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4. Pediatrics MCQs

Practice Set 118 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 2341

Topic: Pediatric Hip

A 12-year-old obese boy is diagnosed with a stable slipped capital femoral epiphysis (SCFE) of the left hip. During surgical counseling, the parents ask about the risk to the contralateral (right) hip. Prophylactic pinning of the contralateral hip is most strongly indicated if the patient has which of the following underlying conditions?

. Down syndrome
. Panhypopituitarism
. Prader-Willi syndrome
. Legg-Calve-Perthes disease
. Achondroplasia

Correct Answer & Explanation

. Panhypopituitarism

Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy) significantly increase the risk of developing bilateral SCFE (approaching 100% in some endocrine subgroups compared to ~20-30% in idiopathic cases). Therefore, prophylactic pinning of the contralateral asymptomatic hip is strongly recommended in patients with an underlying endocrine or metabolic disorder.

Question 2342

Topic: Pediatric Hip

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the Herring Lateral Pillar Classification, which of the following radiographic findings represents a Type C pillar, and what does it signify?

. >50% of the original lateral pillar height is maintained; good prognosis
. >50% of the original lateral pillar height is maintained; poor prognosis
. <50% of the original lateral pillar height is maintained; good prognosis
. <50% of the original lateral pillar height is maintained; poor prognosis
. Total collapse of the medial pillar; requires immediate surgical containment

Correct Answer & Explanation

. <50% of the original lateral pillar height is maintained; poor prognosis

Explanation

The Herring Lateral Pillar Classification is based on the height of the lateral pillar of the capital femoral epiphysis during the fragmentation stage. Type A: no involvement (100% height). Type B: >50% of lateral pillar height is maintained. Type C: <50% of lateral pillar height is maintained. Type C carries a poor prognosis and a high likelihood of a non-spherical femoral head at skeletal maturity, predisposing to early osteoarthritis.

Question 2343

Topic: Pediatric Hip

A 5-year-old girl with developmental dysplasia of the hip (DDH) presents with an acetabular index of 40 degrees and primarily anterolateral deficiency. The surgeon plans an incomplete pericapsular osteotomy that relies on the flexibility of the triradiate cartilage to hinge the acetabular roof downward. Which of the following osteotomies is being described?

. Salter innominate osteotomy
. Pemberton osteotomy
. Chiari osteotomy
. Dega osteotomy
. Ganz periacetabular osteotomy

Correct Answer & Explanation

. Pemberton osteotomy

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the triradiate cartilage, reducing the volume of the acetabulum while improving anterolateral coverage. The Salter osteotomy is a complete innominate osteotomy that hinges at the pubic symphysis. The Dega osteotomy is also incomplete but typically directs the roof laterally and posteriorly, commonly used in spastic dysplasia. The Chiari is a salvage capsular interposition osteotomy.

Question 2344

Topic: Pediatric Hip

A 12-year-old boy undergoes in-situ pinning for a stable Slipped Capital Femoral Epiphysis (SCFE) using a single cannulated screw. If the screw inadvertently penetrates the anterosuperior quadrant of the femoral head during the procedure, the patient is at highest risk for developing which of the following complications?

. Avascular necrosis (AVN)
. Chondrolysis
. Progression of the slip
. Subtrochanteric femur fracture
. Premature physeal closure

Correct Answer & Explanation

. Chondrolysis

Explanation

Unrecognized joint penetration by the hardware during SCFE pinning is the leading cause of chondrolysis (rapid destruction of articular cartilage). The anterosuperior quadrant is the most common location for unrecognized penetration because the screw may appear to be within the head on standard AP and lateral views while actually protruding into the joint.

Question 2345

Topic: 4. Pediatrics

During the correction of idiopathic congenital talipes equinovarus (clubfoot) using the Ponseti method, the deformities must be corrected in a specific anatomical sequence. Which of the following components is addressed LAST in the treatment algorithm?

. Cavus
. Adductus
. Varus
. Equinus
. Forefoot supination

Correct Answer & Explanation

. Equinus

Explanation

The Ponseti method follows the CAVE sequence: Cavus, Adductus, Varus, and Equinus. The equinus deformity is the last to be corrected, often requiring a percutaneous Achilles tenotomy to achieve adequate dorsiflexion before the final cast is applied.

