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4. Pediatrics MCQs

Practice Set 158 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 3141

Topic: 4. Pediatrics

A 5-year-old girl sustains a severely displaced, extension-type supracondylar humerus fracture.

On presentation, her hand is pink and warm, but the radial pulse is absent. After urgent closed reduction and percutaneous pinning, her hand remains pink and warm with brisk capillary refill, but the radial pulse is still not palpable. What is the most appropriate next step in management?

. Immediate open exploration of the brachial artery
. Urgent MR angiography of the upper extremity
. Close observation and hospital admission
. Removal of the pins and attempt at open reduction
. Administration of a stellate ganglion block

Correct Answer & Explanation

. Close observation and hospital admission

Explanation

In the setting of a 'pink, pulseless' hand following the reduction and stabilization of a pediatric supracondylar humerus fracture, current AAOS guidelines and pediatric orthopaedic consensus recommend close observation rather than immediate vascular exploration. Excellent collateral circulation around the elbow often maintains adequate perfusion. Open exploration is indicated if the hand becomes pale, cold, or loses perfusion.

Question 3142

Topic: Pediatric Lower Extremity

An infant is undergoing serial casting for a right idiopathic clubfoot using the Ponseti method.

After 5 weeks of casting, the cavus, adductus, and varus deformities have been fully corrected. However, on examination, there is only 5 degrees of passive ankle dorsiflexion. What is the most appropriate next step?

. Continue serial casting for another 4 weeks
. Perform a percutaneous Achilles tendon lengthening
. Perform a complete posteromedial release
. Discontinue casting and apply a foot abduction orthosis
. Perform an anterior tibial tendon transfer

Correct Answer & Explanation

. Perform a percutaneous Achilles tendon lengthening

Explanation

In the Ponseti method, once the cavus, adductus, and varus have been corrected (typically indicated by 60 degrees of foot abduction), the equinus contracture is addressed. If ankle dorsiflexion is less than 15 degrees, a percutaneous Achilles tendon lengthening (TAL) is indicated. Over 80% of idiopathic clubfeet treated with the Ponseti method require a TAL. Casting alone will not adequately correct persistent equinus, and attempting to force dorsiflexion through casting can cause a rocker-bottom deformity.

Question 3143

Topic: 4. Pediatrics

A 2-year-old girl presents with bilateral genu varum. Her parents are concerned about her bowed legs. To distinguish between physiologic bowing and early infantile Blount disease, a standing AP radiograph of the lower extremities is obtained. Which of the following radiographic findings is most predictive of progression to infantile Blount disease?

. Tibiofemoral angle greater than 15 degrees
. Metaphyseal-diaphyseal angle greater than 16 degrees
. Metaphyseal-diaphyseal angle less than 10 degrees
. Medial physeal slope less than 20 degrees
. Lateral distal femoral angle greater than 90 degrees

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle greater than 16 degrees

Explanation

The metaphyseal-diaphyseal angle (MDA), as described by Levine and Drennan, is the most reliable radiographic parameter to differentiate physiologic bowing from infantile Blount disease in a young child. An MDA > 16 degrees is highly predictive of progression to Blount disease, whereas an angle < 10 degrees typically resolves spontaneously (physiologic bowing).

Question 3144

Topic: Pediatric Upper Extremity & Spine

A 14-year-old girl presents with adolescent idiopathic scoliosis (AIS). Upright radiographs demonstrate a right thoracic curve of 55 degrees and a left lumbar curve of 35 degrees. On supine side-bending radiographs, the thoracic curve reduces to 40 degrees, and the lumbar curve reduces to 15 degrees. The T2-T5 kyphosis is +15 degrees. According to the Lenke classification, what type of curve pattern does she have?

. Type 1 (Main Thoracic)
. Type 2 (Double Thoracic)
. Type 3 (Double Major)
. Type 5 (Thoracolumbar/Lumbar)
. Type 6 (Thoracolumbar/Lumbar-Main Thoracic)

Correct Answer & Explanation

. Type 1 (Main Thoracic)

Explanation

The Lenke classification system defines structural curves based on their flexibility. A minor curve is considered non-structural if it bends out to less than 25 degrees on side-bending films and has normal sagittal alignment. In this patient, the lumbar curve reduces to 15 degrees (non-structural), and the T2-T5 kyphosis is normal (not structural). Thus, only the main thoracic curve is structural, classifying this as a Lenke Type 1 (Main Thoracic) curve.

