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4. Pediatrics MCQs

Practice Set 58 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 1141

Topic: Pediatric Hip

A 12-year-old obese boy presents with insidious onset of left knee pain and a limp. On physical exam, there is obligate external rotation of the left hip with passive hip flexion. What is the most likely diagnosis?

. Legg-Calve-Perthes disease
. Slipped capital femoral epiphysis
. Transient synovitis
. Septic arthritis
. Femoral neck fracture

Correct Answer & Explanation

. Slipped capital femoral epiphysis

Explanation

Slipped capital femoral epiphysis (SCFE) classically presents in obese adolescents with hip or referred knee pain. Obligate external rotation during passive hip flexion is a hallmark physical exam finding due to the anterior and superior displacement of the metaphysis relative to the epiphysis.

Question 1142

Topic: Pediatric Hip

When treating an infant for developmental dysplasia of the hip (DDH) using a Pavlik harness, prolonged hyperflexion of the hips places the patient at highest risk for which complication?

. Femoral nerve palsy
. Sciatic nerve palsy
. Avascular necrosis of the femoral head
. Inferior hip dislocation
. Superior hip dislocation

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Hyperflexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. In contrast, excessive abduction places the hip at higher risk for avascular necrosis of the femoral head.

Question 1143

Topic: 4. Pediatrics

A 12-year-old obese male presents with a 3-week history of left knee pain and a limp. Examination reveals obligate external rotation of the hip during flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). During in situ pinning with a single screw, what is the ideal screw placement?

. Center of the epiphysis, stopping 5 mm short of the subchondral bone
. Anterior-inferior quadrant of the epiphysis
. Posterior-superior quadrant of the epiphysis
. Center of the metaphysis, crossing the physis at a 45-degree angle
. Multiple smooth pins to prevent physeal arrest

Correct Answer & Explanation

. Center of the epiphysis, stopping 5 mm short of the subchondral bone

Explanation

The ideal screw position for a SCFE is in the center-center of the epiphysis on both AP and lateral radiographs, stopping roughly 5 mm short of the subchondral bone. This placement maximizes stability while minimizing the risk of joint penetration and subsequent chondrolysis.

Question 1144

Topic: Pediatric Hip

A 4-month-old female infant is diagnosed with developmental dysplasia of the hip (DDH). Ultrasound confirms a dislocated left hip that is reducible. What is the most appropriate initial treatment?

. Pavlik harness
. Rigid hip abduction orthosis
. Closed reduction and spica casting
. Open reduction and spica casting
. Observation until 6 months of age

Correct Answer & Explanation

. Pavlik harness

Explanation

The Pavlik harness is the gold standard initial treatment for reducible DDH in infants up to 6 months of age. It dynamically maintains the hip in flexion and mild abduction, promoting spontaneous deepening of the acetabulum.

Question 1145

Topic: Pediatric Lower Extremity

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

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

Correct Answer & Explanation

. Cavus, Adductus, Varus, Equinus

Explanation

The Ponseti method dictates sequential correction following the acronym CAVE: Cavus (by elevating the first ray), Adductus, Varus, and finally Equinus. Attempting to correct equinus before the other components often requires an Achilles tenotomy and risks causing a rocker-bottom deformity.

Question 1146

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy presents with a completely displaced, extension-type Gartland III supracondylar humerus fracture. Which of the following neurologic deficits is most commonly associated with this specific injury pattern?

. Anterior interosseous nerve palsy
. Radial nerve palsy
. Ulnar nerve palsy
. Posterior interosseous nerve palsy
. Axillary nerve palsy

Correct Answer & Explanation

. Anterior interosseous nerve palsy

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. It is typically assessed by asking the patient to make an "OK" sign to test the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 1147

Topic: 4. Pediatrics

A 3-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip. The mother reports the infant has stopped kicking the left knee. What is the most likely cause of this complication?

