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4. Pediatrics MCQs

Practice Set 253 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 5041

Topic: Pediatric Hip

A 13-year-old obese boy presents with right groin pain and an antalgic gait. Radiographs reveal a slipped capital femoral epiphysis (SCFE) of the right hip. The left hip is radiographically normal. Which of the following is the most widely accepted absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic hip?

. Patient age older than 15 years at presentation
. Presence of a diagnosed endocrine disorder (e.g., hypothyroidism)
. A severe slip angle (>60 degrees) on the affected side
. Body Mass Index (BMI) greater than 35
. African American ethnicity

Correct Answer & Explanation

. Patient age older than 15 years at presentation

Explanation

Prophylactic pinning of the contralateral hip in SCFE is debated for idiopathic cases but is highly recommended (considered an absolute indication by most authorities) in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, panhypopituitarism), previous radiation therapy, or very young age at presentation (<10 years), as these patients have an exceptionally high risk of a contralateral slip.

Question 5042

Topic: Pediatric Hip

A 6-week-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a follow-up visit, the parents report that the infant is no longer kicking the treated leg. Examination reveals an inability to actively extend the knee, while foot and ankle movements are intact. Which nerve is most likely compressed, and what aspect of the harness positioning is responsible?

. Sciatic nerve; excessive hip flexion
. Femoral nerve; excessive hip flexion
. Obturator nerve; excessive hip abduction
. Femoral nerve; excessive hip abduction
. Sciatic nerve; inadequate hip flexion

Correct Answer & Explanation

. Sciatic nerve; excessive hip flexion

Explanation

Femoral nerve palsy is a known complication of Pavlik harness treatment, typically caused by hyperflexion of the hip (anterior straps pulled too tightly). It presents as an inability to actively extend the knee due to transient loss of quadriceps function. The appropriate management is to loosen the anterior straps or temporarily discontinue the harness to allow nerve recovery.

Question 5043

Topic: 4. Pediatrics

A 6-year-old child sustains a completely displaced, extension-type supracondylar humerus fracture. Upon initial presentation in the emergency department, the child's hand is pink and warm, but the radial pulse is absent. The patient is taken to the operating room, where a successful closed reduction and percutaneous pinning are performed. Post-reduction, the hand remains pink with brisk capillary refill, but the radial pulse remains non-palpable. What is the most appropriate next step in management?

. Immediate vascular surgical exploration of the brachial artery
. CT angiography of the upper extremity
. Observation and hospital admission for serial neurovascular checks
. Prophylactic release of the anterior forearm fascia
. Removal of the pins and open reduction of the fracture

Correct Answer & Explanation

. Immediate vascular surgical exploration of the brachial artery

Explanation

The management of a 'pulseless, pink' hand following reduction of a supracondylar humerus fracture is observation. Because the hand is well-perfused via collateral circulation, immediate vascular exploration is not indicated. These patients should be admitted and undergo close serial neurovascular monitoring. Vascular exploration is indicated for a 'pulseless, pale' (ischemic) hand that does not improve after reduction.

Question 5044

Topic: Pediatric Hip

A 12-year-old obese male presents with left groin and knee pain, and is diagnosed with a slipped capital femoral epiphysis (SCFE). The right hip is completely asymptomatic with normal radiographs. Which of the following is considered an absolute indication for prophylactic in situ pinning of the contralateral, asymptomatic right hip?

. Patient age less than 10 years at presentation
. Male sex
. Concomitant endocrine disorder (e.g., hypothyroidism)
. Severe obesity (BMI > 99th percentile)
. Radiographic evidence of a severe slip angle on the affected side

Correct Answer & Explanation

. Patient age less than 10 years at presentation

Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy) are absolute indications for prophylactic contralateral pinning in SCFE due to the extraordinarily high risk (often >50-100%) of developing a bilateral slip. Other relative indications include young age at presentation (<10 years for girls, <12 years for boys) and poor reliability for follow-up, but endocrine etiology remains the classic absolute indication.

Question 5045

Topic: Pediatric Hip

A 4-month-old female is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up examination, the orthopedist notes that the harness straps are excessively tightened in the anterior aspect, placing the hips in extreme hyperflexion. This specific positioning error puts the child at highest risk for which of the following complications?

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

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

In Pavlik harness treatment for DDH, hyperflexion of the hips (>120 degrees) can compress the femoral nerve against the inguinal ligament, leading to a transient femoral nerve palsy (manifesting as loss of active knee extension). Conversely, excessive forced abduction places the patient at highest risk for avascular necrosis (AVN) of the femoral head due to compression of the medial circumflex femoral artery.

