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4. Pediatrics MCQs

Practice Set 51 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 1001

Topic: 4. Pediatrics
A 6-year-old child presents with progressive bilateral tibia vara. Radiographs reveal a medial physeal beak, epiphyseal-metaphyseal irregularities, and significant physeal widening, consistent with Langenskiöld Stage IV infantile Blount disease. The patient has sufficient remaining growth potential. Based on the case, what is the most appropriate surgical intervention?
. Observation with bracing.
. Lateral proximal tibial hemiepiphysiodesis.
. Medial proximal tibial hemiepiphysiodesis.
. Acute proximal tibial varus-producing osteotomy.
. Permanent lateral proximal tibial physeal arrest (e.g., Phemister technique).

Correct Answer & Explanation

. Lateral proximal tibial hemiepiphysiodesis.

Explanation

The 'Indications for Lateral Hemiepiphysiodesis' section specifically lists: 'Progressive Infantile Blount Disease: Langenskiöld stages II-IV. Age typically between 4 and 8 years (beyond the age of potential spontaneous resolution or bracing efficacy, but before severe physeal damage).' The patient's age (6 years), progressive nature, and Langenskiöld Stage IV classification fall squarely within the indications for lateral proximal tibial hemiepiphysiodesis. Observation with bracing is for Stage I or non-progressive cases. Medial hemiepiphysiodesis would exacerbate the varus. Acute osteotomy is reserved for more severe stages (V-VI) or when guided growth has failed. Permanent physeal arrest is typically for older adolescents nearing skeletal maturity or for LLD management, not primary guided growth for Blount disease.

Question 1002

Topic: 4. Pediatrics
A 16-year-old male presents with severe, progressive adolescent Blount disease. Radiographic evaluation reveals an MPTA of 65 degrees, a MAD of 45 mm, and nearly closed physes with evidence of a significant medial physeal bar (>50% of the physeal cross-sectional area). Based on these findings, which of the following is the absolute contraindication for lateral proximal tibial hemiepiphysiodesis, and what would be the more appropriate surgical approach?
. Obesity; observation with weight management.
. Severe angular deformity (MPTA 65 degrees, MAD 45 mm); medial distal femoral hemiepiphysiodesis.
. Significant medial physeal bar and nearly closed physes; acute proximal tibial varus-producing osteotomy.
. Progressive nature of the deformity; repeated bracing.
. Unilateral involvement; contralateral hemiepiphysiodesis.

Correct Answer & Explanation

. Significant medial physeal bar and nearly closed physes; acute proximal tibial varus-producing osteotomy.

Explanation

Correct Answer: C. The 'Contraindications for Lateral Hemiepiphysiodesis' section clearly lists: 'Skeletal Maturity: Closed physes, as there is no remaining growth potential for guided correction. In these cases, acute osteotomy is indicated.' and 'Significant Physeal Bar: A large medial physeal bar (e.g., >50% of physeal cross-sectional area) will mechanically impede medial growth, rendering guided growth ineffective. Physeal bar resection or osteotomy would be more appropriate.' The patient's nearly closed physes and a significant medial physeal bar are absolute contraindications for guided growth. The severe deformity (MPTA 65 degrees, MAD 45 mm) further supports this. Therefore, an acute proximal tibial varus-producing osteotomy is the indicated alternative. Obesity is a risk factor but not an absolute contraindication for surgery. Medial distal femoral hemiepiphysiodesis is for femoral deformity. Bracing is for mild cases. Contralateral hemiepiphysiodesis is not indicated for unilateral disease.

Question 1003

Topic: 4. Pediatrics

The shift in surgical management of Blount disease from acute osteotomies to guided growth techniques, particularly using eight-plates, is primarily supported by which of the following advantages of guided growth?

. It guarantees a faster rate of correction, regardless of patient growth potential.
. It is a more invasive procedure, leading to stronger bone fusion.
. It offers a dynamic, gradual correction with reduced invasiveness and lower complication rates compared to osteotomy.
. It is effective for all stages of Blount disease, including severe deformities with physeal bars.
. It eliminates the need for any post-operative radiographic follow-up.

