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4. Pediatrics MCQs

Practice Set 315 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 6281

Topic: 4. Pediatrics

A 7-year-old child with spastic quadriplegic cerebral palsy (GMFCS level V) is evaluated for hip surveillance. Anteroposterior pelvic radiographs reveal bilateral hip subluxation with a Reimers migration percentage of 55%. The hips are currently painless, but abduction is symmetrically limited to 15 degrees. What is the most appropriate surgical treatment?

. Bilateral adductor longus and iliopsoas tenotomies
. Bilateral botulinum toxin A injections into the hip adductors
. Bilateral varus derotational femoral osteotomies (VDRO) with pelvic osteotomies
. Bilateral proximal femoral resections (Castle procedure)
. Bilateral total hip arthroplasties

Correct Answer & Explanation

. Bilateral varus derotational femoral osteotomies (VDRO) with pelvic osteotomies

Explanation

In severe spastic cerebral palsy (GMFCS IV/V) with a Reimers migration percentage >40%, soft tissue releases alone have an unacceptably high failure rate. Bony reconstruction with varus derotational femoral osteotomies (VDRO), often combined with an acetabular procedure (e.g., Dega osteotomy), is required to achieve stable concentric reduction.

Question 6282

Topic: 4. Pediatrics

A 10-year-old boy presents with severe leg pain, waddling gait, and progressive weakness. Radiographs demonstrate bilateral symmetrical cortical thickening of the diaphyseal regions of the femurs and tibias, sparing the epiphyses and metaphyses.

Which of the following genetic mutations is responsible for this condition?

. COL1A1
. FGFR3
. TGFB1
. COMP
. EXT1

Correct Answer & Explanation

. TGFB1

Explanation

This is Camurati-Engelmann disease (Progressive Diaphyseal Dysplasia), characterized by diaphyseal cortical thickening. It is caused by an autosomal dominant mutation in the TGFB1 gene, leading to increased bone formation.

Question 6283

Topic: 4. Pediatrics

A 7-year-old boy presents with severe leg pain, easy fatigability, and a waddling gait. Radiographs reveal bilateral, symmetric cortical thickening of the long bone diaphyses.

This condition is most commonly associated with a mutation in which of the following genes?

. COL1A1
. COMP
. FGFR3
. TGFB1
. RUNX2

Correct Answer & Explanation

. TGFB1

Explanation

Camurati-Engelmann disease (progressive diaphyseal dysplasia) is an autosomal dominant disorder caused by a mutation in the TGFB1 gene. It leads to marked cortical thickening of the diaphyses of long bones and presents with bone pain and muscle weakness.

Question 6284

Topic: 4. Pediatrics

A 9-year-old boy presents with severe leg pain, a waddling gait, and delayed puberty. Radiographs show bilateral, symmetric cortical thickening of the diaphyseal regions of the femur and tibia.

Which genetic mutation is characteristic of this condition?

. COL1A1
. FGFR3
. TGFB1
. COMP
. GNAS1

Correct Answer & Explanation

. TGFB1

Explanation

Progressive diaphyseal dysplasia (Camurati-Engelmann disease) is an autosomal dominant disorder caused by mutations in the TGFB1 gene. It is characterized by cortical thickening of the long bone diaphyses, bone pain, and muscle weakness.

Question 6285

Topic: 4. Pediatrics

A 12-year-old boy presents with a waddling gait, severe leg pain, and easy fatigability. Radiographs reveal bilateral, symmetric, fusiform cortical thickening of the femoral and tibial diaphyses, sparing the metaphyses and epiphyses.

What is the genetic basis of this disorder?

. Mutation in the GNAS gene
. Mutation in the COMP gene
. Mutation in the TGFB1 gene
. Mutation in the FGFR3 gene
. Mutation in the COL1A1 gene

Correct Answer & Explanation

. Mutation in the TGFB1 gene

Explanation

Progressive diaphyseal dysplasia (Camurati-Engelmann disease) is an autosomal dominant condition caused by mutations in the TGFB1 gene. It presents with progressive diaphyseal cortical thickening, leg pain, and proximal muscle weakness.

Question 6286

Topic: 4. Pediatrics

A 9-year-old boy presents with severe leg pain, waddling gait, and bilateral muscle weakness. Radiographs demonstrate symmetrical cortical thickening of the diaphyses of the femurs and tibias with sparing of the epiphyses.