Question 2346

Topic: Pediatric Hip

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip. At the 1-week follow-up, the mother notes the infant has stopped kicking her left leg, and the knee remains extended. Which of the following is the most likely cause?

. Excessive flexion of the anterior straps causing femoral nerve palsy
. Excessive adduction causing obturator nerve palsy
. Excessive abduction causing avascular necrosis
. Excessive extension of the posterior straps causing sciatic nerve palsy
. Tight chest strap causing brachial plexus traction

Correct Answer & Explanation

. Excessive flexion of the anterior straps causing femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion when the anterior straps are too tight. It presents with decreased active knee extension. The treatment is adjusting the straps to reduce flexion, and it usually resolves spontaneously.

Question 2347

Topic: Pediatric Hip

Prophylactic pinning of the contralateral hip in a patient with a unilateral Slipped Capital Femoral Epiphysis (SCFE) is most strongly indicated in a patient with which of the following underlying conditions?

. Obesity (BMI > 95th percentile)
. Hypothyroidism
. Male gender
. African American descent
. Age older than 14

Correct Answer & Explanation

. Hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or those with prior radiation therapy, as they have a significantly higher risk of bilateral involvement compared to idiopathic SCFE.

Question 2348

Topic: Pediatric Hip

In the management of Slipped Capital Femoral Epiphysis (SCFE), prophylactic in situ pinning of the asymptomatic contralateral hip is widely debated. However, there is strong consensus to perform prophylactic pinning in which of the following patient presentations?

. A 14-year-old boy with a Body Mass Index (BMI) of 35
. A 12-year-old girl with primary hypothyroidism
. A 13-year-old boy with a strong family history of SCFE
. An 11-year-old girl with a unilateral acute-on-chronic SCFE
. A 15-year-old boy with open triradiate cartilages

Correct Answer & Explanation

. A 12-year-old girl with primary hypothyroidism

Explanation

Patients with underlying endocrine or metabolic disorders (such as hypothyroidism, growth hormone deficiency, or renal osteodystrophy) or a history of pelvic radiation are at a substantially higher risk for bilateral SCFE (up to 100% in some metabolic conditions). In these high-risk cohorts, prophylactic pinning of the contralateral hip is strongly recommended regardless of age or gender.

Question 2349

Topic: Pediatric Hip

A 4-week-old female infant is diagnosed with developmental dysplasia of the hip (DDH) after a positive Ortolani maneuver. A Pavlik harness is applied. At the one-week follow-up, it is noted that the anterior straps are excessively tight, holding the hips in over 120 degrees of flexion. Which peripheral nerve is most at risk for palsy due to this specific positioning error?

. Sciatic nerve
. Obturator nerve
. Femoral nerve
. Lateral femoral cutaneous nerve
. Superior gluteal nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

A common and severe complication of the Pavlik harness is femoral nerve palsy, which is typically caused by hyperflexion of the hips (excessively tight anterior straps) compressing the nerve against the inguinal ligament. Excessive abduction (tight posterior straps) is associated with avascular necrosis of the femoral head.

Question 2350

Topic: Pediatric Hip

In a 20-month-old child undergoing an anterolateral (Smith-Petersen) approach for open reduction of developmental dysplasia of the hip, what is the primary extra-articular block to concentric reduction that must be released first?

. Ligamentum teres
. Transverse acetabular ligament
. Iliopsoas tendon
. Inverted limbus
. Pulvinar

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

The iliopsoas tendon is a primary extra-articular obstacle to reduction in DDH as it passes over the anterior capsule, causing an hourglass constriction of the joint. It is routinely released during the Smith-Petersen approach before addressing intra-articular obstacles like the ligamentum teres, transverse acetabular ligament, and pulvinar.

Question 2351

Topic: Pediatric Upper Extremity & Spine

A 25-year-old soccer player is undergoing anterior cruciate ligament (ACL) reconstruction. The surgeon considers an anterolateral ligament (ALL) reconstruction for residual pivot shift. Which of the following accurately describes the anatomic attachment sites of the ALL?

