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4. Pediatrics MCQs

Practice Set 113 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 2241

Topic: 4. Pediatrics

In a child with infantile Blount's disease, which Langenskiöld radiographic stage is characterized by a distinct 'step' in the medial metaphysis, serving as a critical juncture where proximal tibial osteotomy is typically indicated to prevent permanent physeal arrest?

. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage III

Explanation

Langenskiöld Stage III is characterized by deepening of the metaphyseal depression, forming a distinct 'step'. Stages I and II (ages 2-3) represent early changes (beaking and depression) that may resolve spontaneously or with orthotic management. By Stage III (usually around age 4), spontaneous resolution is rare, and the mechanical forces will progressively damage the physis leading to bar formation (Stages IV-VI). Thus, corrective osteotomy is generally indicated at or before Stage III.

Question 2242

Topic: Pediatric Lower Extremity

According to the Ponseti method for the serial casting of idiopathic clubfoot, what is the correct sequential order of deformity correction?

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

Correct Answer & Explanation

. Cavus, Varus, Adductus, Equinus

Explanation

The Ponseti method follows a strict sequence to correct the complex 3D deformity of a clubfoot, easily remembered by the acronym CAVE: Cavus, Adductus, Varus, Equinus. The cavus is corrected first by supinating the forefoot to align it with the hindfoot (elevating the first ray). Then the midfoot adductus and hindfoot varus are corrected together by abducting the foot around the fixed talar head. Finally, equinus is corrected, which often requires a percutaneous Achilles tenotomy.

Question 2243

Topic: Pediatric Hip

An 8-year-old girl is diagnosed with bilateral slipped capital femoral epiphysis (SCFE). On examination, her height and weight are both below the 5th percentile for her age. Which of the following is the most likely underlying etiology and the most appropriate screening test?

. Hypothyroidism; Thyroid-stimulating hormone (TSH) and Free T4
. Renal osteodystrophy; Parathyroid hormone (PTH) and basic metabolic panel
. Growth hormone deficiency; Insulin-like growth factor 1 (IGF-1)
. Panhypopituitarism; Serum prolactin and cortisol levels
. Hyperthyroidism; Total T3 and T4 levels

Correct Answer & Explanation

. Hypothyroidism; Thyroid-stimulating hormone (TSH) and Free T4

Explanation

SCFE occurring in a child under 10 years of age or presenting bilaterally is highly suspicious for an underlying endocrine or metabolic disorder. Hypothyroidism is the most common endocrine disorder associated with SCFE, often presenting with short stature, delayed bone age, and weight gain, though generalized growth restriction can occur. Screening with TSH and Free T4 is the most appropriate initial step.

Question 2244

Topic: Pediatric Hip

A 4-month-old infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a follow-up visit, the orthopedist notices an absence of active knee extension on the affected side. This complication is most directly related to which of the following harness fitting errors?

. Excessive abduction of the hips
. Insufficient abduction of the hips
. Excessive flexion of the hips
. Insufficient flexion of the hips
. Excessive internal rotation of the hips

Correct Answer & Explanation

. Excessive flexion of the hips

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and presents as an inability to actively extend the knee. It is caused by excessive flexion of the hip (typically > 120 degrees), which compresses the femoral nerve against the rim of the pelvis or the inguinal ligament. Excessive abduction is associated with avascular necrosis of the femoral head.

Question 2245

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a unilateral slipped capital femoral epiphysis (SCFE) of the left hip. The orthopaedic surgeon recommends prophylactic in situ pinning of the contralateral right hip due to a high risk of subsequent slip. Which of the following underlying conditions most strongly warrants prophylactic contralateral pinning in SCFE?

. Obesity with BMI > 95th percentile
. Hypothyroidism
. Attention Deficit Hyperactivity Disorder (ADHD)
. Vitamin D deficiency rickets
. Mild renal osteodystrophy

Correct Answer & Explanation

. Hypothyroidism

Explanation

While idiopathic SCFE is common in obese adolescents, endocrinopathies are strong indications for prophylactic contralateral pinning due to the exceedingly high risk of bilateral involvement. Hypothyroidism, panhypopituitarism, and growth hormone deficiency are the most common endocrine disorders associated with atypical or early/late presentation of SCFE, and prophylactic pinning of the asymptomatic hip is strongly recommended in these patients.

