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 3261
Topic: 4. Pediatrics
A 12-year-old male sustains a Salter-Harris Type II fracture of the distal femur. The fracture cleavage plane primarily propagates through which specific histologic zone of the physis?
Correct Answer & Explanation
. Zone of hypertrophy
Explanation
Salter-Harris fractures typically occur through the zone of hypertrophy of the physis. This zone is mechanically the weakest layer because the chondrocytes are significantly enlarged (hypertrophic), resulting in a relatively low ratio of extracellular matrix to cell volume. Furthermore, the zone lacks the structural reinforcement of calcification, which begins in the adjacent zone of provisional calcification.
Question 3262
Topic: 4. Pediatrics
A 6-year-old boy presents with multiple recurrent fractures with minimal trauma, blue sclerae, and early-onset hearing loss. A genetic defect involving which of the following is most likely responsible for his condition?
Correct Answer & Explanation
. Type I collagen
Explanation
The clinical presentation is classic for Osteogenesis Imperfecta (OI), which is most commonly caused by autosomal dominant mutations in the genes (COL1A1 or COL1A2) encoding Type I collagen. Type I collagen is the primary structural collagen in bone, skin, tendons, and the sclera. FGFR3 mutations are associated with achondroplasia. Fibrillin-1 mutations are the cause of Marfan syndrome.
Question 3263
Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy falls from the monkey bars and sustains a widely displaced Gartland type III supracondylar humerus fracture. On evaluation in the emergency department, his hand is warm and well-perfused (pink), but he has an absent radial pulse. What is the most appropriate initial management?
Correct Answer & Explanation
. Emergent closed reduction and percutaneous pinning
Explanation
In a pediatric patient with a displaced supracondylar humerus fracture and a 'pink, pulseless' hand, collateral circulation is maintaining limb viability. The initial management is emergent closed reduction and percutaneous pinning. The brachial artery is frequently tethered, kinked, or entrapped over the fracture fragments, and anatomical reduction usually restores the pulse. Angiography delays treatment, and open vascular exploration is reserved for a 'white, pulseless' hand that does not improve after reduction.
Question 3264
Topic: 4. Pediatrics
A 6-year-old boy falls from monkey bars and sustains a widely displaced posterolateral extension-type supracondylar humerus fracture. On examination, the hand is pink and warm, but the radial pulse is absent by palpation and Doppler. After closed reduction and percutaneous pinning, the hand remains pink and warm, but the radial pulse is still absent. What is the most appropriate next step in management?
Correct Answer & Explanation
. Observation and admission for neurovascular checks
Explanation
A 'pink, pulseless' hand after reduction and pinning of a pediatric supracondylar humerus fracture indicates that collateral circulation is adequate to perfuse the hand, despite possible spasm, kinking, or intimal injury to the brachial artery. The standard of care for a well-perfused (pink and warm) hand is observation, as the pulse typically returns within several days. Exploration is indicated for a 'white, pulseless' (ischemic) hand.
Question 3265
Topic: 4. Pediatrics
A 6-year-old boy falls from a playground structure and sustains a widely displaced, posteromedial type III supracondylar humerus fracture. On initial presentation, his hand is pink and warm, but the radial pulse is absent. Capillary refill is 2 seconds. After prompt closed reduction and percutaneous pinning in the operating room, the hand remains pink and warm with brisk capillary refill, but the radial pulse remains non-palpable. What is the next best step in management?
Correct Answer & Explanation
. Observation and hospital admission with serial neurovascular checks
Explanation
The 'pulseless, pink hand' is a well-recognized presentation in pediatric supracondylar humerus fractures. It indicates that while the radial pulse is not palpable (often due to brachial artery spasm, kinking, or minor intimal injury), there is adequate collateral circulation to perfuse the hand. If the hand remains well-perfused (pink, warm, brisk capillary refill) after adequate anatomic reduction and pinning, surgical exploration is not indicated. The patient should be observed closely with serial neurovascular checks. Exploration is indicated for a 'pulseless, white (ischemic) hand' that does not improve with reduction.
