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4. Pediatrics MCQs

Practice Set 150 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 2981

Topic: 4. Pediatrics

According to the American Academy of Pediatrics (AAP) guidelines, routine ultrasound screening for DDH at 6 weeks of age is universally recommended for which of the following asymptomatic infants?

. All full-term females
. All premature infants born before 32 weeks
. Female infants with a breech presentation in the third trimester
. Male infants with a unilateral clubfoot
. Infants presenting with a sacral dimple

Correct Answer & Explanation

. All full-term females

Explanation

The AAP recommends targeted ultrasound screening at 6 weeks of age for infants with specific risk factors. Breech presentation (especially in females) and a positive family history are the strongest risk factors warranting routine screening.

Question 2982

Topic: 4. Pediatrics

A 7-year-old boy sustained a Salter-Harris IV fracture of the distal femur 2 years ago. He now presents with a 3 cm leg length discrepancy and a progressive valgus deformity. CT mapping reveals a central physeal bar occupying 40% of the cross-sectional area of the physis. What is the best treatment option?

. Observation until skeletal maturity
. Physeal bar resection and interposition grafting
. Distal femoral osteotomy and completion of the epiphysiodesis
. Epiphysiodesis of the contralateral distal femur
. Guided growth with tension band plates

Correct Answer & Explanation

. Observation until skeletal maturity

Explanation

Physeal bar resection with interposition grafting (e.g., fat or Cranioplast) is indicated when the bar occupies less than 50% of the physeal cross-section and the child has more than 2 years of remaining growth.

Question 2983

Topic: Pediatric Hip

A 5-month-old infant has been treated in a Pavlik harness for 4 weeks for a completely dislocated right hip. A repeat ultrasound shows the hip remains persistently dislocated. What is the most appropriate next step in management?

. Continue the Pavlik harness for an additional 4 weeks
. Switch to a dynamic abduction orthosis
. Perform a closed reduction and place in a spica cast
. Perform an open reduction and pelvic osteotomy
. Observe and plan for an open reduction at 12 months of age

Correct Answer & Explanation

. Continue the Pavlik harness for an additional 4 weeks

Explanation

Failure to achieve reduction in a Pavlik harness after 3 to 4 weeks is an indication to abandon the harness to prevent 'Pavlik harness disease' (posterior acetabular wear). The next step is a closed reduction under anesthesia, typically with an arthrogram, followed by spica casting.

Question 2984

Topic: 4. Pediatrics

Which of the following pediatric lower extremity physeal fractures carries the highest historical rate of premature growth arrest?

. Proximal tibia Salter-Harris I
. Distal fibula Salter-Harris II
. Distal tibia Salter-Harris III
. Distal femur Salter-Harris II
. Proximal femur Salter-Harris I

Correct Answer & Explanation

. Proximal tibia Salter-Harris I

Explanation

Distal femoral physeal fractures, even Salter-Harris II patterns, carry a notoriously high risk of premature growth arrest (often cited between 30% and 50%). This is due to the severe energy required to fracture the undulating contour of the distal femoral physis.

Question 2985

Topic: Pediatric Hip

A 6-week-old female infant presents with a positive Ortolani sign on the left hip. Ultrasound shows an alpha angle of 45 degrees. What is the most appropriate next step in management?

. Reassurance and follow-up in 4 weeks
. Pavlik harness application
. Rigid abduction orthosis
. Closed reduction and spica casting
. Open reduction

Correct Answer & Explanation

. Reassurance and follow-up in 4 weeks

Explanation

The patient presents with clinical DDH and an abnormal ultrasound alpha angle (normal is >60 degrees). The Pavlik harness is the gold standard for reducible hip dysplasia in infants under 6 months of age.

Question 2986

Topic: Pediatric Upper Extremity & Spine

In evaluating a 12-year-old girl with adolescent idiopathic scoliosis, which of the following combinations of factors indicates the highest risk for curve progression?

. Risser stage 4 and a 20-degree curve
. Premenarchal status and a 30-degree curve
. Risser stage 0 and a 15-degree curve
. Postmenarchal status and a 40-degree curve
. Risser stage 2 and a 25-degree curve

Correct Answer & Explanation

. Risser stage 4 and a 20-degree curve

Explanation

Peak height velocity occurs just prior to menarche, making premenarchal status a critical risk factor for progression. A 30-degree curve in a rapidly growing premenarchal girl has the highest risk of progression among the choices provided.

Question 2987

Topic: 4. Pediatrics

A 10-year-old boy sustains a Salter-Harris type II fracture of the distal femur. Despite anatomic closed reduction and casting, the patient is at significant risk for which of the following long-term complications?

. Nonunion
. Avascular necrosis of the femoral condyle
. Premature physeal closure
. Compartment syndrome
. Osteomyelitis

Correct Answer & Explanation

. Nonunion

Explanation

Distal femoral physeal fractures, especially Salter-Harris II, have a notoriously high rate of premature physeal closure and growth arrest. This complication occurs in up to 50% of cases due to the highly undulating anatomy of the distal femoral physis.