. Originates anterior to the lateral epicondyle and inserts on Gerdy's tubercle
. Originates posterior and proximal to the lateral epicondyle and inserts midway between Gerdy's tubercle and the fibular head
. Originates on the popliteus sulcus and inserts on the fibular head
. Originates anterior and distal to the lateral epicondyle and inserts on the anterior horn of the lateral meniscus
. Originates at the lateral supracondylar ridge and inserts on the fibular styloid

Correct Answer & Explanation

. Originates posterior and proximal to the lateral epicondyle and inserts midway between Gerdy's tubercle and the fibular head

Explanation

The anterolateral ligament (ALL) originates slightly posterior and proximal to the lateral femoral epicondyle and inserts on the proximal tibia midway between Gerdy's tubercle and the fibular head. It acts as an important secondary restraint to internal tibial rotation.

Question 2352

Topic: Pediatric Hip

A 12-year-old boy presents with an unstable slipped capital femoral epiphysis (SCFE) and is unable to bear weight. The surgeon performs an in-situ pinning and an open capsulotomy to decompress the joint. This capsulotomy is primarily intended to protect the terminal branches of which artery to prevent avascular necrosis?

. Lateral circumflex femoral artery
. Medial circumflex femoral artery
. Obturator artery
. Inferior gluteal artery
. Pudendal artery

Correct Answer & Explanation

. Medial circumflex femoral artery

Explanation

An unstable SCFE carries a high risk of avascular necrosis (AVN) due to kinking or tamponade of the retinacular vessels. These vessels, particularly the lateral epiphyseal artery, are terminal branches of the medial circumflex femoral artery (MCFA). Capsulotomy reduces intracapsular pressure to maintain perfusion.

Question 2353

Topic: Pediatric Hip
Which of the following is NOT considered one of Catterall's classic 'head-at-risk' radiographic signs in Legg-Calvé-Perthes disease?
. Gage sign
. Lateral calcification
. Lateral subluxation of the femoral head
. Coxa magna
. Metaphyseal cysts

Correct Answer & Explanation

. Coxa magna

Explanation

Catterall's 'head-at-risk' signs predict a poor outcome and hinge abduction in Perthes disease. They include Gage's sign (V-shaped defect in the lateral epiphysis), lateral calcification, lateral subluxation of the head, horizontal growth plate, and diffuse metaphyseal reaction (cysts). Coxa magna (enlarged head) is a later sequela, not a predictive 'head-at-risk' sign.

Question 2354

Topic: Pediatric Hip

A 14-year-old obese boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the right hip. He is unable to bear weight even with the use of crutches. He is treated with single in-situ screw fixation. Which of the following clinical factors places him at the highest risk for developing avascular necrosis (AVN) of the femoral head?

. Obesity
. Use of a single screw instead of two
. Inability to bear weight before surgery
. Male gender
. Age greater than 12 years

Correct Answer & Explanation

. Inability to bear weight before surgery

Explanation

The inability to bear weight defines an 'unstable' SCFE according to the Loder classification. Unstable SCFE is the single greatest predictor for the development of AVN, with rates up to nearly 50%, due to the increased risk of disruption to the retinacular blood supply.

Question 2355

Topic: Pediatric Upper Extremity & Spine

In a 13-year-old female with adolescent idiopathic scoliosis, which of the following radiographic parameters best defines a 'structural' minor curve that must be included in the fusion construct according to the Lenke classification system?

. Coronal Cobb angle > 25 degrees on side-bending radiographs
. Coronal Cobb angle > 40 degrees on standing PA radiographs
. Apical vertebral rotation > Grade 2
. Thoracic kyphosis > +20 degrees
. Sagittal vertical axis > 5 cm

Correct Answer & Explanation

. Coronal Cobb angle > 25 degrees on side-bending radiographs

Explanation

The Lenke classification defines a minor curve as structural if it lacks sufficient flexibility. Specifically, if the coronal Cobb angle remains > 25 degrees on lateral side-bending radiographs, it is considered structural and should be included in the fusion construct.

