4. Pediatrics MCQs

When executing an acute, large-magnitude closing-wedge proximal tibial osteotomy for adolescent Blount's disease, a concurrent fibular osteotomy or proximal tibiofibular joint release is mandated primarily to:

A patient presents with a severe valgus deformity of the lower extremity. Radiographic analysis reveals a mechanical lateral distal femoral angle (mLDFA) of 80 degrees and a medial proximal tibial angle (MPTA) of 95 degrees. What is the most appropriate surgical strategy for correcting the mechanical axis deviation?

Multiple hereditary exostoses (osteochondromatosis) is an autosomal dominant condition characterized by multiple cartilage-capped bony outgrowths. The pathogenesis of this condition is most closely linked to a mutation affecting the synthesis of which of the following?

A 6-month-old infant with diagnosed achondroplasia is evaluated for poor head control and sleep apnea. What is the most common cause of mortality in early childhood for this condition, and which anatomical region requires urgent evaluation?

A 4-year-old child presents with disproportionate short stature, waddling gait, and prominent joint laxity. Radiographs demonstrate delayed ossification of the epiphyses and irregular, flared metaphyses. The child has normal facial features and intelligence. A mutation in which of the following genes is most likely responsible?

A neonate is born with short limbs, severe clubfeet, 'cauliflower' cystic swelling of the ears, and thumbs that are abducted and proximally placed. Radiographs reveal a short, oval first metacarpal. What is the inheritance pattern and affected gene in this dysplasia?

A phenotypically female infant is born with severe bowing of the tibiae with cutaneous dimpling over the convexity, hypoplastic scapulae, and respiratory distress due to tracheobronchomalacia. Genetic karyotyping reveals a 46,XY genotype. Which gene is most likely mutated?

A 12-year-old boy presents with mild short stature, generalized joint pain, and early signs of bilateral hip osteoarthritis. Radiographs of the knees reveal a 'double-layer' appearance of the patellae. Which skeletal dysplasia does he likely have?

Achondroplasia is caused by a gain-of-function mutation in the FGFR3 gene. At the cellular level within the physis, this abnormal signaling primarily results in which of the following alterations?

A newborn presents with short-limbed dwarfism, bilateral rigid clubfeet, "hitchhiker" thumbs, and cystic swelling of the external pinnae. Radiographs show severe kyphoscoliosis. Which gene mutation is responsible for this condition?

A 4-year-old child presents with a waddling gait, disproportionate short stature, and severe genu varum. Clinical examination reveals normal facial features and head circumference. Radiographs show delayed, irregular epiphyseal ossification and platyspondyly. Which of the following proteins is defective?

A 6-year-old girl with a known skeletal dysplasia presents with a waddling gait and neck pain. Radiographs show flattened, irregular vertebral bodies and severe coxa vara. Flexion-extension cervical spine radiographs reveal atlantoaxial instability. What is the underlying genetic defect?

A 5-year-old boy presents with progressive bowing of the lower extremities and a waddling gait. Radiographs show severe coxa vara, as well as flaring and cupping of the metaphyses. The spine and epiphyses are completely radiographically normal. Laboratory values for calcium, phosphorus, and alkaline phosphatase are normal. What is the affected gene?

A 3-year-old boy presents with short stature, a flat midface, cleft palate, and prominently enlarged joints. Radiographs demonstrate "dumbbell-shaped" femora, coronal clefts in the vertebral bodies, and broad metaphyses. Significant sensorineural hearing loss is also noted. What is the most likely diagnosis?

A neonate is born with severe respiratory distress, shortened and anterolaterally bowed tibiae with skin dimpling over the convexity, and bilateral talipes equinovarus. Genetic karyotyping reveals a 46,XY chromosomal pattern, but the infant has unambiguous female external genitalia. A mutation in which gene is responsible?

In patients with achondroplasia, the underlying genetic mutation primarily disrupts endochondral bone growth by inhibiting which specific cellular phase in the physis?

A 3-month-old infant presents with frontal bossing, midface hypoplasia, and rhizomelic shortening of the upper and lower extremities. Genetic testing confirms an autosomal dominant mutation associated with advanced paternal age. The underlying pathophysiological defect in this syndrome primarily affects which specific zone of the physis?

A 5-year-old boy presents with a waddling gait and a markedly short trunk. Radiographs reveal flattened vertebral bodies, severe coxa vara, and an absent ossification center of the femoral head. A thorough ophthalmologic examination notes severe myopia and impending retinal detachment. A mutation in which of the following genes is most likely responsible?

A 4-year-old child presents with a waddling gait and joint laxity. The parents note his limbs appear disproportionately short, though his facial features and intelligence are completely normal. Radiographs reveal small, irregular epiphyses, flared metaphyses, and anterior beaking of the central vertebral bodies. What is the most likely mutated gene in this patient?

A 12-year-old boy with a history of recurrent long bone fractures presents with severely restricted forearm pronation and supination. Radiographs demonstrate a massive hyperplastic callus over a healing radius fracture and extensive calcification of the radioulnar interosseous membrane. Which genetic mutation is diagnostic for this specific variant of osteogenesis imperfecta?