Correct Answer & Explanation

. It offers a dynamic, gradual correction with reduced invasiveness and lower complication rates compared to osteotomy.

Explanation

Correct Answer: CThe 'Summary of Key Literature / Guidelines' section highlights the advantages of guided growth: 'Advantages highlighted: Minimally invasive, outpatient procedure, allows for gradual and physiological correction, avoids osteotomy-related morbidities, permits early weight-bearing and faster return to activity.' This directly supports option C. Guided growth does not guarantee a faster rate of correction (it depends on growth potential), is less invasive, not more. It is not effective for all stages, especially severe deformities or those with significant physeal bars, and it absolutely requires rigorous post-operative radiographic follow-up to prevent overcorrection or undercorrection.

Question 1004

Topic: 4. Pediatrics

A 2-year-old child presents with bilateral genu varum. Standing long-leg radiographs reveal metaphyseal beaking. Which of the following radiographic measurements most strongly supports a diagnosis of infantile Blount disease rather than physiologic bowing?

. Tibiofemoral angle of 10 degrees varus
. Metaphyseal-diaphyseal angle of 18 degrees
. Metaphyseal-diaphyseal angle of 8 degrees
. Mechanical axis deviation 10 mm medial to knee center
. Posterior slope of the proximal tibia of 10 degrees

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle of 18 degrees

Explanation

The metaphyseal-diaphyseal angle (Drennan's angle) is used to differentiate physiologic bowing from infantile Blount disease. An angle greater than 16 degrees has a high predictive value for Blount disease.

Question 1005

Topic: 4. Pediatrics
According to the Langenskiöld classification of infantile Blount disease, which stage is characterized by the presence of an epiphyseal bony bridge (bar) crossing the physis?
. Stage II
. Stage III
. Stage IV
. Stage V
. Stage VI

Correct Answer & Explanation

. Stage VI

Explanation

Langenskiöld Stage VI is characterized by an ossified physeal bar across the medial physis. In contrast, Stage V shows a cleft extending through the epiphysis.

Question 1006

Topic: 4. Pediatrics
A 2.5-year-old obese boy presents with progressive bilateral genu varum. Radiographs show a metaphyseal-diaphyseal angle (MDA) of 18 degrees and medial physeal beaking consistent with Langenskiöld stage II Blount disease. What is the most appropriate initial treatment?
. Observation alone
. Knee-ankle-foot orthoses (KAFOs) during weight-bearing
. High tibial osteotomy
. Hemiepiphysiodesis
. Proximal tibial complete epiphysiodesis

Correct Answer & Explanation

. Knee-ankle-foot orthoses (KAFOs) during weight-bearing

Explanation

For early-stage infantile Blount disease (Langenskiöld I-II) in children under 3 years, bracing with KAFOs is the standard initial treatment. This unloads the medial compartment to allow normal physeal growth.

Question 1007

Topic: 4. Pediatrics
A 2-year-old girl is evaluated for bilateral genu varum. Radiographs show a metaphyseal-diaphyseal angle of 18 degrees bilaterally. Langenskiöld stage is II. What is the most appropriate initial management?
. Reassurance and observation
. Vitamin D supplementation
. Knee-ankle-foot orthosis (KAFO) during weight-bearing
. Proximal tibial osteotomy
. Guided growth with tension band plates

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO) during weight-bearing

Explanation

Infantile Blount disease with a metaphyseal-diaphyseal angle >16 degrees has a high risk of progression. Bracing with a KAFO is indicated for children under 3 years old with Langenskiöld stage I or II disease.

