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4. Pediatrics MCQs

Practice Set 232 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 4621

Topic: 4. Pediatrics
A newborn is evaluated in the nursery for severe radial deviation of the right wrist, an absent thumb, and a foreshortened forearm. Radiographs confirm complete absence of the radius (radial longitudinal deficiency / radial clubhand). Before proceeding with any orthopaedic surgical interventions, which set of screening tests is most critical to perform to rule out associated life-threatening syndromic anomalies?
. Complete blood count (CBC), echocardiogram, and renal ultrasound
. MRI of the brain and entire neuraxis
. Sweat chloride test and pulmonary function testing
. Skeletal survey and genetic testing for Neurofibromatosis Type 1
. Ophthalmologic examination for congenital cataracts and glaucoma

Correct Answer & Explanation

. Complete blood count (CBC), echocardiogram, and renal ultrasound

Explanation

Radial longitudinal deficiency (radial clubhand) is frequently associated with systemic, potentially life-threatening syndromes. These include VACTERL association (requires renal ultrasound for anomalies and echocardiogram), Holt-Oram syndrome (cardiac septal defects requiring an echocardiogram), Thrombocytopenia-Absent Radius (TAR) syndrome, and Fanconi anemia (both requiring a CBC to check for severe cytopenias/aplastic anemia). Therefore, a CBC, echocardiogram, and renal ultrasound are mandatory initial screening tests.

Question 4622

Topic: Pediatric Hip

A 13-year-old obese boy presents with acute on chronic left groin pain and an inability to bear weight on the left leg for the past 24 hours. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Which of the following is the most significant prognostic factor for the development of osteonecrosis in this patient?

. The degree of posterior epiphyseal tilt
. The chronicity of his preceding pain
. His body mass index (BMI)
. The inability to bear weight at presentation
. The presence of bilateral involvement

Correct Answer & Explanation

. The degree of posterior epiphyseal tilt

Explanation

The inability to bear weight (with or without crutches) defines an 'unstable' SCFE according to the Loder classification. This is the most critical prognostic factor for avascular necrosis (AVN). Unstable SCFE has a significantly higher rate of AVN, ranging from 24% to 47%, compared to stable SCFE, where the risk is near zero.

Question 4623

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from the monkey bars and sustains a Gartland type III supracondylar humerus fracture. Upon arrival in the emergency department, his hand is pink but the radial pulse is absent. After closed reduction and percutaneous pinning in the operating room, the hand remains pink and well-perfused with brisk capillary refill, but the pulse remains absent via Doppler. What is the most appropriate next step in management?
. Immediate vascular surgery consultation for brachial artery exploration
. Removal of pins and transition to open reduction
. Observation and hospital admission for close neurovascular monitoring
. Perform a CT angiogram of the upper extremity
. Administer intravenous heparin and systemic vasodilators

Correct Answer & Explanation

. Observation and hospital admission for close neurovascular monitoring

Explanation

In the setting of a 'pink, pulseless' hand following the closed reduction and pinning of a supracondylar humerus fracture, the most appropriate management is observation and close monitoring (admission). As long as the hand remains well-perfused (capillary refill < 2 seconds, warm, pink), surgical vascular exploration is not indicated because collateral circulation is adequate. Routine angiogram or empirical exploration in a well-perfused hand is unnecessary and potentially harmful.

Question 4624

Topic: 4. Pediatrics

A 6-week-old female infant is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a routine follow-up visit 2 weeks after initiation, the mother notes the child is no longer kicking her affected leg. On examination, there is an absence of active knee extension. What is the most appropriate next step in management?

. Readjust the anterior strap to increase hip flexion to 120 degrees
. Discontinue the Pavlik harness and switch immediately to a rigid abduction orthosis
. Remove the harness and observe for neurological recovery
. Order an urgent MRI of the lumbar spine to rule out tethered cord
. Perform a closed reduction and spica casting under general anesthesia

Correct Answer & Explanation

. Readjust the anterior strap to increase hip flexion to 120 degrees

Explanation

The infant has developed a femoral nerve palsy, which is a known complication of the Pavlik harness typically caused by excessive hip flexion (anterior straps adjusted too tightly). The correct initial management is to temporarily remove the harness and allow for neurologic recovery, which almost always occurs spontaneously over several days to weeks. Continuing the harness or increasing flexion would exacerbate the nerve compression.

