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4. Pediatrics MCQs

Practice Set 56 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 1101

Topic: Pediatric Lower Extremity

Which radiographic index for evaluating patella alta is calculated by dividing the distance from the lower articular margin of the patella to the upper tibial articular margin by the articular length of the patella?

. Insall-Salvati index
. Modified Insall-Salvati index
. Caton-Deschamps index
. Blackburne-Peel index
. Blumensaat index

Correct Answer & Explanation

. Caton-Deschamps index

Explanation

The Caton-Deschamps index relies entirely on articular margins to measure patellar height. This makes it particularly useful because it is not affected by alterations to the tibial tubercle, such as previous osteotomies or Osgood-Schlatter disease.

Question 1102

Topic: Pediatric Lower Extremity

Which of the following measurements is the most reliable method for assessing patella alta in a patient who has previously undergone an Osgood-Schlatter procedure?

. Insall-Salvati ratio
. Modified Insall-Salvati ratio
. Caton-Deschamps index
. Blumensaat line method
. Trochlear depth measurement

Correct Answer & Explanation

. Caton-Deschamps index

Explanation

The Caton-Deschamps index relies on the articular surface of the patella and the anterior-superior angle of the tibial plateau, making it independent of the tibial tubercle position. This makes it ideal for patients with prior tubercle surgery or pathology like Osgood-Schlatter disease.

Question 1103

Topic: 4. Pediatrics

A 14-year-old obese male presents with a 3-month history of a painful limp and hip pain that radiates to his knee. He has limited internal rotation and abduction of the hip, and external rotation upon hip flexion (Drehmann sign). Radiographs of the hip show widening of the physis and posterior and inferior displacement of the epiphysis relative to the metaphysis. What is the most appropriate initial management?

. Open reduction and internal fixation
. Percutaneous pinning in situ
. Observation with activity restriction
. Application of a hip spica cast
. Traction and closed reduction

Correct Answer & Explanation

. Percutaneous pinning in situ

Explanation

Correct Answer: BThis clinical presentation is classic for Slipped Capital Femoral Epiphysis (SCFE), characterized by the Drehmann sign and radiographic findings. For stable SCFE, percutaneous pinning in situ with a single screw is the standard of care to prevent further slip and promote physeal closure. This approach minimizes complications and allows for early weight-bearing. Open reduction is reserved for unstable or severely displaced slips. Observation or casting is insufficient and risks progression. Traction and closed reduction are contraindicated due to the risk of avascular necrosis (AVN) as the slip is typically chronic and involves remodeling.

Question 1104

Topic: 4. Pediatrics

A 72-year-old man presents with progressive bowing of his right femur and deep, aching bone pain. Radiographs reveal cortical thickening and increased trabecular markings. Which of the following gene mutations is most strongly associated with this condition?

. COL1A1
. FGFR3
. SQSTM1
. COMP
. CBFA1

Correct Answer & Explanation

. SQSTM1

Explanation

Mutations in the SQSTM1 gene, which encodes the p62 protein, are highly associated with Paget's disease of bone. This mutation leads to increased osteoclastogenesis and the characteristic chaotic bone turnover.

Question 1105

Topic: 4. Pediatrics

A pediatric patient presents with a growth plate injury. Understanding the biology of endochondral ossification, the primary role of Type X collagen is associated with which zone of the physis?

. Resting zone
. Proliferative zone
. Hypertrophic zone
. Calcification zone
. Ossification zone

Correct Answer & Explanation

. Hypertrophic zone

Explanation

Correct Answer: CType X collagen is specifically expressed by chondrocytes in the hypertrophic zone of the growth plate. It plays a crucial role in cartilage maturation, mineralization, and vascular invasion, signaling the transition from cartilage to bone. It is considered a marker of terminal chondrocyte differentiation and hypertrophy. The other zones have different primary collagen types and functions (e.g., Type II in resting and proliferative zones).

Question 1106

Topic: Pediatric Hip

A 13-year-old obese male presents with acute on chronic slipped capital femoral epiphysis (SCFE). He undergoes in situ pinning. Which of the following is the most common complication following this procedure for an unstable SCFE?