Question 3145

Topic: Pediatric Hip

An 18-month-old boy presents with a painless limp and leg length discrepancy. Examination reveals a positive Galeazzi sign on the right and limited right hip abduction. Pelvic radiographs demonstrate a completely dislocated right hip with a dysplastic acetabulum (acetabular index of 38 degrees).

What is the most recommended treatment plan for this child?

. Pavlik harness application
. Closed reduction and spica casting
. Open reduction and pelvic osteotomy, followed by spica casting
. Proximal femoral derotation osteotomy alone
. Observation until age 4, then single-stage reconstruction

Correct Answer & Explanation

. Open reduction and pelvic osteotomy, followed by spica casting

Explanation

In a walking child older than 18 months with developmental dysplasia of the hip (DDH), closed reduction has a high failure rate and an increased risk of avascular necrosis. Additionally, the remaining potential for acetabular remodeling is significantly diminished. Therefore, the standard of care is open reduction combined with a pelvic osteotomy (e.g., Salter or Pemberton) to correct the acetabular dysplasia, often accompanied by a femoral shortening osteotomy to reduce joint reaction forces and AVN risk.

Question 3146

Topic: 4. Pediatrics

A 6-year-old boy with a history of multiple low-energy fractures, blue sclerae, and dentinogenesis imperfecta is diagnosed with Osteogenesis Imperfecta (OI) Type I.

This condition is primarily caused by a genetic mutation affecting the synthesis or structure of which of the following?

. Type II collagen
. Type I collagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)
. Fibrillin-1

Correct Answer & Explanation

. Type I collagen

Explanation

Osteogenesis Imperfecta is a genetic disorder of connective tissue characterized by fragile bones. It is primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode the alpha chains of Type I collagen. Type I collagen is the major structural protein in bone, sclerae, and dentin. Type II collagen defects cause spondyloepiphyseal dysplasia; FGFR3 mutations cause achondroplasia; COMP mutations cause pseudoachondroplasia; and fibrillin-1 mutations cause Marfan syndrome.

Question 3147

Topic: 4. Pediatrics

A 5-year-old girl with spastic quadriplegic cerebral palsy (GMFCS Level V) is undergoing routine orthopedic hip surveillance. She has bilateral hip flexion and severe adductor contractures. Her Reimers migration percentage on a recent surveillance AP pelvis radiograph is calculated at 48% bilaterally. What is the most appropriate orthopedic management?

. Observation and repeat radiographs in 1 year
. Bilateral adductor and psoas tenotomies
. Bilateral proximal femoral varus derotational osteotomies (VDRO) with pelvic osteotomies
. Intrathecal baclofen pump insertion alone
. Selective dorsal rhizotomy

Correct Answer & Explanation

. Bilateral proximal femoral varus derotational osteotomies (VDRO) with pelvic osteotomies

Explanation

In cerebral palsy hip surveillance, a Reimers migration percentage (MP) greater than 40-50% in a child 4 years or older indicates significant subluxation that is unlikely to respond to soft-tissue release alone. At an MP of 48% in a 5-year-old GMFCS V patient, the standard of care is bony reconstruction consisting of proximal femoral varus derotational osteotomies (VDRO) frequently combined with pelvic osteotomies (e.g., Dega or San Diego) to definitively restore joint containment and prevent painful dislocation.

Question 3148

Topic: Pediatric Hip

A 12-year-old boy presents to the emergency department with severe left hip pain and an inability to bear weight on the affected limb for 2 days. He reports a preceding 2-month history of mild, intermittent groin pain. AP and frog-leg lateral radiographs demonstrate a slipped capital femoral epiphysis (SCFE) with a 60% displacement. Which of the following is the most significant risk factor for the development of avascular necrosis (AVN) in this patient?

. The duration of his prodromal symptoms
. The chronicity of the slip prior to the acute episode
. The instability of the slip (inability to bear weight)
. The degree of epiphyseal displacement
. The use of a single cannulated screw for fixation

Correct Answer & Explanation

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

Explanation

Instability is the most significant risk factor for the development of avascular necrosis (AVN) in SCFE. A stable SCFE is defined clinically as the patient being able to bear weight, with or without crutches. An unstable SCFE means the patient is unable to bear weight. The rate of AVN in stable slips is close to 0%, whereas in unstable slips it ranges from 24% to 47%. While the severity of the slip increases the risk of chondrolysis and subsequent cam-type impingement, instability remains the primary predictor of AVN.