Question 4625

Topic: 4. Pediatrics
A 14-year-old girl sustains a twisting ankle injury. Radiographs show a Salter-Harris III fracture of the anterolateral aspect of the distal tibia. Which anatomic structure's avulsion force is directly responsible for this specific fracture pattern?
. Anterior talofibular ligament
. Posterior inferior tibiofibular ligament
. Calcaneofibular ligament
. Anterior inferior tibiofibular ligament
. Deltoid ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament

Explanation

This patient has a juvenile Tillaux fracture, which is a Salter-Harris III fracture of the anterolateral distal tibial epiphysis. It is caused by an avulsion force from the anterior inferior tibiofibular ligament (AITFL) during external rotation of the foot. It occurs in adolescents because the distal tibial physis closes in a specific pattern: central, then medial, and finally lateral, leaving the anterolateral portion vulnerable to avulsion.

Question 4626

Topic: Pediatric Hip
An 8-year-old boy is diagnosed with Legg-Calvé-Perthes disease. Radiographs reveal approximately 25% collapse of the lateral pillar of the femoral head. According to the Herring lateral pillar classification, what is his classification group, and what is the recommended treatment based on prospective multicenter studies?
. Group A; symptomatic treatment only
. Group B; observation with restricted weight-bearing
. Group B; surgical containment (e.g., femoral or pelvic osteotomy)
. Group C; physical therapy and NSAIDs
. Group C; surgical containment

Correct Answer & Explanation

. Group B; surgical containment (e.g., femoral or pelvic osteotomy)

Explanation

This patient has a Herring Lateral Pillar Group B hip (defined as >50% of lateral pillar height maintained; here, 25% collapse means 75% is maintained). According to the benchmark multicenter prospective study by Herring et al., children aged 8 years or older at the time of disease onset with Group B (or B/C border) hips have significantly better radiographic outcomes when treated with surgical containment compared to nonoperative treatment.

Question 4627

Topic: 4. Pediatrics

During the Ponseti method for the treatment of idiopathic congenital talipes equinovarus, what is the specific pathoanatomic structure primarily targeted by the very first casting manipulation?

. Equinus of the hindfoot
. Varus of the subtalar joint
. Adductus of the forefoot
. Plantarflexion of the first metatarsal
. Subluxation of the talonavicular joint

Correct Answer & Explanation

. Equinus of the hindfoot

Explanation

The Ponseti method corrects the components of clubfoot in a specific sequence: CAVE (Cavus, Adductus, Varus, Equinus). The very first step is to correct the cavus deformity. Cavus is primarily driven by a plantarflexed first ray (first metatarsal). The first manipulation involves elevating the first ray to align the forefoot with the hindfoot, supinating it to match the hindfoot varus.

Question 4628

Topic: 4. Pediatrics
A 3-year-old girl is evaluated for worsening genu varum. Standing long-leg radiographs demonstrate a metaphyseal-diaphyseal angle (Drennan's angle) of 18 degrees. What is the most appropriate initial management for this patient?
. Observation and reassurance
. Knee-ankle-foot orthosis (KAFO) during weight-bearing
. Proximal tibial valgus osteotomy
. Guided growth with lateral tension band plating
. Medial plateau elevation osteotomy

Correct Answer & Explanation

. Knee-ankle-foot orthosis (KAFO) during weight-bearing

Explanation

A metaphyseal-diaphyseal angle (Drennan's angle) greater than 16 degrees strongly predicts progression to infantile Blount disease rather than representing benign physiologic bowing. In a 3-year-old with early infantile Blount disease (typically Langenskiöld stages I-II), a trial of bracing with a KAFO during weight-bearing hours is the initial recommended treatment before considering surgical realignment.