. Hyperflexion of the hip causing femoral nerve compression
. Excessive abduction causing avascular necrosis
. Hyperflexion causing obturator nerve palsy
. Excessive adduction causing hip redislocation
. Tight shoulder straps causing brachial plexus injury

Correct Answer & Explanation

. Hyperflexion of the hip causing femoral nerve compression

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness when the hips are placed in excessive flexion. The treatment is to temporarily loosen the anterior straps or remove the harness until nerve function recovers.

Question 1148

Topic: Pediatric Hip

An obese 12-year-old boy presents with left groin pain and a limp. On physical examination, as the affected hip is passively flexed, it demonstrates an obligatory motion. Which obligatory motion is classic for this condition?

. Internal rotation
. External rotation
. Abduction
. Adduction
. Extension

Correct Answer & Explanation

. External rotation

Explanation

The patient has a Slipped Capital Femoral Epiphysis (SCFE). The classic physical exam finding is obligatory external rotation of the thigh as the hip is passively flexed.

Question 1149

Topic: Pediatric Hip

Which of the following is the strongest clinical predictor for the development of avascular necrosis (AVN) following a slipped capital femoral epiphysis (SCFE)?

. Degree of slip angle greater than 50 degrees
. Patient age less than 10 years
. Inability to bear weight on the affected limb
. Male gender
. Bilateral involvement at presentation

Correct Answer & Explanation

. Inability to bear weight on the affected limb

Explanation

Clinical instability, defined as the inability to bear weight even with crutches, is the strongest predictor of AVN in SCFE. Unstable slips have an AVN rate approaching 20 to 50 percent, whereas stable slips have an AVN rate of nearly zero.

Question 1150

Topic: 4. Pediatrics

A 9-year-old female soccer player sustains a mid-substance complete ACL rupture. She has wide-open physes with significant growth remaining. Which of the following surgical techniques is most appropriate to minimize the risk of growth arrest?

. Transphyseal bone-patellar tendon-bone reconstruction
. Transphyseal hamstring reconstruction
. Iliotibial band physeal-sparing extra-articular and intra-articular reconstruction
. Primary repair of the ACL with internal bracing
. Nonoperative management until skeletal maturity

Correct Answer & Explanation

. Iliotibial band physeal-sparing extra-articular and intra-articular reconstruction

Explanation

In prepubescent children with significant growth remaining (Tanner stage 1 or 2), physeal-sparing techniques are indicated to avoid damage to the distal femoral and proximal tibial physes. An iliotibial band (MacIntosh/Micheli) physeal-sparing reconstruction routes the graft extra-articularly and over the top of the condyle, completely avoiding drill holes across the physes.

Question 1151

Topic: 4. Pediatrics

A 10-year-old male with wide-open physes sustains a complete mid-substance ACL tear. Which of the following surgical techniques has the lowest risk of iatrogenic growth disturbance?

. Complete transphyseal reconstruction using a BPTB autograft
. Complete transphyseal reconstruction using soft tissue graft
. Iliotibial band physeal-sparing extra-articular reconstruction
. All-inside transphyseal reconstruction with metallic interference screws
. Primary repair of the ACL midsubstance

Correct Answer & Explanation

. Iliotibial band physeal-sparing extra-articular reconstruction

Explanation

Physeal-sparing techniques, such as an IT band extra-articular reconstruction (e.g., Micheli or Kocher technique), avoid drill holes across the distal femoral and proximal tibial physes. This minimizes the risk of growth arrest in Tanner stage 1 or 2 patients.

Question 1152

Topic: Pediatric Upper Extremity & Spine

A 14-year-old female with adolescent idiopathic scoliosis (AIS) is evaluated. She is pre-menarcheal and Risser 0. Standing radiographs reveal a right thoracic curve measuring 35 degrees. What is the most appropriate management plan?

