Menu

4. Pediatrics MCQs

Practice Set 40 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 781

Topic: 4. Pediatrics

A 6-year-old boy falls from monkey bars and sustains a displaced extension-type supracondylar humerus fracture. Examination reveals an inability to actively flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Which nerve is injured?

. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Anterior interosseous nerve

Explanation

The anterior interosseous nerve (AIN), a branch of the median nerve, is the most commonly injured nerve in pediatric extension-type supracondylar humerus fractures. It innervates the flexor pollicis longus and the flexor digitorum profundus to the index finger.

Question 782

Topic: Pediatric Hip

A 12-year-old boy is diagnosed with a severe, chronic left slipped capital femoral epiphysis (SCFE). Which of the following is the most widely accepted absolute indication for prophylactic in-situ pinning of the asymptomatic contralateral hip?

. Age greater than 14 years at presentation
. Male gender
. Presence of an endocrine disorder such as hypothyroidism
. Slip angle greater than 50 degrees on the affected side
. Body mass index (BMI) greater than 35

Correct Answer & Explanation

. Presence of an endocrine disorder such as hypothyroidism

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine or metabolic disorders (e.g., hypothyroidism, renal osteodystrophy) due to the exceptionally high risk of bilateral involvement. Age less than 10 years or open triradiate cartilage are also strong relative indications.

Question 783

Topic: 4. Pediatrics
Which of the following statements concerning Ehlers-Danlos syndrome (EDS) is true?
. EDS type III is the most severe form of the disease.
. EDS is primarily inherited as an autosomal dominant disorder.
. EDS type VII is characterized by dislocated hips and/or knees at birth.
. Demonstrating joint hyperlaxity or voluntary dislocation in EDS patients does not damage the joint.
. Knowing the subtype of the disease does not affect the overall management of the patient.

Correct Answer & Explanation

. EDS type VII is characterized by dislocated hips and/or knees at birth.

Explanation

Ehlers-Danlos syndrome (EDS) types I, II, III, and VII are commonly seen by orthopedic surgeons. Type VII is characterized by congenital hip and knee dislocations. EDS type III is the mildest form of the disease; the main symptom of this type is hyperlaxity. EDS may be inherited via any of the Mendelian patterns. Children with EDS should be encouraged not to use their hyperlaxity as a 'trick' because of potential long-term joint damage that may occur. Knowing the subtype of the disease is often helpful in management and perioperative planning because then the surgeon may anticipate operative risks and potential complications.

Question 784

Topic: 4. Pediatrics

A 4-year-old child injures his elbow and presents with swelling and limitation of voluntary movement. The radiographs show no obvious fracture, but it does show a Baumann angle of 71° and an elevation of the posterior fat pad. You tell the parents that this most likely represents:

. A congenital anomaly with a valgus deformity of the elbow
. A medial epicondyle fracture
. A Salter I physeal separation
. An occult supracondylar fracture
. A variation of normal

Correct Answer & Explanation

. An occult supracondylar fracture

Explanation

Occult supracondylar fracture was the most common diagnosis assigned after careful study of a clinical series of elevated pediatric posterior fat pads. The value for Baumann angle is normally 81° - 64°. Nothing in this description suggests a congenital anomaly. Medial epicondyle fractures are extremely rare before 9 years of age. Although a Salter I physeal separation is a possibility, it is a rare injury. With an elevation of the posterior fat pad, there is increasing recognition that a fracture exists.

Question 785

Topic: 4. Pediatrics

Which of the following statements is true about the radiographic development of the proximal ulna:

. A small sliver of a secondary ossification center is present at birth.
. A secondary ossification center appears at 5 years of age.
. A secondary ossification center appears at 7 years of age.
. A secondary ossification center appears at 9 years of age.
. There is no secondary ossification center for this region.

Correct Answer & Explanation

. A secondary ossification center appears at 9 years of age.

Explanation

There is a secondary ossification center developing in children approximately 9 years of age. There is no ossification center in the proximal ulna until the child reaches 9 years old.

