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4. Pediatrics MCQs

Practice Set 218 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 4341

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a severe Gartland Type III supracondylar humerus fracture. Upon arrival, his hand is pale and pulseless. After closed reduction and percutaneous pinning, the radial pulse remains unpalpable, but the hand becomes pink, warm, and has a capillary refill of less than 2 seconds. What is the next best step in management?
. Immediate exploration of the brachial artery
. Observation, admission, and close monitoring for 24-48 hours
. Administration of intravenous heparin
. Immediate removal of pins and transition to open reduction
. Emergent CT angiography

Correct Answer & Explanation

. Observation, admission, and close monitoring for 24-48 hours

Explanation

The 'pink, pulseless hand' after reduction of a supracondylar humerus fracture is a well-known clinical entity. If the hand is well-perfused (pink, warm, strong capillary refill), the lack of a palpable radial pulse is likely due to arterial spasm rather than a complete irreversible occlusion or transection. The standard of care is admission, elevation, and close monitoring for 24-48 hours. Immediate surgical exploration is indicated only if the hand remains 'white and pulseless' after a proper reduction.

Question 4342

Topic: 4. Pediatrics

Congenital Pseudarthrosis of the Tibia (CPT) is a notoriously difficult condition to treat and is characterized by bowing and spontaneous fractures that fail to heal. The condition has the strongest genetic and clinical association with a mutation on which chromosome?

. Chromosome 15
. Chromosome 17
. Chromosome 21
. X Chromosome
. Chromosome 4

Correct Answer & Explanation

. Chromosome 17

Explanation

Congenital pseudarthrosis of the tibia (CPT) has a very strong association with Neurofibromatosis Type 1 (NF1), occurring in up to 50% of patients with CPT. NF1 is an autosomal dominant disorder caused by a mutation in the neurofibromin gene, which is located on Chromosome 17 (17q11.2).

Question 4343

Topic: 4. Pediatrics
A 6-year-old girl complains of a painful 'clunk' and a snapping sensation on the lateral aspect of her right knee when moving from flexion to extension. MRI confirms a Watanabe Type III (Wrisberg variant) discoid lateral meniscus. What specific anatomical deficiency characterizes this specific variant?
. Complete obliteration of the medial meniscal body
. Cystic degeneration of the anterior horn of the lateral meniscus
. Absence of the posterior meniscotibial (coronary) ligament attachment
. A congenital horizontal cleavage tear propagating from the popliteus hiatus
. Hypertrophy of the meniscofemoral ligament of Humphry

Correct Answer & Explanation

. Absence of the posterior meniscotibial (coronary) ligament attachment

Explanation

The Watanabe classification describes discoid menisci. Type I is complete, Type II is incomplete, and Type III is the Wrisberg variant. The hallmark of the Wrisberg variant is the absence of the normal posterior meniscotibial (coronary) ligament capsular attachments, leaving only the Wrisberg ligament attached to the posterior horn. This results in hypermobility and a symptomatic 'snapping' knee during extension as the meniscus subluxates.

Question 4344

Topic: 4. Pediatrics
Pediatric hip fractures are rare and associated with a high rate of complications. According to the Delbet classification, which fracture type is associated with the highest rate of avascular necrosis (AVN) of the femoral head?
. Delbet Type I (Transepiphyseal)
. Delbet Type II (Transcervical)
. Delbet Type III (Cervicotrochanteric)
. Delbet Type IV (Intertrochanteric)
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Delbet Type I (Transepiphyseal)

Explanation

The Delbet classification for pediatric hip fractures dictates that Type I (transepiphyseal) fractures have the highest rate of avascular necrosis, approaching 90-100% in some series, because it completely disrupts the precarious retinacular blood supply traversing the neck to the epiphysis. Type II (transcervical) is the most common pediatric hip fracture and also carries a very high AVN rate (~50%). AVN risk decreases moving distally down the neck to the intertrochanteric line.

Question 4345

Topic: 4. Pediatrics

Proximal Focal Femoral Deficiency (PFFD), also known as Congenital Femoral Deficiency, presents with marked limb length discrepancy, external rotation, and flexion at the hip. It is most commonly associated with which of the following intra-articular knee anomalies?

. Posterior cruciate ligament agenesis
. Anterior cruciate ligament agenesis
. Patellar duplication
. Bipartite patella
. Medial collateral ligament hypoplasia

Correct Answer & Explanation

. Anterior cruciate ligament agenesis

Explanation

Proximal Focal Femoral Deficiency (PFFD) is heavily associated with fibular hemimelia, coxa vara, and knee instability. The most common intra-articular anomaly in these patients is agenesis or hypoplasia of the Anterior Cruciate Ligament (ACL). This must be carefully evaluated before attempting major limb lengthening procedures, as lengthening a knee with ACL deficiency can lead to posterior subluxation of the tibia.