Question 3149

Topic: Pediatric Lower Extremity

A 4-year-old boy with a history of idiopathic right clubfoot successfully treated with the Ponseti method during infancy presents with a relapsed deformity. His parents report that he frequently trips when running. Gait analysis and clinical examination reveal dynamic supination of the foot during the swing phase of gait. Passive range of motion demonstrates that the deformity is flexible and fully correctable. Which of the following is the most appropriate surgical treatment?

. Achilles tendon lengthening alone
. Extensive posteromedial soft tissue release
. Split tibialis posterior tendon transfer
. Tibialis anterior tendon transfer to the lateral cuneiform
. Calcaneal sliding osteotomy

Correct Answer & Explanation

. Tibialis anterior tendon transfer to the lateral cuneiform

Explanation

Dynamic supination during the swing phase of gait in a relapsed Ponseti-treated clubfoot is a classic indication for a full Tibialis Anterior Tendon Transfer (TATT) to the lateral cuneiform. This procedure transfers the deforming supinatory force of the tibialis anterior and converts it into an eversion force, balancing the foot dynamically. An Achilles tendon lengthening may be performed concurrently if there is residual fixed equinus, but TATT is specifically required to address the dynamic supination. Extensive posteromedial releases are historically associated with severe stiffness and recurrence, and are no longer standard for this presentation.

Question 3150

Topic: 4. Pediatrics
A 4-year-old boy presents with progressive left leg bowing. He has a BMI above the 95th percentile. Standing radiographs reveal a metaphyseal-diaphyseal angle of 18 degrees on the left, with prominent medial metaphyseal beaking and focal sclerosis of the proximal tibia consistent with Langenskiöld stage III. He has previously failed conservative management with knee-ankle-foot orthoses (KAFOs). What is the most appropriate surgical intervention to correct the deformity and minimize the risk of recurrence?
. Medial hemiepiphysiodesis (guided growth) with a tension band plate
. Proximal tibial and fibular osteotomy with neutral alignment
. Proximal tibial and fibular osteotomy with overcorrection into valgus
. Lateral proximal tibial and distal femoral epiphysiodesis
. Application of a Taylor Spatial Frame for gradual neutral correction

Correct Answer & Explanation

. Proximal tibial and fibular osteotomy with overcorrection into valgus

Explanation

In infantile Blount's disease presenting at an older age (> 3-4 years) with advanced Langenskiöld staging (stage III or higher), surgical intervention with a proximal tibial and fibular osteotomy is the gold standard. To minimize the high risk of recurrence caused by the persistently abnormal growth forces across the medial physis, the mechanical axis must be overcorrected into 5 to 10 degrees of valgus. Neutral correction has an unacceptably high rate of recurrent varus deformity. Guided medial growth is contraindicated because the medial physis is severely diseased and often incapable of spontaneous recovery in advanced stages.

Question 3151

Topic: 4. Pediatrics

A 6-year-old boy falls from the monkey bars and presents with a severely displaced extension-type supracondylar humerus fracture. On examination in the emergency department, his hand is pink, but the radial pulse is not palpable. He is taken to the operating room, where closed reduction and percutaneous pinning are performed. Postoperatively, the hand remains pink and well-perfused, but the radial pulse remains absent. What is the most appropriate next step in management?

. Urgent exploration of the brachial artery
. Observation and admission for 24-48 hours
. Perform an urgent CT angiogram
. Remove the pins and re-reduce the fracture
. Apply a warm compress and elevate the arm

Correct Answer & Explanation

. Observation and admission for 24-48 hours

Explanation

A 'pink, pulseless' hand following closed reduction and percutaneous pinning of a pediatric supracondylar humerus fracture indicates that collateral circulation is adequate to perfuse the hand. The standard of care is observation and admission, as the radial pulse typically returns within 24 to 48 hours once vasospasm subsides. Vascular exploration is indicated for a 'white, pulseless' hand or if adequate perfusion is lost after reduction.

Question 3152

Topic: Pediatric Hip

A 13-year-old obese male presents to the emergency department after a minor slip. He is unable to bear weight on his right leg, even with crutches. Radiographs reveal a severe slipped capital femoral epiphysis (SCFE). Which of the following interventions during surgical treatment has been shown to potentially decrease the risk of osteonecrosis in this specific clinical scenario?

