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4. Pediatrics MCQs

Practice Set 279 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 5561

Topic: 4. Pediatrics

In the Ponseti method for the treatment of congenital talipes equinovarus (clubfoot), what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Equinus, Cavus, Varus, Adductus

Explanation

The correct sequence of correction in the Ponseti method follows the acronym CAVE: Cavus (corrected first by supinating the forefoot to align with the midfoot), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy as the final step).

Question 5562

Topic: Pediatric Hip

A 3-month-old female is being treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). During a follow-up visit, the physician notes an absence of active knee extension on the treated side. Which of the following is the most likely cause of this complication?

. Hyperflexion of the hip by over-tightened anterior straps
. Excessive abduction by over-tightened posterior straps
. Inadequate flexion of the hip due to loose anterior straps
. Avascular necrosis of the femoral head
. Direct compression of the sciatic nerve by the harness

Correct Answer & Explanation

. Hyperflexion of the hip by over-tightened anterior straps

Explanation

The most common nerve palsy associated with the Pavlik harness is a femoral nerve palsy. This complication results from excessive hip flexion caused by over-tightening of the anterior straps, which stretches or compresses the femoral nerve. It presents clinically as a loss of active knee extension.

Question 5563

Topic: Pediatric Hip
A 12-year-old male presents with a unilateral left Slipped Capital Femoral Epiphysis (SCFE). Which of the following is the most widely accepted absolute indication for prophylactic in situ pinning of the asymptomatic contralateral right hip?
. Chronological age > 14 years at presentation
. Presence of a recognized underlying endocrine disorder (e.g., hypothyroidism)
. Body mass index > 95th percentile for age
. Symptom duration of the affected side > 3 weeks
. Grade III severity (slip angle > 50 degrees) on the affected side

Correct Answer & Explanation

. Presence of a recognized underlying endocrine disorder (e.g., hypothyroidism)

Explanation

Contralateral prophylactic pinning in SCFE is universally recommended for patients with atypical or secondary SCFE, which most commonly includes those with underlying endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or radiation therapy, as the risk of contralateral slip is extremely high (up to 100%). While age (especially <10), obesity, and open triradiate cartilage are relative indications in idiopathic SCFE, an endocrine disorder is a definitive indication.

Question 5564

Topic: Pediatric Hip

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed 6 weeks of Pavlik harness treatment for a persistently dislocated left hip. What is the most appropriate next step in management?

. Continue Pavlik harness for 6 additional weeks
. Transition to a rigid abduction orthosis (e.g., Ilfeld)
. Closed reduction and spica casting under anesthesia
. Open reduction and spica casting
. Proximal femoral derotational osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under anesthesia

Explanation

For a persistently dislocated hip at 6 months of age after failed Pavlik harness treatment, closed reduction and spica casting under anesthesia is the standard next step. Prolonging harness use in a dislocated hip increases the risk of "Pavlik harness disease" (posterior acetabular erosion).

Question 5565

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvรฉ-Perthes disease. According to the Herring lateral pillar classification, a Type C hip is characterized by what degree of height loss in the lateral pillar of the femoral head?
. No measurable height loss
. Less than 25% height loss
. Less than 50% height loss
. Greater than 50% height loss
. Complete collapse of the entire femoral epiphysis

Correct Answer & Explanation

. Less than 50% height loss

Explanation

In the Herring lateral pillar classification, Type A indicates no height loss, Type B indicates less than 50% height loss, and Type C denotes greater than 50% height loss of the lateral pillar. Type C is associated with a poor clinical prognosis.

Question 5566

Topic: Pediatric Upper Extremity & Spine
A 6-year-old girl sustains a Gartland type III extension-type supracondylar humerus fracture. Which of the following peripheral nerves is most commonly injured in this specific fracture pattern?
. Anterior interosseous nerve
. Ulnar nerve
. Posterior interosseous nerve
. Superficial radial nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in extension-type supracondylar humerus fractures. Clinically, this presents as an inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (the 'A-OK' sign).

Question 5567

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The harness is incorrectly adjusted, forcing the hip into excessive abduction. Which of the following complications is most closely associated with this positioning error?

. Femoral nerve palsy
. Avascular necrosis of the femoral head
. Inferior hip dislocation
. Obturator nerve palsy
. Transient synovitis

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Excessive abduction in a Pavlik harness places the medial circumflex femoral artery under tension, significantly increasing the risk of avascular necrosis of the femoral head. Excessive flexion, on the other hand, is associated with femoral nerve palsy.

