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4. Pediatrics MCQs

Practice Set 38 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 741

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-month history of right groin pain and a limp. On examination, his right hip obligatory externally rotates when passively flexed to 90 degrees. Radiographs confirm a stable, severe slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate initial management?

. Closed reduction and spica casting
. In situ percutaneous pinning
. Open reduction and internal fixation
. Proximal femoral osteotomy
. Skeletal traction

Correct Answer & Explanation

. In situ percutaneous pinning

Explanation

In situ percutaneous pinning with a single cannulated screw is the gold standard treatment for a stable SCFE to prevent further slippage. Closed reduction is contraindicated due to a high risk of iatrogenic avascular necrosis.

Question 742

Topic: Pediatric Hip

A 7-month-old infant is referred for developmental dysplasia of the hip (DDH) after failing a 6-week trial of a Pavlik harness. Ultrasound confirms persistent superior and lateral displacement of the femoral head. What is the most appropriate next step in management?

. Continue Pavlik harness for 4 more weeks
. Transition to a rigid abduction orthosis
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy
. Varus derotational osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In an infant older than 6 months who has failed Pavlik harness treatment, the next appropriate step is an examination under anesthesia, arthrogram, and closed reduction with spica casting. Continuing a failed harness risks "Pavlik harness disease" (posterior acetabular wear).

Question 743

Topic: 4. Pediatrics

A 3-year-old girl is brought to the emergency department with a 2-day history of right hip pain, refusal to bear weight, a temperature of 39.0 C, a white blood cell count of 15,000/mm3, and an erythrocyte sedimentation rate of 55 mm/hr. What is the most appropriate definitive management?

. Intravenous antibiotics and observation
. Aspiration and cast immobilization
. Emergent surgical irrigation and debridement
. MRI to confirm diagnosis before intervention
. Oral antibiotics and outpatient follow-up

Correct Answer & Explanation

. Emergent surgical irrigation and debridement

Explanation

This child meets all four Kocher criteria, making the probability of septic arthritis >99%. The definitive and limb-saving treatment for a pediatric septic hip is emergent surgical irrigation and debridement to prevent irreversible articular cartilage destruction.

Question 744

Topic: Pediatric Hip

A 13-year-old obese boy presents with sudden inability to bear weight on his left leg after a minor trip. Radiographs show a slipped capital femoral epiphysis (SCFE). What is the most significant risk factor for the development of avascular necrosis (AVN) in this patient?

. Degree of posterior slip
. Patient body mass index (BMI)
. Instability of the slip (inability to bear weight)
. Bilateral involvement
. Age at presentation

Correct Answer & Explanation

. Instability of the slip (inability to bear weight)

Explanation

Slip stability is the primary prognostic factor for developing AVN in SCFE. Unstable slips, defined clinically by the inability to bear weight even with crutches, carry an AVN risk of up to 47%, compared to less than 10% for stable slips.

Question 745

Topic: Pediatric Hip

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the first follow-up, the infant shows decreased active knee extension on the treated side. This complication is most commonly caused by:

. Hyperflexion of the hip in the harness
. Excessive abduction of the hip in the harness
. Inadequate flexion of the hip in the harness
. Excessive adduction of the hip in the harness
. Direct pressure over the fibular head

Correct Answer & Explanation

. Hyperflexion of the hip in the harness

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hips. Management involves adjusting the harness to decrease flexion and monitoring for spontaneous recovery.

Question 746

Topic: 4. Pediatrics

A 13-year-old obese male presents with a 3-week history of groin pain and an antalgic gait. Examination reveals obligatory external rotation of the hip with passive flexion. An AP radiograph of the pelvis shows a widened physis and the 'Klein line' not intersecting the epiphysis. Which of the following complications is most specifically associated with unrecognized penetration of the posterosuperior femoral neck cortex by the screw during in situ fixation?

. Chondrolysis
. Avascular necrosis
. Femoral neck fracture
. Impingement of the anterior femoral head-neck junction
. Slip progression

Correct Answer & Explanation

. Avascular necrosis

Explanation

Unrecognized penetration of the posterosuperior femoral neck cortex during in situ pinning of a slipped capital femoral epiphysis (SCFE) risks direct injury to the lateral epiphyseal vessels. This disruption is a primary iatrogenic cause of avascular necrosis in these patients.

