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4. Pediatrics MCQs

Practice Set 153 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 3041

Topic: Pediatric Upper Extremity & Spine

A lateral approach to the distal femur is utilized for plating a supracondylar femur fracture. As the vastus lateralis is elevated from the lateral intermuscular septum, robust vessels are encountered piercing the septum. These perforating vessels are primarily branches of which artery?

. Superficial femoral artery
. Profunda femoris artery
. Popliteal artery
. Descending genicular artery
. Lateral circumflex femoral artery

Correct Answer & Explanation

. Profunda femoris artery

Explanation

The perforating arteries encountered at the lateral intermuscular septum during a lateral femoral approach are branches of the profunda femoris artery. They must be carefully identified and coagulated to prevent postoperative hematoma.

Question 3042

Topic: Pediatric Hip

A 26-year-old professional hockey player presents with chronic groin pain exacerbated by deep hip flexion and internal rotation. A Dunn lateral radiograph is obtained, and the alpha angle is measured to be 68 degrees. This radiographic finding is most consistent with which of the following pathomorphologies?

. Pincer impingement secondary to focal acetabular retroversion
. Cam impingement due to an abnormal femoral head-neck offset
. Subspine impingement due to a prominent anterior inferior iliac spine
. Ischiofemoral impingement between the lesser trochanter and ischium
. Sequelae of unrecognized slipped capital femoral epiphysis leading to coxa vara

Correct Answer & Explanation

. Cam impingement due to an abnormal femoral head-neck offset

Explanation

The alpha angle is a radiographic measurement used to quantify the sphericity of the anterior femoral head and the head-neck offset, typically measured on a lateral projection such as the Dunn view. An alpha angle greater than 50-55 degrees (with 68 degrees being clearly pathologic) indicates a loss of the normal concave junction between the anterior femoral head and neck. This morphologic abnormality represents a Cam deformity, which engages and damages the anterosuperior acetabular labrum and articular cartilage during hip flexion and internal rotation (Cam-type Femoroacetabular Impingement).

Question 3043

Topic: Pediatric Hip

A 26-year-old male hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. Radiographs show an alpha angle of 65 degrees and a positive crossover sign.

The patient's radiographic findings are most consistent with which of the following?

. Isolated Cam impingement.
. Isolated Pincer impingement.
. Mixed Cam and Pincer impingement.
. Developmental dysplasia of the hip.
. Legg-Calve-Perthes disease.

Correct Answer & Explanation

. Mixed Cam and Pincer impingement.

Explanation

An increased alpha angle (>50-55 degrees) is indicative of a Cam-type morphology (aspherical femoral head-neck junction). The crossover sign indicates focal cranial retroversion of the acetabulum, which is a classic radiographic marker of Pincer-type impingement. The combination of both an elevated alpha angle and a crossover sign indicates mixed femoroacetabular impingement (FAI), which is the most common clinical presentation of FAI.

Question 3044

Topic: Pediatric Hip

A 12-year-old boy with a BMI of 35 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). Which of the following factors is the strongest indication for prophylactic pinning of the contralateral right hip?

. Male gender
. Presentation with a stable slip
. Modified Oxford bone age score of 22
. Concomitant hypothyroidism
. Symptom duration of 3 weeks

Correct Answer & Explanation

. Concomitant hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is generally recommended in patients with endocrine disorders (such as hypothyroidism, renal osteodystrophy, or growth hormone deficiency), previous pelvic radiation, or highly delayed bone age (Modified Oxford bone age score of 16 or less). A score of 22 indicates older bone maturity.

Question 3045

Topic: 4. Pediatrics

A 6-year-old girl sustains a severely displaced, extension-type supracondylar humerus fracture. On arrival, the hand is pink and well-perfused but the radial pulse is absent. She is taken to the operating room for closed reduction and percutaneous pinning. Following anatomic reduction and pinning, the radial pulse remains absent, but the hand remains pink with brisk capillary refill. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. Angiography to evaluate the brachial artery
. Observation and admission for neurovascular monitoring
. Removal of the pins and open reduction
. Arterial duplex ultrasonography

Correct Answer & Explanation

. Observation and admission for neurovascular monitoring

Explanation

In a pediatric supracondylar humerus fracture, a 'pulseless, pink hand' after anatomic reduction and stabilization should be observed closely. Capillary refill and skin color indicate adequate collateral perfusion. Open exploration of the brachial artery is indicated if the hand becomes or remains pulseless and pale/ischemic after reduction.

