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4. Pediatrics MCQs

Practice Set 8 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 141

Topic: 4. Pediatrics

Which of the following genetic inheritance patterns and underlying mutations most accurately describes Achondroplasia?

. Autosomal recessive; COL2A1 mutation
. Autosomal dominant; FGFR3 mutation
. X-linked recessive; DMD mutation
. Autosomal recessive; FGFR3 mutation
. Autosomal dominant; COMP mutation

Correct Answer & Explanation

. Autosomal dominant; FGFR3 mutation

Explanation

Achondroplasia is inherited in an autosomal dominant pattern, although approximately 80% of cases arise from de novo mutations. It is caused by an activating mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene, leading to inhibited chondrocyte proliferation.

Question 142

Topic: Pediatric Upper Extremity & Spine

An 8-year-old boy presents with an isolated pediatric lateral condyle fracture of the humerus. Radiographs show a Milch Type II fracture with 3 mm of displacement. What is the most appropriate management?

. Long arm cast in supination
. Closed reduction and percutaneous pinning
. Open reduction and internal fixation
. Excision of the fragment
. Observation with serial weekly radiographs

Correct Answer & Explanation

. Open reduction and internal fixation

Explanation

Lateral condyle fractures displaced greater than 2 mm have a high rate of nonunion due to synovial fluid bathing the fracture and the pull of the extensor origin. Therefore, open reduction and internal fixation (ORIF) is indicated.

Question 143

Topic: 4. Pediatrics

A 9-year-old boy presents with an obvious cubitus varus deformity 2 years after conservative management of a supracondylar humerus fracture. What is the primary pathophysiologic cause of this late deformity?

. Premature physeal closure of the medial condyle
. Overgrowth of the lateral condyle
. Osteonecrosis of the trochlea
. Malunion of the original fracture
. Unrecognized intercondylar extension

Correct Answer & Explanation

. Malunion of the original fracture

Explanation

Cubitus varus (gunstock deformity) following a supracondylar fracture is overwhelmingly due to initial malunion (specifically inadequate correction of internal rotation, extension, and varus collapse). Physeal arrest is a rare cause in supracondylar fractures.

Question 144

Topic: Pediatric Upper Extremity & Spine

A 12-year-old baseball pitcher presents with chronic medial elbow pain. Radiographs reveal widening of the medial epicondylar apophysis. The biomechanical mechanism responsible for this condition is primarily:

. Valgus overload
. Varus overload
. Hyperextension stress
. Hyperflexion stress
. Direct posterior impact

Correct Answer & Explanation

. Valgus overload

Explanation

Little League Elbow encompasses medial epicondyle apophysitis caused by repetitive valgus overload during the late cocking and early acceleration phases of throwing. This places massive tensile stress on the medial structures.

Question 145

Topic: Pediatric Upper Extremity & Spine

A newborn is diagnosed with bilateral radial clubhands. Which of the following laboratory investigations is most critical to perform early to rule out a potentially fatal condition associated with this deformity?

. Renal function panel
. Complete blood count and chromosomal breakage studies
. Liver function tests
. Serum calcium and phosphate
. Sweat chloride test

Correct Answer & Explanation

. Complete blood count and chromosomal breakage studies

Explanation

Fanconi anemia is a life-threatening aplastic anemia associated with radial clubhand. A CBC and chromosomal breakage test (diepoxybutane test) are critical early screening tools to detect this condition.

Question 146

Topic: Pediatric Upper Extremity & Spine
A newborn has absent radii bilaterally, but both thumbs are distinctly present and well-formed. Blood tests reveal profound thrombocytopenia. This clinical picture is most characteristic of which syndrome?
. Holt-Oram syndrome
. TAR syndrome
. Fanconi anemia
. VACTERL association
. Roberts syndrome

Correct Answer & Explanation

. TAR syndrome

Explanation

Thrombocytopenia-Absent Radius (TAR) syndrome classically presents with bilateral absence of the radii but preservation of the thumbs. This differentiates it from other causes of radial dysplasia where the thumbs are typically absent or hypoplastic.

Question 147

Topic: 4. Pediatrics

What is the maximum acceptable angulation for a midshaft both-bone forearm fracture in a 5-year-old child?

. 5 degrees
. 15 degrees
. 25 degrees
. 35 degrees
. 45 degrees

Correct Answer & Explanation

. 15 degrees

Explanation

In children under 8 years old, up to 15 degrees of angulation is acceptable for midshaft forearm fractures. Distal third fractures can tolerate slightly more (up to 20 degrees) due to greater remodeling potential near the physis.

