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4. Pediatrics MCQs

Practice Set 142 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 2821

Topic: Pediatric Hip

A 14-year-old boy with a history of a chronic, stable slipped capital femoral epiphysis pinned in-situ 1 year ago presents with increasing hip pain and stiffness. Radiographs show joint space narrowing and subchondral cysts in both the femoral head and acetabulum. What is the most likely diagnosis?

. Avascular necrosis
. Chondrolysis
. Septic arthritis
. Pin penetration into the joint
. Cam impingement

Correct Answer & Explanation

. Avascular necrosis

Explanation

Chondrolysis is a severe complication of SCFE characterized by progressive joint space narrowing and stiffness. It is strongly associated with unrecognized intra-articular hardware penetration during pinning.

Question 2822

Topic: Pediatric Hip

On an AP pelvis radiograph of a 12-year-old patient with suspected early SCFE, which line is drawn along the superior margin of the femoral neck to check for intersection with the lateral epiphysis?

. Shenton's line
. Klein's line
. Hilgenreiner's line
. Perkins' line
. Skinner's line

Correct Answer & Explanation

. Shenton's line

Explanation

Klein's line is drawn along the superior aspect of the femoral neck on an AP radiograph. In a normal hip, it should intersect the lateral aspect of the femoral epiphysis.

Question 2823

Topic: Pediatric Upper Extremity & Spine

When evaluating the adequacy of a closed reduction for a pediatric supracondylar humerus fracture, Baumann's angle is primarily used to assess:

. Sagittal plane rotation
. Coronal plane angulation (varus/valgus)
. Flexion/extension of the distal fragment
. Anterior humeral line intersection
. Humeral version

Correct Answer & Explanation

. Sagittal plane rotation

Explanation

Baumann's angle is used to evaluate coronal plane alignment. It helps ensure correct reduction and prevent cubitus varus deformity.

Question 2824

Topic: 4. Pediatrics

A 10-year-old boy has a visible cubitus varus deformity 3 years after a supracondylar humerus fracture. Which of the following statements regarding this deformity is true?

. It typically causes significant functional impairment and loss of elbow range of motion
. It is most commonly caused by physeal arrest of the medial condyle
. It is primarily a cosmetic issue and rarely causes functional limitations
. Spontaneous remodeling usually corrects the deformity by skeletal maturity
. It is associated with a high rate of delayed median nerve palsy

Correct Answer & Explanation

. It typically causes significant functional impairment and loss of elbow range of motion

Explanation

Cubitus varus following a supracondylar humerus fracture is usually due to malunion, not physeal arrest. It is primarily a cosmetic deformity without significant functional limitation.

Question 2825

Topic: 4. Pediatrics

In which of the following scenarios is the use of a Pavlik harness absolutely contraindicated for the treatment of a dislocated hip?

. A 2-week-old infant with a positive Ortolani sign
. A 6-week-old infant with an irreducible hip dislocation (negative Ortolani)
. A 10-week-old infant with teratologic hip dislocation due to arthrogryposis
. A 4-week-old infant with bilateral DDH
. An 8-week-old infant with an ultrasound alpha angle of 45 degrees

Correct Answer & Explanation

. A 2-week-old infant with a positive Ortolani sign

Explanation

Teratologic hip dislocations are rigid and do not respond to Pavlik harness treatment. Attempts to use it can lead to severe complications like iatrogenic fractures or avascular necrosis.

Question 2826

Topic: Pediatric Hip

In a slipped capital femoral epiphysis, the displacement of the femoral neck relative to the capital epiphysis is typically in which direction?

. Posterior and medial
. Anterior and lateral
. Posterior and lateral
. Anterior and medial
. Superior and lateral

Correct Answer & Explanation

. Posterior and medial

Explanation

In SCFE, the epiphysis stays relatively fixed in the acetabulum while the femoral neck displaces anteriorly, laterally, and externally rotates relative to the epiphysis.

Question 2827

Topic: Pediatric Upper Extremity & Spine

A 4-year-old falls on an outstretched hand. Radiographs show a supracondylar humerus fracture with an intact posterior cortex but an anterior humeral line that passes anterior to the capitellum. How is this fracture classified?

. Gartland Type I
. Gartland Type II
. Gartland Type III
. Gartland Type IV
. Flexion-type fracture

Correct Answer & Explanation

. Gartland Type I

Explanation

A Gartland Type II fracture is characterized by displacement (extension) with an intact posterior hinge (cortex). The anterior humeral line will pass anterior to the middle third of the capitellum.