Question 2246

Topic: Pediatric Hip

The primary blood supply to the femoral head in an adolescent with a slipped capital femoral epiphysis (SCFE) is derived from the:

. Lateral epiphyseal branches of the medial circumflex femoral artery
. Medial epiphyseal branches of the obturator artery
. Artery of the ligamentum teres
. Inferior gluteal artery
. Ascending branch of the lateral circumflex femoral artery

Correct Answer & Explanation

. Lateral epiphyseal branches of the medial circumflex femoral artery

Explanation

The lateral epiphyseal artery, a terminal branch of the medial circumflex femoral artery (MCFA), provides the predominant blood supply to the femoral head in older children and adolescents. Disruption of these retinacular vessels during a SCFE or its surgical treatment can lead to avascular necrosis.

Question 2247

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy falls from monkey bars and sustains a widely displaced, extension-type supracondylar humerus fracture. On initial presentation in the emergency department, his hand is pale and pulseless. What is the most appropriate next step in management?

. Immediate CT angiography of the upper extremity
. Open anterior approach for exploration of the brachial artery
. Urgent closed reduction and percutaneous pinning in the operating room
. Application of a warm compress and observation for 2 hours
. Administration of intravenous heparin

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning in the operating room

Explanation

A pale, pulseless hand in the setting of a displaced supracondylar humerus fracture is a surgical emergency. The immediate next step is urgent closed reduction and percutaneous pinning in the OR. Often, realignment of the fracture unkinks the brachial artery and restores perfusion. Routine angiography delays necessary reduction.

Question 2248

Topic: Pediatric Hip

Chondrolysis is a devastating complication following the surgical treatment of Slipped Capital Femoral Epiphysis (SCFE). The development of chondrolysis is most strongly associated with which of the following factors?

. Unrecognized intra-articular penetration of the fixation hardware
. Female sex and early menarche
. Delay in surgical intervention greater than 24 hours
. Use of a single 7.3 mm cannulated screw instead of two
. Concomitant prophylactic pinning of the contralateral hip

Correct Answer & Explanation

. Unrecognized intra-articular penetration of the fixation hardware

Explanation

Unrecognized intra-articular hardware penetration is the most common iatrogenic cause of chondrolysis in SCFE treatment. It causes severe mechanical damage to the articular cartilage, leading to rapid joint space narrowing, stiffness, and pain.

Question 2249

Topic: Pediatric Hip

A 12-year-old obese boy presents with acute right groin pain and an inability to bear weight on his right leg, even with crutches. Radiographs confirm a severe Slipped Capital Femoral Epiphysis (SCFE). According to the Loder classification, what is the primary determinant of this patient's high risk for avascular necrosis (AVN)?

. Slip angle > 50 degrees
. Inability to ambulate with or without crutches
. Duration of symptoms < 3 weeks
. Open triradiate cartilage
. Metaphyseal blanch sign of Steel

Correct Answer & Explanation

. Inability to ambulate with or without crutches

Explanation

The Loder classification defines SCFE as 'stable' or 'unstable' strictly based on the patient's ability to bear weight (ambulate) with or without crutches. Unstable slips (inability to bear weight) carry a significantly higher risk of avascular necrosis (up to 47%) compared to stable slips.

Question 2250

Topic: Pediatric Hip
A 6-week-old female infant undergoes a screening ultrasound for developmental dysplasia of the hip (DDH). The standard coronal view yields an alpha angle of 35 degrees and a beta angle of 85 degrees. According to the Graf classification, what is the diagnosis and the most appropriate next step in management?
. Normal hip (Type I); parental reassurance
. Physiologic immaturity (Type IIa); repeat ultrasound in 4 weeks
. Subluxated hip (Type III); initiate Pavlik harness treatment
. Dislocated hip (Type IV); proceed to closed reduction and spica casting
. Dysplastic hip (Type IIb); immediate open reduction

Correct Answer & Explanation

. Subluxated hip (Type III); initiate Pavlik harness treatment

Explanation

An alpha angle of < 43 degrees with a beta angle > 77 degrees correlates with a Graf Type III hip, which represents a decentered (subluxated) hip with a measurable cartilage roof. The appropriate initial management for a subluxated hip in an infant under 6 months of age is reduction and stabilization utilizing a Pavlik harness.

Question 2251

Topic: Pediatric Hip

A 7-year-old boy presents with a painless limp and is diagnosed with Legg-Calve-Perthes disease in the fragmentation stage. Radiographs reveal that exactly 60% of the lateral pillar of the femoral head maintains its normal radiolucent height. According to the Herring Lateral Pillar Classification, what group is this hip, and what is its prognosis without intervention?

