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4. Pediatrics MCQs

Practice Set 80 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 1581

Topic: 4. Pediatrics
Figure 1 shows the clinical photograph obtained from a child with a congenital difference of the hand. What clinical feature(s) is/are characteristic of this condition?
. Cardiac anomalies
. Radial deviation of the thumb
. Acrosyndactyly with proximal sinus tracts
. Absence of the ulna

Correct Answer & Explanation

. Acrosyndactyly with proximal sinus tracts

Explanation

The clinical photograph reveals a child with amniotic band syndrome or constriction band syndrome. If a band causes an autofusion of the digits without amputation, acrosyndactyly can occur, as demonstrated in the clinical photograph. Typically, a proximal sinus tract with a distal syndactyly is present. Radial deviation of the thumb can be seen most frequently in Apert syndrome. Cardiac anomalies are associated with many congenital upper extremity differences but are not characteristic of amniotic band syndrome. Ulnar longitudinal deficiency is characterized by hypoplasia or complete absence of the ulna.

Question 1582

Topic: 4. Pediatrics
A 7-year-old male is struck by a motor vehicle while crossing the street and suffers an open tibia fracture with a crush injury of the ipsilateral foot. After multiple attempts at limb salvage, the family and treating surgeon elect to proceed with a knee disarticulation. What complication of pediatric amputations is avoided with a knee disarticulation as opposed to a transtibial amputation?
. Neurogenic pain
. Bone overgrowth
. Hip flexion contracture
. Hip adduction contracture
. Leg length inequality

Correct Answer & Explanation

. Bone overgrowth

Explanation

DISCUSSION: Bone overgrowth is a poorly understood phenomenon in which the bone end undergoes disorganized appositional growth following amputation in a skeletally immature patient. Overgrowth is the most common complication following transosseous amputation in pediatric patients. Krajbich reviews the management of pediatric patients with lower-limb deficiencies and amputations. He advocates disarticulation as opposed to transosseous amputation when possible as bone overgrowth has not been observed in bone ends covered by articular cartilage. O'Neal et al retrospectively reviewed their rates of surgical revision for bone overgrowth in pediatric and adolescent amputees. The highest rates of revision were seen with metaphyseal-level amputations (50%) and with traumatic amputations (43%). Benevenia et al reviewed their rates of overgrowth in skeletally immature transosseous amputees using an autogenous epiphyseal transplant from the amputated limb to cap the medullary canal. They found that only 1 of 10 patients undergoing amputation with this technique had complications due to bone overgrowth, compared with 6 of 7 patients undergoing traditional transosseous amputation.

Question 1583

Topic: 4. Pediatrics
A 22-month-old child has scrapes and bruises on his head and a severe deformity of the forearm after being thrown from a car as an unrestrained passenger in a motor vehicle accident. Examination reveals a Glasgow Coma Scale score of 12. Prior to treatment of the forearm, management should include
. a mannitol infusion of 0.25 to 1 g/kg.
. high-dose IV methylprednisolone, consisting of a 30 mg/kg bolus, followed by 5.4 mg/kg/h for 23 hours.
. an immediate CT scan.
. an electroencephalogram.
. radiographs of the skull.

Correct Answer & Explanation

. an immediate CT scan.

Explanation

DISCUSSION: As CT scanning has become available, the use of radiographs of the skull has decreased in importance for evaluation of head trauma. The indications for CT scanning for suspected head trauma include any degree of obtundation, focal neurologic deficit, history of a high-velocity injury, amnesia for the injury, progressive headache, persistent vomiting, children younger than age 2 years, serious facial injury, posttraumatic seizure, skull penetration, or a Glasgow Coma Scale score of 13 or less. Evidence of improved outcome with use of steroids in head trauma is lacking. Steroids are useful for increased intracranial pressure caused by brain tumors or abscesses. High-dose IV methylprednisolone is indicated for spinal cord trauma and improves the ultimate degree of recovery of function. When herniation is suspected in a patient with asymmetric neurologic findings or the patient’s condition is deteriorating rapidly, a mannitol infusion may be used. REFERENCES: Hall DE: Head injuries, in Hoekelman RA (ed): Primary Pediatric Care. St Louis, Mo, Mosby, 1997, pp 1709-1712. Nelson WE, Behrman RE, Kliegman RM (eds): Nelson Essentials of Pediatrics. Philadelphia, Pa, WB Saunders, 1998, p 712. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 123-130.

