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4. Pediatrics MCQs

Practice Set 292 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 5821

Topic: Pediatric Hip
A 6-year-old male presents with acute onset, severe pain in the right hip, inability to bear weight, and a fever of 102°F (38.9°C). Labs show elevated ESR and CRP. Physical exam reveals extreme pain with any hip movement. What is the most critical differential diagnosis to rule out immediately?
. Legg-Calvé-Perthes disease
. Transient synovitis
. Developmental dysplasia of the hip
. Septic arthritis
. Juvenile idiopathic arthritis

Correct Answer & Explanation

. Septic arthritis

Explanation

The clinical picture of acute onset severe hip pain, inability to bear weight, fever, and elevated inflammatory markers (ESR, CRP) is highly suggestive of septic arthritis. This is a surgical emergency requiring immediate diagnosis and treatment to prevent permanent joint destruction. While other conditions are in the differential for hip pain, none present with this acute, febrile, systemic severity requiring immediate intervention. Perthes and DDH are typically chronic or subacute. Transient synovitis is usually less severe, afebrile, and inflammatory markers are often normal or mildly elevated. JIA is chronic.

Question 5822

Topic: 4. Pediatrics

Which of the following factors does NOT increase the risk of developmental dysplasia of the hip?

. Female sex
. Breech presentation
. Large for gestational age (LGA)
. Oligohydramnios
. First-born child

Correct Answer & Explanation

. Large for gestational age (LGA)

Explanation

Being large for gestational age (LGA) is not a recognized risk factor for DDH. In fact, small for gestational age (SGA) infants might have a slightly increased risk, though it's not a primary one. The other options (female sex, breech presentation, oligohydramnios, first-born child) are all well-established risk factors for DDH due to genetic predisposition, hormonal influences, and intrauterine mechanical factors.

Question 5823

Topic: 4. Pediatrics

When performing the Ortolani maneuver, what type of sensation indicates a positive result?

. A soft, grinding sensation
. A palpable 'clunk' as the femoral head reduces into the acetabulum
. A sudden, sharp pain response from the infant
. Audible clicking without palpable movement
. Increased range of motion compared to the contralateral hip

Correct Answer & Explanation

. A palpable 'clunk' as the femoral head reduces into the acetabulum

Explanation

A positive Ortolani sign is characterized by a palpable 'clunk' (not just an audible click) as the dislocated femoral head reduces back into the acetabulum during hip abduction and gentle lifting. A soft grinding sensation or sharp pain is not typical for Ortolani. Audible clicking without palpable movement is often benign, especially if transient. Increased ROM is not indicative of DDH; more often, there is limited abduction.

Question 5824

Topic: 4. Pediatrics

A 1-year-old child presents with a persistent limp. On examination, the examiner notes that when the child stands on one leg, the pelvis drops on the unsupported side. This is indicative of what sign?

. Galeazzi sign
. Barlow sign
. Ortolani sign
. Trendelenburg sign
. Telescoping sign

Correct Answer & Explanation

. Trendelenburg sign

Explanation

The description of the pelvis dropping on the unsupported side when standing on one leg is the classic presentation of a positive Trendelenburg sign. This indicates weakness of the hip abductor muscles (gluteus medius and minimus) on the stance leg side. This can be seen in various conditions, including DDH (due to dislocation or dysplasia leading to abductor insufficiency), LCPD, neurological conditions, or coxa vara. Galeazzi, Barlow, and Ortolani signs are for infant hip instability or limb length discrepancy. Telescoping is for piston mobility in dislocated hips.

Question 5825

Topic: Pediatric Hip

Which of the following interventions is typically contraindicated in the management of DDH with a Pavlik harness?

. Maintaining hips in flexion
. Allowing limited hip adduction
. Forcing hip abduction beyond 60 degrees
. Checking for skin irritation regularly
. Ensuring knees are free to move

Correct Answer & Explanation

. Forcing hip abduction beyond 60 degrees

Explanation

Forcing hip abduction beyond 60 degrees (or to 90 degrees) in a Pavlik harness significantly increases the risk of avascular necrosis (AVN) of the femoral head due to compression of the blood supply. The Pavlik harness works by positioning the hips in flexion (90-110 degrees) and gentle abduction (30-60 degrees) while allowing free movement for the infant to kick, promoting reduction and stability without undue stress. Limited adduction is acceptable, regular skin checks are vital, and free knee movement is essential for proper function and comfort.

Question 5826

Topic: Pediatric Hip

A 4-month-old infant, previously managed with a Pavlik harness for DDH, is now noted to have a stable hip on clinical examination and an alpha angle of 65 degrees on ultrasound. What is the most appropriate next step?

