Menu

4. Pediatrics MCQs

Practice Set 140 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 2781

Topic: 4. Pediatrics
A 13-year-old boy sustains a twisting injury to his ankle while playing soccer. Radiographs demonstrate a Salter-Harris type III fracture of the anterolateral aspect of the distal tibia (Tillaux fracture). This specific fracture pattern is governed by the normal physiological closure pattern of the distal tibial physis. In what order does the distal tibial physis close?
. Central, medial, lateral
. Medial, central, lateral
. Lateral, central, medial
. Anterior, posterior, medial
. Lateral, medial, central

Correct Answer & Explanation

. Central, medial, lateral

Explanation

The juvenile Tillaux fracture occurs due to the asymmetric closure of the distal tibial physis, which typically occurs over an 18-month period. The physis closes first in the central portion, then proceeds medially, and finally closes laterally. Because the anterolateral physis is the last to close, it remains vulnerable to the avulsion force of the anterior inferior tibiofibular ligament (AITFL) during external rotation injuries in adolescents.

Question 2782

Topic: Pediatric Hip

An obese 12-year-old boy presents with acute-on-chronic left thigh pain and is unable to bear weight on the left leg, even with crutches. Radiographs demonstrate a posterior and medial displacement of the proximal femoral epiphysis. According to the Loder classification, what is the most significant complication directly associated with his specific presentation type?

. Chondrolysis
. Avascular necrosis
. Slip progression
. Femoroacetabular impingement
. Leg length discrepancy

Correct Answer & Explanation

. Chondrolysis

Explanation

The Loder classification divides Slipped Capital Femoral Epiphysis (SCFE) into stable and unstable slips based on the patient's ability to bear weight (with or without crutches). This patient cannot bear weight, indicating an unstable SCFE. Unstable SCFE has a notoriously high rate of avascular necrosis (AVN), reported to be as high as 47-50%, compared to nearly 0% in stable SCFE. Chondrolysis is more commonly associated with unrecognized pin penetration into the joint space.

Question 2783

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from monkey bars and sustains a completely displaced, extension-type supracondylar humerus fracture. On arrival at the emergency department, his hand is pink and warm with brisk capillary refill, but no radial pulse is palpable. What is the next best step in management?

. Immediate open exploration of the brachial artery
. Closed reduction and percutaneous pinning followed by observation
. Immediate MR Angiography
. Prophylactic fasciotomies of the forearm
. Stellate ganglion block

Correct Answer & Explanation

. Immediate open exploration of the brachial artery

Explanation

In the setting of a displaced supracondylar humerus fracture with a 'pulseless but pink' (well-perfused) hand, the initial management is urgent closed reduction and percutaneous pinning (CRPP). The pulse often returns following anatomical alignment of the fracture. If the hand remains pink and well-perfused after CRPP, observation is the appropriate management. Open vascular exploration is indicated if the hand is dysvascular (pulseless, white, and cold) before or after reduction.

Question 2784

Topic: 4. Pediatrics

A 6-year-old child with spastic quadriplegic cerebral palsy is evaluated during routine hip surveillance. Radiographs demonstrate a Reimer's migration percentage of 45% in the right hip. There are no advanced degenerative changes. What is the most appropriate management?

. Observation and radiographic follow-up in 1 year
. Adductor tenotomy alone
. Proximal femoral varus derotational osteotomy (VDRO) with pelvic osteotomy
. Total hip arthroplasty
. Proximal femoral resection (Castle procedure)

Correct Answer & Explanation

. Observation and radiographic follow-up in 1 year

Explanation

In children with cerebral palsy, hip subluxation is a common complication. A Reimer's migration index greater than 40% to 50% in an older child (e.g., >4-5 years old) indicates significant hip displacement that typically requires bony reconstruction to prevent complete dislocation and painful arthritis. The standard of care is a proximal femoral varus derotational osteotomy (VDRO) combined with a pelvic osteotomy (e.g., Dega or San Diego) to improve acetabular coverage. Soft tissue release alone (adductor tenotomy) is insufficient for this degree of subluxation at this age.

Question 2785

Topic: Pediatric Hip

A 4-month-old infant with developmental dysplasia of the hip (DDH) has been managed with a Pavlik harness for 4 weeks. Repeat dynamic ultrasound demonstrates that the affected hip remains completely dislocated and cannot be reduced in the harness. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Add a second diaper to maximize abduction
. Discontinue the Pavlik harness and plan for closed reduction and spica casting
. Perform an immediate open reduction
. Perform an isolated adductor tenotomy and reapply the Pavlik harness

Correct Answer & Explanation

. Continue the Pavlik harness for an additional 4 weeks

Explanation

If a dislocated hip fails to reduce after 3 to 4 weeks of Pavlik harness treatment, the harness must be discontinued. Prolonged use of the harness in an unreduced hip can lead to 'Pavlik harness disease' (erosion and damage to the posterior acetabular cartilage) and increases the risk of avascular necrosis. The next step is a transition to an alternative rigid abduction orthosis or, more definitively, a closed reduction with spica casting under general anesthesia (with or without an arthrogram and adductor tenotomy).