. Open reduction and internal fixation via surgical dislocation without capsulotomy
. Urgent closed reduction with forceful manipulation to achieve anatomical alignment
. Spica cast application
. Prophylactic pinning of the contralateral hip
. Capsular decompression (capsulotomy) prior to pinning

Correct Answer & Explanation

. Capsular decompression (capsulotomy) prior to pinning

Explanation

The patient has an unstable SCFE, defined by the inability to bear weight. Unstable SCFE has a significantly higher rate of osteonecrosis (up to 50%) compared to stable SCFE. Urgent capsular decompression (capsulotomy) to relieve intracapsular hematoma tamponade, followed by gentle or no reduction prior to pinning, has been shown to lower the risk of avascular necrosis. Forceful closed reduction is strictly contraindicated as it further disrupts the delicate blood supply.

Question 3153

Topic: Pediatric Lower Extremity
A 4-year-old boy who was treated successfully for idiopathic clubfoot during infancy with the Ponseti method presents with a dynamic supination deformity of the foot during the swing phase of gait. On examination, his ankle passive dorsiflexion is 15 degrees past neutral with the knee extended, and the foot is completely flexible. What is the most appropriate management for this patient?
. Achilles tendon lengthening
. Split tibialis anterior tendon transfer (SPLATT)
. Complete tibialis anterior tendon transfer to the lateral cuneiform
. Triple arthrodesis
. Repeated serial casting without surgery

Correct Answer & Explanation

. Complete tibialis anterior tendon transfer to the lateral cuneiform

Explanation

The child presents with a relapsing clubfoot characterized by a dynamic supination deformity. This is common after Ponseti casting and is driven by a strong tibialis anterior muscle overpowering the weak evertors. For a flexible deformity with adequate passive dorsiflexion, a complete tibialis anterior tendon transfer to the lateral cuneiform is the gold standard treatment to balance the foot. A split transfer is not recommended in idiopathic clubfoot relapse.

Question 3154

Topic: Pediatric Hip

An 8-year-old boy is diagnosed with Legg-Calve-Perthes disease. Anteroposterior pelvic radiographs demonstrate sclerosis and fragmentation of the left capital femoral epiphysis. According to the Herring lateral pillar classification, which of the following radiographic findings indicates a Group C classification, which is associated with the poorest prognosis?

. No involvement of the lateral pillar
. Maintenance of >50% of lateral pillar height
. Maintenance of <50% of lateral pillar height
. Presence of a subchondral radiolucent line (crescent sign)
. Metaphyseal cysts

Correct Answer & Explanation

. Maintenance of <50% of lateral pillar height

Explanation

The Herring lateral pillar classification assesses the height of the lateral pillar of the capital femoral epiphysis on the AP radiograph during the fragmentation phase. Group A has no involvement; Group B maintains >50% of the lateral pillar height; Group C maintains <50% of the lateral pillar height. Group C is associated with the poorest clinical and radiographic outcomes, and patients in this group who are >8 years of age typically benefit from surgical containment.

Question 3155

Topic: 4. Pediatrics
A 14-year-old boy twists his ankle while playing basketball. Radiographs demonstrate a Salter-Harris type III fracture of the anterolateral distal tibial epiphysis. What is the primary mechanism and deforming force responsible for this specific fracture pattern?
. Avulsion by the anterior inferior tibiofibular ligament (AITFL) due to external rotation
. Avulsion by the calcaneofibular ligament due to inversion
. Impaction from the talus due to axial loading
. Avulsion by the posterior inferior tibiofibular ligament (PITFL) due to internal rotation
. Avulsion by the deltoid ligament due to eversion

Correct Answer & Explanation

. Avulsion by the anterior inferior tibiofibular ligament (AITFL) due to external rotation

Explanation

A juvenile Tillaux fracture is a Salter-Harris type III fracture of the anterolateral distal tibial epiphysis. It occurs during adolescence (typically 12-14 years of age) when the medial aspect of the distal tibial physis has closed but the lateral aspect remains open. External rotation of the foot causes the anterior inferior tibiofibular ligament (AITFL) to tension and avulse the anterolateral epiphysis.

Question 3156

Topic: 4. Pediatrics

A 6-year-old girl with spastic quadriplegic cerebral palsy, GMFCS level V, undergoes routine hip surveillance. Anteroposterior pelvic radiographs reveal a migration percentage (Reimers' index) of 45% in the right hip. She experiences minimal pain, but hip abduction is limited to 15 degrees bilaterally. What is the most appropriate next step in surgical management?