Question 2988

Topic: 4. Pediatrics

A 12-year-old boy developed a distal tibial physeal bar following a previous fracture. A scanogram reveals a 2 cm leg length discrepancy and 15 degrees of varus angulation. Mapping shows the bar involves 20% of the cross-sectional area of the physis peripherally. What is the most appropriate treatment?

. Contralateral epiphysiodesis
. Physeal bar resection with interposition graft and corrective osteotomy
. Ipsilateral distal tibia lengthening
. Observation until skeletal maturity
. Complete ipsilateral epiphysiodesis

Correct Answer & Explanation

. Contralateral epiphysiodesis

Explanation

Physeal bar resection is indicated if the bar involves less than 50% of the physis and the patient has more than 2 years of growth remaining. The presence of an associated angular deformity requires a concurrent corrective osteotomy.

Question 2989

Topic: Pediatric Hip

A 4-month-old girl with left developmental dysplasia of the hip has been treated in a Pavlik harness for 4 weeks. Repeat ultrasound shows failure of reduction with the femoral head remaining chronically dislocated. What is the most appropriate next step in management?

. Continue Pavlik harness for 4 more weeks
. Discontinue Pavlik harness and proceed with closed reduction and spica casting
. Increase Pavlik harness flexion to 120 degrees
. Perform immediate open reduction and varus derotational osteotomy
. Observe and re-evaluate at 1 year of age

Correct Answer & Explanation

. Continue Pavlik harness for 4 more weeks

Explanation

If a dislocated hip is not reduced after 3 to 4 weeks of Pavlik harness use, it should be discontinued to prevent "Pavlik disease" (excoriation of the posterior acetabulum). The next appropriate step is transition to a rigid orthosis or closed reduction and spica casting.

Question 2990

Topic: 4. Pediatrics

A 14-year-old boy sustains an ankle injury resulting in a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following best describes the pathomechanics of this specific fracture pattern?

. Avulsion by the anterior inferior tibiofibular ligament during external rotation
. Axial loading combined with hyperplantarflexion
. Avulsion by the deltoid ligament during eversion
. Impaction of the talus into the medial malleolus
. Inversion injury causing tension on the lateral collateral ligaments

Correct Answer & Explanation

. Avulsion by the anterior inferior tibiofibular ligament during external rotation

Explanation

A juvenile Tillaux fracture is a Salter-Harris III fracture of the anterolateral distal tibia. It occurs due to avulsion by the anterior inferior tibiofibular ligament during external rotation, as the medial physis closes before the lateral physis.

Question 2991

Topic: Pediatric Hip

A 38-year-old female presents with persistent groin pain exacerbated by hip flexion. Radiographs demonstrate a crossover sign on the AP pelvis view. This radiographic finding is most strongly associated with which of the following pathologies?

. Cam-type femoroacetabular impingement
. Developmental dysplasia of the hip
. Pincer-type femoroacetabular impingement secondary to acetabular retroversion
. Slipped capital femoral epiphysis
. Legg-Calve-Perthes disease

Correct Answer & Explanation

. Cam-type femoroacetabular impingement

Explanation

The crossover sign on an AP pelvis radiograph indicates cranial retroversion of the acetabulum, where the anterior wall crosses over the posterior wall. This is a classic hallmark of pincer-type femoroacetabular impingement (FAI).

Question 2992

Topic: Pediatric Hip

A 28-year-old male presents with groin pain and decreased internal rotation of the hip. He has a history of a slipped capital femoral epiphysis (SCFE) treated with in situ pinning during adolescence. This patient is at highest risk for developing which of the following conditions?

. Cam-type femoroacetabular impingement
. Pincer-type femoroacetabular impingement
. Coxa valga
. Ischiofemoral impingement
. Greater trochanteric pain syndrome

Correct Answer & Explanation

. Cam-type femoroacetabular impingement

Explanation

In situ pinning of a SCFE often leaves a residual prominent anterior head-neck junction. This decreased offset frequently leads to Cam-type femoroacetabular impingement in early adulthood.

Question 2993

Topic: Pediatric Hip

A 28-year-old hockey player presents with chronic groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate an alpha angle of 70 degrees. This radiographic finding is most consistent with which of the following?

. Acetabular retroversion
. Pincer impingement
. Cam impingement
. Developmental dysplasia of the hip
. Coxa profunda

Correct Answer & Explanation

. Acetabular retroversion

Explanation

An alpha angle greater than 50-55 degrees indicates a loss of the normal femoral head-neck offset, characteristic of Cam impingement. Pincer impingement is associated with acetabular overcoverage, such as retroversion or coxa profunda.

