate a poorer prognosis in Perthes disease. They include lateral subluxation, Gage's sign, calcification lateral to the epiphysis, diffuse metaphyseal reactions (cysts), and a horizontal growth plate.

Question 732

Topic: Pediatric Lower Extremity

In the Ponseti method for correcting idiopathic clubfoot, which deformity is the first to be addressed during serial casting?

. Equinus
. Varus
. Cavus
. Adduction
. Supination

Correct Answer & Explanation

. Cavus

Explanation

The Ponseti method dictates that the cavus deformity must be corrected first by elevating the first metatarsal to align the forefoot with the hindfoot. Adduction and varus are corrected next, with equinus corrected last.

Question 733

Topic: Pediatric Hip

A 12-year-old obese boy presents with a unilateral slipped capital femoral epiphysis (SCFE). Prophylactic in situ pinning of the contralateral asymptomatic hip is most strongly recommended if the patient has a concurrent history of:

. Asthma
. Renal osteodystrophy
. Type 1 Diabetes Mellitus
. Developmental dysplasia of the hip
. Legg-Calve-Perthes disease

Correct Answer & Explanation

. Renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip is indicated in patients at high risk for bilateral disease. This includes those with endocrine disorders (e.g., hypothyroidism) and metabolic bone disease such as renal osteodystrophy.

Question 734

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute-on-chronic left knee pain and an inability to bear weight. He is diagnosed with an unstable slipped capital femoral epiphysis (SCFE). Which of the following interventions carries the highest risk of iatrogenic avascular necrosis (AVN)?

. In situ percutaneous pinning
. Forceful closed reduction to improve alignment prior to pinning
. Open reduction and internal fixation via surgical hip dislocation
. Prophylactic pinning of the contralateral hip
. Capsulotomy at the time of in situ fixation

Correct Answer & Explanation

. Forceful closed reduction to improve alignment prior to pinning

Explanation

Forceful closed reduction of an unstable SCFE severely compromises the already tenuous epiphyseal blood supply, drastically increasing the risk of avascular necrosis. Current recommendations favor either in situ pinning or open reduction using a surgical hip dislocation approach to meticulously protect the retinacular vessels.

Question 735

Topic: 4. Pediatrics

Which of the following conditions is not associated with an increased incidence of congenital vertical talus:

. C erebral palsy
. Myelomeningocele
. Arthrogryposis
. Nail patella syndrome
. Larsen syndrome

Correct Answer & Explanation

. C erebral palsy

Explanation

Patients with cerebral palsy do not have an increased risk of congenital vertical talus, but they may develop an acquired neuromuscular vertical talus. Patients with myelomeningocele have approximately a 5% to 10% risk of vertical talus, far above that of the general population. Arthrogryposis is associated with an increased risk of vertical talus. Nail patella syndrome and Larsen syndrome are associated with an increased risk of vertical talus.

Question 736

Topic: 4. Pediatrics

A 9-year-old boy with cerebral palsy has trouble sitting. His mother states that whenever his diapers are changed or his hips are moved, he begins to cry. Radiographs demonstrate high dislocations of both femoral heads. The femoral heads have an ovoid shape and superolateral flattening. Recommended treatment includes:

. Botulinum toxin injected into the adductors
. Bilateral open adductor tenotomy
. Bilateral femoral osteotomies with acetabuloplasty
. Bilateral proximal femoral resection
. Bilateral C olonna arthroplasty

Correct Answer & Explanation

. Bilateral proximal femoral resection

Explanation

Bilateral proximal femoral resection is the recommended treatment. Femoral head dislocations may become painful in cerebral palsy at a much earlier age than in nonspastic individuals. Botulinum toxin or adductor tenotomy will not solve the problem. Replacing the deformed femoral heads into the acetabulum will not achieve the long-term goal of good hip range of motion.

