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4. Pediatrics MCQs

Practice Set 293 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 5841

Topic: Pediatric Hip

In a 2-year-old child presenting with a limp, what aspect of the physical exam is MOST helpful in differentiating DDH from transient synovitis?

. Presence of fever
. Limitation of hip abduction
. Pain with internal rotation of the hip
. WBC count and ESR/CRP levels
. History of recent viral illness

Correct Answer & Explanation

. Limitation of hip abduction

Explanation

While fever, pain with internal rotation, inflammatory markers, and a history of viral illness are all relevant for transient synovitis (acute, often painful, sometimes low-grade fever, mild inflammatory markers), a key differentiator for DDH (especially an undiagnosed late-presenting case) is the chronic limitation of hip abduction, often without acute pain or systemic signs. DDH manifests as a fixed contracture and structural abnormality. Transient synovitis, while painful, generally affects all ranges of motion and resolves. However, pain with internal rotation is also common in both, but DDH often has limited abduction, while transient synovitis often has more generalized limitations with pain. Limitation of abduction is a hallmark of DDH in older children.

Question 5842

Topic: 4. Pediatrics

When evaluating for DDH using radiographs in a child older than 6 months, which measurement is used to assess the lateral coverage of the femoral head by the acetabulum?

. Hilgenreiner's line
. Perkin's line
. Shenton's line
. Wiberg's center-edge (CE) angle
. Acetabular index

Correct Answer & Explanation

. Wiberg's center-edge (CE) angle

Explanation

Wiberg's center-edge (CE) angle is specifically used in older children and adults to quantify the lateral coverage of the femoral head by the acetabulum. A smaller CE angle indicates less coverage and suggests dysplasia. Hilgenreiner's line and Perkin's line are used to assess femoral head position and acetabular development, creating quadrants. Shenton's line assesses the continuity of the medial femoral neck and superior obturator foramen. The acetabular index measures the slope of the acetabular roof.

Question 5843

Topic: 4. Pediatrics

A 1-month-old infant has been diagnosed with a dislocatable hip (positive Barlow, negative Ortolani). Which of the following is the most appropriate initial treatment?

. Observation for 3 months, then repeat ultrasound
. Immediate closed reduction under general anesthesia
. Pavlik harness application
. Hip spica cast immobilization
. Open reduction surgery

Correct Answer & Explanation

. Pavlik harness application

Explanation

For infants from birth up to approximately 6 months of age with a dislocatable hip (positive Barlow, negative Ortolani), the Pavlik harness is the gold standard initial treatment. It gently holds the hips in a position of flexion and abduction, allowing the femoral head to reduce spontaneously and promoting normal acetabular development. Observation is too risky for a dislocatable hip. Closed reduction under anesthesia and hip spica casting are for irreducible or dislocated hips or Pavlik failures. Open reduction is a last resort.

Question 5844

Topic: 4. Pediatrics

Which of the following associated conditions is a known risk factor for DDH, often termed a 'packaging disorder' due to intrauterine molding?

. Congenital heart disease
. Cleft lip and palate
. Congenital calcaneovalgus foot
. Hirschsprung's disease
. Spina bifida

Correct Answer & Explanation

. Congenital calcaneovalgus foot

Explanation

Congenital calcaneovalgus foot is considered a 'packaging disorder' and is associated with an increased risk of DDH, along with other conditions like metatarsus adductus, clubfoot, and congenital muscular torticollis. These conditions are thought to arise from mechanical forces and restricted fetal movement within the uterus. Congenital heart disease, cleft lip/palate, and Hirschsprung's disease are not typically classified as packaging disorders related to DDH. Spina bifida (myelomeningocele) is a neurological condition that significantly increases DDH risk due to muscle imbalance, but it's not a packaging disorder in the same mechanical sense.

Question 5845

Topic: Pediatric Hip
A 7-month-old presents with asymmetric abduction and a positive Galeazzi sign on the right. An AP pelvis radiograph reveals an increased acetabular index (right > left) and the right femoral head ossific nucleus is superior and lateral to Perkin's line. What is the most likely diagnosis?
. Legg-Calvรฉ-Perthes disease
. Right transient synovitis
. Right developmental dysplasia of the hip
. Right septic arthritis
. Right coxa vara

Correct Answer & Explanation

. Right developmental dysplasia of the hip

Explanation

The clinical findings of asymmetric abduction and a positive Galeazzi sign, combined with radiographic findings of an increased acetabular index (acetabular hypoplasia) and superior/lateral displacement of the femoral head (subluxation/dislocation), are classic for developmental dysplasia of the hip. The age (7 months) makes radiographs the appropriate imaging. Perthes disease, transient synovitis, septic arthritis, and coxa vara would present with different clinical and/or radiographic features.