Question 3046

Topic: 4. Pediatrics

A 6-week-old female infant is treated with a Pavlik harness for a dislocated left hip (Graf type IV). At her 2-week follow-up, the mother reports that the infant is not moving her left leg as much as the right. On examination, the infant lacks active knee extension on the left, but hip and ankle movements are intact. What is the most likely cause of this finding?

. Femoral nerve palsy due to excessive hip flexion
. Obturator nerve palsy due to excessive hip abduction
. Sciatic nerve palsy due to excessive hip flexion
. Avascular necrosis of the femoral head
. Transient synovitis

Correct Answer & Explanation

. Femoral nerve palsy due to excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically caused by hyperflexion of the hip. It presents with decreased or absent active knee extension. The harness should be adjusted to reduce hip flexion or temporarily discontinued if the palsy occurs. Excessive abduction is associated with a risk of avascular necrosis.

Question 3047

Topic: Pediatric Hip

An 8-year-old boy presents with a 2-month history of a painless limp. Radiographs demonstrate sclerosis and fragmentation of the right capital femoral epiphysis. Which of the following radiographic findings at presentation is the most significant indicator of a poor prognosis in Legg-Calvé-Perthes disease?

. Subchondral radiolucent line (Crescent sign)
. Gage sign
. Lateral calcification
. Lateral subluxation of the femoral head
. Coxa magna

Correct Answer & Explanation

. Lateral subluxation of the femoral head

Explanation

Lateral subluxation (extrusion) of the femoral head is one of the 'head-at-risk' signs described by Catterall and is the most significant radiographic indicator of a poor prognosis. It leads to loss of containment, hinge abduction, and severe deformity if not addressed.

Question 3048

Topic: Pediatric Lower Extremity

In the Ponseti method for the treatment of idiopathic clubfoot, what is the correct sequence of deformity correction?

. Cavus, Adductus, Varus, Equinus (CAVE)
. Cavus, Varus, Adductus, Equinus (CVAE)
. Equinus, Varus, Adductus, Cavus (EVAC)
. Adductus, Varus, Cavus, Equinus (AVCE)
. Varus, Adductus, Cavus, Equinus (VACE)

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus (CAVE)

Explanation

The Ponseti method sequentially corrects the deformities of clubfoot in the order of the acronym CAVE: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus (which often requires a percutaneous Achilles tenotomy).

Question 3049

Topic: 4. Pediatrics

A 2-year-old girl presents with progressive bilateral bowing of the legs. Radiographs show an abrupt, sharp varus angulation at the proximal tibial metaphysis with a Drennan metaphyseal-diaphyseal angle of 18 degrees. What is the most appropriate initial management?

. Reassurance and observation
. Knee-ankle-foot orthoses (KAFOs)
. Proximal tibial valgus osteotomy
. Guided growth (hemiepiphysiodesis) of the medial proximal tibia
. Guided growth of the lateral proximal tibia

Correct Answer & Explanation

. Knee-ankle-foot orthoses (KAFOs)

Explanation

Infantile Blount disease typically presents between 2 and 3 years of age. A metaphyseal-diaphyseal angle (MDA) > 16 degrees suggests a high risk of progression to true Blount disease rather than physiologic bowing. The initial treatment for infantile Blount disease in a child under 3 years with early-stage disease (Langenskiöld stage I or II) is bracing with knee-ankle-foot orthoses (KAFOs) during weight-bearing. Surgical intervention is considered if bracing fails or in older children.

Question 3050

Topic: Pediatric Hip

A 4-year-old girl is brought in by her parents for an abnormal gait and limb length discrepancy. She has no prior orthopedic history. Radiographs show a high dislocated left hip with a false acetabulum and severe acetabular dysplasia.