Question 2994

Topic: Pediatric Hip

A 13-year-old obese boy undergoes in situ pinning with a single cannulated screw for a stable slipped capital femoral epiphysis (SCFE). Postoperatively, he develops severe, unrelenting hip stiffness and a dramatic loss of joint space on radiographs. Which of the following is the most likely cause of this complication?

. Avascular necrosis of the femoral head
. Unrecognized pin penetration into the hip joint
. Postoperative septic arthritis
. Heterotopic ossification
. Femoroacetabular impingement

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Chondrolysis is a devastating complication of SCFE characterized by acute loss of articular cartilage and severe stiffness. It is most strongly associated with unrecognized intra-articular hardware penetration during in situ fixation.

Question 2995

Topic: Pediatric Hip

An obese 13-year-old boy presents with left knee pain and a slight limp for 3 weeks. Examination of the hip reveals obligatory external rotation of the thigh during passive flexion of the hip. What is the most appropriate initial management?

. Non-weight bearing and urgent in situ percutaneous pinning
. Physical therapy for IT band stretching
. Aspiration of the hip joint
. Closed reduction and spica casting
. Core decompression of the femoral head

Correct Answer & Explanation

. Non-weight bearing and urgent in situ percutaneous pinning

Explanation

The clinical presentation is classic for a Slipped Capital Femoral Epiphysis (SCFE). Prompt in situ percutaneous pinning with a single screw is the standard of care to prevent further slippage and minimize complications.

Question 2996

Topic: Pediatric Hip

A 45-year-old woman with developmental dysplasia of the hip presents with severe secondary osteoarthritis. Preoperative radiographs reveal that the femoral head is subluxated superiorly by 80% of the height of the normal true acetabulum. According to the Crowe classification, what is her stage?

. Crowe I
. Crowe II
. Crowe III
. Crowe IV
. Crowe V

Correct Answer & Explanation

. Crowe I

Explanation

The Crowe classification stages DDH based on the proximal subluxation of the femoral head relative to the true acetabular height. Crowe I is <50%, Crowe II is 50-74%, Crowe III is 75-100%, and Crowe IV is complete dislocation (>100%).

Question 2997

Topic: Pediatric Hip

A 14-year-old obese male underwent in situ pinning for a severe slipped capital femoral epiphysis (SCFE) 5 years ago. He now presents with groin pain and limited internal rotation. What is the most common long-term biomechanical complication leading to early osteoarthritis in this patient profile?

. Pincer impingement from acetabular retroversion
. Cam impingement due to residual anterior metaphyseal prominence
. Avascular necrosis of the femoral head
. Chondrolysis from unrecognized pin penetration
. Legg-Calve-Perthes disease

Correct Answer & Explanation

. Pincer impingement from acetabular retroversion

Explanation

Following in situ pinning of a SCFE, the residual anterior metaphyseal prominence often acts as a cam lesion. This creates femoroacetabular impingement (FAI), which is a leading cause of early osteoarthritis in these patients.

Question 2998

Topic: Pediatric Upper Extremity & Spine

A 55-year-old man who underwent previous Harrington rod instrumentation for adolescent idiopathic scoliosis now presents with forward-leaning posture, back pain, and thigh fatigue.

What is the primary pathophysiologic mechanism for his thigh fatigue?

. L4 nerve root compression
. Hip flexor contracture
. Compensatory hip extension and knee flexion
. Ischial bursitis
. Femoral nerve stretch

Correct Answer & Explanation

. L4 nerve root compression

Explanation

Flatback syndrome results in a loss of lumbar lordosis and a positive sagittal vertical axis. Patients compensate by extending their hips and flexing their knees, leading to rapid quadriceps and hamstring fatigue.

Question 2999

Topic: Pediatric Upper Extremity & Spine

In the Lenke classification for adolescent idiopathic scoliosis, a curve is considered 'structural' if it lacks flexibility on side-bending radiographs. What residual Cobb angle on side-bending defines a structural curve?

. 10 degrees or greater
. 15 degrees or greater
. 20 degrees or greater
. 25 degrees or greater
. 30 degrees or greater

Correct Answer & Explanation

. 10 degrees or greater

Explanation

In the Lenke classification system, a minor curve is defined as structural if it does not bend down to less than 25 degrees (i.e., remains 25 degrees or greater) on coronal side-bending radiographs.

Question 3000

Topic: Pediatric Upper Extremity & Spine

In the evaluation of Adolescent Idiopathic Scoliosis (AIS), the Lenke classification system utilizes the flexibility of curves on side-bending radiographs to determine fusion levels. A minor thoracic curve is considered "structural" if the Cobb angle on the side-bending radiograph fails to reduce below what specific threshold?

. 10 degrees
. 15 degrees
. 20 degrees
. 25 degrees
. 30 degrees

Correct Answer & Explanation

. 10 degrees

Explanation

In the Lenke classification for AIS, a minor curve is considered structural if it remains 25 degrees or greater on lateral side-bending radiographs, or if there is local kyphosis >20 degrees.

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