. Chondrolysis
. Avascular necrosis (AVN)
. Femoral neck fracture
. Deep space infection
. Premature physeal closure

Correct Answer & Explanation

. Avascular necrosis (AVN)

Explanation

Avascular necrosis is the most devastating and relatively common complication following an unstable SCFE, occurring in up to 47% of cases. Chondrolysis is more commonly associated with unrecognized hardware penetration into the joint.

Question 1107

Topic: Pediatric Hip

A 4-month-old female with developmental dysplasia of the hip (DDH) has been treated with a Pavlik harness for 4 weeks. Ultrasound demonstrates continued posterior dislocation of the femoral head with no reduction. What is the most appropriate next step in management?

. Continue Pavlik harness for an additional 4 weeks
. Switch to a rigid abduction orthosis (e.g., Ilfeld splint)
. Closed reduction and spica casting under general anesthesia
. Open reduction via an anterior approach
. Observation until 6 months of age followed by pelvic osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under general anesthesia

Explanation

Failure to achieve reduction in a Pavlik harness within 3 to 4 weeks is an indication to abandon the harness to prevent Pavlik harness disease (posterior acetabular erosion). The standard next step is closed reduction and spica casting under anesthesia.

Question 1108

Topic: Pediatric Hip

During an oral examination, you are presented with a 12-year-old obese male complaining of chronic left knee pain. Physical exam reveals obligatory external rotation of the left hip during passive hip flexion. Which of the following radiographic findings is MOST characteristic of this condition?

. Anterior displacement of the femoral epiphysis
. Failure of Klein's line to intersect the lateral epiphysis
. A crescent sign in the superior femoral head
. Widening of the sacroiliac joint
. A fragmented, sclerotic capital femoral epiphysis

Correct Answer & Explanation

. Failure of Klein's line to intersect the lateral epiphysis

Explanation

The clinical presentation is classic for a Slipped Capital Femoral Epiphysis (SCFE). On the AP pelvis radiograph, the Trethowan sign is positive when Klein's line (drawn along the superior femoral neck) fails to intersect the lateral portion of the femoral epiphysis.

Question 1109

Topic: Pediatric Hip

An infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, the parents report the infant is no longer actively kicking the affected leg. On examination, the hip is held in excessive hyperflexion. Which nerve is most likely compressed?

. Sciatic nerve
. Obturator nerve
. Femoral nerve
. Superior gluteal nerve
. Lateral femoral cutaneous nerve

Correct Answer & Explanation

. Femoral nerve

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness when the hip is placed in excessive hyperflexion. If this occurs, the harness must be removed or adjusted immediately to allow nerve recovery.

Question 1110

Topic: Pediatric Hip
You are evaluating a 12-year-old obese boy who presents with inability to bear weight on his right leg after a minor fall. Radiographs reveal a severe, displaced slipped capital femoral epiphysis (SCFE). Which of the following factors represents the greatest risk for the development of avascular necrosis (AVN) in this patient?
. The degree of radiographic slip angle
. The duration of symptoms prior to presentation
. The patient's elevated body mass index (BMI)
. The inability to bear weight (instability) at presentation
. The use of a single cannulated screw for fixation

Correct Answer & Explanation

. The inability to bear weight (instability) at presentation

Explanation

The clinical stability of the slip, defined as the ability to bear weight with or without crutches, is the greatest predictor of AVN. Unstable SCFE has an AVN risk of up to 50%, whereas stable SCFE has a nearly zero risk.

Question 1111

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy falls from monkey bars and presents with a Gartland Type III supracondylar humerus fracture. On exam, the hand is pink but the radial pulse is absent. After emergent closed reduction and percutaneous pinning in the operating room, the hand remains pink, capillary refill is brisk, but the radial pulse is still absent on Doppler. What is the most appropriate next step in management?
. Immediate exploration of the brachial artery
. Perform a CT angiogram of the upper extremity
. Remove the pins and open the fracture anteriorly
. Close observation with pulse oximetry and serial exams
. Perform a prophylactic forearm fasciotomy

Correct Answer & Explanation

. Close observation with pulse oximetry and serial exams

Explanation

For a 'pulseless but pink' hand after anatomic reduction and stabilization of a pediatric supracondylar humerus fracture, the standard of care is close clinical observation. The collateral circulation is sufficient for hand viability, and the radial pulse often returns over time.