What is the most appropriate surgical management?

. Closed reduction and spica cast application
. Open reduction and spica cast application
. In situ Shelf arthroplasty
. Open reduction with pelvic osteotomy and femoral shortening osteotomy
. Varus derotational osteotomy (VDO) alone

Correct Answer & Explanation

. Open reduction with pelvic osteotomy and femoral shortening osteotomy

Explanation

In children older than 3 years with neglected or untreated developmental dysplasia of the hip (DDH), open reduction alone is associated with an unacceptably high rate of avascular necrosis (AVN) and redislocation due to soft tissue contractures and bony deformity. A concomitant femoral shortening osteotomy is necessary to relieve soft tissue tension and decrease the risk of AVN. A pelvic osteotomy (e.g., Dega, Salter, or Pemberton) is required to address the underlying acetabular dysplasia and provide adequate anterolateral coverage for the reduced femoral head.

Question 3051

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from the monkey bars and sustains a widely displaced Gartland type III supracondylar humerus fracture. On arrival at the emergency department, his hand is pink but the radial pulse is not palpable. Closed reduction and percutaneous pinning are performed. After pinning, the hand remains well-perfused and pink, but the radial pulse is still absent on palpation and Doppler. What is the most appropriate next step in management?

. Immediate vascular exploration of the brachial artery
. Observation and admission for 24 to 48 hours
. Removal of the pins and extension of the elbow to 45 degrees
. Administration of a sympathetic nerve block
. Immediate emergent CT angiography of the upper extremity

Correct Answer & Explanation

. Observation and admission for 24 to 48 hours

Explanation

The management of a 'pink, pulseless' hand following an acceptable reduction and pinning of a supracondylar humerus fracture is observation. Collateral circulation in the pediatric elbow is robust, providing adequate perfusion to the hand even if the brachial artery is in spasm or sustains a localized intimal injury. Current AAOS guidelines support observation; the pulse typically returns within 24 to 48 hours. Vascular exploration is strictly indicated if the hand is white, cold, and poorly perfused (ischemic) after reduction.

Question 3052

Topic: Pediatric Hip

A 12-year-old obese boy presents with a left chronic stable slipped capital femoral epiphysis (SCFE) and undergoes uncomplicated in situ pinning. Which of the following is the most significant risk factor indicating the need for prophylactic pinning of the contralateral asymptomatic hip?

. Age less than 10 years or open triradiate cartilage
. Male sex
. African American race
. Symptom duration greater than 6 months
. High slip angle (greater than 50 degrees) on the affected side

Correct Answer & Explanation

. Age less than 10 years or open triradiate cartilage

Explanation

The status of the triradiate cartilage and the modified Oxford bone age are the strongest predictors for the development of a contralateral slip in SCFE. An open triradiate cartilage or a chronologic age of less than 10 years (or less than 12 years in boys) indicates significant remaining growth and a high risk of subsequent contralateral SCFE. In these patients, prophylactic pinning of the contralateral hip is strongly recommended.

Question 3053

Topic: Pediatric Hip

An 8-year-old boy with a chronic limp is diagnosed with Legg-Calvé-Perthes disease. Which of the following radiographic findings is considered a 'head at risk' sign according to Catterall, indicating a poor prognosis and a higher risk of femoral head deformation?

. Waldenström sign
. Gage sign
. Sagging rope sign
. Crescent sign
. Teardrop sign

Correct Answer & Explanation

. Gage sign

Explanation

Catterall identified several 'head at risk' signs in Legg-Calvé-Perthes disease that correlate with a poor prognosis and progressive deformity. These include Gage's sign (a V-shaped radiolucency in the lateral portion of the epiphysis and adjacent metaphysis), calcification lateral to the epiphysis, lateral subluxation of the femoral head, a horizontal growth plate, and metaphyseal cysts. The Waldenström sign is widening of the medial joint space, and the crescent sign indicates subchondral fracture, which are standard findings rather than specific Catterall risk factors.