Question 786

Topic: 4. Pediatrics

A 6-year-old child falls and suffers a fracture of the elbow. The tenderness is mostly lateral. A fracture line may be seen separating a fragment of the humeral metaphysis and physis 3 mm from the lateral portion of the elbow, but the distal extension of the fracture cannot be visualized because of lack of ossification at this age. Treatment should consist of:

. No immobilization and early range of motion
. Application of a long arm cast for 4 weeks followed by early motion
. Application of a long arm cast for 8 weeks
. C losed reduction and percutaneous pin fixation
. Open reduction and plate fixation

Correct Answer & Explanation

. C losed reduction and percutaneous pin fixation

Explanation

Closed reduction and pin fixation should be attempted for all lateral condyle fractures that are displaced more than 2 mm. If closed reduction is not successful, open reduction should be performed. This is a lateral condyle fracture; nonunion may result with no immobilization and early range of motion. With more than 2 mm of displacement, reduction and fixation should be carried out. Plate fixation is not feasible because of the presence of the physis. Rigid fixation beyond the use of pins is not required.

Question 787

Topic: Pediatric Upper Extremity & Spine

A 2-year-old boy fell 4 feet from a countertop and landed on his outstretched hand. There is circumferential swelling and tenderness. Radiographs show no fracture, but the posterior fat pad elbow is elevated and the radius and ulna are translated slightly laterally on the anteroposterior view, and posteriorly on the lateral view. The most likely diagnosis is:

. Undisplaced supracondylar fracture
. Transphyseal fracture of the distal humerus
. Lateral condyle fracture
. Traumatic elbow dislocation
. C ongenital elbow dislocation

Correct Answer & Explanation

. Transphyseal fracture of the distal humerus

Explanation

The separation occurs through cartilage, so it is not visible as a fracture on plain films. However, the translation indicates a problem and elbow dislocation does not occur with any frequency at this age. An undisplaced supracondylar fracture would not produce translation of the radius and ulna. A lateral condyle fracture would not produce translation of the ulna. Traumatic dislocation is extremely uncommon in this age group. C ongenital elbow subluxation would not account for the swelling and tenderness. This is an extremely rare condition.

Question 788

Topic: 4. Pediatrics
A 12-year-old boy presents to the emergency department after being struck by a car. His only complaint at the time of presentation is right ankle pain. After obtaining an excellent reduction and casting the leg, the risks of a future growth disturbance through the involved physis must be discussed with the family. What are the chances of a significant growth disturbance of his leg?
. < 1%
. 2% to 3%
. 10% to 15%
. 45% to 55%
. 80% to 90%

Correct Answer & Explanation

. 10% to 15%

Explanation

This is a Salter-Harris type II fracture of the distal tibia. The distal tibia is at moderate risk for growth arrest after physeal injury. The average incidence of growth disturbance is 15% for all physeal injuries in this area. The marked displacement and mechanism of injury in this patient increase the risk of permanent physeal damage. The patient's age and remaining growth also increase the likelihood of a growth arrest causing a significant deformity or leg length discrepancy. Correct Answer: 10% to 15%

Question 789

Topic: 4. Pediatrics

Three years after a Salter-Harris type I physeal fracture of the right distal femur, a 12-year-old boy presents with complaints of knee pain and a limp. On examination, the boy has a valgus alignment of his right knee and a 2-cm leg length discrepancy with the right leg shorter than the left. Plain radiographs and a scanogram showed 30% growth plate closure with a femoral-tibial angle of 12° of valgus and 2.5 cm of shortening of the right femur. What is the best treatment:

. Lengthening procedure on the right leg
. Varus osteotomy of the right femur and bilateral distal femur epiphyseodesis
. Physeal bar resection of the right distal femur and opening wedge lateral osteotomy
. Right medial hemiepiphyseal stapling
. C ompletion of distal femoral epiphyseal closure

Correct Answer & Explanation

. Physeal bar resection of the right distal femur and opening wedge lateral osteotomy

Explanation

The bar resection has a reasonable chance of success. The angulation can be corrected by the osteotomy and the length would be partially corrected. Correction of the length (2 cm) is less important than prevention of future angulation and shortening. At 12 years old, if varus osteotomy of the right femur and bilateral distal femur epiphyseodesis were performed, the patient would be sacrificing 6 cm of leg length which most patients would consider unacceptable. Right medial hemiepiphyseal stapling and completion of distal femoral epiphyseal closure would neither produce significant length equalization nor correct the angulation.