Question 4346

Topic: 4. Pediatrics
Madelung deformity is a congenital wrist deformity characterized by premature closure of the volar-ulnar aspect of the distal radial physis. It frequently presents bilaterally in adolescent females. This specific deformity is the hallmark skeletal manifestation of Léri-Weill dyschondrosteosis, which is caused by a mutation in which gene?
. FGFR3
. COL1A1
. SHOX
. FBN1
. COMP

Correct Answer & Explanation

. SHOX

Explanation

Madelung deformity presents with a V-shaped radiocarpal joint and dorsal prominence of the distal ulna due to tethering by Vickers' ligament and premature distal radial physeal arrest. While it can occur idiopathically, when present as part of Léri-Weill dyschondrosteosis (mesomelic dwarfism), it is due to a mutation or deletion of the SHOX (Short Stature Homeobox) gene, which is located on the pseudoautosomal region of the X and Y chromosomes.

Question 4347

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for an ultrasonographically confirmed irreducible right hip dislocation. At the 2-week follow-up, the parents report the infant is no longer kicking her right leg. Examination reveals absent active knee extension on the right, but active ankle dorsiflexion and plantarflexion are preserved. Ultrasound confirms the hip remains dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness and add targeted physical therapy for the quadriceps.
. Adjust the anterior straps to increase hip flexion past 100 degrees to facilitate reduction.
. Abandon the Pavlik harness and immediately transition to a rigid abduction orthosis.
. Remove the Pavlik harness and allow a period of rest to facilitate neurologic recovery before attempting alternative treatment.
. Perform an immediate closed reduction and application of a hip spica cast under general anesthesia.

Correct Answer & Explanation

. Remove the Pavlik harness and allow a period of rest to facilitate neurologic recovery before attempting alternative treatment.

Explanation

The patient has developed a femoral nerve palsy, a known complication of the Pavlik harness, typically caused by excessive hip flexion pressing the nerve against the inguinal ligament. If the hip is still dislocated and a femoral nerve palsy develops, the harness must be discontinued (the so-called 'Pavlik holiday'). A period of rest allows for neurologic recovery before pursuing alternative treatments, such as closed reduction and spica casting. Continuing the harness or increasing flexion risks permanent nerve damage and vascular compromise.

Question 4348

Topic: Pediatric Hip
An 8.5-year-old boy presents with a 4-month history of a painless limp. Radiographs demonstrate fragmentation of the capital femoral epiphysis with >50% maintenance of the lateral pillar height. He has 15 degrees of abduction and a 10-degree flexion contracture. Based on his age and radiographic classification, which treatment provides the best long-term radiographic outcome?
. Strict non-weight bearing in a wheelchair
. Application of an A-frame abduction orthosis
. Proximal femoral varus osteotomy
. In situ percutaneous pinning of the epiphysis
. Core decompression of the femoral head

Correct Answer & Explanation

. Proximal femoral varus osteotomy

Explanation

This patient has Legg-Calvé-Perthes disease with a Herring lateral pillar B classification (maintenance of >50% lateral pillar height). The Herring classification and age at onset dictate treatment. Studies have shown that for patients > 8 years old with Herring B or B/C border hips, surgical containment (such as a proximal femoral varus osteotomy or pelvic osteotomy) significantly improves radiographic outcomes (Stulberg classification) and reduces the risk of early osteoarthritis compared to nonoperative management.

Question 4349

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a Gartland type III extension supracondylar humerus fracture. On presentation, his hand is pink and warm, but the radial pulse is non-palpable. Urgent closed reduction and percutaneous pinning are performed. Postoperatively, the fracture is anatomically aligned on fluoroscopy, but the radial pulse remains absent. Capillary refill is 2 seconds and the hand remains warm. What is the most appropriate management?
. Immediate exploration of the brachial artery in the antecubital fossa.
. Perform a CT angiogram of the upper extremity.
. Observation and hospital admission for close serial neurovascular monitoring.
. Remove the pins and open the fracture anteriorly to clear the neurovascular bundle.
. Prescribe intravenous heparin and obtain a vascular surgery consult.

Correct Answer & Explanation

. Observation and hospital admission for close serial neurovascular monitoring.

Explanation

The management of a 'pulseless pink hand' following anatomical closed reduction and pinning of a pediatric supracondylar humerus fracture is close observation. The hand's pink color, warmth, and brisk capillary refill indicate that collateral circulation is sufficient to perfuse the extremity despite a presumed brachial artery vasospasm or non-occlusive intimal flap. Immediate vascular exploration is strictly indicated if the hand becomes dysvascular (white, cold, absent capillary refill) after reduction.