Question 747

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 is:

. 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 748

Topic: 4. Pediatrics

A 7-year-old boy is brought in for an examination due to back pain. He has limited forward bending. Neurologic examination is normal. Radiographs reveal a uniform flattening of the third lumbar vertebra to 10% of its normal height. His temperature is 37.1° C and his white blood count is 11,000. The erythrocyte sedimentation rate is 18. The most likely diagnosis is:

. Osteogenesis imperfecta
. Eosinophilic granuloma
. Tuberculosis
. Bacterial infection
. C ompression fracture

Correct Answer & Explanation

. Eosinophilic granuloma

Explanation

Eosinophilic granuloma often produces complete flattening of a single vertebral body in the absence of trauma or neurologic deficit. Osteogenesis imperfecta produces a more uniform flattening of the vertebrae but not by this degree. Tuberculosis rarely produces this much flattening of a single vertebra. The erythrocyte sedimentation rate is elevated in this condition. Bacterial infection rarely produces this much flattening of a single vertebral body without associated disk changes. The lab studies should suggest an inflammatory process. C ompression fracture produces less complete flattening of the vertebral bodies.

Question 749

Topic: 4. Pediatrics

An infant is born with fibular hemimelia and has 20% shortening of the involved below-knee segment. Four rays are present on the foot, and the ankle is in slight valgus. Limb lengthening is likely to be superior to Syme disarticulation in which of the following parameters:

. Pain
. Function
. Psychological acceptance
. Number of procedures
. Prosthetic costs

Correct Answer & Explanation

. Number of procedures

Explanation

The cost of prosthetics is greater in the disarticulation group. Pain is greater in the lengthened group. Function is equal to or better in the group who had disarticulation. Psychological acceptance is greater in the disarticulation group. The lengthened group requires more than twice the number of procedures.

Question 750

Topic: 4. Pediatrics

Morquio syndrome is caused by a deficiency in:

. Alpha-L-iduronidase
. Galactose-6-sulfatase
. Beta-glucuronidase
. Fibroblast growth factor receptor protein
. Sulfate transport protein

Correct Answer & Explanation

. Galactose-6-sulfatase

Explanation

Morquio syndrome is a member of the family of mucopolysaccharidoses. Morquio syndrome is a deficiency in the enzyme galactose-6-sulfatase. A deficiency in galactose-6-sulfatase results in increased urinary excretion of keratosulfate. Alpha-L-iduronidase is deficient in Hurler syndrome. Beta-glucuronidase is deficient in some rare mucopolysaccharidoses. Fibroblast growth factor receptor protein is deficient in achondroplasia. Sulfate transport protein is deficient in diastrophic dysplasia.

Question 751

Topic: 4. Pediatrics

Pleiotropy is demonstrated by which of the following examples:

. Patients with osteogenesis imperfecta differ in the number of fractures they have received.
. Patients with hemophilia A have different target joints.
. Hurler syndrome is usually not present in prior generations of an affected patient.
. Some patients with Marfan syndrome have scoliosis or pectus carinatum, while other patients with Marfan syndrome do not.
. Patients with Ollier disease often have more involvement on one side of the body.

Correct Answer & Explanation

. Some patients with Marfan syndrome have scoliosis or pectus carinatum, while other patients with Marfan syndrome do not.

Explanation

The term pleiotropy refers to a disease taking different shapes in various patients. Variation in the severity of a given problem is better termed "variable expressivity." Target joints are not genetically determined. Hurler syndrome usually not being present in prior generations of an affected patient is an example of autosomal recessive inheritance. The term pleiotropy refers to a disease taking different shapes in different subjects, whereas the cause of patients with Ollier disease having more involvement on one side of the body is unknown.

Question 752

Topic: 4. Pediatrics

A 6-year-old child suffers a displaced fracture of the distal humerus in the supracondylar region. The surgeon decides to reduce and pin the fracture. Which of the following risks increases if the procedure is delayed more than 8 hours?

. Brachial artery damage
. Median nerve palsy
. Radial nerve palsy
. Need for an open reduction
. No risks increase

Correct Answer & Explanation

. No risks increase

Explanation

A retrospective comparison study has shown no increase of risks in delayed treatment of supracondylar fractures as long as the neurovascular examination is within normal limits.

Question 753

Topic: 4. Pediatrics

Which of the following statements is true regarding the growth plates around the ankle:

. The distal fibula grows more than the distal tibia.
. The distal tibia grows more than the distal fibula.
. The anterolateral portion of the tibial physis ceases growing first.
. The two physes should be at an even level.
. The two growth plates are part of a common physis.

Correct Answer & Explanation

. The distal tibia grows more than the distal fibula.