. Continue Pavlik harness for another 2 months to ensure stability
. Immediately discontinue the harness and begin physical therapy
. Begin weaning from the Pavlik harness over several weeks
. Switch to an abduction brace for continued immobilization
. Refer for open reduction to prevent recurrence

Correct Answer & Explanation

. Begin weaning from the Pavlik harness over several weeks

Explanation

Once the hip is clinically and sonographically stable and mature (alpha angle >60 degrees) after Pavlik harness treatment, the harness is typically weaned gradually over several weeks, rather than immediately discontinued. This allows for soft tissue adaptation and reduces the risk of recurrence. Continuing the harness when no longer needed is unnecessary. Switching to an abduction brace is usually done after successful closed reduction and spica casting, or as a step-down from a spica cast, not typically after successful Pavlik treatment. Open reduction is not indicated for a stable and mature hip.

Question 5827

Topic: 4. Pediatrics

When assessing an infant for DDH, a 'click' heard or felt during hip manipulation, without frank dislocation or reduction, is most likely due to what structure?

. Ligamentum teres
. Acetabular labrum
. Iliofemoral ligament
. Capsular laxity
. IT band friction

Correct Answer & Explanation

. Iliofemoral ligament

Explanation

A benign 'click' without frank dislocation or reduction is often attributed to the normal movement of the iliofemoral ligament over the femoral head, or sometimes the acetabular labrum. While the labrum can be involved in true instability, an isolated click without other signs is usually not indicative of DDH and often resolves spontaneously. Ligamentum teres is intra-articular and unlikely to click. Capsular laxity contributes to instability, but a specific click is less about the capsule itself. IT band friction is a phenomenon typically seen in older individuals with hip problems.

Question 5828

Topic: 4. Pediatrics

In the context of DDH screening, what is the current recommendation for selective screening using hip ultrasound?

. All newborns should receive a hip ultrasound at 6 weeks of age.
. Only infants with a positive family history should undergo ultrasound.
. Infants with identified risk factors (e.g., breech, female first-born) should receive ultrasound.
. Ultrasound is only indicated for infants with a clinically positive Ortolani or Barlow test.
. Ultrasound should replace clinical examination as the primary screening tool.

Correct Answer & Explanation

. Infants with identified risk factors (e.g., breech, female first-born) should receive ultrasound.

Explanation

Current guidelines recommend selective screening with hip ultrasound for infants with identified risk factors for DDH, such as breech presentation (even if corrected before birth), female sex, first-born status, oligohydramnios, or a strong family history. Ultrasound is not recommended for all newborns as a universal screening tool, nor is it only for clinically positive exams (which would miss subtle dysplasia). Clinical examination remains the primary screening tool for all infants, with ultrasound reserved for those at higher risk or with suspicious clinical findings.

Question 5829

Topic: 4. Pediatrics
Which of the following conditions is most likely to present with a positive Trendelenburg sign due to primary gluteal muscle weakness, rather than mechanical instability or bony deformity?
. Unilateral congenital hip dislocation
. Legg-Calvé-Perthes disease
. Cerebral palsy
. Slipped capital femoral epiphysis
. Coxa vara

Correct Answer & Explanation

. Cerebral palsy

Explanation

Cerebral palsy is a neurological condition that often results in muscular imbalance and weakness, including weakness of the gluteal abductor muscles, leading to a positive Trendelenburg sign due to primary neuromuscular dysfunction. While unilateral congenital hip dislocation, LCPD, SCFE, and coxa vara can all cause a Trendelenburg gait, they do so primarily through mechanical insufficiency of the abductor mechanism (e.g., dislocated greater trochanter, altered biomechanics, pain), not intrinsic weakness of the muscle itself as seen in CP.

Question 5830

Topic: 4. Pediatrics

A newborn presents with bilateral contractures of the elbows, knees, and hips, consistent with arthrogryposis multiplex congenita. What is the prevalence of DDH in this patient population compared to the general population?

. Significantly lower
. Similar
. Slightly lower
. Significantly higher
. Unknown, no clear association

Correct Answer & Explanation

. Significantly higher

Explanation

Arthrogryposis multiplex congenita, a condition characterized by multiple congenital contractures, is associated with a significantly higher prevalence of DDH compared to the general population. This is due to the severe intrauterine constraint and reduced fetal movement that contributes to both the contractures and the impaired development of the hip joint. Other neuromuscular conditions like myelomeningocele also have a high incidence of DDH.

Question 5831

Topic: 4. Pediatrics

A 10-month-old infant presents with a left-sided limp. Physical examination reveals limited hip abduction on the left and a positive Galeazzi sign on the left. Radiographs confirm a left hip dislocation. What is the most appropriate initial management approach for this patient?