Question 4350

Topic: Pediatric Upper Extremity & Spine
A newborn male presents with bilateral radial longitudinal deficiency (absent radii and absent thumbs). A chromosomal breakage test using diepoxybutane is positive. If left untreated, what is the most common cause of mortality associated with this patient's underlying diagnosis?
. Congenital heart failure
. End-stage renal disease
. Bone marrow failure
. Tracheoesophageal fistula complications
. Severe immunodeficiency

Correct Answer & Explanation

. Bone marrow failure

Explanation

The patient's clinical presentation (radial clubhand) combined with a positive chromosomal breakage test using diepoxybutane (DEB) or mitomycin C definitively diagnoses Fanconi anemia. Fanconi anemia is an autosomal recessive condition that leads to progressive pancytopenia and bone marrow failure, which is the most common cause of mortality in these patients. It is critical to differentiate it from other causes of radial longitudinal deficiency, such as Holt-Oram (cardiac), TAR syndrome (thrombocytopenia but thumbs are present), and VACTERL.

Question 4351

Topic: 4. Pediatrics

A 5-year-old child with a history of multiple low-energy fractures, easy bruising, and blue sclerae is diagnosed with Osteogenesis Imperfecta type I. Genetic testing is most likely to reveal a defect in the synthesis or structure of which of the following?

. Type II collagen
. Type I collagen
. Cartilage oligomeric matrix protein (COMP)
. Fibroblast growth factor receptor 3 (FGFR3)
. Type IX collagen

Correct Answer & Explanation

. Type I collagen

Explanation

Osteogenesis Imperfecta (OI) is a genetic disorder of connective tissue primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes. These genes are responsible for the production of Type I collagen, the major structural protein found in bone, skin, and sclerae. Type I OI is the most common and mildest form, resulting from a quantitative defect (decreased production) of structurally normal Type I collagen. Type II collagen defects are associated with spondyloepiphyseal dysplasia, COMP with pseudoachondroplasia, and FGFR3 with achondroplasia.

Question 4352

Topic: Pediatric Hip

A 9-year-old male presents with bilateral knee pain and a waddling gait. He is in the 10th percentile for weight and 5th percentile for height. Radiographs reveal bilateral slipped capital femoral epiphyses (SCFE). Given the patient's age and bilateral presentation, an endocrine workup is initiated. Which of the following conditions is most commonly associated with this presentation?

. Hypothyroidism
. Hyperthyroidism
. Hyperparathyroidism
. Type 1 Diabetes Mellitus
. Cushing's disease

Correct Answer & Explanation

. Hypothyroidism

Explanation

Atypical Slipped Capital Femoral Epiphysis (SCFE) occurs in patients who fall outside the classic age range (boys <12 or >14), those who are underweight or short-statured, or those who present with synchronous bilateral involvement. These patients have a high likelihood of an underlying endocrine or metabolic disorder. Hypothyroidism is the single most common endocrine disorder associated with atypical SCFE. Other causes include panhypopituitarism, growth hormone deficiency, and renal osteodystrophy.

Question 4353

Topic: Pediatric Hip

A 12-year-old girl with primary hypothyroidism presents with a stable left Slipped Capital Femoral Epiphysis (SCFE) and undergoes in situ pinning. Her right hip is currently asymptomatic and radiographically normal. What is the most appropriate management regarding her contralateral right hip?

. Clinical and radiographic observation every 6 months
. Prophylactic pinning in situ of the right hip
. Application of a hip spica cast
. Prophylactic epiphysiodesis of the greater trochanter
. Arthroscopic capsulotomy of the right hip

Correct Answer & Explanation

. Prophylactic pinning in situ of the right hip

Explanation

Patients with endocrine disorders (such as hypothyroidism) have a significantly higher risk (up to 80-100%) of developing a contralateral SCFE. Prophylactic in situ pinning of the contralateral hip is highly recommended in these patients.

Question 4354

Topic: Pediatric Hip

A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother reports the infant is not kicking the left leg as much. On examination, the infant exhibits absent active knee extension on the left. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to increase hip abduction
. Remove the harness for a period of rest and observation
. Switch immediately to a rigid abduction orthosis (e.g., Rhino cruiser)
. Perform a closed reduction and application of a spica cast

Correct Answer & Explanation

. Remove the harness for a period of rest and observation

Explanation

Decreased active knee extension in a Pavlik harness is the classic presentation of a femoral nerve palsy, typically caused by excessive hip flexion. The harness must be removed immediately to allow for neurologic recovery, which usually occurs within a few weeks.