Question 5568

Topic: 4. Pediatrics

A 2-week-old infant is undergoing serial casting using the Ponseti method for congenital talipes equinovarus (clubfoot). According to the Ponseti principles, what is the final component of the deformity to be corrected?

. Cavus
. Adductus
. Varus
. Equinus
. Supination

Correct Answer & Explanation

. Equinus

Explanation

The Ponseti method sequentially corrects the clubfoot deformity in a specific order: Cavus, Adductus, Varus, and finally Equinus (CAVE mnemonic). Equinus is corrected last, frequently requiring a percutaneous Achilles tenotomy.

Question 5569

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated in a Pavlik harness. During a follow-up visit, the mother notes the child is not actively moving her leg. Examination reveals an inability to actively extend the knee on the affected side. This complication is most directly related to which improper harness setting?

. Excessive hip abduction
. Excessive hip flexion
. Inadequate hip abduction
. Inadequate hip flexion
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

The most common nerve injury associated with the Pavlik harness is transient femoral nerve palsy, which manifests as an inability to extend the knee. This is typically caused by excessive hip flexion in the anterior straps, compressing the nerve against the inguinal ligament.

Question 5570

Topic: Pediatric Hip

An 8-month-old female is diagnosed with developmental dysplasia of the hip (DDH) after failing Pavlik harness treatment for 6 weeks. Physical examination reveals a reducible but unstable hip. What is the most appropriate next step in management?

. Continue Pavlik harness treatment for another 4 weeks.
. Initiate a program of physical therapy and observation.
. Proceed with closed reduction and hip spica cast application.
. Schedule for an open reduction with potential femoral shortening.
. Order a CT scan to assess hip morphology more precisely.

Correct Answer & Explanation

. Proceed with closed reduction and hip spica cast application.

Explanation

For DDH, if Pavlik harness treatment fails in an infant between 6-18 months of age (and sometimes earlier), closed reduction under general anesthesia followed by hip spica cast immobilization is the next standard of care. The goal is to achieve and maintain a concentric reduction. Open reduction is typically reserved for cases where closed reduction is unsuccessful or if there are specific anatomical impediments. CT scans are usually performed post-reduction in a spica cast to confirm reduction rather than as a primary diagnostic step to guide the next treatment after failed Pavlik.

Question 5571

Topic: 4. Pediatrics

A 13-year-old obese male presents with left groin pain and a limp. On examination, his left hip obligatorily externally rotates when flexed to 90 degrees. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Through which histologic zone of the physis does this slippage primarily occur?

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

Correct Answer & Explanation

. Hypertrophic zone

Explanation

Slipped capital femoral epiphysis (SCFE) typically occurs through the hypertrophic zone of the physis. This zone is biomechanically the weakest due to its large cell volume and lack of extensive collagen matrix.

Question 5572

Topic: Pediatric Upper Extremity & Spine
A 6-year-old girl sustains a severely displaced (Gartland Type III) supracondylar humerus fracture. On presentation, her radial pulse is absent, but the hand is warm, pink, and has capillary refill less than 2 seconds. What is the most appropriate initial management?
. Immediate open exploration of the brachial artery
. Urgent CT angiography of the upper extremity
. Urgent closed reduction and percutaneous pinning
. Observation with splinting in 90 degrees of flexion
. Thrombolytic therapy

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning

Explanation

A pulseless but well-perfused (pink, warm) hand following a displaced supracondylar humerus fracture should undergo urgent closed reduction and percutaneous pinning in the operating room. Anatomical reduction often relieves arterial kinking or spasm, restoring the pulse without needing vascular exploration.

Question 5573

Topic: 4. Pediatrics

An infant is diagnosed with idiopathic congenital talipes equinovarus (clubfoot). The treating orthopedic surgeon plans to utilize the Ponseti method of serial casting. In what sequence should the components of the deformity be corrected?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method systematically corrects clubfoot deformities using the 'CAVE' sequence: Cavus (elevating the first ray), Adductus, Varus, and finally Equinus. The equinus correction is typically achieved last, often requiring a percutaneous Achilles tenotomy.

Question 5574

Topic: 4. Pediatrics

A 13-year-old obese male presents with a 4-week history of left groin and knee pain. On examination, as the left hip is passively flexed, it obligatorily externally rotates. Radiographs show a widening of the left proximal femoral physis. What is the most appropriate definitive management?