. Pavlik harness application
. Watchful waiting with serial clinical exams
. Closed reduction under anesthesia and hip spica casting
. Open reduction with capsulorrhaphy
. Traction followed by open reduction

Correct Answer & Explanation

. Closed reduction under anesthesia and hip spica casting

Explanation

For an infant of 6 months or older with a confirmed dislocated hip, especially one that is unlikely to reduce spontaneously or with gentle manipulation (as indicated by the age and limited abduction), the standard initial management is a closed reduction under general anesthesia followed by immobilization in a hip spica cast. The Pavlik harness is generally ineffective and contraindicated after 6 months of age due to increasing rigidity of soft tissues. Watchful waiting is inappropriate for a dislocated hip at this age. Open reduction is typically reserved for cases where closed reduction fails or for older children with irreducible dislocations. Traction might be used pre-operatively, but not as a stand-alone initial step without subsequent reduction.

Question 5832

Topic: Pediatric Hip

Which of the following radiographic findings is considered the earliest indicator of acetabular dysplasia in a child over 6 months of age?

. Increased Wiberg's CE angle
. Interruption of Shenton's line
. Increased acetabular index (angle)
. Lateral displacement of the ossified femoral head
. Decreased femoral neck-shaft angle

Correct Answer & Explanation

. Increased acetabular index (angle)

Explanation

An increased acetabular index (or acetabular angle) is the earliest and most direct radiographic indicator of acetabular dysplasia, reflecting a shallow, more vertical acetabular roof. Interruption of Shenton's line and lateral displacement of the femoral head are signs of subluxation or dislocation, which are more advanced stages of DDH. Wiberg's CE angle is useful but often becomes abnormal later. Decreased femoral neck-shaft angle (coxa vara) can be associated but is not the primary or earliest sign of acetabular dysplasia.

Question 5833

Topic: Pediatric Hip

What is the typical timeframe within which a positive Ortolani or Barlow sign should resolve spontaneously if DDH is not present?

. Within the first 24 hours of life
. By 2 weeks of age
. By 4-6 weeks of age
. By 3 months of age
. By 6 months of age

Correct Answer & Explanation

. By 4-6 weeks of age

Explanation

Many newborns exhibit a degree of transient hip laxity due to maternal hormones, which often resolves spontaneously. A positive Ortolani or Barlow test that is due to physiologic laxity (and not true DDH) typically resolves by 4-6 weeks of age. If instability persists beyond this point, it is more likely to represent true DDH and warrants further investigation and/or treatment. This is why initial observation is often recommended for stable but immature hips in the first few weeks of life.

Question 5834

Topic: 4. Pediatrics

In a 3-year-old child with a dislocated hip due to DDH, what is the most common reason for failure of closed reduction?

. Insufficient anesthesia
. Parental non-compliance
. Interposition of the psoas tendon or inverted labrum
. Severe capsular laxity
. Lack of skilled surgeon

Correct Answer & Explanation

. Interposition of the psoas tendon or inverted labrum

Explanation

In older children (typically >1 year) with a dislocated hip, soft tissue contractures and mechanical blocks are the most common reasons for failed closed reduction. The hypertrophied and inverted acetabular labrum and the tight, medially displaced iliopsoas tendon are classic obstructions. Insufficient anesthesia can certainly be a factor, but a true mechanical block persists. Parental non-compliance is a treatment issue, not a reason for reduction failure. Severe capsular laxity would make reduction easier, not harder. Lack of skilled surgeon is a human factor, not a biomechanical reason.

Question 5835

Topic: Pediatric Hip

A 2-week-old female, born via spontaneous vaginal delivery, has an asymptomatic, stable hip on clinical exam. However, she was born breech. What is the most appropriate next step in her evaluation for DDH?

. No further action, as the clinical exam is negative.
. Repeat clinical exam at 6 weeks of age.
. Perform a hip ultrasound at 4-6 weeks of age.
. Initiate Pavlik harness treatment empirically.
. Order an AP pelvis radiograph immediately.

Correct Answer & Explanation

. Perform a hip ultrasound at 4-6 weeks of age.

Explanation

Despite a negative clinical exam, breech presentation is a significant risk factor for DDH, warranting imaging. However, due to the high rate of physiological laxity in the first few weeks of life that can spontaneously resolve, hip ultrasound is typically performed at 4-6 weeks of age for breech infants. This allows time for any transient laxity to resolve, reducing false positives, while still allowing for early diagnosis if true dysplasia is present. Immediate Pavlik is not indicated for a stable hip. Radiographs are not optimal before 4-6 months due to significant cartilage.

