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4. Pediatrics MCQs

Practice Set 185 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 3681

Topic: Pediatric Hip

An 11-year-old boy with a BMI in the 99th percentile presents with 3 weeks of knee pain and a limp. Examination reveals obligate external rotation of the hip with passive flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). During in situ pinning, where should the single screw be positioned within the epiphysis?

. Anterior and superior
. Anterior and inferior
. Central and central
. Posterior and superior
. Posterior and inferior

Correct Answer & Explanation

. Central and central

Explanation

In situ pinning of a SCFE aims to place the screw in the center of the epiphysis to maximize mechanical stability and minimize the risk of joint penetration. The guide wire and screw should be placed centrally in both the anteroposterior and lateral planes.

Question 3682

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. On presentation, his hand is pale, pulseless, and cold. After rapid closed reduction and percutaneous pinning, his hand becomes warm and pink, with a capillary refill of 2 seconds, but the radial pulse remains absent. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. Perform an upper extremity angiogram
. Administer intravenous heparin
. Observe and admit for 24 to 48 hours
. Remove the pins and perform an open reduction

Correct Answer & Explanation

. Observe and admit for 24 to 48 hours

Explanation

A pulseless but well-perfused (pink) hand after closed reduction of a supracondylar fracture typically results from arterial vasospasm or non-occlusive tethering. Observation is the standard of care, as collateral circulation is adequate and the pulse usually returns within a few days.

Question 3683

Topic: Pediatric Lower Extremity

A 2-week-old infant with idiopathic clubfoot is undergoing serial casting using the Ponseti method. The first casting maneuver should primarily aim to correct the cavus deformity. Which of the following describes the correct technique for this initial step?

. Pronate the forefoot and elevate the first ray
. Supinate the forefoot and elevate the first ray
. Dorsiflex the ankle and abduct the forefoot
. Plantarflex the ankle and evert the hindfoot
. Abduct the forefoot against pressure on the calcaneocuboid joint

Correct Answer & Explanation

. Supinate the forefoot and elevate the first ray

Explanation

The initial step in the Ponseti method is correcting the cavus deformity by supinating the forefoot to visually align it with the supinated hindfoot. This is achieved by elevating the first ray while applying counter-pressure to the head of the talus.

Question 3684

Topic: Pediatric Hip

An 8-year-old boy presents with a painless limp. Radiographs demonstrate sclerosis and fragmentation of the left capital femoral epiphysis with lateral subluxation. According to the Herring lateral pillar classification, he has a Group B/C lesion. Which of the following factors is the strongest predictor of a poor long-term outcome in this patient?

. Age at onset greater than 8 years
. Male sex
. Involvement of the medial pillar
. Early loss of internal rotation
. Sclerosis of the metaphysis

Correct Answer & Explanation

. Age at onset greater than 8 years

Explanation

Age greater than 8 years at the onset of Legg-Calve-Perthes disease is the most significant predictor of a poor outcome. This is due to the limited remaining growth potential for femoral head remodeling before skeletal maturity.

Question 3685

Topic: 4. Pediatrics
A 4-year-old girl with a history of multiple fractures, blue sclerae, and normal dentition is diagnosed with Osteogenesis Imperfecta (OI) type I. Which of the following genetic mechanisms is most likely responsible for her condition?
. Mutation in the FGFR3 gene
. Defect in type II collagen synthesis
. Quantitative deficiency of structurally normal type I collagen
. Qualitative (structural) defect in type I collagen
. Mutation in the COMP gene

Correct Answer & Explanation

. Quantitative deficiency of structurally normal type I collagen

Explanation

Osteogenesis imperfecta type I is the mildest and most common form, characterized by a quantitative deficiency (decreased production) of structurally normal type I collagen. Types II, III, and IV typically involve qualitative (structural) mutations in the collagen chains, resulting in more severe phenotypes.

Question 3686

Topic: Pediatric Upper Extremity & Spine

A 5-year-old girl falls on an outstretched hand and sustains a lateral condyle fracture of the humerus with 1 mm of displacement. She is treated in a long-arm cast. At her 4-week follow-up, radiographs show delayed union but no change in displacement. What is the most appropriate management?

. Immediate open reduction and internal fixation
. Closed reduction and percutaneous pinning
. Continue cast immobilization for an additional 2 to 4 weeks
. Remove the cast and begin aggressive physical therapy
. Perform an MRI to assess the cartilaginous hinge

Correct Answer & Explanation

. Continue cast immobilization for an additional 2 to 4 weeks

Explanation

Minimally displaced lateral condyle fractures often exhibit delayed radiographic union. If there is no further displacement, extending cast immobilization for up to 6 to 8 weeks total is appropriate and usually results in successful union.

Question 3687

Topic: 4. Pediatrics

A 6-year-old boy with spastic quadriplegic cerebral palsy (GMFCS level V) has progressive right hip subluxation with a migration percentage of 55%. He has pain during diaper changes and difficulty sitting. Which of the following surgical interventions is most appropriate?