. Observation and repeat radiographs in 1 year
. Bilateral adductor and psoas tenotomies
. Varus derotational osteotomy (VDRO) of the proximal femur, likely with pelvic osteotomy
. Total hip arthroplasty
. Proximal femoral resection arthroplasty

Correct Answer & Explanation

. Varus derotational osteotomy (VDRO) of the proximal femur, likely with pelvic osteotomy

Explanation

In children with cerebral palsy, a migration percentage > 40% indicates structural hip subluxation with a high risk of progression to dislocation, particularly in non-ambulatory patients (GMFCS IV/V). While soft tissue releases are appropriate for at-risk hips with < 30% migration, once significant structural dysplasia and subluxation (>40%) occur, bony reconstruction is required. This typically consists of a proximal femoral varus derotational osteotomy (VDRO) combined with a pelvic osteotomy (e.g., Dega or San Diego) to restore joint congruity and prevent painful dislocation.

Question 3157

Topic: Pediatric Hip

A 3-year-old girl is diagnosed with a neglected developmental dysplasia of the left hip. Radiographs show a high dislocation of the femoral head. What is the standard surgical management for this patient?

. Closed reduction and spica casting
. Open reduction and spica casting
. Open reduction and femoral shortening osteotomy
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy
. Pelvic osteotomy alone

Correct Answer & Explanation

. Open reduction, femoral shortening osteotomy, and pelvic osteotomy

Explanation

In children older than 2 to 3 years with a neglected developmental dysplasia of the hip, the risk of redislocation and avascular necrosis is high due to soft tissue contractures and secondary acetabular dysplasia. The standard of care typically involves an open reduction, a femoral shortening osteotomy (to relieve soft tissue tension and reduce the risk of AVN), and a pelvic osteotomy (e.g., Dega or Salter) to address acetabular dysplasia and provide stable coverage.

Question 3158

Topic: Pediatric Lower Extremity

A 2-year-old boy who was treated for idiopathic clubfoot with the Ponseti method presents with recurrent equinovarus deformity. What is the most common cause of relapse in this clinical scenario?

. Under-correction of the cavus deformity initially
. Non-compliance with the foot abduction orthosis
. Failure to perform a percutaneous Achilles tenotomy
. Premature cessation of serial casting
. Extensor hallucis longus overactivity

Correct Answer & Explanation

. Non-compliance with the foot abduction orthosis

Explanation

Non-compliance with the foot abduction orthosis (FAO) is widely recognized as the most common cause of relapse in clubfoot treated with the Ponseti method. Bracing protocols typically require 23-hour wear for 3 months, followed by nighttime wear until 4-5 years of age. Without bracing, relapse rates can exceed 80%.

Question 3159

Topic: Pediatric Hip

A 14-year-old boy is evaluated for hip pain and severe stiffness 6 months after undergoing in situ pinning for a stable slipped capital femoral epiphysis (SCFE) of the right hip. On examination, he has globally restricted range of motion of the right hip. Radiographs reveal narrowing of the joint space to less than 3 mm, osteopenia, and no evidence of hardware penetration into the joint. What is the most likely diagnosis?

. Avascular necrosis
. Septic arthritis
. Chondrolysis
. Cam impingement
. Hardware failure

Correct Answer & Explanation

. Chondrolysis

Explanation

Chondrolysis is characterized by acute cartilage necrosis, presenting with severe stiffness, pain, and globally restricted range of motion. Radiographically, it is defined by a joint space of less than 3 mm. Although historically associated with unrecognized hardware penetration, it can occur in unpinned SCFEs or following in situ pinning without joint penetration. AVN typically presents with sclerosis and collapse of the femoral head rather than isolated symmetric joint space narrowing.

Question 3160

Topic: Pediatric Hip
An 8-year-old boy presents with a painless limp of 3 months' duration. Radiographs show fragmentation of the femoral head consistent with Legg-Calvé-Perthes disease. According to the Herring Lateral Pillar classification, which of the following radiographic findings portends the worst prognosis?
. Greater than 50% maintenance of the lateral pillar height
. Less than 50% maintenance of the lateral pillar height
. Central pillar depression
. Subchondral radiolucent line (crescent sign)
. Metaphyseal cysts

Correct Answer & Explanation

. Less than 50% maintenance of the lateral pillar height

Explanation

The Herring Lateral Pillar classification is strongly correlated with prognosis in Legg-Calvé-Perthes disease. Group C (less than 50% lateral pillar height maintained) indicates severe involvement and carries the worst prognosis for femoral head sphericity and future joint congruity. Age at onset (>8 years) and Group C classification are the strongest predictors of a poor outcome.

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