Question 1584

Topic: 4. Pediatrics

Six months later, the patient’s fracture has healed and a CT scan to further evaluate the physis is performed (Video 85). Based on these findings, how should you advise the family?

. The fracture is healed and the physis is growing well with no problems expected.
. Complete physeal closure has occurred. There will be no significant leg length difference because the patient is almost done growing.
. Complete physeal closure has occurred. There will be a significant (> 2-cm) leg length difference if no other surgical treatment is offered.
. Asymmetric physeal closure has occurred. There will be an increasing angular deformity at the knee as well as a significant (> 2-cm) leg length difference if no other surgical treatment is offered.

Correct Answer & Explanation

. The fracture is healed and the physis is growing well with no problems expected.

Explanation

DISCUSSIONThe hypertrophic zone is the weakest biomechanical zone of the physis and is most likely to fracture. The deep peroneal nerve supplies motor innervation to the ankle and toedorsiflexors (anterior compartment) and the first web space, which, in this history, have deficits. The superficial peroneal nerve supplies sensation to the dorsum of the foot and motor to the lateral compartment peroneal musculature (ankle evertors), which also has deficits. The injury must involve both peroneal branches (the common peroneal nerve). Because sensation to the sole of the foot and toe/ankle plantar flexion is intact, the tibial nerve is intact.Because the nerve was visualized intact, a neuropraxia is the most likely type of nerve injury. This should recover in time and does not necessitate urgent exploration. In pediatric patients, an advancing Tinel sign and partial nerve recovery by 3 months is expected and can be followed clinically. If there is no sign of nerve recovery, an electromyogram should be ordered with consideration for nerve exploration if there is no sign of reinnervation. There is no sign of compartment syndrome because the patient has an unchanged neurologic deficit, is comfortable, and has no pain with passive range of motion.These injuries are associated with a very high rate of growth arrest (up to 80% in some studies). The CT scan shows an asymmetric growth arrest, which suggests angulation through the distal femur.

Question 1585

Topic: 4. Pediatrics
What radiographic measurement is best used to assess the adequacy of deformity correction for the patient shown in Figure 22?
. Reimers index (migration index)
. Acetabular index
. Center edge angle of Wiberg
. Hilgenreiner physeal angle
. Head-shaft angle (Southwick angle)

Correct Answer & Explanation

. Hilgenreiner physeal angle

Explanation

Developmental coxa vara develops in early childhood and results in a progressive decrease in the proximal femoral neck-shaft angle with growth. The characteristic radiographic features include a decreased neck-shaft angle, a more vertical position of the physeal plate, and a triangular metaphyseal fragment in the inferior femoral neck, surrounded by an inverted radiolucent Y pattern. The main goal of surgery is to correct the varus angulation into a more normal range. Valgus overcorrection is preferred. A recent study emphasized the importance of adequately correcting the Hilgenreiner physeal angle to less than 38 degrees to minimize the risk of recurrent angulation. No study has documented the use of any of the other listed radiographic measurements to the outcome of treating developmental coxa vara.

Question 1586

Topic: Pediatric Upper Extremity & Spine
A 7-year-old boy has a swollen and deformed right arm after falling off his bicycle. Radiographs reveal a completely displaced posterolateral supracondylar humeral fracture. Examination reveals a warm, pink hand and forearm but absent pulses. What is the next most appropriate step in management?
. Angiography
. Immediate closed reduction and casting in extension
. Surgical exploration and repair of the artery, followed by skeletal stabilization
. Closed reduction and pinning, followed by reassessment of the vascular status
. Magnetic resonance angiography (MRA)

Correct Answer & Explanation

. Closed reduction and pinning, followed by reassessment of the vascular status

Explanation

The incidence of vascular injury in supracondylar humeral fractures is directly related to the degree and direction of displacement. The brachial artery is always injured at the level of the fracture; therefore, angiography or MRA will not assist in locating the injury. The treatment of choice is surgical reduction and stabilization of the fracture, followed by reassessment of the vascular status. If the hand is pink and warm or pulses can be detected with doppler, it is reasonable to follow the extremity closely after surgery. If the arm becomes pulseless and white, immediate anterior exploration of the arm is indicated.