. Group A; excellent prognosis
. Group B; good prognosis given his age is < 8 years
. Group B/C border; poor prognosis requiring surgery
. Group C; poor prognosis requiring immediate containment
. Group C; excellent prognosis with simple bracing

Correct Answer & Explanation

. Group B; good prognosis given his age is < 8 years

Explanation

Herring's Lateral Pillar Classification assesses the height of the lateral aspect of the femoral head. Group A has >100% (no involvement), Group B maintains >50% of lateral pillar height, and Group C maintains <50%. With 60% preserved, this is Group B. Patients in Group B who are under 8 years of age at the onset of the disease generally have a good prognosis and often do well with conservative management.

Question 2252

Topic: Pediatric Hip

A 4-month-old female is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the mother reports that the infant has stopped actively extending her knee on the treated side. Upon examination, the hip is well-reduced. Which of the following is the most appropriate management regarding the harness?

. Tighten the anterior straps to maintain reduction
. Loosen the anterior straps to reduce hip flexion
. Tighten the posterior straps to increase abduction
. Loosen the posterior straps to decrease abduction
. Discontinue the harness immediately and schedule a closed reduction

Correct Answer & Explanation

. Loosen the anterior straps to reduce hip flexion

Explanation

Decreased active knee extension in an infant treated with a Pavlik harness is highly suspicious for a femoral nerve palsy. This complication is typically caused by excessive hip flexion, which compresses the femoral nerve against the inguinal ligament. The correct management is to immediately loosen the anterior flexion straps. Once the nerve function returns, the straps can be cautiously readjusted. Femoral nerve palsy in this setting usually resolves completely if addressed promptly.

Question 2253

Topic: 4. Pediatrics

A 6-year-old child presents with a notably short neck, a low posterior hairline, and restricted cervical range of motion. Radiographs demonstrate congenital fusion of C3-C4 and C5-C6. Because of the diagnosis, which of the following is the most appropriate initial screening test?

. Echocardiogram for aortic root dilation
. Renal ultrasound to evaluate for genitourinary anomalies
. Brain MRI to evaluate for Arnold-Chiari malformation
. Chest radiograph to evaluate for pulmonary hypoplasia
. Skeletal survey to evaluate for widespread osteochondrodysplasia

Correct Answer & Explanation

. Renal ultrasound to evaluate for genitourinary anomalies

Explanation

This patient presents with the classic triad of Klippel-Feil syndrome (short neck, low hairline, limited cervical ROM). Patients with Klippel-Feil syndrome have a high incidence of associated systemic anomalies. Up to 35% of these patients have genitourinary tract anomalies, most commonly unilateral renal agenesis. Therefore, a screening renal ultrasound is highly recommended. Congenital heart defects (such as VSD) and hearing loss are also common, warranting further evaluation, but renal US is standard for initial workup.

Question 2254

Topic: Pediatric Hip

A 9-year-old male presents with a slipped capital femoral epiphysis (SCFE) of the right hip. Under which of the following conditions is prophylactic in situ pinning of the contralateral asymptomatic left hip most strongly indicated?

. The patient has a BMI > 95th percentile
. The patient has a diagnosis of renal osteodystrophy
. The slip is classified as unstable
. The slip angle on the right is greater than 50 degrees
. The patient is male

Correct Answer & Explanation

. The patient has a diagnosis of renal osteodystrophy

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is strictly indicated in patients who have a high likelihood of a subsequent contralateral slip. Absolute or strong indications include underlying endocrine disorders (such as hypothyroidism or growth hormone deficiency), metabolic bone disease (such as renal osteodystrophy), prior radiation therapy to the pelvis, and very young age (typically females <10 and males <12). Obesity or slip severity on the affected side are not absolute indications on their own.

Question 2255

Topic: Pediatric Hip
A 6-year-old boy is diagnosed with Legg-Calvé-Perthes disease. During the fragmentation stage, an AP radiograph of his pelvis is used to determine his prognosis according to the Herring lateral pillar classification. To be classified as Group C (which carries the worst prognosis), the lateral pillar of the femoral head must demonstrate what percentage of maintained height compared to the contralateral normal hip?
. Less than 50%
. 50% to 100%
. Greater than 75%
. Complete collapse (0%) only
. Maintains 100% height but with extensive sclerosis

Correct Answer & Explanation

. Less than 50%

Explanation

The Herring lateral pillar classification is assessed on an AP radiograph during the fragmentation phase of Legg-Calvé-Perthes disease. It is based on the height of the lateral third (pillar) of the capital femoral epiphysis. Group A: 100% of the lateral pillar height is maintained. Group B: >50% of the lateral pillar height is maintained. Group C: <50% of the lateral pillar height is maintained. Patients in Group C have the poorest outcomes, often developing aspherical incongruency and early osteoarthritis.