Question 2786

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp. Radiographs demonstrate fragmentation of the capital femoral epiphysis consistent with Legg-Calvé-Perthes disease. The lateral pillar maintains 60% of its normal height. According to the prospective multicenter study by Herring et al., what is the most appropriate management for this specific presentation?
. Observation and activity modification only
. Surgical containment (e.g., proximal femoral or pelvic osteotomy)
. Total hip arthroplasty
. Core decompression of the femoral head
. Prophylactic epiphysiodesis of the contralateral hip

Correct Answer & Explanation

. Surgical containment (e.g., proximal femoral or pelvic osteotomy)

Explanation

The patient has Legg-Calvé-Perthes disease. Maintaining 60% of the lateral pillar height places him in Herring Lateral Pillar Group B. The multicenter prospective study by Herring et al. demonstrated that children aged 8 years or older at the time of disease onset who have Group B (or B/C border) lateral pillar involvement have significantly better long-term radiographic and clinical outcomes when treated with surgical containment (such as a proximal femoral varus osteotomy or pelvic osteotomy) compared to non-operative management.

Question 2787

Topic: 4. Pediatrics

A 2-week-old infant is diagnosed with congenital idiopathic clubfoot and is scheduled to begin serial casting using the Ponseti method. What is the correct chronological sequence of deformity correction in this technique?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method addresses the components of a clubfoot deformity in a specific sequential order, best remembered by the acronym CAVE: Cavus, Adductus, Varus, and Equinus. The cavus is corrected first by supinating the forefoot to elevate the first ray. The adductus and varus are then corrected simultaneously by abducting the foot around the fixed head of the talus. Finally, the equinus is addressed, which frequently requires a percutaneous Achilles tenotomy.

Question 2788

Topic: 4. Pediatrics

A 12-year-old boy sustains a Salter-Harris type II fracture of the distal femur. The fracture is managed with a closed reduction and percutaneous pinning. Post-operative radiographs show perfect anatomical alignment. Despite an optimal reduction, the parents should be thoroughly counseled that the child remains at significant risk for which of the following complications?

. Atrophic nonunion
. Compartment syndrome
. Physeal growth arrest
. Avascular necrosis of the femoral condyle
. Chronic osteomyelitis

Correct Answer & Explanation

. Atrophic nonunion

Explanation

Distal femoral physeal fractures are notorious for having a very high rate of premature physeal closure and subsequent growth arrest, reported to occur in 40% to 90% of cases. This complication can happen regardless of the exact Salter-Harris classification or the quality of the anatomical reduction. The vulnerability is largely due to the undulating, wave-like anatomy of the distal femoral physis, which sustains significant microscopic crushing and shearing forces at the time of injury.

Question 2789

Topic: 4. Pediatrics

A 2-week-old infant is brought to the clinic for evaluation of a bilateral congenital foot deformity. Examination reveals rigid equinus, varus of the hindfoot, adductus of the forefoot, and a cavus midfoot. The decision is made to initiate the Ponseti method of serial casting. According to the principles of this technique, what is the correct sequence of deformity correction?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method is the gold standard for the treatment of idiopathic clubfoot. The correction follows a specific sequence remembered by the acronym CAVE: Cavus, Adductus, Varus, and Equinus. The cavus is corrected first by elevating the first ray, which aligns the forefoot with the hindfoot. Subsequent casts correct the adductus and varus by abducting the foot around the talar head. Finally, the equinus is corrected, which often requires a percutaneous Achilles tenotomy in the majority of patients.

Question 2790

Topic: 4. Pediatrics

A 6-year-old boy falls from the monkey bars and sustains a completely displaced, extension-type supracondylar fracture of the humerus. On presentation to the emergency department, his hand is pink and well-perfused. However, neurologic examination reveals that he is unable to flex the interphalangeal joint of his thumb or the distal interphalangeal joint of his index finger. Which of the following nerve structures is most likely injured?

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

Correct Answer & Explanation

. Radial nerve

Explanation

The anterior interosseous nerve (AIN), a motor branch of the median nerve, is the most commonly injured nerve in extension-type pediatric supracondylar humerus fractures. It innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index and middle fingers, and the pronator quadratus. The classic physical exam finding for AIN palsy is the inability to make an 'OK' sign, presenting as a 'pinch' posture instead due to the inability to flex the IP joint of the thumb and the DIP joint of the index finger. Sensory examination remains intact.