Question 3054

Topic: Pediatric Lower Extremity

An infant is undergoing serial casting for idiopathic clubfoot using the Ponseti method. After the fifth cast, the midfoot cavus, forefoot adductus, and hindfoot varus have been fully corrected. However, evaluation reveals only 0 degrees of ankle dorsiflexion. What is the most appropriate next step in management?

. Continue serial casting until 15 degrees of dorsiflexion is achieved
. Perform a percutaneous Achilles tenotomy
. Perform a formal posteromedial release
. Apply a Denis Browne splint immediately
. Perform a tibialis anterior tendon transfer

Correct Answer & Explanation

. Perform a percutaneous Achilles tenotomy

Explanation

In the Ponseti method for clubfoot, the deformities are corrected in a specific order: cavus, adductus, varus, and finally equinus. Once the midfoot and hindfoot are corrected (abducted to about 60 degrees), equinus often persists. If there is less than 15 degrees of ankle dorsiflexion, a percutaneous Achilles tenotomy is indicated. Attempting to forcefully cast out the equinus without a tenotomy risks creating a iatrogenic rocker-bottom foot deformity.

Question 3055

Topic: Pediatric Hip

A 13-year-old boy presents with severe groin pain after a minor fall. He is completely unable to bear weight, even with crutches. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE).

What is the most devastating complication specific to this type of presentation, and what surgical technique is frequently utilized to minimize its risk?

. Chondrolysis; prophylactic contralateral pinning
. Avascular necrosis; anterior capsulotomy with gentle or no reduction
. Osteoarthritis; primary Dunn osteotomy
. Nonunion; vascularized bone grafting
. Septic arthritis; delayed closed reduction and spica casting

Correct Answer & Explanation

. Avascular necrosis; anterior capsulotomy with gentle or no reduction

Explanation

The patient's inability to bear weight even with crutches defines an unstable SCFE. Unstable SCFE carries a significantly high risk of avascular necrosis (AVN), historically reported to be up to 50%. To minimize this risk, surgeons often employ an anterior capsulotomy (to decompress the intracapsular hematoma and reduce tamponade effect on the epiphyseal vessels) and perform gentle, incidental reduction or fix the slip in situ without forceful manipulation.

Question 3056

Topic: 4. Pediatrics

A 2-year-old boy with a history of anterolateral bowing of the tibia presents with a new diaphyseal fracture that fails to heal after 3 months of immobilization. Physical examination reveals multiple café-au-lait spots on his trunk.

What is the most likely underlying diagnosis and the optimal surgical strategy for achieving union?

. Osteogenesis imperfecta; bisphosphonates and telescoping rodding
. Neurofibromatosis type 1; excision of the pseudarthrosis, bone grafting, and intramedullary fixation
. Neurofibromatosis type 2; prolonged bracing and pulsed electromagnetic fields
. Fibrous dysplasia; intralesional curettage and cortical bone grafting
. Cleidocranial dysplasia; vascularized free fibular graft

Correct Answer & Explanation

. Neurofibromatosis type 1; excision of the pseudarthrosis, bone grafting, and intramedullary fixation

Explanation

Anterolateral bowing of the tibia progressing to a non-healing fracture is classic for congenital pseudarthrosis of the tibia (CPT), which is highly associated with Neurofibromatosis type 1 (NF1). The presence of café-au-lait spots strongly supports this diagnosis. Achieving union in CPT is notoriously difficult; the standard surgical strategy involves radical excision of the hamartomatous pseudarthrosis tissue, robust autologous bone grafting, and rigid intramedullary fixation (e.g., Williams rod, Fassier-Duval rod), often augmented with an external fixator.

Question 3057

Topic: 4. Pediatrics

A 14-year-old girl sustains an ankle injury while playing soccer. Radiographs and a CT scan reveal a Salter-Harris III fracture of the anterolateral distal tibial epiphysis with 4 mm of displacement.

What is the specific pathomechanics of this fracture pattern?