Question 5846

Topic: 4. Pediatrics
What is the primary concern for a missed or late diagnosis of DDH in an older child (e.g., >2 years old)?
. Increased risk of avascular necrosis from subsequent treatment
. Higher likelihood of requiring open reduction and more complex surgical procedures
. Development of compensatory scoliosis
. Chronic knee pain due to gait abnormality
. Psychological distress for the child and family

Correct Answer & Explanation

. Higher likelihood of requiring open reduction and more complex surgical procedures

Explanation

A primary concern for missed or late diagnosis of DDH in older children is the increased likelihood of requiring more invasive and complex surgical procedures, such as open reduction with capsulorrhaphy and acetabular or femoral osteotomies. This is due to progressive bony and soft tissue adaptations that make closed reduction difficult or impossible. While AVN is a risk of treatment, and gait abnormalities can lead to other joint pain, the direct consequence of late diagnosis is the need for more extensive and often less predictable reconstructive surgery. Psychological distress is a valid concern but not the primary orthopedic one.

Question 5847

Topic: 4. Pediatrics

Which of the following describes the anatomical defect in 'teratologic dislocation' of the hip, a severe form of DDH, often seen in conditions like arthrogryposis or myelomeningocele?

. Mild acetabular hypoplasia with a reducible femoral head.
. A hip that is dislocatable but reducible with a Pavlik harness.
. A hip that dislocates after an injury in a previously normal joint.
. A fixed, often irreducible hip dislocation with severe acetabular and femoral head dysplasia present at birth.
. A hip with an inverted labrum but otherwise normal bony anatomy.

Correct Answer & Explanation

. A fixed, often irreducible hip dislocation with severe acetabular and femoral head dysplasia present at birth.

Explanation

Teratologic dislocation refers to a severe form of hip dislocation that is fixed, often irreducible, and associated with profound acetabular and femoral head dysplasia present at birth. It is commonly seen in patients with neuromuscular disorders (e.g., myelomeningocele) or generalized arthrogryposis. These hips are much more difficult to treat than typical developmental dislocations. The other options describe milder forms of DDH, traumatic dislocation, or isolated findings.

Question 5848

Topic: 4. Pediatrics

What is the most effective method for evaluating the success of closed reduction of the hip in a child over 6 months of age, while still under anesthesia?

. Repeat clinical Ortolani and Barlow tests
. Fluoroscopic imaging with or without arthrography
. Plain AP pelvis and frog-leg lateral radiographs
. Post-reduction hip ultrasound
. Visual inspection of limb length equality

Correct Answer & Explanation

. Fluoroscopic imaging with or without arthrography

Explanation

After closed reduction of the hip in a child over 6 months of age, fluoroscopic imaging, often combined with arthrography (injection of contrast into the joint), is the most effective method to confirm concentric reduction and assess for any interposed soft tissues (like the labrum or psoas tendon) before applying a spica cast. Clinical tests are less reliable under anesthesia and for confirming concentricity. Plain radiographs provide static views, which are less informative than dynamic fluoroscopy under anesthesia. Ultrasound is less effective at this age, and limb length is an indirect measure.

Question 5849

Topic: Pediatric Hip

What is the MOST common cause of a 'click' heard or felt in the hip of a newborn that is NOT indicative of DDH?

. Snapping of the iliopsoas tendon over the femoral head.
. Articular cartilage degeneration.
. Transient subluxation of the patella.
. Ligamentum teres rupture.
. Meniscal tear of the hip.

Correct Answer & Explanation

. Snapping of the iliopsoas tendon over the femoral head.

Explanation

A benign 'click' in a newborn's hip, in the absence of a positive Ortolani or Barlow sign, is most commonly due to the snapping of the iliopsoas tendon over the femoral head or the bony prominence. This is a common, normal variant and usually resolves spontaneously. Articular cartilage degeneration, patellar subluxation, ligamentum teres rupture, and meniscal tears are either extremely rare in newborns or not relevant to this benign clicking phenomenon.

Question 5850

Topic: 4. Pediatrics

When advising parents on preventing DDH recurrence after successful treatment with a Pavlik harness, what is a key recommendation regarding infant care?