Question 1008

Topic: 4. Pediatrics
A 14-year-old boy presents after twisting his ankle. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. What is the mechanism of injury and the anatomical basis for this specific fracture pattern?
. External rotation; the anterolateral physis is the last to close
. Internal rotation; the posteromedial physis is the last to close
. Plantarflexion; the anterior physis is the first to close
. Dorsiflexion; the central physis is the last to close
. Axial load; the entire physis closes simultaneously

Correct Answer & Explanation

. External rotation; the anterolateral physis is the last to close

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis caused by the anterior inferior tibiofibular ligament (AITFL) during external rotation. It occurs in adolescents because the distal tibial physis closes asymmetrically, leaving the anterolateral portion open last.

Question 1009

Topic: 4. Pediatrics
A 13-year-old male sustains an ankle fracture. CT imaging demonstrates a fracture pattern that is sagittal in the epiphysis, axial through the physis, and coronal in the metaphysis. This fracture is considered an equivalent to which Salter-Harris classification?
. Salter-Harris I
. Salter-Harris II
. Salter-Harris III
. Salter-Harris IV
. Salter-Harris V

Correct Answer & Explanation

. Salter-Harris IV

Explanation

A triplane fracture involves the epiphysis, physis, and metaphysis in three different planes (sagittal, axial, coronal). Because it traverses all three zones, it is considered a Salter-Harris IV equivalent fracture.

Question 1010

Topic: 4. Pediatrics

A 13-year-old obese African American male presents with unilateral progressive genu varum. Radiographs reveal wedging of the medial aspect of the proximal tibial epiphysis and widening of the medial physis. Which of the following is true regarding adolescent Blount disease compared to the infantile form?

. It is more commonly bilateral
. It typically involves a prominent metaphyseal beak
. It is less likely to cause a limb length discrepancy
. It rarely resolves with bracing
. It is caused by an underlying metabolic bone disease

Correct Answer & Explanation

. It rarely resolves with bracing

Explanation

Adolescent Blount disease occurs in older, heavier children and is typically unilateral. Unlike infantile Blount's, bracing is generally ineffective for the adolescent form, and surgical intervention is usually required to prevent joint degeneration.

Question 1011

Topic: Pediatric Hip

During shoulder arthroscopy for recurrent anterior instability, the labrocapsular complex is found to be avulsed from the anterior glenoid rim and displaced medially, having healed onto the anterior neck of the glenoid. Which of the following acronyms describes this specific lesion?

. GLAD
. HAGL
. ALPSA
. Perthes
. SLAP

Correct Answer & Explanation

. ALPSA

Explanation

An ALPSA (Anterior Labroligamentous Periosteal Sleeve Avulsion) lesion occurs when the anterior labrum is avulsed but the periosteum remains intact, allowing it to displace medially and heal abnormally. It must be mobilized laterally for anatomical repair.

Question 1012

Topic: 4. Pediatrics
According to the Langenskiöld classification of infantile Blount disease, at which stage does a definitive physeal bony bar form across the medial aspect of the proximal tibia, preventing normal growth?
. Stage II
. Stage III
. Stage IV
. Stage V
. Stage VI

Correct Answer & Explanation

. Stage V

Explanation

In the Langenskiöld classification of infantile Blount disease, Stage VI is characterized by the formation of a definitive bony bridge (physeal bar) across the medial aspect of the proximal tibial physis. This requires complex surgical correction.

Question 1013

Topic: 4. Pediatrics
A 9-year-old boy falls onto his shoulder from a bicycle and sustains what appears radiographically to be a severe acromioclavicular (AC) joint dislocation. However, based on the patient's age, what is the most likely true pathology of this 'pseudodislocation'?
. The AC ligaments remain attached to the clavicle, but the CC ligaments are torn mid-substance.
. The clavicle displaces superiorly, but the CC ligaments remain attached to the intact inferior periosteal sleeve.
. Complete rupture of both AC and CC ligaments occurs similar to adult Type III injuries.
. A greenstick fracture of the medial third of the clavicle masquerading as an AC injury.
. Avulsion of the coracoid process with intact ligaments.

Correct Answer & Explanation

. The clavicle displaces superiorly, but the CC ligaments remain attached to the intact inferior periosteal sleeve.