Question 3266
Topic: 4. Pediatrics
A 6-year-old boy falls from the monkey bars and presents with a widely displaced extension-type supracondylar humerus fracture. On examination, the hand is pink but the radial pulse is absent. Capillary refill is brisk. The child is unable to make an 'OK' sign. What is the most appropriate initial management step?
Correct Answer & Explanation
. Urgent closed reduction and percutaneous pinning
Explanation
In a 'pink, pulseless' hand associated with a pediatric supracondylar humerus fracture, the initial step is urgent closed reduction and percutaneous pinning (CRPP). Often, the brachial artery is kinked or in spasm over the proximal fracture fragment, and anatomical reduction will restore the pulse. Immediate vascular imaging or exploration delays necessary fracture reduction and is not the first step. The inability to make an 'OK' sign indicates an anterior interosseous nerve (AIN) palsy, the most common nerve injury in extension-type fractures.
Question 3267
Topic: Pediatric Upper Extremity & Spine
A 14-year-old female presents with Adolescent Idiopathic Scoliosis. Radiographs demonstrate a main thoracic curve of 55 degrees and a lumbar curve of 35 degrees. On dynamic side-bending films, the lumbar curve corrects to 15 degrees. The proximal thoracic curve measures 20 degrees and corrects to 10 degrees on side bending.
According to the Lenke classification system, what is the curve type?
Correct Answer & Explanation
. Type 1 (Main Thoracic)
Explanation
In the Lenke classification, a curve is considered 'structural' if it fails to correct to <25 degrees on side-bending films. Here, the main thoracic curve is 55 degrees (major curve). The proximal thoracic corrects to 10 degrees (<25, so non-structural) and the lumbar curve corrects to 15 degrees (<25, so non-structural). Because only the Main Thoracic curve is structural, this is a Lenke Type 1 curve.
Question 3268
Topic: Pediatric Upper Extremity & Spine
A 13-year-old premenarchal female presents with a right thoracic curve. She has not had her first menstrual period and is Risser stage 0. Standing PA radiograph shows a Cobb angle of 35 degrees. According to the Bracing in Adolescent Idiopathic Scoliosis Trial (BRAIST), what is the most appropriate management for this patient?
Correct Answer & Explanation
. Thoracolumbosacral orthosis (TLSO) bracing for 18-23 hours per day
Explanation
The patient is a skeletally immature female (Risser 0, premenarchal) with an Adolescent Idiopathic Scoliosis (AIS) curve in the bracing threshold range (25 to 45 degrees). The BRAIST study conclusively demonstrated that high-hour TLSO bracing (18-23 hours/day) significantly decreases the progression of high-risk curves to the surgical threshold (>50 degrees) compared to observation.
Question 3269
Topic: Pediatric Upper Extremity & Spine
A 12-year-old premenarchal girl presents with an asymmetric Adam's forward bending test. Standing scoliosis radiographs reveal a right thoracic curve measuring 32 degrees with an apex at T8. Her Risser stage is 0, and the tri-radiate cartilages are open. What is the most appropriate management for this patient?
Correct Answer & Explanation
. Thoracolumbosacral orthosis (TLSO) bracing
Explanation
The patient has Adolescent Idiopathic Scoliosis (AIS). Indications for bracing in AIS include an actively growing child (Risser 0-2, premenarchal or <1 year postmenarchal) with a curve between 25 and 40 degrees. Bracing (such as a TLSO for > 18 hours per day) has been shown in the BRAIST trial to significantly decrease the rate of curve progression to the surgical threshold (≥ 50 degrees). Observation alone is appropriate for curves < 25 degrees, while surgery is generally reserved for curves > 45-50 degrees.
Question 3270
Topic: Pediatric Upper Extremity & Spine
In the evaluation of Adolescent Idiopathic Scoliosis (AIS) using the Lenke classification system, a proximal thoracic curve is considered "structural" and must be included in the fusion construct if the Cobb angle on the side-bending radiograph is at least:
Correct Answer & Explanation
. 25 degrees
Explanation
In the Lenke classification system for AIS, a minor curve is considered structural if it does not bend out to less than 25 degrees on side-bending radiographs, or if there is local kyphosis of +20 degrees or more across that region. Identifying structural minor curves is critical for determining the proper levels for spinal fusion.