Question 1112

Topic: Pediatric Hip

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed 6 weeks of Pavlik harness treatment. Ultrasound confirms persistent dislocation of the left hip. What is the MOST appropriate next step in management?

. Transition to a rigid abduction orthosis (e.g., Ilfeld brace)
. Closed reduction and spica casting under general anesthesia with an arthrogram
. Open reduction via an anterior approach and spica casting
. Varus derotational osteotomy (VDRO) of the proximal femur
. Pemberton pelvic osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting under general anesthesia with an arthrogram

Explanation

When a Pavlik harness fails to achieve reduction in an infant with DDH around 6 months of age, the next standard step is an examination under anesthesia, arthrogram, and attempted closed reduction followed by spica cast application.

Question 1113

Topic: 4. Pediatrics

A 6-year-old boy presents with a completely displaced, extension-type supracondylar humerus fracture. The hand is pink, but the radial pulse is absent. After urgent closed reduction and percutaneous pinning, the hand remains pink and warm, but the pulse is still non-palpable. What is the most appropriate next step in management?

. Immediate vascular surgery consult and arterial exploration
. Perform a bedside fasciotomy of the forearm
. Observation with close clinical monitoring and pulse oximetry
. Remove the pins and perform an open reduction
. Perform a brachial artery angiogram

Correct Answer & Explanation

. Observation with close clinical monitoring and pulse oximetry

Explanation

A "pink, pulseless" hand following reduction and pinning of a pediatric supracondylar humerus fracture is well-perfused through collateral circulation. The standard of care is close observation and monitoring, as the pulse often returns within 24-48 hours.

Question 1114

Topic: 4. Pediatrics
A 10-year-old boy falls while snowboarding and complains of severe pain at the ulnar aspect of his thumb MCP joint. Valgus stress testing reveals significant laxity compared to the contralateral side without a definitive endpoint. Radiographs show a widened physis at the ulnar base of the proximal phalanx. What is the most likely diagnosis in this pediatric patient?
. Stener lesion with complete UCL rupture
. Salter-Harris I fracture of the first metacarpal
. Salter-Harris III fracture of the proximal phalanx base
. Isolated tear of the accessory UCL
. Avulsion of the adductor pollicis insertion

Correct Answer & Explanation

. Salter-Harris III fracture of the proximal phalanx base

Explanation

In pediatric patients with open physes, the UCL is stronger than the epiphyseal plate. The pediatric equivalent of a Skier's thumb is typically a Salter-Harris III fracture of the ulnar base of the proximal phalanx.

Question 1115

Topic: 4. Pediatrics

A 10-year-old boy presents with a crush injury to his right long finger tip after it was caught in a door. Clinically, he has a flexed posture of the DIP joint and a laceration through the nail bed with the nail plate avulsed proximally. Radiographs show a widening of the distal phalanx physis. What is the most appropriate definitive management?

. Continuous extension splinting for 6 weeks
. Removal of the nail plate and simple laceration repair
. Irrigation, debridement, nail bed repair, and physeal reduction with or without pinning
. Closed reduction and application of a stack splint
. Amputation of the distal phalanx at the level of the injury

Correct Answer & Explanation

. Irrigation, debridement, nail bed repair, and physeal reduction with or without pinning

Explanation

This presentation describes a Seymour fracture, which is an open Salter-Harris I or II fracture of the distal phalanx associated with a nail bed laceration. Appropriate management mandates surgical irrigation, debridement, anatomic repair of the nail bed to prevent growth arrest, and fracture reduction often requiring K-wire fixation.

