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4. Pediatrics MCQs

Practice Set 294 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 5861

Topic: Pediatric Hip

A 13-year-old obese boy presents with severe right hip pain and inability to bear weight after a minor fall 2 days ago. Radiographs confirm a slipped capital femoral epiphysis. According to the Loder classification, what is his primary risk for the most devastating complication of this specific type of slip?

. Chondrolysis
. Avascular necrosis (AVN) of the femoral head
. Coxa magna
. Femoroacetabular impingement
. Leg-length discrepancy

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

This is an unstable SCFE (defined by the inability to bear weight), which carries a high risk (up to 47%) of avascular necrosis (AVN). Stable slips have a much lower AVN risk but may lead to FAI or chondrolysis.

Question 5862

Topic: 4. Pediatrics

A 3-year-old girl weighing above the 95th percentile presents with bilateral genu varum. Standing radiographs demonstrate a metaphyseal-diaphyseal angle (Drennan's angle) of 18 degrees and medial metaphyseal beaking. What is the most appropriate initial treatment?

. Reassurance and observation
. Bilateral guided growth (eight-plates)
. Knee-ankle-foot orthoses (KAFOs)
. Proximal tibial valgus osteotomies
. Epiphysiodesis of the lateral proximal tibia

Correct Answer & Explanation

. Knee-ankle-foot orthoses (KAFOs)

Explanation

The patient has infantile Blount's disease, suggested by age, weight, and a metaphyseal-diaphyseal angle > 16 degrees. For children under 3 to 4 years of age with Langenskiold stage I or II, daytime use of KAFOs is the standard initial non-operative treatment.

Question 5863

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calve-Perthes disease. Radiographs show that 40% of the lateral pillar height is maintained. According to the Herring lateral pillar classification, what is his classification and associated prognosis?

. Group A; excellent prognosis without surgery
. Group B; good prognosis with containment surgery
. Group B; poor prognosis despite surgery
. Group C; poor prognosis regardless of treatment
. Group C; excellent prognosis with bracing

Correct Answer & Explanation

. Group C; poor prognosis regardless of treatment

Explanation

Herring Group C is defined by less than 50% maintenance of lateral pillar height. It carries a poor prognosis, and studies show little to no benefit from surgical containment in this group, particularly in older children.

Question 5864

Topic: 4. Pediatrics

A 10-year-old boy undergoes placement of a tension-band construct (eight-Plate) on the medial distal femur for a valgus deformity. Which of the following is the mechanism of action of this device?

. Hueter-Volkmann principle
. Wolff's Law
. Heuter-Volkmann principle combined with osteotomy
. Distraction osteogenesis
. Chondral autolysis

Correct Answer & Explanation

. Hueter-Volkmann principle

Explanation

Guided growth (hemiepiphysiodesis) relies on the Hueter-Volkmann principle, which states that increased compression across a physis slows longitudinal bone growth. Medial tethering slows medial growth while the lateral physis continues to grow, correcting the valgus.

Question 5865

Topic: Pediatric Hip

In a patient with Legg-Calve-Perthes disease, which of the following is considered a head at risk sign as described by Catterall?

. Gage sign
. Decreased medial joint space
. Intact lateral pillar
. Central calcification of the epiphysis
. Medial subluxation of the femoral head

Correct Answer & Explanation

. Gage sign

Explanation

Catterall's head-at-risk signs indicate a poorer prognosis in LCP disease. They include Gage sign (a V-shaped radiolucency in the lateral epiphysis/metaphysis), lateral subluxation, calcification lateral to the epiphysis, and a horizontal growth plate.

Question 5866

Topic: 4. Pediatrics

A 6-week-old infant is treated with a Pavlik harness for developmental dysplasia of the hip. At the two-week follow-up, the parents report the infant has stopped kicking the affected leg. On exam, there is absent active knee extension. Which of the following positioning errors most likely caused this complication?

. Excessive hip abduction
. Excessive hip adduction
. Excessive hip flexion
. Excessive hip extension
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Excessive hip flexion (typically greater than 120 degrees) in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy. Excessive abduction is associated with avascular necrosis of the femoral head.

Question 5867

Topic: Pediatric Hip

According to the Loder classification, an unstable slipped capital femoral epiphysis (SCFE) is defined by which of the following criteria, and carries what primary complication risk?

. Inability to ambulate with or without crutches; high risk of chondrolysis
. Inability to ambulate with or without crutches; high risk of avascular necrosis
. Slip angle greater than 50 degrees; high risk of avascular necrosis
. Slip angle greater than 50 degrees; high risk of chondrolysis
. Duration of symptoms less than 3 weeks; high risk of delayed union

Correct Answer & Explanation

. Inability to ambulate with or without crutches; high risk of avascular necrosis

Explanation

The Loder classification defines an unstable SCFE by the patient's inability to ambulate, even with crutches. Unstable SCFE carries a significantly higher risk of avascular necrosis (up to nearly 50%) compared to stable SCFE.