A mutation in which of the following genes is most likely responsible for this condition?

. COL1A1
. FGFR3
. COMP
. TGFB1
. SOX9

Correct Answer & Explanation

. TGFB1

Explanation

This presentation is characteristic of Camurati-Engelmann disease (progressive diaphyseal dysplasia). It is an autosomal dominant disorder caused by a mutation in the TGFB1 gene on chromosome 19. The mutation leads to increased osteoblastic activity resulting in cortical thickening.

Question 6287

Topic: 4. Pediatrics

A 10-year-old child presents with progressive waddling gait, severe lower extremity pain, and diminished muscle mass. Radiographs reveal symmetric bilateral cortical thickening of the diaphyseal regions of the long bones.

Which portion of the bone remains characteristically uninvolved in this disease?

. The endosteum
. The periosteum
. The diaphysis
. The epiphysis
. The medullary canal

Correct Answer & Explanation

. The periosteum

Explanation

In Camurati-Engelmann disease (progressive diaphyseal dysplasia), new bone formation occurs on both the endosteal and periosteal surfaces of the diaphysis. The defining radiographic feature is that the epiphyses and metaphyses are characteristically spared.

Question 6288

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents with a pink, pulseless hand following a Gartland type III supracondylar humerus fracture. After careful closed reduction and percutaneous pinning, the hand remains pink but pulseless. A Doppler ultrasound confirms biphasic flow in the palmar arch. What is the most appropriate next step in management?
. Immediate vascular exploration
. Observation and hospital admission for serial exams
. Local intra-arterial infusion of papaverine
. Removal of pins and immediate open reduction
. Prophylactic anterior compartment fasciotomy

Correct Answer & Explanation

. Observation and hospital admission for serial exams

Explanation

In a pink, pulseless hand after adequate reduction of a supracondylar humerus fracture, observation is indicated because collateral circulation is sufficient. Vascular exploration is only required if the hand remains white and pulseless after fracture reduction.

Question 6289

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute on chronic knee pain and an inability to bear weight. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant prognostic risk factor for the development of avascular necrosis (AVN) in this patient?

. Failure to perform a capsulotomy
. Time to surgery greater than 24 hours
. Concomitant obesity
. An unstable slip
. Bilateral involvement

Correct Answer & Explanation

. An unstable slip

Explanation

The most significant risk factor for AVN in slipped capital femoral epiphysis is an unstable slip, defined clinically by the patient's inability to bear weight. While timing of surgery and decompression are debated, instability remains the strongest predictor.

Question 6290

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy falls from monkey bars and presents with a swollen, painful left elbow. Radiographs reveal an extension-type Gartland III supracondylar humerus fracture with posterolateral displacement of the distal fragment. Which of the following nerve injuries is most likely to be associated with this specific fracture pattern, and what is the corresponding clinical finding?
. Anterior interosseous nerve; inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger
. Radial nerve; inability to extend the wrist and fingers
. Ulnar nerve; inability to cross the index and middle fingers
. Median nerve (main trunk); decreased sensation over the thenar eminence
. Musculocutaneous nerve; weakness in elbow flexion

Correct Answer & Explanation

. Anterior interosseous nerve; inability to flex the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger

Explanation

In extension-type supracondylar humerus fractures, the direction of displacement of the distal fragment dictates the structures at risk. Posterolateral displacement of the distal fragment causes the proximal fragment to displace anteromedially, putting the median nerve—specifically its anterior interosseous nerve (AIN) branch—at the greatest risk. The AIN is a purely motor nerve that innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index and middle fingers, and the pronator quadratus. Injury results in the inability to make an 'A-OK' sign. Posteromedial displacement of the distal fragment puts the radial nerve at risk. Flexion-type fractures put the ulnar nerve at risk.

Question 6291

Topic: Pediatric Hip

A 12-year-old obese boy presents with a 3-week history of left groin pain and a limp. He is diagnosed with a stable left slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. The parents ask about the risk to the right hip. Prophylactic pinning of the contralateral, asymptomatic hip is most strongly indicated in patients with which of the following characteristics?