. Observation with radiographs every 6 months
. Thoracolumbosacral orthosis (TLSO) bracing for 16-23 hours daily
. Nighttime bending brace only
. Posterior spinal fusion with pedicle screws
. Anterior tethering procedure

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing for 16-23 hours daily

Explanation

In a skeletally immature patient (Risser 0-2, pre-menarcheal) with an AIS curve between 25 and 45 degrees, bracing is indicated to halt progression. A dose-response relationship exists, with >18 hours of daily wear showing the greatest benefit.

Question 1153

Topic: Pediatric Hip

A 12-year-old obese male presents with acute-on-chronic hip pain and an inability to bear weight. Radiographs confirm a severe Slipped Capital Femoral Epiphysis (SCFE). Why is forceful closed reduction of the slippage strictly contraindicated?

. It causes premature closure of the triradiate cartilage
. It significantly increases the risk of avascular necrosis
. It promotes the development of cam-type femoroacetabular impingement
. It leads to severe chondrolysis of the hip joint
. It exacerbates limb length discrepancy

Correct Answer & Explanation

. It significantly increases the risk of avascular necrosis

Explanation

The standard of care for a SCFE is in situ pinning. Forceful closed reduction of the epiphysis severely compromises the fragile retinacular blood supply, exponentially increasing the risk of iatrogenic avascular necrosis.

Question 1154

Topic: Pediatric Hip

A 13-year-old obese male presents with a left slipped capital femoral epiphysis (SCFE). Which of the following is an absolute indication for prophylactic pinning of the contralateral asymptomatic hip?

. Age greater than 14 years
. Male sex
. Presence of an endocrine disorder such as hypothyroidism
. Body mass index > 95th percentile
. A slip angle > 50 degrees on the affected side

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended and considered an absolute indication in patients with underlying endocrine or renal disorders. These metabolic conditions carry an extremely high risk for bilateral involvement.

Question 1155

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy undergoes closed reduction and percutaneous pinning of a Gartland type III extension-type supracondylar humerus fracture. Post-operatively, he is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which iatrogenic or traumatic nerve injury has likely occurred?
. Ulnar nerve injury from medial pin placement
. Radial nerve injury from lateral pin placement
. Anterior interosseous nerve injury during displacement or reduction
. Posterior interosseous nerve injury from lateral pin placement
. Median nerve injury from cubitus varus

Correct Answer & Explanation

. Anterior interosseous nerve injury during displacement or reduction

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type pediatric supracondylar humerus fractures. It innervates the flexor pollicis longus and the flexor digitorum profundus to the index finger, resulting in the inability to form an 'OK' sign.

Question 1156

Topic: Pediatric Hip

A 13-year-old obese boy presents with severe left hip pain and an inability to bear weight after a minor fall. Radiographs confirm an acute, unstable slipped capital femoral epiphysis (SCFE). What is the primary theoretical rationale for performing an urgent capsulotomy prior to percutaneous pinning?

. To allow direct anatomical reduction of the displaced epiphysis
. To decompress an intracapsular hematoma and reduce the risk of osteonecrosis
. To facilitate accurate, direct placement of the central guide wire
. To prevent the subsequent development of chondrolysis
. To remove loose osteochondral fragments from the joint space

Correct Answer & Explanation

. To decompress an intracapsular hematoma and reduce the risk of osteonecrosis

Explanation

Unstable SCFE carries a high risk of avascular necrosis (AVN) due to kinking or compression of the delicate retinacular vessels. An urgent capsulotomy decompresses the intracapsular hematoma, which can lower intracapsular pressure, potentially restoring blood flow and reducing AVN risk.

Question 1157

Topic: Pediatric Hip

A 12-year-old obese male presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE). He is in severe pain and completely unable to bear weight. What is the most critical risk factor for the subsequent development of avascular necrosis (AVN) in this patient?

