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4. Pediatrics MCQs

Practice Set 32 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 621

Topic: 4. Pediatrics
A 13-year-old girl sustains a Salter-Harris type III fracture of the anterolateral aspect of the distal tibial epiphysis. The mechanism of this injury is primarily due to avulsion by which of the following structures?
. Anterior talofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Posterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

A juvenile Tillaux fracture is an avulsion of the anterolateral distal tibial epiphysis caused by tension from the anterior inferior tibiofibular ligament (AITFL). It occurs in adolescents because the central and medial physes close before the anterolateral aspect.

Question 622

Topic: 4. Pediatrics

A 2-month-old infant is noted to have a right-sided congenital muscular torticollis. The head is tilted to the right and rotated to the left. Which of the following conditions has the highest rate of association with this presentation and requires mandatory screening?

. Developmental dysplasia of the hip
. Scoliosis
. Clubfoot
. Metatarsus adductus
. Sprengel deformity

Correct Answer & Explanation

. Developmental dysplasia of the hip

Explanation

Congenital muscular torticollis has a well-known association with developmental dysplasia of the hip (DDH), occurring in up to 20% of cases. All infants presenting with muscular torticollis must undergo screening for DDH.

Question 623

Topic: Pediatric Hip

A 13-year-old boy undergoes in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). Which of the following is the most common major complication if the screw penetrates the joint anteriorly and is left unrecognized?

. Avascular necrosis
. Chondrolysis
. Infection
. Premature physeal closure
. Femoral neck fracture

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a devastating complication in SCFE management, frequently caused by unrecognized hardware penetration into the joint space. Proper fluoroscopic evaluation with an approach-withdrawal technique is crucial to ensure the screw is entirely within the bone.

Question 624

Topic: Pediatric Hip

A 2-year-old girl is diagnosed with a neglected left developmental dysplasia of the hip (DDH). The hip is completely dislocated. Which of the following surgical strategies is most likely necessary to achieve a stable, concentric reduction?

. Closed reduction and spica cast alone
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy
. Pavlik harness application
. Adductor tenotomy and abduction bracing
. Greater trochanteric epiphysiodesis

Correct Answer & Explanation

. Open reduction, femoral shortening osteotomy, and pelvic osteotomy

Explanation

In children older than 18-24 months with a completely dislocated DDH, open reduction is almost universally required. Femoral shortening osteotomy is typically necessary to relieve soft tissue tension, and a pelvic osteotomy is needed to correct acetabular dysplasia.

Question 625

Topic: Pediatric Hip
A 6-year-old boy presents with right hip pain, a limp, and limited internal rotation. Radiographs demonstrate a subchondral radiolucent line in the anterolateral aspect of the femoral head. What is this sign called and what does it indicate?
. Crescent sign; indicating Legg-Calvé-Perthes disease
. Klein line; indicating SCFE
. Gage sign; indicating Legg-Calvé-Perthes disease
. Thurston Holland sign; indicating a physeal fracture
. Hilgenreiner line; indicating DDH

Correct Answer & Explanation

. Crescent sign; indicating Legg-Calvé-Perthes disease

Explanation

The subchondral radiolucent line is the "crescent sign", representing a subchondral fracture occurring in the early stages of avascular necrosis, such as Legg-Calvé-Perthes disease. It typically dictates the extent of epiphyseal involvement.

Question 626

Topic: Pediatric Hip

A 12-year-old obese boy presents with left knee pain and a waddling gait. Radiographs reveal a severe slipped capital femoral epiphysis (SCFE) on the left. The right hip is radiographically normal. Which of the following is the primary indication for prophylactic pinning of the contralateral right hip?

. Male sex
. Age greater than 14 years
. Endocrine disorders such as hypothyroidism
. Duration of symptoms greater than 3 weeks
. Severity of the left-sided slip

Correct Answer & Explanation

. Endocrine disorders such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is strongly indicated in patients with underlying endocrine disorders (such as hypothyroidism) or those treated prior to age 10. These factors significantly increase the risk of a contralateral slip.

Question 627

Topic: Pediatric Hip

A 6-week-old female infant with developmental dysplasia of the hip (DDH) is treated with a Pavlik harness. During a follow-up visit, she is noted to have an inability to actively extend the knee on the treated side. This complication is most likely due to excessive positioning in which direction?

. Excessive hip extension
. Excessive hip adduction
. Excessive hip flexion
. Excessive hip abduction
. Excessive knee flexion

Correct Answer & Explanation

. Excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and is typically caused by excessive hip flexion. The harness should be adjusted or temporarily discontinued until quadriceps function returns.