Question 3271
Topic: Pediatric Upper Extremity & Spine
A 12-year-old girl is evaluated for a spinal deformity. Radiographs demonstrate a right thoracic curve of 25 degrees. She has not yet reached menarche. Her Risser stage is 0, and her Sanders bone age stage is 2. Which of the following factors is most predictive of curve progression in this patient?
Correct Answer & Explanation
. Curve magnitude and remaining skeletal growth
Explanation
The risk of curve progression in adolescent idiopathic scoliosis is primarily determined by two main factors: the magnitude of the curve at presentation and the amount of remaining skeletal growth. Remaining growth is assessed using indicators such as Risser stage, menarcheal status, and Sanders bone age. A 25-degree curve in a pre-menarcheal girl with a Risser stage of 0 has a high risk of progression, and bracing is typically indicated.
Question 3272
Topic: Pediatric Upper Extremity & Spine
An 11-year-old girl is evaluated for scoliosis. She is premenarchal. Radiographs demonstrate a right thoracic curve with a Cobb angle of 32 degrees. Her Risser stage is 0. What is the most appropriate recommendation?
This patient has adolescent idiopathic scoliosis (AIS) with a high risk of curve progression due to her significant skeletal immaturity (premenarchal, Risser 0) and curve magnitude (32 degrees). The BrAIST (Bracing in Adolescent Idiopathic Scoliosis Trial) study definitively showed that full-time bracing (at least 16-18 hours per day) significantly decreases the progression of high-risk curves to the surgical threshold (curves between 25 and 45 degrees in skeletally immature patients).
Question 3273
Topic: 4. Pediatrics
A 28-year-old skier presents with a snapping sensation behind the lateral malleolus after a twisting fall. Examination reveals anterior subluxation of the peroneal tendons with resisted eversion. What is the most common anatomic injury causing this pathology?
Correct Answer & Explanation
. Avulsion or rupture of the superior peroneal retinaculum
Explanation
Acute peroneal tendon dislocation is primarily caused by disruption or periosteal stripping of the superior peroneal retinaculum (SPR) from its attachment on the distal fibula.
Question 3274
Topic: 4. Pediatrics
A 6-year-old boy is brought to the emergency department after falling from monkey bars. He has a widely displaced, extension-type supracondylar humerus fracture. His hand is pink and warm, but the radial pulse is absent to palpation. He undergoes closed reduction and percutaneous pinning. Post-operatively, the hand remains pink, warm, and well-perfused with brisk capillary refill, but the radial pulse remains non-palpable and is faintly audible on Doppler. What is the most appropriate next step in management?
Correct Answer & Explanation
. Observation and hospital admission for serial neurovascular checks
Explanation
In a pediatric patient with a supracondylar humerus fracture presenting with a "pulseless, pink" hand, the most appropriate management after successful closed reduction and pinning—provided the hand remains well-perfused (warm, pink, brisk capillary refill)—is admission for close observation and serial neurovascular checks. Routine vascular exploration is not indicated if distal perfusion is clinically adequate.
Question 3275
Topic: 4. Pediatrics
A 13-year-old elite baseball pitcher presents with a 4-week history of gradual-onset shoulder pain during the cocking and early acceleration phases of pitching. Radiographs (Figure 5) reveal widening and irregularity of the proximal humeral physis. What is the most appropriate initial management for this patient?
Correct Answer & Explanation
. Complete cessation of throwing for 3 months followed by a gradual return-to-throwing program
Explanation
The patient has 'Little League Shoulder' (proximal humeral epiphysiolysis), a stress injury to the proximal humeral physis caused by repetitive rotational torque during throwing. The standard treatment is complete cessation of throwing (rest), usually for 3 months or until symptoms resolve and radiographic healing is evident. This is followed by a structured physical therapy and progressive return-to-throwing program. Surgery is not indicated.
Question 3276
Topic: 4. Pediatrics
A 6-year-old boy falls off monkey bars and sustains a significantly displaced extension-type supracondylar humerus fracture. On presentation, the hand is pink and warm, but the radial pulse is nonpalpable. The neurologic examination shows an anterior interosseous nerve palsy. Following closed reduction and percutaneous pinning, the hand remains pink and warm, with a capillary refill of less than 2 seconds, but the radial pulse remains nonpalpable. What is the most appropriate next step in management?