Explanation

In pediatric patients, AC joint 'dislocations' are usually physeal separations (pseudodislocations). The distal clavicle tears through the superior periosteum, while the robust coracoclavicular ligaments remain attached to the intact inferior periosteal sleeve.

Question 1014

Topic: Pediatric Hip

The patient's clinical presentation included insidious onset of progressive groin and lateral thigh pain, mechanical catching, and morning stiffness lasting 45 minutes. Radiographs showed severe tricompartmental joint space narrowing, subchondral sclerosis, extensive osteophytes, and subchondral cysts. Inflammatory markers (ESR, CRP) were normal.

Considering these findings, which of the following conditions is least likely to be the primary diagnosis?

. Primary osteoarthritis of the hip.
. Avascular necrosis (AVN) of the femoral head.
. Rheumatoid arthritis (RA).
. Post-traumatic osteoarthritis.
. Developmental dysplasia of the hip (DDH) leading to secondary OA.

Correct Answer & Explanation

. Rheumatoid arthritis (RA).

Explanation

Correct Answer: CRheumatoid arthritis (RA) is least likely to be the primary diagnosis. The patient's presentation with mechanical pain, morning stiffness lasting 45 minutes (typical for OA, RA is usually >1 hour), and radiographic findings of osteophytes, subchondral sclerosis, and cysts are classic for osteoarthritis. RA typically presents with inflammatory pain (worse with rest), symmetric polyarthritis, and radiographic features of concentric joint space narrowing, erosions, and juxta-articular osteopenia, with an absence of osteophytes. Furthermore, inflammatory markers (ESR, CRP) would typically be elevated in active RA, which were normal in this patient. Primary osteoarthritis (A) is the most likely diagnosis. AVN (B) can cause similar pain but has distinct radiographic features (crescent sign, patchy sclerosis/lucency) and MRI is diagnostic. Post-traumatic OA (D) and DDH leading to secondary OA (E) are forms of osteoarthritis and would present with similar clinical and radiographic features to primary OA, making them plausible differential diagnoses for thetypeof OA, but not fundamentally different conditions like RA.

Question 1015

Topic: 4. Pediatrics

When constructing an Ilizarov circular external fixator for a tibial lengthening procedure, what is the primary biomechanical effect of tensioning the smooth transfixion wires?

. Increases the axial stiffness of the construct.
. Decreases the bending stiffness of the construct.
. Increases the risk of wire pullout without affecting stiffness.
. Converts the frame into a dynamic, non-weight-bearing fixator.
. Promotes primary (osteonal) bone healing.

Correct Answer & Explanation

. Increases the axial stiffness of the construct.

Explanation

Tensioning the fine wires in a circular fixator dramatically increases the construct's axial stiffness and stability. Without adequate tension, the thin wires would easily buckle under axial physiological loads.

Question 1016

Topic: Pediatric Hip

A 50-year-old male with a history of developmental dysplasia of the hip (DDH) and subsequent severe osteoarthritis is undergoing a primary total hip replacement. Pre-operative templating reveals a shallow, anteverted acetabulum. The surgeon plans to use a posterior approach. To optimize stability and minimize dislocation risk in this challenging case, which of the following combined anteversion targets is generally considered optimal?