Question 2791

Topic: Pediatric Hip

A 7-month-old girl presents for evaluation of a persistent limp and asymmetric thigh folds. She has had no prior orthopedic treatment. Ultrasound and plain radiographs confirm a completely dislocated left hip consistent with developmental dysplasia of the hip (DDH). Clinical examination demonstrates limited abduction of the left hip and a positive Galeazzi sign. What is the most appropriate initial management for this patient?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction and spica casting
. Varus derotational osteotomy of the proximal femur
. Salter innominate osteotomy

Correct Answer & Explanation

. Pavlik harness application

Explanation

For children 6 to 18 months of age with previously untreated developmental dysplasia of the hip (DDH), closed reduction with hip spica casting is generally the initial treatment of choice. The Pavlik harness is highly successful in infants under 6 months of age but has a significantly higher failure rate in older, larger, and more active infants. Open reduction is indicated if closed reduction fails to achieve a stable, concentric reduction within a safe zone, or as a primary option in children presenting over 18 months of age. Pelvic or femoral osteotomies are typically reserved for children older than 18 months or those with residual dysplasia following successful reduction.

Question 2792

Topic: Pediatric Hip

A 12-year-old obese boy with a history of end-stage renal disease presents with a 3-week history of left thigh pain and a noticeable limp. He denies trauma. Examination reveals obligate external rotation of the left hip upon passive flexion. Radiographs demonstrate a mild left slipped capital femoral epiphysis (SCFE). Radiographs of the right hip appear normal. What is the most appropriate definitive management?

. In situ pinning of the left hip only
. In situ pinning of the left hip and prophylactic pinning of the right hip
. Closed reduction and pinning of the left hip
. Spica cast immobilization of the left hip
. Proximal femoral osteotomy of the left hip

Correct Answer & Explanation

. In situ pinning of the left hip only

Explanation

This patient presents with a stable slipped capital femoral epiphysis (SCFE) and underlying chronic renal failure (renal osteodystrophy). The standard treatment for a stable SCFE is in situ single-screw fixation. Prophylactic pinning of the contralateral asymptomatic hip remains controversial in purely idiopathic SCFE but is highly recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, chronic renal failure, prior radiation, growth hormone therapy). These patients have an exceptionally high risk (up to 50-100%) of developing a bilateral slip. Closed reduction of a SCFE is contraindicated as it significantly increases the risk of avascular necrosis (AVN).

Question 2793

Topic: 4. Pediatrics

A 5-year-old girl with spastic quadriplegic cerebral palsy is evaluated in the clinic. She is non-ambulatory (GMFCS Level V) and requires full assistance for transfers. Pelvic radiographs reveal an anteroposterior view with a bilateral migration percentage (Reimers' index) of 45%. Clinical examination shows bilateral hip abduction is limited to 20 degrees with the hips in extension. She has an established coxa valga deformity. What is the most appropriate management to prevent painful hip dislocation?

. Observation with repeat radiographs in 12 months
. Bilateral adductor tenotomies
. Bilateral proximal femoral varus derotational osteotomies (VDRO)
. Bilateral botulinum toxin A injections to the adductors
. Bilateral total hip arthroplasties

Correct Answer & Explanation

. Observation with repeat radiographs in 12 months

Explanation

Hip displacement is a common and severe complication in patients with spastic quadriplegic cerebral palsy (GMFCS IV and V). A migration percentage (Reimers' index) greater than 30-40% indicates significant subluxation requiring surgical intervention. While isolated soft tissue releases (adductor tenotomies) may be effective early on (migration <30%), once the migration percentage exceeds 40% and structural bony changes (coxa valga, excessive femoral anteversion) are present, soft tissue releases alone have an unacceptably high failure rate. Bony reconstruction, specifically bilateral proximal femoral varus derotational osteotomies (often combined with a pelvic osteotomy), is the standard of care to achieve concentric reduction and prevent progression to a painful dislocated hip.

Question 2794

Topic: 4. Pediatrics

A 6-year-old boy sustains a traumatic posterior hip dislocation following a low-energy fall from a playground structure. Reduction is performed urgently under conscious sedation. Which of the following best describes the prognosis and management regarding avascular necrosis (AVN) in this pediatric patient?