Question 1587

Topic: 4. Pediatrics
A 9-year-old child sustains a proximal tibial physeal fracture with a hyperextension mechanism. What structure is at most risk for serious injury?
. Tibial nerve
. Popliteal artery
. Common peroneal nerve
. Posterior cruciate ligament
. Popliteus muscle

Correct Answer & Explanation

. Popliteal artery

Explanation

The most serious injury associated with proximal tibial physeal fracture is vascular trauma. The popliteal artery is tethered by its major branches near the posterior surface of the proximal tibial epiphysis. During tibial physeal displacement, the popliteal artery is susceptible to injury. Injuries to the other structures are less common.

Question 1588

Topic: 4. Pediatrics

-is the photograph of a 2-month-old infant with a left leg deformity. The mother’s pregnancy and delivery were unremarkable, and the infant is otherwise healthy. What is the most appropriate course of action?

. Osteotomy of the tibia and fibula
. Clamshell knee-ankle-foot orthotic
. Serial casts
. Observation and a repeat visit in 4 monthsDISCUSSION-The photograph shows posteromedial bowing of the tibia. The child should be followed for later limblength discrepancy, which may need treatment. Treatment with bracing or serial casts has not been shown to alter this condition. Surgery is not indicated in infancy because much of the deformity corrects with time. At a later age, treatment of a limb-length discrepancy or residual deformity can be addressed.

Correct Answer & Explanation

. Osteotomy of the tibia and fibula

Explanation

Question 1589

Topic: Pediatric Upper Extremity & Spine
A 5-year-old boy sustained an elbow injury. Examination in the emergency department reveals that he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. The radial pulse is palpable at the wrist, and sensation is normal throughout the hand. Radiographs are shown. In addition to reduction and pinning of the fracture, initial treatment should include:
. repair of the posterior interosseous nerve.
. repair of the median nerve at the elbow.
. neurolysis of the anterior interosseous nerve.
. observation of the nerve palsy.
. immediate electromyography and nerve conduction velocity studies.

Correct Answer & Explanation

. observation of the nerve palsy.

Explanation

Discussion: The findings are consistent with a neurapraxia of the anterior interosseous branch of the median nerve. This is the most common nerve palsy seen with supracondylar humerus fractures, followed closely by radial nerve palsy. Nearly all cases of neurapraxia following supracondylar humerus fractures resolve spontaneously, and therefore, further diagnostic studies and surgery are not indicated.

Question 1590

Topic: 4. Pediatrics

A 6-year-old sustains the injury shown in Figures A and B. The nerve most commonly affected by this fracture pattern innervates which of the following motor groups?

. Intrinsics of the hand
. Wrist extensor
. Thumb extensor
. Thumb IP flexor
. Digital extensor

Correct Answer & Explanation

. Intrinsics of the hand

Explanation

This patient has sustained a displaced extension-type supracondylar fracture. The most commonly affected nerve in this setting is the anterior interosseous nerve (AIN). This will affect thumb IP flexion.The most common neurapraxia after pediatric extension-type supracondylar fractures involve the AIN. It supplies the FPL (thumb IP flexion), the pronator quadratus, and the FDP of the index/long fingers. Subsequently, patients are often unable to make an “a-ok” sign. Most of these neuropraxias resolve without complication. The ulnar nerve is most commonly implicated with flexion-type supracondylar fractures.Abzug et al. review management of supracondylar fractures. They note that the AINis most commonly injured nerve in extension type supracondylar fractures. They note that nerve injuries often resolve within 6-12 weeks.Babal et al. completed a meta-analysis to determine the risk of neurapraxia associated with pediatric supracondylar fractures. The rate of traumatic neurapraxia was 11.4% amongst 5000 patients. The AIN was affected 34.1% of the time. AIN neurapraxia was most common in extension type injuries.Figures A and B show an AP and lateral radiographs of a displaced pediatric supracondylar fractureIncorrect Answers