Question 2828

Topic: Pediatric Upper Extremity & Spine

Which of the following is true regarding flexion-type supracondylar humerus fractures compared to extension-type fractures?

. They are more common, accounting for 70% of cases
. They require the elbow to be immobilized in full flexion to maintain reduction
. They are more likely to require open reduction due to entrapped periosteum or muscle
. They are most commonly associated with anterior interosseous nerve injuries
. The distal fragment is displaced posteriorly relative to the humerus

Correct Answer & Explanation

. They are more common, accounting for 70% of cases

Explanation

Flexion-type supracondylar fractures frequently require open reduction because the reduction is often blocked by interposed tissue. They are immobilized in relative extension, and the ulnar nerve is most commonly injured.

Question 2829

Topic: Pediatric Hip

While performing a closed reduction and spica casting for a 9-month-old with DDH, what is the optimal "safe zone" of Ramsey to ensure joint stability while minimizing the risk of avascular necrosis?

. Maximal abduction and internal rotation
. The arc between the angle of redislocation (adduction) and the angle of maximal abduction
. The arc between 0 degrees and 30 degrees of flexion
. The arc between maximal internal and external rotation
. 90 degrees of flexion and 90 degrees of abduction

Correct Answer & Explanation

. Maximal abduction and internal rotation

Explanation

The safe zone of Ramsey is the arc of abduction between the angle where the hip redislócates and the angle of maximal abduction. Extreme abduction dramatically increases the risk of avascular necrosis.

Question 2830

Topic: Pediatric Hip

When performing in-situ percutaneous pinning of a severe slipped capital femoral epiphysis, the starting point for the guide wire on the lateral femur should be:

. Distal to the lesser trochanter
. At the level of the greater trochanteric tip
. Anterior and proximal on the femoral neck
. Anterior to the mid-axial line of the proximal femur
. At the exact center of the lateral cortex

Correct Answer & Explanation

. Distal to the lesser trochanter

Explanation

Because the femoral neck displaces anteriorly and externally rotates, the starting point for the screw must be more anterior and proximal on the femoral neck to achieve the correct trajectory.

Question 2831

Topic: 4. Pediatrics

A 6-year-old child presents with a displaced extension-type supracondylar fracture. On neurologic examination, the child is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is injured?

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

Correct Answer & Explanation

. Ulnar nerve

Explanation

The anterior interosseous nerve (AIN) innervates the flexor pollicis longus and the radial half of the flexor digitorum profundus. Injury is indicated by the inability to make an 'OK' sign.

Question 2832

Topic: Pediatric Hip

A 4-month-old girl is currently being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). Her mother reports that the infant has stopped actively extending her knee on the treated side. Which of the following is the most appropriate next step in management?

. Increase the hip flexion in the harness to improve stability
. Reassure the mother and continue the current harness settings
. Discontinue the harness temporarily or adjust to decrease hip flexion
. Switch immediately to a rigid hip spica cast
. Perform an emergent closed reduction in the operating room

Correct Answer & Explanation

. Increase the hip flexion in the harness to improve stability

Explanation

Decreased active knee extension in a Pavlik harness suggests a femoral nerve palsy, typically caused by hyperflexion of the hip. The harness should be temporarily removed or adjusted to decrease flexion until neurologic function returns.

Question 2833

Topic: Pediatric Hip

A 13-year-old boy presents to the emergency department with acute-onset left hip pain after tripping. He is completely unable to bear weight on the left leg, even with crutches. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Based on the Loder classification, what is the most significant complication risk associated with this specific presentation?

. Chondrolysis
. Avascular necrosis (AVN)
. Leg length discrepancy
. Premature osteoarthritis
. Femoroacetabular impingement

Correct Answer & Explanation

. Chondrolysis

Explanation

According to the Loder classification, a SCFE is unstable if the patient cannot bear weight even with crutches. Unstable slips carry a significantly higher risk of avascular necrosis (AVN), historically reported to be up to 47%.

Question 2834

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a severe extension-type supracondylar humerus fracture (Gartland Type III). On examination, he cannot flex the interphalangeal joint of his thumb or the distal interphalangeal joint of his index finger. Which nerve is most likely injured?

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

Correct Answer & Explanation

. Ulnar 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. Injury presents as an inability to form the 'A-OK' sign due to weakness of the flexor pollicis longus and flexor digitorum profundus.