. Age greater than 14 years at presentation
. Underlying endocrine disorder, such as hypothyroidism
. Body Mass Index (BMI) greater than the 95th percentile
. Presentation with an acute-on-chronic slip
. Slip angle greater than 50 degrees on the affected side

Correct Answer & Explanation

. Underlying endocrine disorder, such as hypothyroidism

Explanation

Correct Answer: Underlying endocrine disorder, such as hypothyroidismThe risk of developing a contralateral SCFE is approximately 20-40% overall. However, prophylactic pinning of the contralateral hip is generally reserved for patients at exceptionally high risk. Strong indications for prophylactic pinning include underlying endocrine disorders (e.g., hypothyroidism, growth hormone deficiency), renal osteodystrophy, previous radiation therapy to the pelvis, and very young age at presentation (typically less than 10 years old for boys). While obesity (high BMI) is a risk factor for SCFE, it alone is not an absolute indication for prophylactic pinning of the contralateral side. The severity of the initial slip or an acute-on-chronic presentation does not dictate contralateral prophylactic pinning.

Question 6292

Topic: 4. Pediatrics

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a routine follow-up, the mother reports that the infant is not kicking her right leg as much as before. On examination, there is decreased active knee extension on the right, but sensation appears intact and the child cries when the foot is tickled. What is the most likely cause of this finding, and what is the appropriate management?

. Femoral nerve palsy; discontinue the harness temporarily
. Obturator nerve palsy; adjust the anterior straps to decrease flexion
. Avascular necrosis of the femoral head; immediate closed reduction and spica casting
. Sciatic nerve palsy; loosen the posterior straps to decrease abduction
. Transient synovitis; observe and continue the harness

Correct Answer & Explanation

. Femoral nerve palsy; discontinue the harness temporarily

Explanation

Correct Answer: Femoral nerve palsy; discontinue the harness temporarilyThe clinical presentation of decreased active knee extension in an infant wearing a Pavlik harness is highly suspicious for a femoral nerve palsy. This complication typically occurs due to hyperflexion of the hip, which compresses the femoral nerve against the inguinal ligament. The appropriate management is to temporarily discontinue the harness or significantly loosen the anterior straps to reduce hip flexion until nerve function returns, which usually happens within a few days to weeks. Sciatic nerve palsy is less common and would present with decreased ankle/toe movement. Avascular necrosis is a severe complication related to excessive abduction, not hyperflexion, and does not present acutely with isolated loss of knee extension.

Question 6293

Topic: Pediatric Hip
A 7-year-old boy presents with a painless limp of 2 months' duration. Radiographs of the pelvis demonstrate fragmentation and sclerosis of the right capital femoral epiphysis, consistent with Legg-Calvé-Perthes disease. Which of the following is considered the most important prognostic factor for the final radiographic outcome of the hip?
. Gender of the patient
. Age of the patient at the time of clinical onset
. Body mass index
. Presence of a metaphyseal cyst
. Degree of initial pain

Correct Answer & Explanation

. Age of the patient at the time of clinical onset

Explanation

In Legg-Calvé-Perthes disease, the age of the patient at the onset of the disease is the single most important prognostic factor. Children who develop the disease at a younger age (typically under 6 years) have a much better prognosis because they have more time for the femoral head to remodel before skeletal maturity. Patients who present at an older age (especially over 8 years) have a higher risk of developing a permanently deformed femoral head (coxa magna, coxa plana) and subsequent early-onset osteoarthritis. While lateral pillar involvement (Herring classification) is also a critical prognostic radiographic factor, age is the most important demographic/clinical factor.

Question 6294

Topic: 4. Pediatrics

A 2-week-old infant is undergoing serial casting for idiopathic congenital talipes equinovarus (clubfoot) using the Ponseti method. To achieve optimal results and avoid creating a midfoot breach (rocker-bottom foot), the deformities must be corrected in a specific sequence. What is the correct order of deformity correction in the Ponseti method?

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

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

Correct Answer: Cavus, Adductus, Varus, EquinusThe Ponseti method relies on a specific sequence of correction, easily remembered by the acronym CAVE: Cavus, Adductus, Varus, Equinus. The first step is to correct the cavus deformity by elevating the first ray (supinating the forefoot) to align it with the hindfoot. Once the cavus is corrected, the midfoot is abducted around the head of the talus to correct the adductus and varus deformities simultaneously. The equinus deformity is corrected last, often requiring a percutaneous Achilles tenotomy, as attempting to correct equinus too early can lead to a midfoot break (rocker-bottom deformity).