Question 148

Topic: Pediatric Upper Extremity & Spine

A 13-year-old gymnast sustains a dislocated elbow with an associated medial epicondyle fracture. Following closed reduction of the elbow joint, what is the absolute indication for open reduction and internal fixation of the medial epicondyle?

. Displacement greater than 2 mm
. Ulnar nerve neurapraxia
. Incarceration of the medial epicondyle fragment within the joint
. High demand athletic status
. Dominant arm involvement

Correct Answer & Explanation

. Incarceration of the medial epicondyle fragment within the joint

Explanation

Incarceration of the medial epicondyle within the ulnohumeral joint after an attempted closed reduction is an absolute indication for surgical extraction and internal fixation. Most other criteria are relative indications depending on the surgeon and patient demands.

Question 149

Topic: Pediatric Upper Extremity & Spine

A 5-year-old sustains a completely displaced supracondylar humerus fracture. On arrival, the hand is pink but the radial pulse is absent. After successful closed reduction and pinning, the hand remains pink and warm with a capillary refill of 2 seconds, but the pulse remains absent. What is the most appropriate next step?

. Immediate vascular exploration
. Fasciotomy of the forearm
. Observation with close continuous clinical monitoring
. Local intra-arterial vasodilators
. Angiography

Correct Answer & Explanation

. Observation with close continuous clinical monitoring

Explanation

A "pink, pulseless" hand after a well-reduced supracondylar fracture indicates adequate collateral circulation. Current AAOS guidelines support close observation rather than immediate vascular exploration in this scenario.

Question 150

Topic: 4. Pediatrics

A 6-year-old girl is evaluated for asymmetric shoulder height. Examination reveals a high, hypoplastic left scapula with restricted shoulder abduction. Which of the following conditions is most frequently associated with this deformity?

. Congenital pseudoarthrosis of the clavicle
. Klippel-Feil syndrome
. Cleidocranial dysplasia
. Osteogenesis imperfecta
. Holt-Oram syndrome

Correct Answer & Explanation

. Klippel-Feil syndrome

Explanation

Sprengel deformity (congenital high scapula) is frequently associated with Klippel-Feil syndrome. Patients often have an omovertebral connection (bone, cartilage, or fibrous) tethering the scapula to the cervical spine.

Question 151

Topic: 4. Pediatrics

Congenital pseudarthrosis of the clavicle is characterized by an absence of a history of trauma and presents as a painless mass. In nearly all typical cases without dextrocardia (situs inversus), which side is predominantly affected?

. Always left-sided
. Always right-sided
. Bilateral in 50% of cases
. Depends on handedness
. Random distribution

Correct Answer & Explanation

. Always right-sided

Explanation

Congenital pseudarthrosis of the clavicle occurs almost exclusively on the right side. It is thought to be caused by pressure from the pulsating subclavian artery, which is higher on the right side unless the patient has dextrocardia.

Question 152

Topic: 4. Pediatrics

A 5-year-old girl sustains a severely displaced supracondylar humerus fracture. Her hand is pink and well-perfused, but the radial pulse is absent on palpation. After closed reduction and percutaneous pinning, the hand remains pink and warm, but the pulse remains absent. What is the most appropriate next step in management?

. Immediate exploration of the brachial artery
. Perform a sympathectomy
. Observe with close neurovascular monitoring
. Remove the pins and perform open reduction
. Obtain an urgent MR angiogram

Correct Answer & Explanation

. Observe with close neurovascular monitoring

Explanation

A 'pulseless, pink hand' after satisfactory reduction and pinning of a pediatric supracondylar fracture should be closely observed. Vascular exploration is only indicated if the hand becomes dusky, cool, and poorly perfused (pulseless and white).

Question 153

Topic: Pediatric Upper Extremity & Spine

When attempting closed reduction of a typical extension-type supracondylar fracture of the humerus with medial comminution, which position of the forearm is utilized to tension the intact medial periosteal hinge and prevent varus malalignment?

. Maximum supination
. Maximum pronation
. Neutral rotation
. Palmar flexion
. Ulnar deviation

Correct Answer & Explanation

. Maximum pronation

Explanation

Pronation of the forearm tightens the medial periosteal hinge. This helps close the lateral fracture gap and prevents cubitus varus deformity, which is the most common cosmetic complication of medial comminution.