Question 5046

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls off monkey bars and presents to the emergency department with a Gartland Type III extension-type supracondylar humerus fracture. Radiographs indicate that the distal fracture fragment is severely posterolaterally displaced. Based on this specific displacement pattern, which neurologic structure is at the greatest risk of injury from the proximal fragment?
. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve (AIN) / Median nerve
. Posterior interosseous nerve (PIN)
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN) / Median nerve

Explanation

In extension-type supracondylar humerus fractures, the displacement of the distal fragment dictates the location of the sharp proximal fragment. If the distal fragment goes posterolaterally, the proximal fragment is driven anteromedially. This anteromedial spike puts the median nerve (and its anterior interosseous branch) and the brachial artery at highest risk. Conversely, if the distal fragment displaces posteromedially, the proximal fragment goes anterolaterally, risking the radial nerve.

Question 5047

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy sustains a Gartland type III supracondylar humerus fracture. Following closed reduction and percutaneous pinning in the operating room, the child's hand is warm and pink, but the radial pulse remains absent. What is the most appropriate next step in management?
. Immediate vascular exploration by a vascular surgeon
. Close observation for 24 to 48 hours
. Removal of pins and extension of the elbow
. Stat CT angiography of the upper extremity
. Immediate forearm fasciotomy

Correct Answer & Explanation

. Close observation for 24 to 48 hours

Explanation

A 'pink, pulseless' hand following stable reduction and pinning of a supracondylar fracture indicates adequate collateral perfusion. Close clinical observation is the standard of care, as the pulse often returns within a few days as vasospasm resolves.

Question 5048

Topic: Pediatric Hip

A 6-week-old female infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother notes the infant has stopped kicking her left leg. Examination reveals decreased active knee extension on the left. What is the most appropriate next step in management?

. Adjust the anterior straps to increase hip flexion
. Adjust the posterior straps to increase hip abduction
. Remove the harness immediately and switch to rigid spica casting
. Discontinue the harness and observe for neurologic recovery
. Obtain an emergent MRI of the lumbar spine

Correct Answer & Explanation

. Adjust the anterior straps to increase hip flexion

Explanation

The infant has developed a femoral nerve palsy, a known complication of excessive hip flexion in a Pavlik harness. The most appropriate management is to temporarily discontinue the harness until neurologic function returns.

Question 5049

Topic: Pediatric Hip

A 13-year-old boy presents with a limp and obligate external rotation of his right hip when flexed. He is diagnosed with a severe, stable slipped capital femoral epiphysis (SCFE). Which of the following is the most common serious complication of in situ single-screw fixation for this condition?

. Chondrolysis
. Avascular necrosis
. Osteoarthritis
. Femoral neck fracture
. Screw cutout

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is a major complication of SCFE treatment, often associated with unrecognized joint penetration by the hardware during in situ pinning. Avascular necrosis is more commonly associated with unstable SCFE.

Question 5050

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents with a Gartland type III extension-type supracondylar humerus fracture. Examination reveals a pulseless but well-perfused, pink hand. After closed reduction and percutaneous pinning, the hand remains pink but the radial pulse remains absent. What is the most appropriate next step in management?
. Immediate open vascular exploration
. Observation and admission for close monitoring
. Perform an emergency MR angiogram
. Administer intravenous heparin
. Remove the pins and perform open reduction

Correct Answer & Explanation

. Observation and admission for close monitoring

Explanation

In a pulseless but well-perfused (pink) hand after adequate reduction and pinning of a pediatric supracondylar humerus fracture, observation is recommended. Collateral circulation is sufficient, and the pulse typically returns within 24-48 hours.

Question 5051

Topic: Pediatric Hip

A 6-week-old female infant is brought to the clinic. The Ortolani maneuver is positive on the left hip. Ultrasound demonstrates an alpha angle of 45 degrees. Which of the following is the most appropriate initial treatment?

. Observation and repeat ultrasound in 4 weeks
. Pavlik harness application
. Closed reduction and spica casting
. Open reduction and spica casting
. Denis Browne splint

Correct Answer & Explanation

. Observation and repeat ultrasound in 4 weeks

Explanation

A positive Ortolani sign indicates a dislocated but reducible hip, confirming DDH, and an alpha angle <60 degrees is abnormal. The Pavlik harness is the gold standard initial treatment for infants under 6 months of age.

Question 5052

Topic: Pediatric Hip

An 11-year-old obese male complains of left knee and groin pain for 3 weeks. Radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE). During physical examination, when the affected hip is passively flexed, which obligate motion is classically observed?

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

Correct Answer & Explanation

. Internal rotation

Explanation

In patients with SCFE, the femoral neck typically displaces anteriorly and superiorly relative to the epiphysis. This anatomical change causes obligate external rotation of the hip during passive hip flexion.

Question 5053

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents with an extension-type, Gartland type III supracondylar humerus fracture with posteromedial displacement of the distal fragment. Which nerve is tethered over the proximal fragment and at the highest risk of injury in this specific displacement pattern?
. Median nerve
. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In extension-type supracondylar humerus fractures, posteromedial displacement of the distal fragment pushes the sharp proximal fragment anterolaterally. This classically stretches or tethers the radial nerve. Conversely, posterolateral displacement endangers the median nerve (specifically the AIN branch) and brachial artery as the proximal fragment is pushed anteromedially.