. The absolute severity of the slip angle
. The patient's BMI being greater than the 95th percentile
. The clinical instability of the slip (inability to bear weight)
. Prophylactic pinning of the asymptomatic contralateral hip
. The utilization of a single fully-threaded screw for fixation

Correct Answer & Explanation

. The clinical instability of the slip (inability to bear weight)

Explanation

The clinical stability of the slip, defined strictly by the inability to bear weight even with crutches (an unstable SCFE), is the single most important risk factor for developing AVN. Rates of AVN in unstable SCFE can reach up to nearly 50%, whereas stable SCFE rarely results in osteonecrosis.

Question 1158

Topic: 4. Pediatrics

Dr. Rodriguez is undergoing his oral viva. During a discussion on pediatric supracondylar humerus fractures, an examiner challenges one of Dr. Rodriguez's statements regarding nerve injury rates. Dr. Rodriguez is confident in his answer, having recently reviewed a landmark paper on the topic. According to the case, what is the most appropriate course of action for Dr. Rodriguez in this situation?

. A. Immediately retract his statement and agree with the examiner to avoid confrontation.
. B. State, 'I think you have got a bit mixed up with the answer,' to assert his confidence.
. C. Politely reiterate his point, referencing the specific paper he reviewed, while assessing the examiner's demeanor and their established rapport.
. D. Ask the examiner, 'Can I interest you in the complications of elbow replacements?' to redirect the conversation.
. E. Clarify the examiner's challenge multiple times to ensure he fully understands their objection.

Correct Answer & Explanation

. C. Politely reiterate his point, referencing the specific paper he reviewed, while assessing the examiner's demeanor and their established rapport.

Explanation

Correct Answer: CThe case provides nuanced advice on challenging examiners: "If you are challenged about an answer take the hint you may be wrong even if you think you are right. That said, some examiners suggest standing your ground if you are convinced you are correct. The decision depends very much on the context of the question and how well you are doing and what sort of rapport you have developed with the examiners." Since Dr. Rodriguez is confident and has a specific paper to reference (which also boosts marks), politely reiterating his point with evidence, while being mindful of the context and rapport, is the most appropriate and strategic approach.A. Immediately retract his statement and agree with the examiner to avoid confrontation.While taking a hint is advised, if a candidate is genuinely convinced and has evidence, retracting immediately might be a missed opportunity to demonstrate depth of knowledge and conviction.B. State, 'I think you have got a bit mixed up with the answer,' to assert his confidence.This is explicitly listed as a phrase to avoid, as it is considered rude and will "wind up the examiners."D. Ask the examiner, 'Can I interest you in the complications of elbow replacements?' to redirect the conversation.This is also explicitly listed as an inappropriate behavior that will "wind up the examiners."E. Clarify the examiner's challenge multiple times to ensure he fully understands their objection.While clarifying is acceptable occasionally, repeatedly doing so, especially in a challenging situation, can "annoy them immensely."

Question 1159

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy undergoes closed reduction and percutaneous pinning for a completely displaced supracondylar humerus fracture. Post-operatively, the hand is pink and well-perfused with a brisk capillary refill, but the radial pulse remains unpalpable. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery.
. Removal of the pins and placement in a long arm cast.
. Observation and hospital admission for 24 hours.
. Performance of a local sympathetic block.
. Immediate CT angiography of the upper extremity.

Correct Answer & Explanation

. Observation and hospital admission for 24 hours.

Explanation

A 'pink, pulseless' hand following reduction of a supracondylar humerus fracture indicates adequate collateral circulation. The standard of care is close observation, as the pulse often returns within 24 to 48 hours without surgical intervention.

Question 1160

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, you notice the infant is lacking active knee extension on the treated side. This complication is most likely due to which improper positioning of the harness?

. Excessive hip hyperflexion.
. Excessive hip abduction.
. Inadequate hip flexion.
. Inadequate hip abduction.
. Excessive knee flexion.

Correct Answer & Explanation

. Excessive hip hyperflexion.

Explanation

Excessive hyperflexion in a Pavlik harness can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy characterized by a lack of active knee extension. Excessive abduction, conversely, increases the risk of avascular necrosis.

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