. The risk of AVN is negligible due to the robust ligamentum teres blood supply at this age
. The risk of AVN significantly increases if reduction is delayed beyond 6 hours
. Routine prophylactic core decompression should be performed within 1 week
. The child should be placed in a spica cast for 12 weeks to prevent AVN
. MRI is contraindicated in pediatric hip dislocations

Correct Answer & Explanation

. The risk of AVN is negligible due to the robust ligamentum teres blood supply at this age

Explanation

Pediatric hip dislocations can occur with low-energy trauma due to ligamentous laxity. Similar to adults, the risk of avascular necrosis (AVN) is closely tied to the time to reduction, with a significant increase in AVN incidence if reduction is delayed beyond 6 hours.

Question 2795

Topic: Pediatric Hip

Following a complex total hip arthroplasty via a posterior approach for developmental dysplasia of the hip (DDH), the patient is noted to have a foot drop. They cannot dorsiflex the great toe but have preserved plantar flexion. Which nerve division is most likely injured, and what is the typical mechanism?

. Tibial division of the sciatic nerve from direct transection
. Peroneal division of the sciatic nerve from excessive lengthening
. Femoral nerve from anterior retractor placement
. Superior gluteal nerve from proximal extension of the split
. Obturator nerve from extruded cement

Correct Answer & Explanation

. Tibial division of the sciatic nerve from direct transection

Explanation

The peroneal division of the sciatic nerve is the most commonly injured nerve during THA, particularly in cases involving significant limb lengthening (e.g., DDH). It is more susceptible to stretch injury than the tibial division because it is tethered at the fibular head and has less supportive connective tissue.

Question 2796

Topic: 4. Pediatrics

A pediatric patient presents with bowing of the legs and widening of the physes. Laboratory studies show normal calcium, markedly decreased phosphate, and normal vitamin D levels. A mutation in which of the following is most likely responsible?

. 1-alpha-hydroxylase
. PHEX gene
. Calcium-sensing receptor
. Type I collagen
. FGFR3

Correct Answer & Explanation

. 1-alpha-hydroxylase

Explanation

The scenario describes X-linked hypophosphatemic rickets, typically caused by a PHEX gene mutation leading to elevated FGF-23. This results in renal phosphate wasting and impaired mineralization of bone.

Question 2797

Topic: 4. Pediatrics

A 6-year-old child sustains a physeal injury to the distal femur, leading to asymmetric physeal arrest and subsequent angular deformity. This process of altered bone growth due to increased compressive forces is described by:

. Wolff's Law
. Heuter-Volkmann Law
. Hilton's Law
. Starling's Law
. Hooke's Law

Correct Answer & Explanation

. Wolff's Law

Explanation

The Heuter-Volkmann Law states that increased compressive forces across a physis inhibit growth, whereas decreased compressive forces stimulate growth. This mechanism explains the progressive angular deformity seen after certain physeal injuries.

Question 2798

Topic: 4. Pediatrics

In a 6-year-old child, the predominant blood supply to the proximal femoral epiphysis is derived from branches of which of the following vessels?

. Artery of the ligamentum teres
. Medial femoral circumflex artery
. Lateral femoral circumflex artery
. Inferior gluteal artery
. Superior gluteal artery

Correct Answer & Explanation

. Artery of the ligamentum teres

Explanation

The medial femoral circumflex artery, specifically its lateral epiphyseal branches, is the predominant blood supply to the femoral head in pediatric and adult populations. The contribution from the artery of the ligamentum teres is variable and relatively insignificant.

Question 2799

Topic: 4. Pediatrics
When evaluating pediatric hip vascularity to understand the risk of avascular necrosis in Legg-Calvé-Perthes disease, which of the following vessels provides the predominant blood supply to the capital femoral epiphysis in a 6-year-old child?
. Artery of the ligamentum teres
. Inferior metaphyseal vessels
. Lateral epiphyseal vessels from the medial femoral circumflex artery
. Ascending branch of the lateral femoral circumflex artery
. Medial epiphyseal vessels from the obturator artery

Correct Answer & Explanation

. Lateral epiphyseal vessels from the medial femoral circumflex artery

Explanation

Between ages 3 and 10, the growth plate acts as a barrier to metaphyseal vessels, and the artery of the ligamentum teres is not yet a significant contributor. The primary blood supply to the capital femoral epiphysis is via the lateral epiphyseal branches of the medial femoral circumflex artery (MFCA).

Question 2800

Topic: 4. Pediatrics

An 8-year-old boy sustains a Salter-Harris Type II fracture of the distal radius. The fracture line passes through the growth plate and exits through the metaphysis. Through which histologic zone of the physis does the fracture line primarily propagate?

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

Correct Answer & Explanation

. Reserve zone

Explanation

Physeal fractures classically propagate through the zone of hypertrophy, specifically the layer of degenerating chondrocytes. This zone lacks both the abundant extracellular matrix of the proliferative zone and the structural reinforcement found in the zone of calcification.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page