Question 5054

Topic: Pediatric Lower Extremity

A 45-year-old female with a history of chronic, worsening midfoot pain presents with a severe, progressive flatfoot deformity. Radiographs show a unique comma-shaped deformity of the tarsal navicular characterized by fragmentation, lateral collapse, and medial protrusion. Which of the following diagnoses best describes this specific pathologic entity?

. Kohler disease
. Freiberg's infraction
. Muller-Weiss disease
. Charcot neuroarthropathy
. Sever's disease

Correct Answer & Explanation

. Kohler disease

Explanation

Muller-Weiss disease is a spontaneous osteonecrosis of the adult tarsal navicular. It classically presents bilaterally in middle-aged females. Radiographically, the navicular appears 'comma-shaped' due to lateral collapse, often resulting in a paradoxical planovarus deformity. In contrast, Kohler disease refers to osteonecrosis of the navicular occurring in early childhood.

Question 5055

Topic: 4. Pediatrics

A 9-year-old obese boy presents with a 3-week history of right groin pain and a limp. Examination reveals obligate external rotation with hip flexion. Radiographs confirm a mild Slipped Capital Femoral Epiphysis (SCFE). Given the patient's age, what underlying systemic condition must be considered and screened for?

. Hyperthyroidism
. Hypothyroidism
. Achondroplasia
. Marfan syndrome
. Neurofibromatosis type 1

Correct Answer & Explanation

. Hyperthyroidism

Explanation

SCFE is typically seen in early adolescence. When it occurs in children younger than 10 or older than 16 years, or in those under the 50th percentile for weight, an underlying endocrine disorder such as hypothyroidism or renal osteodystrophy should be suspected.

Question 5056

Topic: Pediatric Hip

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). The mother notes that the child is no longer extending her knee actively on the treated side. What is the most likely cause of this complication?

. Avascular necrosis of the femoral head
. Excessive abduction causing obturator nerve palsy
. Excessive flexion causing femoral nerve palsy
. Ischemic contracture of the quadriceps
. Development of a septic hip

Correct Answer & Explanation

. Avascular necrosis of the femoral head

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness if the hip is positioned in excessive flexion. It is typically reversible upon releasing or adjusting the harness to reduce the flexion angle.

Question 5057

Topic: 4. Pediatrics

Slipped Capital Femoral Epiphysis (SCFE) is characterized by displacement of the proximal femoral epiphysis relative to the femoral neck. In this condition, the failure of the physis predominantly occurs through which specific histological zone?

. Reserve zone
. Proliferative zone
. Zone of provisional calcification
. Hypertrophic zone
. Primary spongiosa

Correct Answer & Explanation

. Reserve zone

Explanation

The biomechanical failure in Slipped Capital Femoral Epiphysis occurs almost exclusively through the hypertrophic zone of the physis. This zone is the weakest portion of the growth plate due to the lack of collagenous bridging and the large size of the chondrocytes.

Question 5058

Topic: 4. Pediatrics

A 10-year-old boy sustains a Salter-Harris Type I fracture of the distal radius. The fracture line typically propagates through which layer of the physis?

. Reserve zone
. Proliferative zone
. Zone of maturation
. Zone of provisional calcification
. Primary spongiosa

Correct Answer & Explanation

. Reserve zone

Explanation

Salter-Harris fractures typically propagate through the weakest zone of the physis, which is the zone of provisional calcification (specifically the hypertrophic zone's lower part). This zone has increased cell volume and decreased matrix, making it biomechanically vulnerable.

Question 5059

Topic: 4. Pediatrics
During longitudinal growth at the physis, which zone is primarily responsible for providing the mechanical weak point where Salter-Harris fractures most commonly occur?
. Reserve zone
. Proliferative zone
. Zone of maturation
. Zone of provisional calcification
. Hypertrophic zone

Correct Answer & Explanation

. Hypertrophic zone

Explanation

The hypertrophic zone lacks significant extracellular matrix and collagen, making it the weakest part of the physis. This zone is typically where separations occur in most Salter-Harris type I, II, and III fractures.

Question 5060

Topic: Pediatric Upper Extremity & Spine

During a closed reduction and percutaneous pinning of a supracondylar humerus fracture, a 6-year-old patient develops an unexplained rise in end-tidal CO2, tachycardia, and masseter muscle rigidity. Administration of which medication is the definitive treatment?

. Epinephrine
. Atropine
. Succinylcholine
. Dantrolene
. Propofol

Correct Answer & Explanation

. Epinephrine

Explanation

The patient is exhibiting signs of malignant hyperthermia, an autosomally dominant condition typically triggered by volatile anesthetics and succinylcholine. Dantrolene, a ryanodine receptor antagonist, is the specific antidote.

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