Question 5868

Topic: Pediatric Hip
In the Herring lateral pillar classification for Legg-Calvé-Perthes disease, a Type B hip is characterized by:
. 100% preservation of the lateral pillar height
. Greater than 50% preservation of the lateral pillar height
. Less than 50% preservation of the lateral pillar height
. Complete collapse of the lateral pillar
. Central pillar collapse with lateral extrusion

Correct Answer & Explanation

. Greater than 50% preservation of the lateral pillar height

Explanation

In the Herring classification, Type B is defined by the preservation of >50% of the lateral pillar height. Type A has no lateral pillar involvement, and Type C has <50% of the lateral pillar maintained.

Question 5869

Topic: 4. Pediatrics
A 4-year-old child with infantile Blount's disease is noted to have a permanent metaphyseal-epiphyseal bony bridge on imaging. This complete medial physeal bar corresponds to which Langenskiöld stage?
. Stage II
. Stage III
. Stage IV
. Stage V
. Stage VI

Correct Answer & Explanation

. Stage V

Explanation

Langenskiöld Stage VI is characterized by the formation of a true bony bridge (physeal bar) across the medial physis. This requires complex surgical management, often involving bar resection or concurrent physeal distraction.

Question 5870

Topic: 4. Pediatrics

In a patient with congenital coxa vara, surgical intervention (such as a valgus producing subtrochanteric osteotomy) is generally indicated when the Hilgenreiner epiphyseal angle (HEA) exceeds what threshold?

. 25 degrees
. 35 degrees
. 45 degrees
. 60 degrees
. 90 degrees

Correct Answer & Explanation

. 60 degrees

Explanation

A Hilgenreiner epiphyseal angle (HEA) greater than 60 degrees is a classic indication for surgical correction in congenital coxa vara, as it is associated with progression of the deformity. An HEA of less than 45 degrees usually resolves or remains stable.

Question 5871

Topic: Pediatric Hip

When performing a closed reduction and spica casting for developmental dysplasia of the hip (DDH), the 'safe zone' of Ramsey defines the range between:

. Maximum extension and minimum flexion
. Maximum abduction and the angle of re-dislocation in adduction
. Maximum internal rotation and minimum external rotation
. Maximum adduction and the angle of re-dislocation in abduction
. Maximum flexion and the angle of re-dislocation in extension

Correct Answer & Explanation

. Maximum abduction and the angle of re-dislocation in adduction

Explanation

Ramsey's safe zone is the range of abduction between the angle of re-dislocation (when the hip is adducted) and maximum abduction. Keeping the hip within this zone minimizes the risk of re-dislocation while mitigating the risk of avascular necrosis caused by forced extreme abduction.

Question 5872

Topic: Pediatric Hip

Prophylactic in situ pinning of the contralateral asymptomatic hip in a patient with a unilateral slipped capital femoral epiphysis (SCFE) is most strongly indicated in which of the following scenarios?

. A 14-year-old male with a BMI of 25
. A 10-year-old female with idiopathic SCFE
. A 12-year-old male with underlying chronic renal failure
. An 11-year-old female with a slip angle of 15 degrees
. A 15-year-old male with acute trauma

Correct Answer & Explanation

. A 12-year-old male with underlying chronic renal failure

Explanation

Prophylactic contralateral pinning is highly recommended in patients with SCFE related to underlying endocrinopathies or metabolic bone diseases (like chronic renal failure), as well as in patients undergoing radiation therapy or those under 10 years of age, due to the high risk of bilateral involvement.

Question 5873

Topic: Pediatric Hip
In the treatment of Legg-Calvé-Perthes disease, surgical containment yields the most significant improvement in radiographic outcomes compared to nonoperative treatment in which specific patient population?
. Children less than 6 years of age at onset
. Children over 8 years of age at onset with Lateral Pillar B or B/C involvement
. Children over 8 years of age with Lateral Pillar A involvement
. Children of any age with complete Lateral Pillar C collapse
. Adolescents with healed, spherical femoral heads

Correct Answer & Explanation

. Children over 8 years of age at onset with Lateral Pillar B or B/C involvement

Explanation

Studies (e.g., Herring et al.) have demonstrated that surgical containment provides significantly better radiographic outcomes than nonoperative management in children who are over 8 years old at symptom onset and have Lateral Pillar B or B/C border disease. Type C hips perform poorly regardless of treatment.

Question 5874

Topic: 4. Pediatrics

A 7-year-old boy undergoes temporary hemiepiphysiodesis using tension band plates for genu valgum. Following complete correction and implant removal, the family should be counseled that the risk of 'rebound deformity' is highest in which demographic?