Question 737

Topic: 4. Pediatrics

A patient with L4 level myelomeningocele has developed a full-thickness pressure sore on the heel that has a central necrosis and is draining. While undergoing debridement in the local emergency department, the patient develops labored respiration and a nondetectable blood pressure. The most likely cause is:

. Latex allergy
. Aortic dissection
. Septic shock
. Spontaneous tension pneumothorax
. Shunt failure

Correct Answer & Explanation

. Latex allergy

Explanation

Latex sensitivity is common in patients with spina bifida because of frequent exposure through catherizations and procedures. Latex avoidance is becoming the standard in institutions that commonly treat patients with spina bifida, but community hospitals that rarely see such patients may not always be aware of this problem. Dissection is not likely unless the patient has a connective tissue disorder. Septic shock is not likely to develop from a freely draining peripheral ulcer. Tension pneumothorax is not any more likely in patients with spina bifida than in the general population. Although it is important to be aware of shunt failure, it is not likely in this procedure which is done without anesthetic.

Question 738

Topic: 4. Pediatrics

Which of the following statements correctly represents the definitions of C hiari I and C hiari II malformations:

. A C hiari I malformation is displacement of the brainstem through the foramen magnum; a C hiari II malformation also includes the cerebellum.
. A C hiari I malformation is displacement of the cerebellum through the foramen magnum; a C hiari II malformation also includes the brainstem.
. A C hiari I malformation is a cyst in the pons; a C hiari II malformation is a cyst including the cerebellum.
. A C hiari I malformation is an absence of the fourth ventricle; a C hiari II malformation also includes the presence of hydrocephalus.
. A C hiari I malformation is a split in the spinal cord; a C hiari II malformation also includes a tight filum terminale.

Correct Answer & Explanation

. A C hiari I malformation is displacement of the cerebellum through the foramen magnum; a C hiari II malformation also includes the brainstem.

Explanation

A Chiari I malformation involves displacement of the cerebellum through the foramen magnum. A C hiari II malformation involves similar displacement of the brainstem, as well. In a C hiari II malformation, there is almost always a myelomeningocele in the lower cord. Sometimes a syrinx is also present.

Question 739

Topic: Pediatric Hip
Which of the following findings is an indication for the Bernese (Ganz) osteotomy?
. Acetabular dysplasia in a 10-year-old boy.
. A 20-year-old woman with a complete developmental dislocation of the hip.
. A 19-year-old man with osteonecrosis (Stulberg-Stage 4) secondary to Perthes disease.
. A 30-year-old woman with an anteroposterior (AP) center-edge angle of 10° and a joint space of 1 mm.
. A 35-year-old woman with an AP center-edge angle of 0° and a joint space of 2 mm

Correct Answer & Explanation

. A 30-year-old woman with an anteroposterior (AP) center-edge angle of 10° and a joint space of 1 mm.

Explanation

The Bernese (Ganz) osteotomy is contraindicated in patients with open triradiate cartilages because it crosses the cartilage. The procedure is also contraindicated in complete dislocations, incongruous hips, and advanced osteoarthritis with a joint space of 1 mm or less.

Question 740

Topic: 4. Pediatrics

Which of the following is known about the genetics of multiple hereditary exostosis (MHE):

. There is no genetic pattern for this condition.
. MHE follows an x-linked inheritance pattern.
. MHE follows an autosomal recessive pattern.
. MHE encodes glycosyltransferases needed for biosynthesis of heparan sulfate.
. MHE involves a defect in fibroblast growth factor.

Correct Answer & Explanation

. MHE encodes glycosyltransferases needed for biosynthesis of heparan sulfate.

Explanation

Multiple hereditary exostosis (MHE) is inherited as an autosomal dominant condition. There are three genes known to be involved: EXT 1, 2, and 3. EXT 1 and 2 encode glycosyltransferases needed for biosynthesis of heparan sulfate. Fibroblast growth factor receptor is abnormal in achondroplasia.

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