Question 4355

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs demonstrate exactly 50% loss of lateral pillar height. According to the Herring lateral pillar classification and patient age, which treatment has been shown to provide the best long-term radiographic outcome (Stulberg I or II)?
. Strict weight-bearing restriction and crutches
. Physical therapy focusing on abduction exercises
. Surgical containment (e.g., femoral or pelvic osteotomy)
. Observation with serial radiographs
. Botulinum toxin injection to the adductors

Correct Answer & Explanation

. Surgical containment (e.g., femoral or pelvic osteotomy)

Explanation

This patient has Herring Group B/C border disease. Multicenter prospective studies have shown that children over 8 years of age at the onset of symptoms with Herring Group B or B/C border hips have significantly better radiographic outcomes with surgical containment compared to nonoperative treatment.

Question 4356

Topic: Pediatric Upper Extremity & Spine
A 6-year-old girl sustains an extension-type Gartland III supracondylar humerus fracture. Examination reveals an inability to actively flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is most likely injured?
. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve (AIN)
. Posterior interosseous nerve (PIN)
. 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. Injury presents with an inability to form an 'OK' sign due to weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 4357

Topic: 4. Pediatrics
A 14-year-old boy presents with an ankle injury after an external rotation force. Radiographs demonstrate a Salter-Harris III fracture of the anterolateral distal tibia (Tillaux fracture). Which of the following describes the normal sequence of distal tibial physeal closure that explains this fracture pattern?
. Central -> Anteromedial -> Posteromedial -> Anterolateral
. Central -> Posteromedial -> Anteromedial -> Anterolateral
. Anterolateral -> Anteromedial -> Posteromedial -> Central
. Posteromedial -> Central -> Anteromedial -> Anterolateral
. Anteromedial -> Central -> Posteromedial -> Anterolateral

Correct Answer & Explanation

. Central -> Posteromedial -> Anteromedial -> Anterolateral

Explanation

The distal tibial physis closes in a predictable pattern: Central, followed by Posteromedial, then Anteromedial, and finally Anterolateral. Because the anterolateral physis is the last to close, it is susceptible to avulsion (Tillaux fracture) from the anterior inferior tibiofibular ligament during external rotation.

Question 4358

Topic: 4. Pediatrics

A 2-year-old boy with neurofibromatosis type 1 (NF1) presents with pronounced anterolateral bowing of the left tibia and a frank pseudarthrosis on radiographs. What is the most definitive surgical management strategy to achieve long-term union?

. Serial casting until age 5 followed by bracing
. Resection of the pseudarthrosis, bone grafting, and intramedullary fixation
. Ilizarov external fixation with gradual angular correction
. Compression plate fixation without bone grafting
. Below-knee amputation

Correct Answer & Explanation

. Resection of the pseudarthrosis, bone grafting, and intramedullary fixation

Explanation

Congenital pseudarthrosis of the tibia in NF1 is notoriously difficult to heal. The gold standard surgical management involves complete resection of the hamartomatous tissue, autogenous bone grafting, and intramedullary rodding (often combined with a cross-union to the fibula).

Question 4359

Topic: 4. Pediatrics

A 4-year-old child with achondroplasia presents to the clinic with progressive weakness in the lower extremities, hyperreflexia, and new-onset central sleep apnea. What is the most critical anatomical region to evaluate urgently with an MRI?

. Cervicomedullary junction (Foramen magnum)
. Thoracolumbar junction
. Lumbosacral junction
. Subaxial cervical spine
. Atlantoaxial articulation

Correct Answer & Explanation

. Cervicomedullary junction (Foramen magnum)

Explanation

Achondroplasia causes impaired endochondral bone formation, leading to a narrowed foramen magnum. Severe stenosis at the cervicomedullary junction can cause profound upper motor neuron signs, central sleep apnea, and sudden death, requiring urgent decompression.

Question 4360

Topic: Pediatric Lower Extremity
A 4-year-old boy, previously treated successfully with the Ponseti method for idiopathic clubfoot, presents with dynamic supination of the foot during the swing phase of gait. Passive range of motion of the ankle and subtalar joints is normal. What is the most appropriate surgical treatment?
. Repeat percutaneous Achilles tenotomy
. Split anterior tibial tendon transfer (SPLATT)
. Full anterior tibial tendon transfer to the lateral cuneiform
. Extensive posterior medial surgical release
. Lateral sliding calcaneal osteotomy

Correct Answer & Explanation

. Full anterior tibial tendon transfer to the lateral cuneiform

Explanation

Dynamic supination in a relapsed clubfoot that has maintained passive flexibility is treated with a full transfer of the anterior tibial tendon to the lateral cuneiform. A split transfer (SPLATT) does not provide enough eversion power in true clubfoot relapse.

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