Question 2835

Topic: Pediatric Hip

A 2-year-old girl is diagnosed with untreated developmental dysplasia of the left hip. Radiographs show a dislocated left hip with a false acetabulum and an acetabular index of 42 degrees. Which of the following surgical strategies is most appropriate for achieving a stable, concentric reduction?

. Closed reduction and spica casting
. Open reduction alone
. Open reduction with a pelvic osteotomy and possible femoral shortening
. In situ shelf arthroplasty
. Pavlik harness trial

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In a child older than 18-24 months, open reduction is typically required. Due to secondary adaptive changes like severe acetabular dysplasia and capsular laxity, a concomitant pelvic osteotomy (and often femoral shortening) is necessary to maintain stability.

Question 2836

Topic: Pediatric Hip

An 11-year-old girl with chronic kidney disease secondary to focal segmental glomerulosclerosis presents with a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic pinning of the contralateral, asymptomatic hip in this patient?

. Her age at presentation
. Her sex
. Her underlying endocrinopathy or renal osteodystrophy
. The severity of the unilateral slip
. Presence of a positive Drehmann sign on the affected side

Correct Answer & Explanation

. Her age at presentation

Explanation

Patients with underlying metabolic or endocrine disorders (such as renal osteodystrophy, hypothyroidism, or growth hormone therapy) have a high rate of bilateral SCFE. Prophylactic pinning of the contralateral hip is highly recommended in these populations.

Question 2837

Topic: Pediatric Upper Extremity & Spine

A 5-year-old boy presents with a Gartland Type III supracondylar humerus fracture. The hand is pink, but the radial pulse is absent. After a satisfactory closed reduction and percutaneous pinning, the hand remains pink and well-perfused, but the radial pulse remains absent. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. Administration of intra-arterial vasodilators
. Observation and hospital admission for close neurovascular monitoring
. Removal of pins and open reduction
. Perform a forearm fasciotomy

Correct Answer & Explanation

. Immediate exploration of the brachial artery

Explanation

In a 'pink, pulseless' hand after satisfactory reduction of a supracondylar fracture, capillary refill indicates adequate collateral circulation. The standard of care is careful observation and hospital admission; surgical exploration is generally reserved for a white, pulseless hand.

Question 2838

Topic: 4. Pediatrics

A 6-week-old female infant, born breech, undergoes a screening hip ultrasound. The coronal view reveals an alpha angle of 48 degrees and a beta angle of 80 degrees on the right side. The femoral head is subluxated. What is the most appropriate initial management?

. Reassurance and repeat ultrasound in 6 weeks
. Application of a Pavlik harness
. Closed reduction and spica casting
. Rigid abduction bracing
. Open reduction and capsulorrhaphy

Correct Answer & Explanation

. Reassurance and repeat ultrasound in 6 weeks

Explanation

An alpha angle less than 60 degrees indicates acetabular dysplasia. The standard first-line treatment for an infant under 6 months of age with a reducible dysplastic or dislocated hip is a Pavlik harness.

Question 2839

Topic: Pediatric Hip

During the percutaneous pinning of a stable slipped capital femoral epiphysis (SCFE), the surgeon uses the approach-withdraw technique under fluoroscopy. Unrecognized pin penetration into the joint space most directly increases the risk of which of the following complications?

. Avascular necrosis
. Chondrolysis
. Implant failure
. Slip progression
. Femoral neck fracture

Correct Answer & Explanation

. Avascular necrosis

Explanation

Unrecognized hardware penetration into the joint space is a major risk factor for chondrolysis. Fluoroscopic evaluation with continuous internal-external rotation (approach-withdraw technique) is critical to confirm the pin is completely within the bone.

Question 2840

Topic: 4. Pediatrics

A newborn boy with arthrogryposis multiplex congenita is found to have bilateral teratologic hip dislocations. Which of the following statements regarding the management of his hips is most accurate?

. A Pavlik harness is the treatment of choice and highly successful
. Early open reduction before 3 months of age yields the best functional outcome
. Treatment is primarily aimed at closed reduction using prolonged traction
. Pavlik harness treatment is generally contraindicated and usually fails
. Observation is recommended as these hips typically relocate spontaneously

Correct Answer & Explanation

. A Pavlik harness is the treatment of choice and highly successful

Explanation

Teratologic dislocations, such as those seen in arthrogryposis or myelomeningocele, do not respond well to Pavlik harness treatment. Its use is typically contraindicated due to high failure rates and risk of iatrogenic injury, necessitating open reduction.

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