Question 154

Topic: 4. Pediatrics
A newborn infant presents with a short, bowed right upper extremity and an absent thumb. Radiographs confirm congenital radial clubhand. Which of the following tests is mandatory in the initial workup of this patient?
. Echocardiogram and renal ultrasound
. CT scan of the cervical spine
. MRI of the brain
. Muscle biopsy
. Bone marrow aspiration

Correct Answer & Explanation

. Echocardiogram and renal ultrasound

Explanation

Radial clubhand is strongly associated with systemic syndromes such as VACTERL, Holt-Oram, TAR, and Fanconi anemia. A cardiac echocardiogram and renal ultrasound are essential to rule out life-threatening congenital heart or kidney defects.

Question 155

Topic: 4. Pediatrics

Congenital pseudarthrosis of the clavicle most frequently presents as a painless mass in the middle third of the clavicle. It almost exclusively occurs on the right side. If it is found on the left side, which associated condition must be strongly suspected?

. Neurofibromatosis type 1
. Osteogenesis imperfecta
. Dextrocardia
. Cleidocranial dysplasia
. Fanconi anemia

Correct Answer & Explanation

. Dextrocardia

Explanation

Congenital pseudarthrosis of the clavicle is almost always right-sided due to normal subclavian artery hemodynamics. When present on the left side, it is highly associated with situs inversus or dextrocardia.

Question 156

Topic: 4. Pediatrics

In a child with a typical Salter-Harris Type II fracture of the distal radius, what is the anatomical path of the fracture line?

. Straight across the physis only
. Through the physis and exiting through the metaphysis
. Through the physis and exiting through the epiphysis
. Through the metaphysis, physis, and epiphysis
. A compression injury to the physis without a visible fracture line

Correct Answer & Explanation

. Through the physis and exiting through the metaphysis

Explanation

A Salter-Harris Type II fracture travels along the growth plate (physis) and then turns to exit through the metaphysis. It is the most common type of physeal fracture and creates a characteristic Thurston-Holland fragment.

Question 157

Topic: 4. Pediatrics

A 35-year-old man presents with progressive numbness in his ring and small fingers, and clawing of his hand. He has a history of an elbow fracture as a child and currently has a cubitus valgus deformity. Which of the following pediatric fractures is most likely responsible for his current condition?

. Supracondylar humerus fracture
. Medial epicondyle fracture
. Radial neck fracture
. Lateral condyle fracture
. Olecranon fracture

Correct Answer & Explanation

. Supracondylar humerus fracture

Explanation

Nonunion of a lateral condyle fracture often leads to a progressive cubitus valgus deformity. This deformity causes stretching of the ulnar nerve over time, resulting in tardy ulnar nerve palsy.

Question 158

Topic: 4. Pediatrics

In a 10-year-old child with an acute elbow dislocation and a medial epicondyle fracture, which of the following is an absolute indication for operative fixation?

. Displacement greater than 5 mm
. Ulnar nerve symptoms
. Incarceration of the fragment within the joint
. Valgus instability
. High-demand overhead athlete

Correct Answer & Explanation

. Displacement greater than 5 mm

Explanation

Incarceration of the medial epicondyle fragment in the ulnohumeral joint is an absolute indication for open reduction and internal fixation. Other options are relative indications depending on patient activity and surgeon preference.

Question 159

Topic: Pediatric Hip

A 12-year-old obese boy presents with a 3-week history of left knee pain and an antalgic gait. Examination shows obligatory external rotation of the left hip during flexion. Which of the following is the most appropriate initial management?

. Non-weight bearing with crutches and urgent in situ pinning
. MRI of the left knee
. Physical therapy for hip strengthening
. Closed reduction and spica casting
. Capsulotomy and surgical dislocation

Correct Answer & Explanation

. Non-weight bearing with crutches and urgent in situ pinning

Explanation

This patient has a Slipped Capital Femoral Epiphysis (SCFE), presenting typically with knee pain and obligatory external rotation during hip flexion. Initial management requires strict non-weight bearing to prevent further slip, followed by urgent in situ pinning.

Question 160

Topic: Pediatric Lower Extremity

During the Ponseti method for correcting congenital talipes equinovarus (clubfoot), which deformity is corrected LAST?

. Cavus
. Adductus
. Varus
. Equinus
. Tibial torsion

Correct Answer & Explanation

. Cavus

Explanation

The Ponseti method corrects clubfoot deformities in a specific sequence (CAVE): Cavus, Adductus, Varus, and finally Equinus. The equinus is often corrected last with a percutaneous Achilles tenotomy.

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