Question 2256

Topic: Pediatric Hip

In which of the following scenarios is prophylactic in situ pinning of the contralateral, asymptomatic hip most strongly indicated in a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE)?

. A 13-year-old male with a BMI in the 95th percentile
. A 12-year-old female with primary hyperparathyroidism
. A 14-year-old male with an acute, unstable SCFE
. An 11-year-old female with a chronic, stable SCFE
. A 15-year-old male with a positive family history of SCFE

Correct Answer & Explanation

. A 12-year-old female with primary hyperparathyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial for idiopathic cases but is highly recommended in patients with endocrine disorders (e.g., hypothyroidism, renal osteodystrophy, hyperparathyroidism, growth hormone deficiency) or prior radiation therapy. These patients have a significantly higher risk (up to 100% in some metabolic conditions) of developing a contralateral slip compared to those with idiopathic SCFE.

Question 2257

Topic: 4. Pediatrics

A 6-week-old female infant is undergoing treatment with a Pavlik harness for a dislocated left hip (Graf Type IV). During a routine follow-up, the parents note the infant is not kicking the left leg as much. On examination, there is decreased active extension of the left knee, though the infant cries and withdraws when the heel is stimulated. What is the most likely cause of this finding?

. Femoral nerve palsy secondary to hyperflexion of the hip
. Sciatic nerve palsy secondary to excessive hip flexion
. Obturator nerve palsy secondary to excessive hip abduction
. Ischemic necrosis of the proximal femoral epiphysis
. Avulsion of the patellar tendon

Correct Answer & Explanation

. Femoral nerve palsy secondary to hyperflexion of the hip

Explanation

Femoral nerve palsy is a well-known complication of Pavlik harness treatment, usually caused by excessive hip flexion (typically > 100-120 degrees) which places traction on or compresses the femoral nerve against the pelvis. It presents as an inability or decreased tendency to actively extend the knee. The management is to temporarily remove the harness or adjust the flexion straps to a less flexed position. The nerve palsy almost always resolves spontaneously once the tension is relieved.

Question 2258

Topic: 4. Pediatrics
A 13-year-old girl sustains an ankle injury. Radiographs reveal a Salter-Harris III fracture of the anterolateral distal tibia. Which of the following best describes the anatomical basis for this specific fracture pattern?
. The physis closes from central to anteromedial to posteromedial to anterolateral.
. The physis closes from central to anteromedial to posterolateral to anterolateral.
. The physis closes from central to posteromedial to anteromedial to anterolateral.
. The physis closes from central to anterolateral to posteromedial to anteromedial.
. The physis closes from central to posterolateral to anteromedial to posteromedial.

Correct Answer & Explanation

. The physis closes from central to posteromedial to anteromedial to anterolateral.

Explanation

The distal tibial physis closes in a specific predictable pattern: central, then posteromedial, then anteromedial, and finally anterolateral. Because the anterolateral portion is the last to close (fuse), it is susceptible to avulsion via the anterior inferior tibiofibular ligament (AITFL) resulting in a juvenile Tillaux fracture.

Question 2259

Topic: Pediatric Hip

An 11-year-old obese boy is diagnosed with a unilateral, stable slipped capital femoral epiphysis (SCFE). Prophylactic pinning of the contralateral asymptomatic hip is being considered. Which of the following factors most strongly increases the risk of a contralateral slip and supports the decision for prophylactic pinning?

. Male gender
. African American race
. Age greater than 14 years at presentation
. Open triradiate cartilage at the time of presentation
. Presence of a metaphyseal blanch sign of Steel

Correct Answer & Explanation

. Open triradiate cartilage at the time of presentation

Explanation

Patients with an initial SCFE have a significant risk of contralateral slip (up to 20-60%). The risk is highest in patients with endocrine disorders (e.g., hypothyroidism) and those with significant remaining growth. An open triradiate cartilage indicates significant skeletal immaturity and remaining growth, representing a strong predictor for subsequent contralateral slip, thus often serving as a relative indication for prophylactic pinning.

Question 2260

Topic: Pediatric Hip

A 12-year-old boy presents with an acute-on-chronic slipped capital femoral epiphysis (SCFE) of the left hip. Under which of the following conditions is prophylactic pinning of the asymptomatic contralateral hip most strongly indicated?

. Age greater than 14 years
. Female gender
. Presence of an endocrine disorder such as hypothyroidism
. Grade I slip on the affected side
. BMI less than 85th percentile

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) due to the high risk of bilateral involvement (up to 100% in some endocrine conditions). Other risk factors include age <10 years (or open triradiate cartilage) and prior radiation therapy.

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