. Swaddling the infant tightly with legs extended and adducted.
. Using a front-facing baby carrier that keeps the hips extended.
. Encouraging free hip motion in a flexed and abducted position (e.g., 'M' position).
. Limiting the infant's time out of the car seat to prevent hip movement.
. Avoiding any further hip abductor strengthening exercises.

Correct Answer & Explanation

. Encouraging free hip motion in a flexed and abducted position (e.g., 'M' position).

Explanation

To prevent DDH recurrence, parents should be advised to avoid practices that force the hips into extension and adduction. Instead, they should encourage positions that promote hip flexion and abduction, often referred to as the 'M' position or 'frog-leg' position. This includes using baby carriers or slings that support the hips in this natural position, and avoiding tight swaddling that restricts hip movement and promotes adduction/extension. Limiting time out of a car seat or avoiding abductor exercises are not appropriate or accurate recommendations.

Question 5851

Topic: Pediatric Hip
A 14-year-old female presents with chronic, insidious onset right hip pain, worse with activity. She has a subtle limp and limited internal rotation and abduction of the right hip. Radiographs are subtly abnormal, showing mild flattening of the superior acetabular rim and a slightly increased acetabular index. There is no evidence of avascular necrosis or slipped epiphysis. What is the most likely diagnosis?
. Legg-Calvรฉ-Perthes disease
. Slipped capital femoral epiphysis (SCFE)
. Adolescent idiopathic scoliosis
. Developmental dysplasia of the hip (late presentation)
. Transient synovitis

Correct Answer & Explanation

. Developmental dysplasia of the hip (late presentation)

Explanation

This clinical picture, especially with the radiographic findings of mild acetabular dysplasia (flattening of the superior acetabular rim, increased acetabular index) in an adolescent, is highly suggestive of a late presentation of developmental dysplasia of the hip. Symptoms like chronic pain, limp, and limited motion are common as the dysplastic hip begins to fail. Perthes and SCFE are ruled out by the lack of characteristic radiographic findings. Adolescent idiopathic scoliosis is a spinal condition. Transient synovitis is acute and self-limiting, not chronic. The subtle radiographic findings are key to identifying this late-presenting DDH.

Question 5852

Topic: Pediatric Hip

A 13-year-old boy presents with severe groin pain and inability to bear weight. Radiographs demonstrate a severe slipped capital femoral epiphysis (SCFE) with a slip angle of 60 degrees. The surgeon performs an open surgical dislocation and a subcapital realignment (modified Dunn procedure). What is the primary blood supply at critical risk during the subcapital osteotomy, requiring the careful creation of a retinacular flap?

. Medial femoral circumflex artery
. Lateral femoral circumflex artery
. Obturator artery
. Inferior gluteal artery
. First perforating artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The deep branch of the medial femoral circumflex artery (MFCA) provides the primary blood supply to the femoral head. It is at significant risk during a Dunn osteotomy and must be meticulously protected by developing a retinacular flap.

Question 5853

Topic: Pediatric Hip
A 7-year-old boy with Legg-Calvรฉ-Perthes disease demonstrates a 'hinge abduction' on dynamic arthrography, causing significant mechanical restriction and pain. Which of the following is the most appropriate surgical management?
. Continued observation with restricted weight-bearing
. Petrie casting in internal rotation and abduction
. Salter innominate osteotomy
. Valgus extension proximal femoral osteotomy
. Varus derotational proximal femoral osteotomy

Correct Answer & Explanation

. Valgus extension proximal femoral osteotomy

Explanation

Hinge abduction occurs when the extruded, deformed lateral femoral head impinges against the lateral acetabular margin. A valgus extension osteotomy repositions the deformed segment away from the margin, relieving the hinge effect and improving joint congruency.

Question 5854

Topic: Pediatric Hip

Which of the following pelvic osteotomies used for developmental dysplasia of the hip (DDH) is an incomplete, volume-reducing osteotomy that hinges on the triradiate cartilage?

. Salter osteotomy
. Pemberton osteotomy
. Chiari osteotomy
. Steel triple osteotomy
. Ganz periacetabular osteotomy

Correct Answer & Explanation

. Pemberton osteotomy

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the flexible triradiate cartilage. It changes the volume and shape of the acetabulum, making it ideal for a dysplastic, capacious acetabulum.

Question 5855

Topic: Pediatric Hip

A 12-year-old boy undergoes in situ pinning with a single screw for a stable slipped capital femoral epiphysis (SCFE). Two years later, he presents with limited hip internal rotation and a positive impingement test. The screw is radiographically extra-articular. What is the most likely cause of his symptoms?