. Patients with younger chronological age and substantial remaining growth
. Patients approaching skeletal maturity with fused physes
. Patients with post-traumatic physeal bars
. Patients with Blount's disease
. Adolescent females past menarche

Correct Answer & Explanation

. Patients with younger chronological age and substantial remaining growth

Explanation

Rebound deformity after hardware removal in guided growth is most frequently observed in younger children with substantial remaining growth, requiring close clinical and radiographic monitoring. Overcorrection is sometimes recommended in this high-risk group.

Question 5875

Topic: Pediatric Hip

A 12-year-old obese male presents with acute-on-chronic left hip pain and inability to bear weight. Radiographs confirm an unstable slipped capital femoral epiphysis (SCFE). What is the most significant risk factor for developing avascular necrosis (AVN) following surgical fixation?

. Open physes
. Obesity
. Degree of initial slip
. Preoperative instability
. Choice of single vs dual screw fixation

Correct Answer & Explanation

. Preoperative instability

Explanation

Preoperative instability (inability to bear weight even with crutches) is the highest risk factor for AVN in SCFE. The risk of AVN in unstable SCFE can be up to 50%, compared to near zero in stable slips.

Question 5876

Topic: Pediatric Hip
In a 7-year-old boy with Legg-Calvé-Perthes disease, which of the following radiographic "head-at-risk" signs (Catterall) suggests a poor prognosis and potential need for surgical containment?
. Increased medial joint space
. Gage sign
. Subchondral fracture
. Calcification lateral to the epiphysis
. Lateral subluxation of the femoral head

Correct Answer & Explanation

. Lateral subluxation of the femoral head

Explanation

Lateral subluxation of the femoral head is a critical "head-at-risk" sign indicating loss of containment and impending hinge abduction. This finding often prompts surgical intervention, such as a varus derotational osteotomy or pelvic osteotomy.

Question 5877

Topic: Pediatric Hip
A 16-year-old female presents with persistent lateral hip pain. Radiographs show a lateral center edge angle (LCEA) of 15 degrees and a Tönnis angle of 18 degrees with an intact Shenton's line. Joint space is preserved. What is the most appropriate surgical treatment?
. Total hip arthroplasty
. Bernese periacetabular osteotomy (PAO)
. Proximal femoral varus osteotomy
. Hip arthroscopy with labral repair
. Shelf arthroplasty

Correct Answer & Explanation

. Bernese periacetabular osteotomy (PAO)

Explanation

This patient has symptomatic developmental dysplasia of the hip (DDH) with preserved joint space. PAO allows powerful reorientation of the acetabulum while preserving the posterior column, making it the ideal treatment for symptomatic dysplasia in adolescents and young adults.

Question 5878

Topic: 4. Pediatrics

A 5-year-old boy presents with a painless limp and a positive Trendelenburg sign. Radiographs show a neck-shaft angle of 90 degrees and an inverted Y-shaped radiolucency in the inferior femoral neck. What is the most appropriate surgical treatment?

. Observation until age 10
. Proximal femoral valgus-producing osteotomy
. Proximal femoral varus-producing osteotomy
. Core decompression
. In situ pinning

Correct Answer & Explanation

. Proximal femoral valgus-producing osteotomy

Explanation

The presentation and "inverted Y" or "triangle" fragment (Fairbank's triangle) are classic for congenital coxa vara. A proximal femoral valgus osteotomy is indicated when the Hilgenreiner-epiphyseal (H-E) angle is >60 degrees to convert shear forces into compressive forces.

Question 5879

Topic: 4. Pediatrics

According to Ilizarov principles of distraction osteogenesis, what is the optimal rate and rhythm for bone lengthening?

. 0.25 mm four times a day
. 1.0 mm once a day
. 0.5 mm twice a day
. 2.0 mm twice a day
. 0.25 mm once a day

Correct Answer & Explanation

. 0.25 mm four times a day

Explanation

Ilizarov found that a high-frequency, small-step rhythm (e.g., 0.25 mm four times daily for a total of 1 mm/day) provides the best environment for bone regeneration while minimizing soft tissue complications.

Question 5880

Topic: 4. Pediatrics

A 4-year-old child with Osteogenesis Imperfecta presents with severe anterior bowing of bilateral femurs preventing ambulation. What is the gold standard surgical management to correct the deformity and prevent further fractures?

. Distal femoral guided growth
. Bilateral external fixation with distraction osteogenesis
. Multiple level osteotomies with intramedullary rodding (Fassier-Duval)
. Casting in extension
. Open reduction and internal fixation with locking plates

Correct Answer & Explanation

. Multiple level osteotomies with intramedullary rodding (Fassier-Duval)

Explanation

The Sofield-Millar operation (multiple osteotomies) stabilized by a telescoping intramedullary rod (like the Fassier-Duval) is the gold standard for correcting severe long bone deformities in growing children with Osteogenesis Imperfecta.

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