Explanation

The distal tibia grows more than the distal fibula. The anterolateral portion of the tibial physis ceases growing last, thus explaining the phenomenon of the Tillaux fracture. The physis of the distal fibula is always located more distally than the distal tibia. The two physes are not conjoined.

Question 754

Topic: 4. Pediatrics

A 5-year-old boy presents with short stature, a short trunk, and a barrel chest. Radiographs show delayed ossification of the epiphyses and a hypoplastic odontoid. What is the genetic mutation associated with this condition?

. FGFR3
. COMP
. COL1A1
. COL2A1
. RUNX2

Correct Answer & Explanation

. COL2A1

Explanation

Spondyloepiphyseal dysplasia congenita (SEDC) is caused by a mutation in the COL2A1 gene. It is characterized by short-trunk dwarfism, coxa vara, and atlantoaxial instability due to odontoid hypoplasia.

Question 755

Topic: 4. Pediatrics

A 9-year-old boy presents with bilateral knee pain and a waddling gait. Radiographs show a "double-layer" patella. Which of the following genes is most commonly mutated in this condition?

. COMP
. SOX9
. FGFR3
. COL1A1
. GNAS

Correct Answer & Explanation

. COMP

Explanation

A double-layer patella is a classic radiographic sign of multiple epiphyseal dysplasia (MED). The most common mutation in MED is in the COMP gene (Cartilage Oligomeric Matrix Protein).

Question 756

Topic: 4. Pediatrics

A 14-year-old female presents with broad shoulders and the ability to appose her shoulders in the midline anteriorly. She has delayed closure of her cranial sutures. Which orthopedic condition is she at highest risk of developing?

. Anterolateral tibial bowing
. Coxa vara
. Spondylolisthesis
. Odontoid hypoplasia
. Tarsal coalition

Correct Answer & Explanation

. Coxa vara

Explanation

Cleidocranial dysplasia is caused by a RUNX2 (CBFA1) mutation. Patients classically have hypoplastic or absent clavicles and are at high risk for developing progressive coxa vara.

Question 757

Topic: 4. Pediatrics

A 1-year-old child with multiple cafe-au-lait spots is noted to have isolated anterolateral bowing of the tibia. What is the recommended initial management to prevent fracture and progression to pseudarthrosis?

. Observation alone
. Total contact orthosis
. Corrective osteotomy and plate fixation
. Intramedullary rodding
. Vascularized fibular graft

Correct Answer & Explanation

. Total contact orthosis

Explanation

Anterolateral bowing of the tibia is associated with Neurofibromatosis Type 1 and often progresses to congenital pseudarthrosis of the tibia (CPT). A total contact orthosis is initially used to brace the limb and delay or prevent fracture.

Question 758

Topic: 4. Pediatrics

A patient with osteogenesis imperfecta type I is undergoing intramedullary rodding of the femur. Which of the following anesthetic considerations is uniquely crucial for this patient population?

. Risk of malignant hyperthermia
. Increased risk of basilar invagination during intubation
. Absolute contraindication to regional anesthesia
. Propofol infusion syndrome
. Hyperkalemic arrest with succinylcholine

Correct Answer & Explanation

. Increased risk of basilar invagination during intubation

Explanation

Patients with OI, especially severe types, frequently have basilar invagination and cervical instability. Extreme care must be taken during neck extension for intubation to avoid spinal cord compression.

Question 759

Topic: 4. Pediatrics

An infant with achondroplasia presents with sleep apnea, hypotonia, and hyperreflexia. An MRI reveals stenosis of the foramen magnum. Which of the following mechanisms best explains this pathophysiology?

. Premature fusion of the neurocentral synchondroses
. Premature closure of the sagittal suture
. Defective endochondral ossification of the cranial base
. Defective intramembranous ossification of the calvaria
. Hypertrophy of the ligamentum flavum

Correct Answer & Explanation

. Defective endochondral ossification of the cranial base

Explanation

Achondroplasia is caused by an FGFR3 mutation that inhibits endochondral ossification. The cranial base forms via endochondral ossification, leading to premature synchondrosis closure and foramen magnum stenosis.

Question 760

Topic: 4. Pediatrics

A 6-year-old child presents with a short, webbed neck and a low posterior hairline. Radiographs show multiple fused cervical vertebrae. Which of the following organ systems must be evaluated as a priority in this patient?

. Pulmonary
. Gastrointestinal
. Renal
. Endocrine
. Hematopoietic

Correct Answer & Explanation

. Renal

Explanation

Klippel-Feil syndrome is associated with renal anomalies in up to 30% of patients, including unilateral renal agenesis. Renal ultrasonography is a critical part of the initial screening protocol.

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