. Avascular necrosis of the femoral head
. Chondrolysis from unrecognized joint penetration
. Anterior metaphyseal prominence leading to cam impingement
. Heterotopic ossification of the abductors
. Femoral neck nonunion

Correct Answer & Explanation

. Anterior metaphyseal prominence leading to cam impingement

Explanation

In situ pinning leaves the residual slippage uncorrected. The resulting anterior metaphyseal prominence frequently abuts the acetabular rim during flexion and internal rotation, causing secondary cam-type femoroacetabular impingement.

Question 5856

Topic: 4. Pediatrics

According to Ilizarov's principles of distraction osteogenesis, what is the optimal rate of distraction to balance robust bone regeneration with soft tissue accommodation in a healthy adult tibia?

. 0.25 mm/day
. 0.5 mm/day
. 1.0 mm/day
. 1.5 mm/day
. 2.0 mm/day

Correct Answer & Explanation

. 1.0 mm/day

Explanation

The Ilizarov principle dictates an optimal distraction rate of 1.0 mm per day, classically divided into four equal increments of 0.25 mm, to optimize osteogenesis while preventing premature consolidation or soft tissue injury.

Question 5857

Topic: 4. Pediatrics

A 45-year-old man with an Ilizarov frame for a tibial non-union presents with localized pain, erythema, and soft tissue tenting at a tensioned wire site. There is no purulent drainage. What is the most appropriate initial step in management?

. Admit for intravenous antibiotics
. Remove the tensioned wire immediately
. Release the wire site under local anesthesia
. Prescribe oral antibiotics and observe
. Add a half-pin to offload the wire

Correct Answer & Explanation

. Release the wire site under local anesthesia

Explanation

Tenting of the skin by a wire causes focal ischemia, pain, and erythema, mimicking infection. Relieving the skin tension by extending the incision locally with a scalpel is the most appropriate initial step and resolves most cases.

Question 5858

Topic: Pediatric Lower Extremity

A 1-year-old is diagnosed with Aitken Class A proximal focal femoral deficiency (PFFD). The femoral head is present in the acetabulum, but a severe subtrochanteric varus pseudarthrosis is identified. What is the most important early surgical intervention to optimize the extremity for future lengthening?

. Syme amputation of the foot
. Knee arthrodesis
. Valgus osteotomy to heal the pseudarthrosis
. Immediate Ilizarov lengthening of the femur
. Van Nes rotationplasty

Correct Answer & Explanation

. Valgus osteotomy to heal the pseudarthrosis

Explanation

In Aitken Class A PFFD, addressing the proximal varus deformity and healing the pseudarthrosis with a valgus osteotomy is critical early in life. This establishes a biomechanically sound proximal femur capable of withstanding future lengthening.

Question 5859

Topic: Pediatric Hip

During an open reduction and subcapital realignment (modified Dunn procedure) for a severe slipped capital femoral epiphysis (SCFE), how is the surgical approach optimized to protect the medial femoral circumflex artery (MFCA)?

. By utilizing a direct anterior (Smith-Petersen) approach
. By dissecting the periosteum off the anterior neck exclusively
. By performing a trochanteric flip osteotomy
. By temporarily ligating the lateral epiphyseal artery
. By dividing the ligamentum teres prior to dislocation

Correct Answer & Explanation

. By performing a trochanteric flip osteotomy

Explanation

The modified Dunn procedure utilizes a surgical hip dislocation via a trochanteric flip osteotomy. This extensile approach allows direct visualization and protection of the retinacular vessels, which are meticulously peeled back to preserve the MFCA.

Question 5860

Topic: 4. Pediatrics

A 4-year-old child presents with a waddling gait and a painless limp. Radiographs reveal a decreased neck-shaft angle and a vertically oriented proximal femoral physis. Measurement of the Hilgenreiner epiphyseal angle (HEA) is 65 degrees. What is the most appropriate management?

. Observation with serial radiographs
. Spica casting
. Proximal femoral valgus osteotomy
. In situ pinning
. Pavlik harness application

Correct Answer & Explanation

. Proximal femoral valgus osteotomy

Explanation

Developmental coxa vara with a Hilgenreiner epiphyseal angle greater than 60 degrees has a high risk of progression and pseudarthrosis. Proximal femoral valgus osteotomy is the standard treatment to alter the shear forces across the physis.

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