. Avulsion of the anterolateral epiphysis by the anterior inferior tibiofibular ligament due to an external rotation force
. Axial loading leading to compression of the medial physis and tension failure laterally
. Plantarflexion and inversion causing lateral ligament avulsion of the fibula
. Direct impact to the medial malleolus translating the talus laterally
. Hyperdorsiflexion causing anterior distal tibial lip impaction

Correct Answer & Explanation

. Avulsion of the anterolateral epiphysis by the anterior inferior tibiofibular ligament due to an external rotation force

Explanation

This is a juvenile Tillaux fracture, a Salter-Harris III fracture of the anterolateral distal tibia. It occurs during the transitional period of physeal closure (typically ages 12-14). The distal tibial physis closes from central, to medial, to lateral. Because the anterolateral physis is the last to close, an external rotation force on the foot causes the anterior inferior tibiofibular ligament (AITFL) to avulse the anterolateral epiphyseal fragment. Operative reduction and internal fixation are indicated for displacement >2 mm.

Question 3058

Topic: 4. Pediatrics

A 4-year-old girl is evaluated for severe and worsening bilateral bowlegs. Her BMI is in the 98th percentile. Standing radiographs reveal bilateral genu varum with sharp varus angulation at the proximal tibial metaphysis and significant medial metaphyseal beaking (Langenskiöld stage III).

Which of the following is the most definitively appropriate initial management for this patient?

. Observation with annual radiographs until age 7
. Daytime and nighttime use of knee-ankle-foot orthoses (KAFOs)
. Proximal tibial valgus osteotomy
. Hemiepiphysiodesis of the medial proximal tibia
. Administration of high-dose Vitamin D and calcium

Correct Answer & Explanation

. Proximal tibial valgus osteotomy

Explanation

This child has progressed infantile Blount's disease (tibia vara). Orthotic management (KAFOs) may be effective in children under 3 years old with early-stage disease (Langenskiöld stages I-II). However, in a 4-year-old with advanced deformity (stage III) and high BMI, bracing is ineffective. Surgical intervention with a proximal tibial valgus osteotomy (often with derotation and fibular osteotomy) is the standard of care to restore the mechanical axis and offload the sick medial physis before permanent physeal arrest occurs.

Question 3059

Topic: 4. Pediatrics

A 5-year-old boy with spastic quadriplegic cerebral palsy (Gross Motor Function Classification System [GMFCS] level V) is evaluated in the clinic. He is nonambulatory and nonverbal. His mother reports difficulty with perineal care, but there is no apparent pain with passive range of motion.

According to established international hip surveillance guidelines, how frequently should this patient undergo screening AP pelvis radiographs?

. Every 6 months
. Every 12 months
. Every 2 years
. Only when he becomes symptomatic with pain
. No further screening is needed after age 5

Correct Answer & Explanation

. Every 6 months

Explanation

Children with Cerebral Palsy are at high risk for progressive hip displacement, which correlates directly with their GMFCS level. Children at GMFCS level V have the highest risk, approaching 90%. Consensus guidelines (e.g., AACPDM Hip Surveillance Guidelines) mandate that children at GMFCS levels IV and V undergo an AP pelvis radiograph every 6 months until age 7, and then annually until skeletal maturity, to monitor the Reimers migration percentage and intervene before painful, irreversible dislocation occurs.

Question 3060

Topic: 4. Pediatrics

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. Upon initial presentation, he has a pink, pulseless hand. Urgent closed reduction and percutaneous pinning is performed. In the recovery room, the hand remains pink and pulseless with a capillary refill time of less than 2 seconds. What is the most appropriate next step in management?

. Immediate open exploration of the brachial artery
. Doppler ultrasound to confirm flow
. Angiogram of the upper extremity
. Observation and close clinical monitoring
. Removal of pins and revision of the reduction

Correct Answer & Explanation

. Observation and close clinical monitoring

Explanation

A pink, pulseless hand after closed reduction and percutaneous pinning (CRPP) of a supracondylar humerus fracture typically indicates adequate collateral perfusion. Current pediatric orthopedic guidelines recommend observation and close clinical monitoring if the hand remains well-perfused (pink, warm, brisk capillary refill). Immediate vascular exploration is indicated for a persistently 'white and pulseless' hand following reduction.

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