. Adductor tenotomy alone
. Varus derotational proximal femoral osteotomy (VDRO) with pelvic osteotomy
. Proximal femoral resection (Castle procedure)
. Total hip arthroplasty
. Selective dorsal rhizotomy

Correct Answer & Explanation

. Varus derotational proximal femoral osteotomy (VDRO) with pelvic osteotomy

Explanation

In a patient with spastic cerebral palsy and a high migration percentage (>50%), bony reconstruction is required. A combined VDRO and pelvic osteotomy (e.g., Dega or San Diego) is the gold standard to achieve a stable, painless hip.

Question 3688

Topic: Pediatric Hip
A 45-year-old female presents with secondary osteoarthritis due to developmental dysplasia of the hip (DDH). Preoperative radiographs reveal a subluxation of 60% of the femoral head relative to the true acetabulum. How is this classified according to the Crowe classification?
. Crowe I
. Crowe II
. Crowe III
. Crowe IV
. Crowe V

Correct Answer & Explanation

. Crowe II

Explanation

The Crowe classification grades DDH by proximal subluxation: I (<50%), II (50-74%), III (75-100%), and IV (>100%). A 60% subluxation falls into the Crowe II category.

Question 3689

Topic: Pediatric Hip

A 28-year-old male athlete presents with chronic groin pain exacerbated by hip flexion and internal rotation. A Dunn view radiograph shows an alpha angle of 65 degrees. This radiographic finding is most indicative of which of the following pathomorphologies?

. Decreased femoral head-neck offset (Cam morphology)
. Acetabular retroversion (Pincer morphology)
. Coxa profunda
. Developmental dysplasia of the hip
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Decreased femoral head-neck offset (Cam morphology)

Explanation

An alpha angle greater than 50-55 degrees indicates a decreased femoral head-neck offset, characteristic of Cam-type femoroacetabular impingement. This bony prominence impinges on the anterosuperior acetabular rim during hip flexion.

Question 3690

Topic: Pediatric Hip

Which of the following is considered the most critical prerequisite for a successful periacetabular osteotomy (Ganz osteotomy) in an adult patient with symptomatic developmental dysplasia of the hip?

. Presence of a cam deformity
. Alpha angle less than 45 degrees
. Open triradiate cartilage
. Joint congruency on functional (abduction/internal rotation) radiographs
. Tonnis grade 3 osteoarthritis

Correct Answer & Explanation

. Joint congruency on functional (abduction/internal rotation) radiographs

Explanation

A periacetabular osteotomy (PAO) relies on reorienting the acetabulum. Preoperative joint congruency in the anticipated corrected position (assessed via abduction/internal rotation views) is critical. Advanced arthritis (Tonnis 3) or lack of congruency are contraindications.

Question 3691

Topic: Pediatric Hip

A 12-year-old obese male presents with a slipped capital femoral epiphysis (SCFE) of the left hip. Radiographs show a slip angle of 40 degrees. Under which of the following circumstances is prophylactic in situ pinning of the contralateral, asymptomatic right hip most strongly indicated?

. Patient age greater than 14 years
. Presence of an underlying endocrine disorder such as hypothyroidism
. The symptomatic hip slip angle is >30 degrees
. Closed triradiate cartilage on the contralateral side
. Male sex

Correct Answer & Explanation

. Presence of an underlying endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with an underlying endocrine disorder (e.g., hypothyroidism, renal osteodystrophy) due to the exceedingly high risk of bilateral involvement. A modified Oxford bone age score < 16 is also considered a strong predictor for bilateral disease.

Question 3692

Topic: Pediatric Hip
A 6-year-old boy presents with a painless limp and limited abduction and internal rotation of the right hip. Radiographs show sclerosis and fragmentation of the capital femoral epiphysis. According to the Herring lateral pillar classification, which of the following radiographic findings determines a Type B categorization?
. Greater than 50% maintenance of lateral pillar height
. Less than 50% maintenance of lateral pillar height
. No structural involvement of the lateral pillar
. Complete resorption of the lateral pillar
. Extrusion of the femoral head beyond the acetabular margin

Correct Answer & Explanation

. Greater than 50% maintenance of lateral pillar height

Explanation

In the Herring lateral pillar classification for Legg-Calvé-Perthes disease, Type B indicates that the lateral pillar maintains more than 50% of its original height. Type C indicates less than 50% height is maintained, which carries a worse prognosis and higher risk of aspherical head healing.

Question 3693

Topic: Pediatric Hip

When templating for a total hip arthroplasty in a patient with Crowe IV developmental dysplasia of the hip (DDH), where is the optimal location for the placement of the acetabular component to restore the anatomic center of rotation?

. Superior to the radiographic teardrop
. At the level of the radiographic teardrop
. Lateral to the ilioischial line
. Inferior to the obturator foramen
. Anterior to the anterior pelvic plane

Correct Answer & Explanation

. At the level of the radiographic teardrop

Explanation

In Crowe IV DDH, the hip is completely dislocated superiorly. The true acetabulum is located at the level of the radiographic teardrop, which remains the target for cup placement to restore the anatomic center of rotation and optimize abductor mechanics.