Question 4629

Topic: 4. Pediatrics

A newborn is evaluated in the nursery and diagnosed with isolated fibular hemimelia. Which of the following associated physical findings or structural anomalies is MOST likely to be present in this patient?

. Absent medial rays of the foot
. Anterior cruciate ligament deficiency
. Developmental dysplasia of the hip
. Sprengel deformity
. Radial clubhand

Correct Answer & Explanation

. Absent medial rays of the foot

Explanation

Fibular hemimelia is the most common congenital long bone deficiency. It is highly associated with anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) deficiency, absent lateral rays of the foot, a ball-and-socket ankle joint, tarsal coalition, and anteromedial tibial bowing. Absent medial rays are classically associated with tibial hemimelia.

Question 4630

Topic: 4. Pediatrics

A 2-year-old child presents with a significantly shortened lower extremity. Radiographs reveal a severe congenital anomaly of the femur characterized by a complete lack of osseous connection between the femoral head and the short femoral shaft, although a competent femoral head is present within a normal acetabulum. According to the Aitken classification of Proximal Focal Femoral Deficiency (PFFD), which class does this represent?

. Class A
. Class B
. Class C
. Class D
. Class E

Correct Answer & Explanation

. Class A

Explanation

In the Aitken classification of PFFD: Class A has a short femur with a femoral head and a cartilaginous connection that eventually ossifies. Class B has a femoral head present in the acetabulum but no osseous connection between the head and the short femoral shaft (pseudarthrosis). Class C lacks a femoral head or has a severely dysplastic one, with an absent connection. Class D has neither a femoral head nor an acetabulum, and a severely shortened femur.

Question 4631

Topic: 4. Pediatrics

A 7-year-old non-ambulatory child with spastic quadriplegic cerebral palsy (GMFCS Level V) is undergoing routine radiographic hip surveillance. Measurement of the Reimers Migration Percentage (RMP) is obtained. At what specific RMP threshold is surgical intervention (e.g., adductor/iliopsoas release or varus derotational osteotomy) most widely recommended to prevent progression to complete dislocation?

. 10%
. 20%
. 30-40%
. 70%
. 90%

Correct Answer & Explanation

. 10%

Explanation

In children with cerebral palsy, a Reimers Migration Percentage (RMP) greater than 30% to 40% is highly predictive of continued lateral subluxation and eventual painful dislocation. Orthopedic guidelines universally recommend surgical intervention (which may range from soft tissue release to bony reconstruction, depending on age and femoral head deformity) once the RMP exceeds the 30-40% threshold to maintain a concentric, painless hip.

Question 4632

Topic: 4. Pediatrics

A 1-month-old infant is brought to the clinic for a right-sided neck mass and a persistent head tilt to the right with the chin rotated to the left. The mass is firm, non-tender, and located within the sternocleidomastoid muscle. What associated condition must be actively screened for in this patient?

. Vesicoureteral reflux
. Sprengel deformity
. Developmental dysplasia of the hip
. Congenital scoliosis
. Craniosynostosis

Correct Answer & Explanation

. Vesicoureteral reflux

Explanation

The infant's presentation is classic for congenital muscular torticollis (CMT), which typically presents with a palpable sternocleidomastoid 'tumor' (fibrosis) at 2 to 4 weeks of age. There is a well-established clinical association between CMT and developmental dysplasia of the hip (DDH), occurring in up to 8-20% of cases. Rigorous screening for DDH, usually including an ultrasound of the hips, is the standard of care for these infants.