Question 6295

Topic: 4. Pediatrics
A 14-year-old girl sustains an ankle injury while playing soccer. Radiographs reveal a Salter-Harris III fracture of the anterolateral aspect of the distal tibial epiphysis. This fracture pattern is primarily due to the asymmetric closure of the distal tibial physis. Which ligament is responsible for the avulsion of this specific fracture fragment?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament (AITFL)
. Posterior inferior tibiofibular ligament (PITFL)
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

The patient has a juvenile Tillaux fracture, which is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. This occurs in adolescents because the distal tibial physis closes in a specific pattern: central, then anteromedial, then posteromedial, and finally lateral. When an external rotation force is applied to the ankle during the period when the medial physis is closed but the lateral physis remains open, the anterior inferior tibiofibular ligament (AITFL) avulses the anterolateral epiphysis. The ATFL and CFL are lateral ankle ligaments involved in sprains, while the PITFL is involved in Volkmann fractures (posterior malleolus).

Question 6296

Topic: 4. Pediatrics

A 6-year-old boy with spastic quadriplegic cerebral palsy (GMFCS Level V) is evaluated in the orthopaedic clinic. He has no hip pain, but his parents report difficulty with perineal hygiene. An AP pelvis radiograph demonstrates a Reimers migration percentage of 45% on the right hip and 15% on the left. The right acetabular index is 30 degrees. What is the most appropriate next step in management for the right hip?

. Observation with repeat radiographs in 1 year
. Botulinum toxin injection to the adductors and hamstrings
. Soft tissue release (adductor tenotomy and psoas lengthening)
. Varus derotational osteotomy (VDRO) of the proximal femur and pelvic osteotomy
. Total hip arthroplasty

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) of the proximal femur and pelvic osteotomy

Explanation

Correct Answer: Varus derotational osteotomy (VDRO) of the proximal femur and pelvic osteotomyHip surveillance is critical in children with cerebral palsy, especially those with higher GMFCS levels (IV and V), as they are at high risk for progressive hip displacement. The Reimers migration percentage (MP) guides treatment. An MP < 30% is typically observed. An MP between 30% and 40% in a young child may be treated with soft tissue releases (adductor/psoas). However, an MP > 40-50%, especially with acetabular dysplasia (acetabular index > 25-30 degrees), indicates significant bony deformity that will not respond to soft tissue release alone. Bony reconstruction with a proximal femoral varus derotational osteotomy (VDRO) and a pelvic osteotomy (e.g., Dega or San Diego) is the standard of care to achieve a stable, concentric reduction.

Question 6297

Topic: 4. Pediatrics
A 3-year-old obese African American girl presents with progressive bowing of her left leg. Standing radiographs demonstrate a sharp varus angulation at the proximal tibial metaphysis. The metaphyseal-diaphyseal angle (Drennan angle) is measured at 18 degrees. What is the most likely diagnosis and the most appropriate initial treatment?
. Physiologic bowing; observation and reassurance
. Infantile Blount disease; Knee-ankle-foot orthosis (KAFO) bracing
. Infantile Blount disease; proximal tibial valgus osteotomy
. Nutritional rickets; Vitamin D and calcium supplementation
. Adolescent Blount disease; guided growth (hemiepiphysiodesis)

Correct Answer & Explanation

. Infantile Blount disease; Knee-ankle-foot orthosis (KAFO) bracing

Explanation

The patient presents with infantile Blount disease (tibia vara), characterized by a localized disorder of the posteromedial proximal tibial physis. Risk factors include early walking, obesity, and African American descent. The metaphyseal-diaphyseal angle (Drennan angle) is crucial for distinguishing Blount disease from physiologic bowing. An angle > 16 degrees is highly predictive of Blount disease, whereas < 10 degrees suggests physiologic bowing. For children under the age of 3 to 4 years with early-stage infantile Blount disease (Langenskiöld stages I-II), the initial treatment is full-time bracing with a KAFO. If bracing fails or the child presents at an older age/higher stage, a proximal tibial osteotomy is indicated.