Question 3694

Topic: Pediatric Hip



An anteroposterior pelvis radiograph of a 28-year-old male with groin pain demonstrates a crossover sign and a prominent ischial spine sign. Which of the following pathologies do these findings most strongly suggest?

. Cam impingement with decreased femoral head-neck offset
. Pincer impingement due to acetabular retroversion
. Developmental dysplasia of the hip
. Slipped capital femoral epiphysis
. Coxa profunda

Correct Answer & Explanation

. Pincer impingement due to acetabular retroversion

Explanation

The crossover sign (anterior wall crossing lateral to the posterior wall) and the prominent ischial spine sign are classic radiographic indicators of true acetabular retroversion. This represents focal overcoverage leading to Pincer-type femoroacetabular impingement.

Question 3695

Topic: Pediatric Hip

A 35-year-old female with a history of untreated developmental dysplasia of the hip (DDH) presents for THA. Radiographs demonstrate a Crowe type IV dysplasia. If the surgeon decides to place the acetabular component at the true anatomic hip center, which concomitant procedure will most likely be required?

. Greater trochanteric advancement
. Iliopsoas tenotomy alone
. Extensive abductor release
. Distal femoral shortening
. Subtrochanteric shortening osteotomy

Correct Answer & Explanation

. Subtrochanteric shortening osteotomy

Explanation

In Crowe IV DDH, the femoral head is highly dislocated. Bringing the hip down to the true anatomic center severely stretches the sciatic nerve and surrounding soft tissues, nearly always necessitating a subtrochanteric shortening osteotomy to prevent neurologic injury.

Question 3696

Topic: Pediatric Hip

A 13-year-old boy with obesity undergoes in situ pinning for a severe, stable slipped capital femoral epiphysis (SCFE). Six months postoperatively, he develops severe hip stiffness and worsening pain. Radiographs demonstrate concentric joint space narrowing and subchondral osteopenia. What is the most likely diagnosis?

. Avascular necrosis of the femoral head
. Chondrolysis
. Slipped contralateral epiphysis
. Femoroacetabular impingement
. Hardware failure

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a severe complication of SCFE characterized by acute cartilage destruction, leading to global stiffness and rapid concentric joint space narrowing. It is strongly associated with severe slips and unrecognized intra-articular hardware penetration.

Question 3697

Topic: Pediatric Hip
In a patient diagnosed with Legg-Calvé-Perthes disease, which of the following clinical or radiographic factors is most strongly associated with a poor long-term prognosis?
. Age less than 6 years at the time of symptom onset
. Catterall Group I classification
. Herring Lateral Pillar Group A classification
. Age greater than 8 years at the time of symptom onset
. Minimal epiphyseal involvement on initial radiographs

Correct Answer & Explanation

. Age greater than 8 years at the time of symptom onset

Explanation

Age at onset is the most critical prognostic factor in Legg-Calvé-Perthes disease. Patients older than 8 years have less remaining growth potential to remodel the deformed femoral head, leading to a higher risk of early osteoarthritis.

Question 3698

Topic: Pediatric Hip



A 45-year-old man presents with deep groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate a 'pistol grip' deformity of the proximal femur. Which pathophysiologic mechanism best describes his condition?

. Pincer-type femoroacetabular impingement
. Cam-type femoroacetabular impingement
. Developmental dysplasia of the hip
. Avascular necrosis of the femoral head
. Legg-Calve-Perthes disease

Correct Answer & Explanation

. Cam-type femoroacetabular impingement

Explanation

A 'pistol grip' deformity indicates a loss of the normal anterior head-neck offset, characteristic of Cam-type femoroacetabular impingement. This leads to shear stress on the anterosuperior labrum and articular cartilage.

Question 3699

Topic: Pediatric Hip

A 24-year-old collegiate hockey player complains of anterior groin pain exacerbated by hip flexion and internal rotation.

An AP pelvis radiograph demonstrates a prominent crossover sign and a lateral center-edge angle of 45 degrees. Which of the following is the most likely diagnosis?

. Cam impingement
. Pincer impingement
. Femoral retroversion
. Legg-Calve-Perthes sequelae
. Slipped capital femoral epiphysis

Correct Answer & Explanation

. Pincer impingement

Explanation

A positive crossover sign and a lateral center-edge angle greater than 40 degrees indicate acetabular retroversion and overcoverage. These are the classic radiographic hallmarks of Pincer-type femoroacetabular impingement.

Question 3700

Topic: Pediatric Hip

A 13-year-old boy is diagnosed with a unilateral left-sided slipped capital femoral epiphysis (SCFE).

Prophylactic in situ pinning of the contralateral asymptomatic right hip is most strongly indicated in the presence of which of the following patient factors?

. Patient age > 14 years
. An underlying endocrine disorder
. Male gender
. Body Mass Index > 30
. Left SCFE slip angle > 50 degrees

Correct Answer & Explanation

. An underlying endocrine disorder

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy). These patients have an exceptionally high incidence of developing subsequent contralateral slips.

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