Question 4633

Topic: 4. Pediatrics
A 12-year-old girl presents with bilateral wrist pain and a noticeable prominence of the distal ulna. Radiographs show increased volar tilt and ulnar inclination of the distal radial articular surface, with premature fusion of the ulnar half of the distal radial physis. If this condition is part of an underlying genetic syndrome, what is the most likely gene mutation?
. COL1A1
. FGFR3
. SHOX
. EXT1
. FBN1

Correct Answer & Explanation

. SHOX

Explanation

The clinical and radiographic presentation is classic for Madelung deformity, characterized by premature closure of the volar-ulnar aspect of the distal radial physis. When presenting bilaterally and associated with mesomelic short stature, it is often part of Léri-Weill dyschondrosteosis. This condition is inherited in a pseudoautosomal dominant manner due to mutations or deletions in the SHOX gene.

Question 4634

Topic: 4. Pediatrics

A 2-year-old boy presents with severe anterolateral bowing of his left tibia that recently sustained a low-energy fracture. Radiographs show a midshaft tibial nonunion with 'hourglass' tapering of the sclerotic bone ends. What systemic condition is overwhelmingly associated with this specific orthopedic pathology?

. Osteogenesis Imperfecta
. Neurofibromatosis type 1
. Achondroplasia
. Ehlers-Danlos Syndrome
. McCune-Albright Syndrome

Correct Answer & Explanation

. Osteogenesis Imperfecta

Explanation

Anterolateral bowing of the tibia and subsequent congenital pseudarthrosis of the tibia (CPT) are highly associated with Neurofibromatosis type 1 (NF1). Over 50% of patients with CPT have an underlying diagnosis of NF1. CPT is notorious for being refractory to standard fracture healing, often requiring complex reconstructive surgery (e.g., Ilizarov bone transport, vascularized free fibular grafts) or occasionally amputation.

Question 4635

Topic: 4. Pediatrics
A 10-year-old girl sustains a valgus injury to her knee. Radiographs reveal a fracture passing completely through the physis of the distal femur without any extension into the metaphysis or epiphysis. According to the Salter-Harris classification, what type of fracture is this, and what is its unique prognostic characteristic at this specific anatomical location?
. Type I; associated with a high rate of physeal growth arrest
. Type I; low risk of growth arrest due to an intact germinal layer
. Type II; characterized by a metaphyseal flag and extremely low risk of deformity
. Type III; completely extra-articular but high risk of nonunion
. Type V; invariably benign outcome despite initial appearance

Correct Answer & Explanation

. Type I; associated with a high rate of physeal growth arrest

Explanation

A fracture entirely through the physis without metaphyseal or epiphyseal extension is a Salter-Harris Type I. While Type I fractures generally have a low risk of growth arrest in most locations, the distal femoral physis is a notable exception. Salter-Harris I and II fractures of the distal femur have a notoriously high rate of growth arrest (up to 40-50%) because the undulating, highly interdigitated nature of this physis sustains significant crushing force to the germinal layer during displacement.

Question 4636

Topic: 4. Pediatrics

A 6-year-old child presents with a short neck, low posterior hairline, and severely limited cervical range of motion. A diagnosis of Klippel-Feil syndrome is clinically suspected and confirmed on radiographs showing multiple fused cervical vertebrae. Which associated systemic anomaly is most critical to evaluate for in the initial screening of this patient?

. Congenital heart defects
. Renal anomalies
. Sensorineural hearing loss
. Intestinal malrotation
. Hypothyroidism

Correct Answer & Explanation

. Congenital heart defects

Explanation

Klippel-Feil syndrome is characterized by congenital fusion of two or more cervical vertebrae. The classic triad (short neck, low hairline, restricted neck motion) is present in fewer than 50% of patients. Renal anomalies (e.g., unilateral kidney, horseshoe kidney, duplication of the collecting system) are highly prevalent (occurring in 30-35% of cases) and can be life-threatening if missed. Therefore, renal ultrasound screening is universally mandated in orthopedic guidelines for these patients.

Question 4637

Topic: 4. Pediatrics

A 2-year-old presents with anteromedial bowing of the tibia and a shortened lower extremity. Radiographs

reveal an absent fibula. Which of the following findings is most commonly associated with this condition?