Question 790

Topic: 4. Pediatrics

Two years after a Salter-Harris type II fracture of the right distal femur, a 12-year-old girl presents to the clinic with knee pain. On examination, she is found to have a valgus alignment of the right knee and a 3-cm leg length discrepancy with the right leg shorter than the left leg. The scanogram confirms 3 cm of shortening in the right femur. The next step in the management of this patient is:

. Obtain a magnetic resonance image of the right distal femoral physis
. Obtain a computed tomography scan of the right distal femoral physis
. Obtain a bone scan
. Obtain a single photon emission computed tomography scan
. Patients return in 9 months for a repeat scanogram

Correct Answer & Explanation

. Obtain a magnetic resonance image of the right distal femoral physis

Explanation

A magnetic resonance image of the right distal femoral physis provides the best detail of the physis if the correct region and sequences are ordered. A computed tomography scan is not the preferred method to allow visualization of the physis. A bone scan or photon emission computed tomography scan will not highlight a bar of the physis. Waiting 9 months would allow for worsening of the deformity.

Question 791

Topic: 4. Pediatrics

The mutations underlying Stickler syndrome have been identified in which of the following molecules:

. Type I collagen
. Type II collagen
. Fibrillin
. Sulfate transport protein
. Fibroblast growth factor receptor protein

Correct Answer & Explanation

. Type II collagen

Explanation

Type II collagen is abnormal in the classic form of Stickler syndrome, but in a few patients, type XI collagen has been found to be the causative mutation. Type 1 collagen is predominant in bone and is abnormal in osteogenesis imperfecta, for example. Stickler syndrome is characterized by a defect in type II collagen. Fibrillin is abnormal in Marfan syndrome, but in Stickler syndrome, the causative abnormalities have been found in type II collagen. Sulfate transport protein has been found abnormal in diastrophic dysplasia Fibroblast growth factor proteins are abnormal in achondroplasia and hypochondroplasia, but the basic defect in Stickler syndrome is type II collagen.

Question 792

Topic: 4. Pediatrics

The radiographic feature that is most characteristic of infantile Blount disease is:

. Widening and irregularity of the entire proximal tibial physis
. Poor bone mineralization
. Focal bowing of the distal medial femur
. Focal bowing of the proximal medial tibia
. External tibial torsion

Correct Answer & Explanation

. Focal bowing of the proximal medial tibia

Explanation

Bowing is focally located at the proximal medial tibia in infantile Blount disease. The physis may be widened medially, but it is normal laterally. Bone mineralization is not impaired in Blount disease. Bowing is focally located at the proximal tibia, not the distal femur. Blount disease is associated with internal, not external, tibial torsion.

Question 793

Topic: 4. Pediatrics

Hip subluxation is most likely to occur in patients with this type of cerebral palsy:

. Athetoid
. Diplegic
. Hemiplegic
. Total involvement
. Monoplegic

Correct Answer & Explanation

. Total involvement

Explanation

Patients with total involvement have the highest degree of axial muscle imbalance; therefore, they have the highest risk of hip subluxation (greater than 50%). Hip dysplasia is uncommon in athetoid cerebral palsy (CP). Diplegic C P has the second highest incidence of neuromuscular hip dysplasia, but total involvement has the highest rate. Hip subluxation is not common in hemiplegic CP. Monoplegia is a rare form of CP with a low rate of subluxation.

Question 794

Topic: Pediatric Hip

The following parameter is the most useful in predicting the need for surgical correction of developmental coxa vara:

. The range of active abduction
. The epiphyseal extrusion index
. The acetabular index
. The Hilgenreiner-epiphyseal angle
. Presence of a Trendelenburg gait

Correct Answer & Explanation

. The Hilgenreiner-epiphyseal angle

Explanation

The Hilgenreiner-epiphyseal angle is a measure of the shear stress on the femoral neck. A value greater than 60° is an indication for surgery. The range of abduction does not directly reflect the mechanical stresses on the femoral neck that may need correction. The epiphyseal extrusion index is a parameter used in Perthes disease. The acetabular index is used in developmental hip dysplasia. It is usually essentially within normal limits, even in severe coxa vara.