Question 2356

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a Gartland type III supracondylar humerus fracture. Upon presentation, his hand is pale and pulseless. After urgent closed reduction and percutaneous pinning, the hand becomes pink and warm with brisk capillary refill, but the radial pulse remains impalpable. What is the most appropriate next step in management?
. Immediate open surgical exploration of the brachial artery
. Perform a CT angiogram of the upper extremity
. Observe and admit for serial neurovascular checks
. Remove the pins and perform open reduction
. Administer intravenous heparin

Correct Answer & Explanation

. Observe and admit for serial neurovascular checks

Explanation

In a 'pink, pulseless' hand after reduction of a pediatric supracondylar humerus fracture, as long as peripheral perfusion (warmth, color, capillary refill) is adequate, the current standard of care is careful clinical observation. The lack of a palpable pulse is often due to vasospasm or non-flow-limiting intimal injury.

Question 2357

Topic: Pediatric Hip

A 9-year-old boy presents with a left-sided Slipped Capital Femoral Epiphysis (SCFE) and undergoes in situ single-screw fixation. Under which of the following conditions is prophylactic pinning of the contralateral, asymptomatic right hip most strongly indicated?

. If the patient has a body mass index (BMI) in the 85th percentile
. If the left-sided SCFE was graded as mild (less than 33% slip)
. If the patient has a known diagnosis of renal osteodystrophy
. If the patient is of African American descent
. If the initial presentation was a chronic slip rather than acute

Correct Answer & Explanation

. If the patient has a known diagnosis of renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is universally recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy, growth hormone supplementation) due to the exceedingly high risk of bilateral involvement. Age at presentation (boys <10, girls <8) is also a strong indication.

Question 2358

Topic: Pediatric Hip

A 4-week-old female infant is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. Ultrasound confirms the hip is completely dislocated. After 3 weeks of strict, full-time wear, repeat ultrasound demonstrates that the hip remains persistently dislocated. What is the next best step in management?

. Continue Pavlik harness for an additional 3 weeks
. Adjust the harness to increase hip flexion beyond 120 degrees
. Discontinue the Pavlik harness and transition to a rigid abduction orthosis or proceed to closed reduction
. Perform immediate open reduction with pelvic osteotomy
. Transition to a Denis Browne bar

Correct Answer & Explanation

. Discontinue the Pavlik harness and transition to a rigid abduction orthosis or proceed to closed reduction

Explanation

If a hip remains completely dislocated after 3 to 4 weeks of proper Pavlik harness treatment, the harness should be discontinued. Prolonged use of a harness on an irreducible hip leads to 'Pavlik harness disease' (excoriation/flattening of the posterior acetabulum) and increases the risk of avascular necrosis. The next step is a rigid abduction orthosis (e.g., Ilfeld or von Rosen) or proceeding directly to closed reduction and spica casting.

Question 2359

Topic: 4. Pediatrics

When treating a newborn with idiopathic congenital talipes equinovarus (clubfoot) using the Ponseti method, serial manipulations and casting are performed. What is the correct anatomical sequence of deformity correction in this technique?

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method follows the CAVE sequence of correction: 1) Cavus (corrected first by elevating the first ray to supinate the forefoot and align it with the hindfoot), 2) Adductus, 3) Varus (adductus and varus correct simultaneously as the foot is abducted around the fixed head of the talus), 4) Equinus (corrected last, usually requiring a percutaneous Achilles tenotomy once the foot is fully abducted).

Question 2360

Topic: Pediatric Hip

A 14-year-old obese male presents with an acute exacerbation of chronic left knee pain and a severe limp. Examination reveals obligate external rotation of the hip during passive flexion. He is completely unable to bear weight on the left leg. Radiographs confirm a severe, acute-on-chronic slipped capital femoral epiphysis (SCFE). Which of the following is the most serious and highly prevalent complication specifically associated with this patient's inability to bear weight?

. Chondrolysis of the hip joint
. Avascular necrosis (AVN) of the femoral head
. Femoroacetabular impingement (FAI)
. Slipped capital femoral epiphysis of the contralateral hip
. Premature spontaneous closure of the physis

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

This patient's inability to bear weight defines his condition as an 'unstable' SCFE. Unstable SCFE is associated with a markedly higher risk of avascular necrosis (AVN) of the femoral head—reported to be up to 50% in some series. While chondrolysis, FAI, and contralateral slips are also complications of SCFE, AVN is the most devastating complication intrinsically tied to the vascular insult that occurs during an unstable slip.

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