. Anterolateral tibial bowing
. Polydactyly of the foot
. Anterior cruciate ligament deficiency
. Congenital coxa vara
. Talocalcaneal coalition

Correct Answer & Explanation

. Anterolateral tibial bowing

Explanation

Fibular hemimelia is the most common congenital long bone deficiency. It presents with anteromedial bowing of the tibia, limb shortening, and is frequently associated with an absent or deficient anterior cruciate ligament (ACL) (up to 100% of cases), absent lateral rays of the foot, ball-and-socket ankle joint, and tarsal coalitions (most commonly talocalcaneal). Anterolateral tibial bowing is associated with congenital pseudarthrosis of the tibia.

Question 4638

Topic: 4. Pediatrics

A 6-year-old child with GMFCS level IV spastic quadriplegic cerebral palsy is evaluated during routine hip surveillance. Radiographs demonstrate a Reimers migration index of 45% bilaterally with disruption of Shenton's line, but no advanced degenerative changes or head deformation. What is the most appropriate management?

. Botulinum toxin injections to the adductors
. Adductor and iliopsoas tenotomies alone
. Bilateral varus derotational osteotomies (VDRO) with or without pelvic osteotomies
. Bilateral proximal femoral resection (Castle procedure)
. Observation and repeat radiograph in 6 months

Correct Answer & Explanation

. Botulinum toxin injections to the adductors

Explanation

In children with spastic cerebral palsy, hip subluxation is common and monitored via the Reimers migration index (percentage of the femoral head uncovered by the acetabulum). Soft tissue releases alone are indicated for early disease (migration index 20-30%, generally in children <4 years old). Once the migration index exceeds 30-40%, or in older children (like this 6-year-old), bony reconstruction with a Varus Derotational Osteotomy (VDRO) and frequently a concomitant pelvic osteotomy is indicated to safely center the hip and prevent painful dislocation. Salvage procedures like a Castle procedure are for chronically painful, dislocated hips with severe articular damage.

Question 4639

Topic: 4. Pediatrics
A 4-year-old boy presents with multiple low-energy fractures, blue sclerae, and dentinogenesis imperfecta. He is diagnosed with Osteogenesis Imperfecta (OI) type I. The genetic defect most likely involves a mutation resulting in which of the following abnormalities?
. Defective mineralization of the osteoid matrix
. Quantitative deficiency in the production of normal type I collagen
. Qualitative defect in type II collagen synthesis
. Fibroblast growth factor receptor 3 (FGFR3) gain-of-function
. Defect in Cartilage Oligomeric Matrix Protein (COMP)

Correct Answer & Explanation

. Quantitative deficiency in the production of normal type I collagen

Explanation

Osteogenesis Imperfecta (OI) type I is the mildest and most common form of the disease. According to the Sillence classification, Type I is characterized by a null mutation in the COL1A1 gene, leading to a decreased amount (quantitative defect) of structurally normal type I collagen. This leads to mild to moderate bone fragility, blue sclerae, and hearing loss. In contrast, OI types II, III, and IV typically involve missense mutations causing structurally abnormal (qualitative defect) type I collagen, resulting in more severe phenotypes.

Question 4640

Topic: 4. Pediatrics

An infant presents with unilateral anterolateral bowing of the tibia. A radiograph

demonstrates medullary narrowing and cortical sclerosis at the apex of the bow. This condition has the strongest association with which of the following genetic disorders?

. Neurofibromatosis type 1
. Marfan syndrome
. Osteogenesis imperfecta
. Achondroplasia
. Ehlers-Danlos syndrome

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

Anterolateral bowing of the tibia is characteristic of Congenital Pseudarthrosis of the Tibia (CPT). The tissue at the pseudoarthrosis site is a fibrous hamartoma. Approximately 50% of patients diagnosed with CPT also have Neurofibromatosis type 1 (NF1). Patients with NF1 must be screened clinically for this deformity. In contrast, posteromedial bowing is typically physiological or associated with a calcaneovalgus foot and resolves spontaneously, and anteromedial bowing is seen with fibular hemimelia.

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