. Non-weight bearing and observation
. Closed reduction and spica casting
. In situ single screw fixation
. Open reduction and internal fixation
. Proximal femoral osteotomy

Correct Answer & Explanation

. In situ single screw fixation

Explanation

The patient has a slipped capital femoral epiphysis (SCFE). The gold standard treatment is immediate in situ fixation with a single cannulated screw to prevent further slippage and reduce the risk of osteonecrosis.

Question 5575

Topic: Pediatric Hip

A 9-year-old male presents with right hip pain and a limp. BMI is in the 90th percentile. Radiographs reveal a mild right slipped capital femoral epiphysis (SCFE). What is the most appropriate routine screening indicated for this patient?

. Renal ultrasound
. Thyroid function tests
. DEXA scan
. Genetic testing for COL1A1
. Bone marrow biopsy

Correct Answer & Explanation

. Thyroid function tests

Explanation

Patients presenting with SCFE at an atypical age (less than 10 or greater than 16 years old) or with a weight less than the 50th percentile should be evaluated for endocrine disorders. Hypothyroidism is the most common associated endocrine abnormality in this population.

Question 5576

Topic: Pediatric Lower Extremity

A 2-week-old male infant is brought to the clinic with bilateral idiopathic clubfoot. The parents elect to proceed with the Ponseti method of serial casting. What is the correct order of deformity correction in this technique?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method corrects the clubfoot deformity in a specific sequence remembered by the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. The cavus is corrected first by elevating the first metatarsal to align the forefoot with the hindfoot.

Question 5577

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from monkey bars and sustains a Gartland type III extension supracondylar humerus fracture. On examination, the hand is pink but the radial pulse is absent. The child has strong capillary refill and normal motor function. What is the most appropriate next step in management?
. Emergent brachial artery exploration
. Immediate closed reduction and percutaneous pinning
. Angiography of the upper extremity
. Application of a long arm cast in 120 degrees of flexion
. Observe with hourly neurovascular checks

Correct Answer & Explanation

. Immediate closed reduction and percutaneous pinning

Explanation

For a "pulseless pink hand" following a severe supracondylar humerus fracture, the initial step is prompt closed reduction and percutaneous pinning to restore alignment. If the hand remains well-perfused despite an absent pulse post-reduction, observation is generally acceptable, avoiding immediate vascular exploration.

Question 5578

Topic: 4. Pediatrics

A 13-year-old obese boy presents with a 2-month history of left knee pain and an antalgic gait. Examination shows obligatory external rotation of the left hip when it is passively flexed. Radiographs reveal a widening of the left capital femoral physis. What is the most appropriate definitive management?

. In situ percutaneous pinning with a single cannulated screw
. Closed reduction and spica casting
. Open reduction and internal fixation
. Proximal femoral osteotomy
. Physical therapy and non-weight bearing

Correct Answer & Explanation

. In situ percutaneous pinning with a single cannulated screw

Explanation

The patient has a slipped capital femoral epiphysis (SCFE), characterized by obligatory external rotation during hip flexion. The gold standard treatment is in situ fixation using a single, centrally placed cannulated screw to prevent further slippage without risking osteonecrosis from forceful reduction.

Question 5579

Topic: Pediatric Hip

A 13-year-old obese boy presents to the emergency department unable to bear weight on his right leg after a minor fall. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Which of the following is the most devastating complication associated specifically with this presentation?

. Chondrolysis
. Avascular necrosis (AVN)
. Leg length discrepancy
. Coxa magna
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

The inability to bear weight defines an unstable SCFE. Unstable slips carry a notoriously high risk of avascular necrosis (AVN) of the femoral head, approaching 47%, which is the most devastating complication in this scenario.

Question 5580

Topic: 4. Pediatrics

A 65-year-old man presents with a bowing deformity of his tibia and enlarging hat size. Laboratory studies show normal calcium and phosphorus, but significantly elevated alkaline phosphatase. Which of the following is the primary cellular defect initiating this disease process?

. Defective osteoid mineralization
. Excessive osteoclastic bone resorption
. Impaired type I collagen synthesis
. Monoclonal proliferation of plasma cells
. Mutation in the FGFR3 gene

Correct Answer & Explanation

. Excessive osteoclastic bone resorption

Explanation

Paget's disease is characterized by an initial, aggressive lytic phase of excessive osteoclastic bone resorption. This is followed by a mixed phase and finally a sclerotic phase of disorganized, mechanically weak osteoblastic bone formation.

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