Question 6298

Topic: 4. Pediatrics

A 4-year-old boy is evaluated for a history of three low-energy long bone fractures. On examination, he has a triangular facies, blue sclerae, and brownish, opalescent teeth (dentinogenesis imperfecta). Genetic testing is ordered. This patient's condition is most likely caused by a mutation affecting which of the following structural proteins?

. Fibroblast growth factor receptor 3 (FGFR3)
. Type I collagen
. Type II collagen
. Cartilage oligomeric matrix protein (COMP)
. Core binding factor alpha 1 (CBFA1 / RUNX2)

Correct Answer & Explanation

. Type I collagen

Explanation

Correct Answer: Type I collagenThe clinical presentation of multiple fractures, blue sclerae, and dentinogenesis imperfecta is classic for Osteogenesis Imperfecta (OI). OI is primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode the alpha-1 and alpha-2 chains of Type I collagen. Type I collagen is the major structural protein in bone, skin, sclera, and dentin. FGFR3 mutations cause achondroplasia. Type II collagen mutations cause various skeletal dysplasias, including spondyloepiphyseal dysplasia (SED). COMP mutations are associated with pseudoachondroplasia and multiple epiphyseal dysplasia (MED). CBFA1 (RUNX2) mutations cause cleidocranial dysplasia.

Question 6299

Topic: Pediatric Hip

A 13-year-old boy presents with a stable left slipped capital femoral epiphysis (SCFE) and undergoes in situ pinning. The parents inquire about the risk of the right hip developing a similar problem. Which of the following is the strongest radiographic predictor for the development of a contralateral slip?

. Posterior sloping angle greater than 15 degrees
. Open triradiate cartilage
. Klein's line intersecting less than 10% of the epiphysis
. Alpha angle greater than 55 degrees
. Metaphyseal blanch sign of Steel

Correct Answer & Explanation

. Open triradiate cartilage

Explanation

Correct Answer: BThe status of the triradiate cartilage is a strong radiographic predictor of future contralateral slip in patients presenting with a unilateral SCFE. An open triradiate cartilage indicates significant remaining skeletal growth and correlates with a high risk (up to 80% in some studies) of developing a contralateral SCFE. The modified Oxford bone age score is also used to assess this risk, heavily weighting the triradiate cartilage and iliac apophysis. Prophylactic pinning of the contralateral hip is often considered in patients with open triradiate cartilage, endocrine disorders, or an inability to follow up reliably. The posterior sloping angle and Klein's line are used to diagnose or quantify the severity of the current slip, not predict contralateral occurrence. The alpha angle is used to assess for femoroacetabular impingement (cam morphology), which can be a sequela of SCFE. The metaphyseal blanch sign of Steel is a radiographic sign of SCFE on an AP pelvis radiograph, representing the overlapping of the posteriorly displaced epiphysis and the metaphysis.

Question 6300

Topic: Pediatric Hip

A 4-week-old female is being treated with a Pavlik harness for a dislocated right hip. At her 2-week follow-up appointment, the parents report that she is not kicking her right leg as much as her left. On examination, she has absent active knee extension on the right, but normal active ankle and toe movements. What is the most likely cause of this finding?

. Obturator nerve palsy from excessive abduction
. Femoral nerve palsy from excessive hyperflexion
. Sciatic nerve palsy from excessive extension
. Avascular necrosis of the femoral head
. Transient synovitis of the hip

Correct Answer & Explanation

. Femoral nerve palsy from excessive hyperflexion

Explanation

Correct Answer: BThe clinical presentation of absent active knee extension with preserved distal motor function in an infant wearing a Pavlik harness is classic for a femoral nerve palsy. This complication is typically caused by excessive hyperflexion of the hip in the harness, which compresses the femoral nerve against the inguinal ligament or pelvic brim. The appropriate management is to temporarily remove the harness or adjust it to decrease the amount of flexion, allowing the nerve palsy to resolve, which it almost always does. Excessive abduction in a Pavlik harness is associated with avascular necrosis (AVN) of the femoral head, not an isolated obturator nerve palsy. Sciatic nerve palsy is not a typical complication of Pavlik harness treatment and would present with distal deficits (ankle/toe movement). Transient synovitis is a cause of hip pain in older children (typically 3-8 years) and does not cause isolated motor nerve palsies.

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