. 10-20 degrees
. 20-30 degrees
. 35-45 degrees
. 50-60 degrees
. 65-75 degrees

Correct Answer & Explanation

. 35-45 degrees

Explanation

Correct Answer: CThe teaching case, under 'Biomechanics of Prosthetic Stability' and 'Summary of Key Literature / Guidelines,' states: 'Combined Anteversion: The sum of acetabular anteversion and femoral anteversion. Optimal combined anteversion (typically 35-45°) provides stability across a functional range of motion, minimizing both anterior and posterior impingement.' While Lewinnek's safe zone provides guidelines for individual component placement, the concept of combined anteversion is increasingly recognized as critical for overall hip stability, especially in complex cases like DDH where native anatomy might be altered. Achieving a combined anteversion of 35-45 degrees helps ensure that the hip remains stable through its functional range of motion, balancing the risk of anterior and posterior impingement.A. 10-20 degrees:This range is too low for combined anteversion and would likely lead to posterior impingement and instability.B. 20-30 degrees:This is still on the lower side for optimal combined anteversion and may not provide sufficient stability against posterior dislocation.D. 50-60 degrees:This range is too high for combined anteversion and would likely lead to anterior impingement and instability.E. 65-75 degrees:This range is excessively high and would almost certainly result in anterior impingement and dislocation.

Question 1017

Topic: Pediatric Hip

A 45-year-old female with Crowe IV developmental dysplasia of the hip undergoes a complex total hip arthroplasty with a subtrochanteric shortening osteotomy. What is the primary purpose of utilizing a subtrochanteric shortening osteotomy in this setting?

. To increase the abductor moment arm
. To allow placement of the acetabular cup in the true acetabulum without excessive sciatic nerve traction
. To prevent limb length discrepancy in the contralateral limb
. To reduce the risk of heterotopic ossification
. To bypass an associated proximal femoral deformity

Correct Answer & Explanation

. To allow placement of the acetabular cup in the true acetabulum without excessive sciatic nerve traction

Explanation

In Crowe IV DDH, the hip center is extremely high. Bringing the femur down to a cup placed in the true acetabulum risks massive sciatic nerve traction injury. A subtrochanteric shortening osteotomy prevents this overtensioning while restoring native hip biomechanics.

Question 1018

Topic: 4. Pediatrics

A 5-year-old child with fibular deficiency is noted to have a characteristic deformity of the tibia. Clinically, the tibia appears bowed, and radiographs confirm this angulation. The parents are concerned about the progression of this deformity and its potential impact on the skin.

Which of the following best describes the typical tibial deformity seen in fibular deficiency?

. Posterior-lateral bowing
. Anterior-medial bowing
. Genu recurvatum
. Valgus deformity of the proximal tibia
. Varus deformity of the distal tibia

Correct Answer & Explanation

. Anterior-medial bowing

Explanation

Correct Answer: BThe correct answer is anterior-medial bowing. The case explicitly states that 'The tibia, in the absence of its fibular buttress, often exhibits anterior-medial bowing.' This deformity can range from subtle curvature to severe angulation, sometimes complicated by skin tethering or impending pseudoarthrosis. This characteristic bowing is a direct consequence of the fibula's absence, which normally provides a lateral buttress and influences tibial growth. The other options describe different types of deformities not specifically highlighted as the typical tibial deformity in fibular deficiency.

Question 1019

Topic: 4. Pediatrics

Fibular deficiency (fibular hemimelia) is the most common congenital long bone deficiency. Which of the following associated tibial deformities is classically seen in these patients?

. Posteromedial bowing
. Anterolateral bowing
. Anteromedial bowing
. Posterolateral bowing
. Pure valgus bowing without sagittal plane deformity

Correct Answer & Explanation

. Anteromedial bowing

Explanation

Congenital fibular deficiency is classically associated with anteromedial bowing of the tibia. This contrasts with posteromedial bowing (often benign/calcaneovalgus) and anterolateral bowing (associated with neurofibromatosis and congenital pseudarthrosis).

Question 1020

Topic: Pediatric Lower Extremity

In addition to a missing or hypoplastic fibula, patients with fibular hemimelia frequently have specific anomalies of the foot and ankle. Which of the following is most commonly observed in these patients?

. Tarsal coalition
. Clubfoot (talipes equinovarus)
. Cavovarus deformity
. Vertical talus
. Polydactyly

Correct Answer & Explanation

. Tarsal coalition

Explanation

Fibular deficiency is part of a spectrum of postaxial limb deficiencies. It is frequently associated with tarsal coalitions (most commonly talocalcaneal), a ball-and-socket ankle joint, and absent lateral rays.

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