Correct Answer & Explanation
. Admission for observation with the arm elevated
Explanation
The management of the 'pulseless, pink hand' in pediatric supracondylar humerus fractures after acceptable closed reduction and pinning is observation. If the hand remains well-perfused (pink, warm, brisk capillary refill) despite an absent palpable radial pulse, collateral circulation is adequate. Routine vascular exploration or advanced imaging in a well-perfused extremity is not indicated. Exploration is required if the hand becomes cold, pale, and poorly perfused (a pulseless, white hand) after reduction, which implies an arterial injury without sufficient collateral flow.
Question 3277
Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents to the emergency department after falling off monkey bars. Radiographs reveal a Gartland Type III extension supracondylar humerus fracture with posteromedial displacement of the distal fragment. Which of the following neurologic deficits is most likely to be observed on physical examination?
Correct Answer & Explanation
. Inability to extend the metacarpophalangeal joints of the fingers
Explanation
In an extension-type supracondylar fracture of the humerus, the distal fragment is displaced posteriorly. If the distal fragment is displaced posteromedially, the proximal fragment acts as a lateral spike, which puts the radial nerve at the highest risk of injury. A radial nerve palsy presents with the inability to extend the wrist and metacarpophalangeal joints. Posterolateral displacement of the distal fragment puts the median nerve (particularly the anterior interosseous nerve) and brachial artery at risk due to the medial spike of the proximal fragment.
Question 3278
Topic: 4. Pediatrics
A 6-year-old boy sustains a lateral condyle fracture of the humerus. Radiographs show a Milch Type II fracture pattern with 4 mm of displacement. The family refuses surgery and the patient is treated in a cast. Six months later, the patient returns and radiographs demonstrate an established nonunion of the lateral condyle. If left untreated, this child is at highest risk for developing which of the following long-term complications?
Correct Answer & Explanation
. Cubitus valgus and tardy ulnar nerve palsy
Explanation
Nonunion is a known complication of displaced, nonoperatively treated pediatric lateral condyle fractures. Because the lateral column fails to grow normally while the medial column continues to grow, the patient progressively develops a cubitus valgus deformity. Over time, this valgus angulation stretches the ulnar nerve behind the medial epicondyle, classically leading to a tardy ulnar nerve palsy years or even decades later. Cubitus varus is the classic complication of supracondylar humerus malunions.
Question 3279
Topic: 4. Pediatrics
A 5-year-old child with a history of multiple low-energy fractures, blue sclerae, and hearing loss is diagnosed with Osteogenesis Imperfecta. Which of the following molecular defects is most commonly responsible for this condition?
Correct Answer & Explanation
. Substitution of the amino acid glycine by bulkier amino acids in the collagen triple helix
Explanation
Osteogenesis imperfecta (OI) is primarily caused by autosomal dominant mutations in the COL1A1 or COL1A2 genes, which encode type I collagen. The most common pathophysiologic mutation results in the substitution of the critical amino acid glycine (the smallest amino acid) with a bulkier amino acid within the collagen triple helix. Because glycine normally occupies the crowded center of the triple helix, this substitution disrupts the tight helical structure, leading to fragile, poorly formed bone.
Question 3280
Topic: 4. Pediatrics
A 9-year-old boy presents with anterolateral bowing of his left tibia. Physical examination reveals six large cafe-au-lait macules and axillary freckling. The primary underlying genetic defect in this patient results in an abnormality of which of the following cellular signaling pathways?
Correct Answer & Explanation
. Downregulation of Ras GTPase activating protein (neurofibromin)
Explanation
The clinical presentation of anterolateral tibial bowing (often progressing to congenital pseudarthrosis of the tibia), cafe-au-lait spots, and axillary freckling is diagnostic of Neurofibromatosis type 1 (NF1). NF1 is caused by a mutation in the NF1 gene, which encodes neurofibromin. Neurofibromin is a Ras-GTPase activating protein (Ras-GAP) that normally downregulates Ras signaling. Loss-of-function mutations in NF1 lead to hyperactive Ras signaling, resulting in abnormal cellular proliferation.
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