Question 628

Topic: 4. Pediatrics

A 13-year-old obese male presents with left hip pain and an antalgic gait. Radiographs reveal a 'slip' of the capital femoral epiphysis. The pathophysiology of this condition involves mechanical failure through which specific histologic zone of the physis?

. Zone of resting cartilage
. Zone of proliferation
. Zone of hypertrophy
. Zone of provisional calcification
. Zone of ossification

Correct Answer & Explanation

. Zone of hypertrophy

Explanation

Slipped capital femoral epiphysis (SCFE) occurs through the hypertrophic zone of the physis. This zone is the weakest layer biomechanically as it lacks the collagen shear strength found in other zones.

Question 629

Topic: Pediatric Hip

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed 6 weeks of strict Pavlik harness treatment. What is the next best step in management?

. Continue Pavlik harness for an additional 6 weeks
. Closed reduction and spica casting under anesthesia
. Open reduction and Pemberton pelvic osteotomy
. Botulinum toxin injection into the adductors
. Observation until 1 year of age followed by a Salter osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under anesthesia

Explanation

In an infant (typically under 18 months) who fails Pavlik harness treatment, the next appropriate step is an examination under anesthesia, arthrogram, and closed reduction with spica casting. Open reduction is reserved for failure of closed reduction.

Question 630

Topic: Pediatric Hip

A 13-year-old overweight boy presents with left knee pain and a limp for 3 weeks. Examination reveals limited internal rotation of the left hip. What obligatory motion of the hip during passive flexion is classic for this condition?

. Obligatory adduction
. Obligatory internal rotation
. Obligatory external rotation
. Obligatory abduction
. Obligatory extension

Correct Answer & Explanation

. Obligatory external rotation

Explanation

Slipped capital femoral epiphysis (SCFE) typically presents with an obligatory external rotation of the thigh as the hip is passively flexed, due to the posterior and inferior displacement of the femoral head.

Question 631

Topic: Pediatric Hip

A 4-month-old infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. To avoid iatrogenic avascular necrosis (AVN) of the femoral head, which position must be strictly avoided during harness application?

. Excessive flexion
. Excessive adduction
. Excessive external rotation
. Excessive abduction
. Excessive extension

Correct Answer & Explanation

. Excessive abduction

Explanation

Excessive abduction in a Pavlik harness places extreme pressure on the vascular supply to the femoral head, drastically increasing the risk of iatrogenic avascular necrosis. Care must be taken to keep the hips in a safe zone of abduction.

Question 632

Topic: 4. Pediatrics

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip. At the two-week follow-up, the mother reports the infant is no longer kicking the affected leg. On examination, there is an absence of active knee extension. What is the most likely cause?

. Avascular necrosis of the femoral head
. Excessive hip flexion causing femoral nerve palsy
. Excessive hip abduction causing obturator nerve palsy
. Septic arthritis of the hip
. Transient synovitis

Correct Answer & Explanation

. Excessive hip flexion causing femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment caused by excessive hyperflexion of the hip. The appropriate management is to temporarily discontinue the harness or adjust the flexion straps until neurologic function returns.

Question 633

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents with a completely displaced posteromedial supracondylar fracture of the humerus (Gartland Type III). Which nerve is most commonly injured in this specific fracture pattern?
. Ulnar nerve
. Median nerve
. Anterior interosseous nerve
. Radial nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

Posteromedial displacement of the distal fragment puts the radial nerve at greatest risk as it gets tethered over the proximal fragment. In contrast, posterolateral displacement places the anterior interosseous nerve (AIN) and median nerve at higher risk.

Question 634

Topic: Pediatric Hip

A 13-year-old obese boy presents with a 3-week history of left thigh pain and a limp. On examination, he has an obligate external rotation of the left hip during flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). Which of the following is the most devastating long-term complication of in-situ pinning of this condition?

. Chondrolysis
. Avascular necrosis
. Femoroacetabular impingement
. Leg length discrepancy
. Hardware failure

Correct Answer & Explanation

. Avascular necrosis

Explanation

While chondrolysis and impingement can occur, avascular necrosis (AVN) of the femoral head is the most devastating complication following SCFE and its surgical treatment. Unstable SCFEs carry a much higher risk of AVN than stable ones, but poor pin placement can also precipitate it.