Question 1116

Topic: Pediatric Hip
A 6-year-old boy presents with a limp and pain in his right hip. On examination, he has limited abduction and internal rotation of the hip. X-rays show flattening and increased density of the right femoral epiphysis. What is the most likely diagnosis?
. Developmental dysplasia of the hip (DDH)
. Slipped capital femoral epiphysis (SCFE)
. Transient synovitis
. Legg-Calvรฉ-Perthes disease (LCPD)
. Septic arthritis of the hip

Correct Answer & Explanation

. Legg-Calvรฉ-Perthes disease (LCPD)

Explanation

The clinical presentation of a 6-year-old boy with a limp, limited abduction and internal rotation, and radiographic findings of flattening and increased density (sclerosis) of the femoral epiphysis are classic for Legg-Calvรฉ-Perthes disease (LCPD). SCFE typically occurs in older, often obese, adolescents. DDH presents earlier in infancy/toddlerhood. Transient synovitis is a self-limiting inflammatory condition without radiographic changes of epiphyseal collapse. Septic arthritis would present with acute, severe pain, fever, and systemic signs of infection, and often rapid joint destruction, not chronic epiphyseal changes.

Question 1117

Topic: 4. Pediatrics

A 7-year-old child with Hereditary Multiple Exostoses (HME) presents with progressive genu valgum and a noticeable limb length discrepancy. What is the most common mechanism leading to angular deformities in HME?

. Premature physeal closure on the convex side of the deformity
. Overgrowth of the physis adjacent to the osteochondroma
. Mechanical block to joint movement
. Growth retardation due to nutrient artery compression
. Asymmetric physeal growth secondary to local growth plate disturbance

Correct Answer & Explanation

. Asymmetric physeal growth secondary to local growth plate disturbance

Explanation

Correct Answer: EAngular deformities and limb length discrepancies in HME are primarily due to asymmetric growth plate disturbance. Osteochondromas arising from the physis can tether or distort a portion of the growth plate, leading to asymmetric growth arrest or retardation, thereby causing progressive angulation (e.g., genu valgum from lateral tibial physis involvement) and limb length discrepancies. Premature physeal closure on the convex side is incorrect; it's the concave side that's often affected by growth disturbance. Other options are less common or incorrect mechanisms.

Question 1118

Topic: 4. Pediatrics

A 12-year-old boy presents with multiple bony prominences around his knees and wrists. Radiographs reveal numerous sessile and pedunculated lesions pointing away from the joints. A mutation in which of the following genes, leading to impaired heparan sulfate synthesis, is most likely responsible?

. FGFR3
. COL1A1
. EXT1
. COMP
. RUNX2

Correct Answer & Explanation

. EXT1

Explanation

Multiple hereditary exostoses (MHE) is an autosomal dominant disorder caused by mutations in the EXT1 or EXT2 genes. These genes are involved in heparan sulfate synthesis, which affects normal chondrocyte proliferation and maturation.

Question 1119

Topic: Pediatric Lower Extremity

A 4-year-old boy presents with an asymmetric, painless swelling on the medial aspect of his ankle. Radiographs reveal an irregular, lobulated, ossified mass arising from the medial epiphysis of the distal tibia. What is the most likely diagnosis?

. Multiple epiphyseal dysplasia
. Chondroblastoma
. Dysplasia epiphysealis hemimelica (Trevor's disease)
. Osteochondritis dissecans
. Sinding-Larsen-Johansson syndrome

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica (Trevor's disease)

Explanation

Dysplasia epiphysealis hemimelica, or Trevor's disease, is characterized by an asymmetric overgrowth of cartilage (essentially an intra-articular osteochondroma) originating from an epiphysis. It most commonly affects the medial side of the knee or ankle in young children.

Question 1120

Topic: Pediatric Upper Extremity & Spine

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. On presentation, the radial pulse is absent, but the hand is warm and pink with brisk capillary refill. What is the most appropriate initial management?

. Immediate open vascular exploration
. Urgent closed reduction and percutaneous pinning
. CT angiography of the upper extremity
. Observation and casting in 90 degrees of flexion
. Fasciotomy of the forearm

Correct Answer & Explanation

. Urgent closed reduction and percutaneous pinning

Explanation

For a pulseless but well-perfused ('pink') hand associated with a completely displaced supracondylar humerus fracture, the standard of care is urgent closed reduction and percutaneous pinning. Vascular exploration is reserved for limbs that remain under-perfused (pale/white) after reduction.

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