Question 795

Topic: 4. Pediatrics
A 7-month-old girl is newly seen for a dislocation of the left hip. The newborn exam was unremarkable; there was no history of trauma or evidence of spasticity. Recommended treatment includes:
. Exam, arthrogram and attempted closed reduction under anesthesia to guide treatment
. Pavlik harness
. Open reduction through a medial approach
. Open reduction through a lateral approach
. A Salter osteotomy

Correct Answer & Explanation

. Exam, arthrogram and attempted closed reduction under anesthesia to guide treatment

Explanation

An exam under anesthesia and arthrogram should be performed. Closed reduction must be performed if the hip reduces with a medial dye pool less than 4 mm and a safe zone greater than 20°. The Pavlik harness is not strong enough to hold an infant older than 4 to 6 months. Open reduction is reserved for hips that do not reduce by closed means. A Salter osteotomy is only indicated if the hip is still unstable after an open reduction.

Question 796

Topic: Pediatric Hip

A 13-year-old obese male presents with right groin pain and an obligatory external rotation of the hip when it is passively flexed. If this condition is treated with forceful closed reduction, what is the most significant and devastating complication?

. Avascular necrosis (AVN) of the femoral head
. Chondrolysis of the hip joint
. Premature closure of the triradiate cartilage
. Nonunion of the proximal femur
. Septic arthritis

Correct Answer & Explanation

. Avascular necrosis (AVN) of the femoral head

Explanation

The presentation is classic for Slipped Capital Femoral Epiphysis (SCFE). Forceful closed reduction of a SCFE significantly increases the risk of avascular necrosis of the femoral head, which is the most devastating complication.

Question 797

Topic: Pediatric Hip

A 3-month-old infant is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). What is the most common nerve palsy associated with excessive hip flexion in this device?

. Sciatic nerve palsy
. Femoral nerve palsy
. Obturator nerve palsy
. Superior gluteal nerve palsy
. Pudendal nerve palsy

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Femoral nerve palsy is a known complication of treating DDH with a Pavlik harness when the hips are placed in excessive hyperflexion, which compresses the nerve against the inguinal ligament.

Question 798

Topic: 4. Pediatrics

Which of the following genetic defects is most commonly associated with Marfan syndrome?

. Fibrillin-1 (FBN1) mutation
. Type I collagen mutation
. FGFR3 mutation
. COMP mutation
. Runx2 mutation

Correct Answer & Explanation

. Fibrillin-1 (FBN1) mutation

Explanation

Marfan syndrome is an autosomal dominant connective tissue disorder caused by mutations in the FBN1 gene on chromosome 15, which encodes fibrillin-1. This leads to skeletal, cardiovascular, and ocular abnormalities.

Question 799

Topic: 4. Pediatrics

Achondroplasia is the most common form of short-limb dwarfism. It is caused by a gain-of-function mutation in which of the following genes?

. FGFR3
. COL1A1
. COL2A1
. COMP
. SOX9

Correct Answer & Explanation

. FGFR3

Explanation

Achondroplasia is an autosomal dominant disorder caused by a gain-of-function mutation in the FGFR3 gene. This mutation inhibits chondrocyte proliferation in the proliferative zone of the physis.

Question 800

Topic: 4. Pediatrics
Osteogenesis imperfecta (OI) type I is characterized by which of the following defects?
. Decreased quantity of normal type I collagen
. Abnormal structural type I collagen
. Absence of type II collagen
. Defect in lysyl hydroxylase
. Mutation in the FBN1 gene

Correct Answer & Explanation

. Decreased quantity of normal type I collagen

Explanation

Type I OI is a mild form characterized by a decreased production of structurally normal type I collagen (quantitative defect). In contrast, types II, III, and IV involve qualitative defects in collagen structure.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page