Question 635

Topic: Pediatric Hip

A 13-year-old obese male presents with progressively worsening right knee pain for 3 weeks and an inability to bear weight on the right leg for the past 24 hours. Radiographs demonstrate a severe, unstable slipped capital femoral epiphysis (SCFE). Which of the following best describes the primary rationale for performing an anterior capsulotomy prior to surgical pinning of this condition?

. To allow for direct visualization and anatomical reduction of the displaced epiphysis.
. To decrease intracapsular pressure and reduce the subsequent risk of osteonecrosis.
. To facilitate the removal of loose intra-articular cartilage fragments.
. To improve the trajectory and accuracy of percutaneous screw placement.
. To prevent the future development of cam-type femoroacetabular impingement (FAI).

Correct Answer & Explanation

. To decrease intracapsular pressure and reduce the subsequent risk of osteonecrosis.

Explanation

In an unstable SCFE, a massive intracapsular hematoma increases pressure, which can tamponade retinacular blood flow and lead to osteonecrosis (avascular necrosis). An anterior capsulotomy effectively decompresses the joint, thereby mitigating this critical complication.

Question 636

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy presents with a completely displaced, extension-type supracondylar humerus fracture. He has an absent radial pulse but the hand is warm and pink. What is the most appropriate next step in management?

. Immediate open vascular exploration
. Closed reduction and percutaneous pinning
. CT angiography of the upper extremity
. Application of a long arm cast in hyperflexion
. Observation and elevation only

Correct Answer & Explanation

. Closed reduction and percutaneous pinning

Explanation

A "pink, pulseless" hand in the setting of a supracondylar humerus fracture is generally managed with urgent closed reduction and percutaneous pinning. Vascular exploration is indicated if the hand remains dysvascular (white and pulseless) after anatomical reduction is achieved.

Question 637

Topic: 4. Pediatrics

A 13-year-old obese boy presents with an atraumatic limp and right groin pain for 3 weeks. On examination, he has obligate external rotation of the right hip with passive flexion. What is the most appropriate initial treatment?

. Observation and non-weight bearing with crutches
. In situ fixation with a single cannulated screw
. Open reduction and internal fixation
. Proximal femoral osteotomy
. Spica cast immobilization

Correct Answer & Explanation

. In situ fixation with a single cannulated screw

Explanation

The clinical presentation is classic for a slipped capital femoral epiphysis (SCFE). The standard initial treatment is in situ percutaneous fixation with a single partially threaded cannulated screw to stabilize the physis and prevent further slippage.

Question 638

Topic: Pediatric Hip

A 6-week-old female infant is noted to have an asymmetric thigh crease and a positive Ortolani test on the left side. Ultrasound confirms an unstable left hip. What is the first-line treatment?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction
. Observation and repeat ultrasound in 6 weeks
. Bilateral hip abduction orthosis (Ilfeld splint)

Correct Answer & Explanation

. Pavlik harness application

Explanation

The Pavlik harness is the gold standard first-line treatment for reducible developmental dysplasia of the hip (DDH) in infants younger than 6 months. It dynamically maintains the hip in flexion and abduction, promoting normal acetabular development.

Question 639

Topic: Pediatric Hip

A 7-year-old boy presents with a painless limp that has worsened over the past few months. He has limited internal rotation and abduction of his left hip. Radiographs reveal fragmentation and sclerosis of the proximal femoral epiphysis. What is the most likely diagnosis?

. Slipped capital femoral epiphysis
. Transient synovitis
. Septic arthritis
. Legg-Calve-Perthes disease
. Developmental dysplasia of the hip

Correct Answer & Explanation

. Legg-Calve-Perthes disease

Explanation

Legg-Calve-Perthes disease is an idiopathic avascular necrosis of the proximal femoral epiphysis, typically occurring in boys aged 4-8 years. Radiographic progression follows stages of initial sclerosis, fragmentation, reossification, and finally healing or remodeling.

Question 640

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy diagnosed with Duchenne Muscular Dystrophy requires an urgent closed reduction and percutaneous pinning of a displaced supracondylar humerus fracture. Which of the following anesthetic agents is absolutely contraindicated in this patient?

. Propofol
. Ketamine
. Succinylcholine
. Fentanyl
. Rocuronium

Correct Answer & Explanation

. Succinylcholine

Explanation

Succinylcholine, a depolarizing neuromuscular blocker, is absolutely contraindicated in patients with Duchenne Muscular Dystrophy. Its use can cause massive potassium efflux from fragile, unstable muscle cells, leading to life-threatening hyperkalemia and cardiac arrest.

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