Question 5836

Topic: Pediatric Hip

Which of the following is considered a 'soft sign' of DDH, often necessitating further investigation, but not diagnostic on its own?

. Positive Ortolani sign
. Positive Barlow sign
. Limited hip abduction
. Asymmetric thigh folds
. Positive Galeazzi sign

Correct Answer & Explanation

. Asymmetric thigh folds

Explanation

Asymmetric thigh folds are considered a 'soft sign' of DDH. While suggestive, they are often seen in infants without DDH and can be present with normal hips. Therefore, they necessitate further investigation (e.g., ultrasound) but are not diagnostic on their own. Positive Ortolani and Barlow signs indicate hip instability and are considered 'hard signs.' Limited hip abduction and a positive Galeazzi sign are stronger indicators of DDH, particularly in older infants/toddlers.

Question 5837

Topic: Pediatric Hip

What is the primary goal of early diagnosis and treatment of developmental dysplasia of the hip?

. To prevent limb length discrepancy in adulthood.
. To avoid the need for reconstructive surgery later in life.
. To ensure normal development of the acetabulum and prevent future osteoarthritis.
. To correct a waddling gait in early childhood.
. To minimize the risk of avascular necrosis of the femoral head.

Correct Answer & Explanation

. To ensure normal development of the acetabulum and prevent future osteoarthritis.

Explanation

The primary goal of early diagnosis and treatment of DDH is to ensure normal development of the acetabulum and femoral head. This helps to prevent progressive acetabular dysplasia, femoral head deformity, and ultimately, the development of early-onset osteoarthritis in adulthood. While preventing the need for reconstructive surgery, correcting gait, and minimizing AVN are important outcomes, the fundamental aim is to achieve a stable, anatomically normal hip joint to prevent long-term sequelae.

Question 5838

Topic: 4. Pediatrics

In an infant with a 'clicky hip' where both Ortolani and Barlow tests are negative and hip abduction is full, what is the most appropriate recommendation?

. Immediate hip ultrasound
. Initiate Pavlik harness treatment
. Reassurance and routine follow-up, as isolated clicks are usually benign
. Referral to pediatric orthopedic surgeon for diagnostic arthroscopy
. Serial plain radiographs every 3 months

Correct Answer & Explanation

. Reassurance and routine follow-up, as isolated clicks are usually benign

Explanation

An isolated 'click' without any palpable instability on Ortolani or Barlow testing, and with full range of motion, is generally considered a benign finding (often due to snapping soft tissues or minor ligamentous laxity) and typically resolves spontaneously. Reassurance and routine follow-up are appropriate. Immediate ultrasound or Pavlik harness are not indicated. Diagnostic arthroscopy and serial plain radiographs are overly aggressive and unnecessary for this benign presentation.

Question 5839

Topic: Pediatric Hip

A 5-month-old infant has been in a Pavlik harness for 10 weeks for a dislocated hip. On follow-up, the hip remains dislocated and irreducible on clinical exam. What is the most appropriate next step in management?

. Increase the abduction in the Pavlik harness
. Discontinue the Pavlik harness and observe for spontaneous reduction
. Perform a closed reduction under anesthesia followed by spica casting
. Refer for open reduction and possible osteotomy
. Initiate traction therapy immediately

Correct Answer & Explanation

. Perform a closed reduction under anesthesia followed by spica casting

Explanation

If a Pavlik harness has failed to achieve reduction of a dislocated hip after an adequate trial (typically 3-6 weeks, and certainly after 10 weeks) and the hip remains irreducible, then a failed Pavlik harness indicates the need for more definitive intervention. At 5 months, if the hip is irreducible, the next step is typically a closed reduction under anesthesia followed by hip spica casting. Open reduction and possible osteotomy are considered if closed reduction fails, or for older children with highly unstable or chronically dislocated hips. Increasing abduction in a failed Pavlik is ineffective and risks AVN. Discontinuing treatment is inappropriate. Traction may be used as a preparatory step but not as the sole next step.

Question 5840

Topic: Pediatric Hip
Which type of DDH, according to Graf's classification, is most often managed with watchful waiting and considered a physiologically immature hip that may resolve spontaneously?
. Type Ia
. Type Ib
. Type IIa-
. Type IIc
. Type III

Correct Answer & Explanation

. Type IIa-

Explanation

Graf's Type IIa- hip, characterized by an alpha angle between 50-59 degrees and an age less than 3 months, is considered a physiologically immature hip. Many of these hips will mature spontaneously without intervention, making watchful waiting with a follow-up ultrasound the appropriate initial management. Type Ia and Ib are mature hips. Type IIc, III, and IV are dysplastic or decentered hips that generally require treatment.

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