Question 1591

Topic: 4. Pediatrics
A well-developed college football player reports swelling and a heaviness in the arm after lifting weights. Examination reveals that distal pulses are normal and equal in both arms. A venogram is shown in Figure 13. What is the most likely cause of this condition?
. Intimal tearing of the subclavian artery
. Compression of the subclavian vein by scalene muscle hypertrophy
. Postural compression of the neurovascular bundle between the clavicle and the first rib
. A congenital cervical rib
. Arterial thrombosis induced by repeated overhead activities

Correct Answer & Explanation

. Compression of the subclavian vein by scalene muscle hypertrophy

Explanation

DISCUSSION: The clinical findings indicate venous obstruction without arterial compression, and the venogram reveals occlusion of the subclavian vein, which is most likely the result of thoracic outlet compression. In the developed athlete, scalene muscle hypertrophy (Paget-Schroetter syndrome) causes compression of the subclavian vein. Treatment should consist of thrombolysis followed by decompressive surgery. REFERENCES: Angle N, Gelabert HA, Farooq MM, et al: Safety and efficacy of early surgical decompression of the thoracic outlet for Paget-Schroetter syndrome. Ann Vasc Surg 2001;15:37-42. Azakie A, McElhinney DB, Thompson RW, et al: Surgical management of subclavian-vein effort thrombosis as a result of thoracic outlet compression. J Vasc Surg 1998;28:777-786.

Question 1592

Topic: 4. Pediatrics

A 13-year-old boy was evaluated for leg length difference. His pelvis balanced when a 1-inch (2.54 cm) block was placed under his left foot. History revealed he had a left distal femur physeal fracture treated with casting at age 10. Radiographs show normal limb alignment, but his left distal femoral physis is closed and his left femur is 2.5 cm shorter than the right. All other physes are open. His bone age is equal to his chronologic age. What surgical treatments will best equalize his discrepancy? Review Topic

. Right distal femoral and proximal tibia/fibula epiphysiodesis
. Right distal femoral epiphysiodesis
. Right proximal tibia/fibula epiphysiodesis
. Left proximal tibia/fibula epiphysiodesis

Correct Answer & Explanation

. Right distal femoral and proximal tibia/fibula epiphysiodesis

Explanation

Because the left distal femoral physis is closed with a leg length difference already at 1 inch, epiphysiodesis of both the right distal femur and proximal tibia/fibula is needed. The amount of correction will be the amount of growth remaining in the left proximal tibia. Presuming the standard rates of growth of 10 mm per year distal femur, 6 mm per year proximal tibia, and 4 mm per year distal tibia, this should yield a correction of 6 mm x 3 years = 1.8 cm by skeletal maturity at age 16. This would leave the boy with an acceptable discrepancy of 7 mm, well under 1 inch/2.54 cm. Closing only the right distal femoral physis will leave the discrepancy unchanged at 1 inch/2.54 cm because no growth differential will exist. Closing the right proximal tibia/fibular physis would mean the left knee will grow at 6 mm per year, but the right will grow at 10 mm per year. The discrepancy would increase by 4 mm per year, or

Question 1593

Topic: 4. Pediatrics
During the first 2 years of life, which of the following actions is most responsible for increasing structural stability of the physis?
. The change from a flat to an undulating physis
. The growth of the zone of Ranvier
. Increased strength of the points of insertion of muscles onto bone
. Increased penetration of proprioceptive nerve endings about the physis
. Increased capillary penetration about the physis

Correct Answer & Explanation

. The growth of the zone of Ranvier

Explanation

The zone of Ranvier provides the earliest increase in strength of the physis. During the first year of life, the zone spreads over the adjacent metaphysis to form a fibrous circumferential ring bridging from the epiphysis to the diaphysis. This ring increases the mechanical strength of the physis. The zone also helps the physis grow latitudinally. In turn, the increased width of the physis helps the physis further resist mechanical forces.

Question 1594

Topic: Pediatric Hip
A 48-year-old woman reports bilateral thigh pain that is limiting her function as a librarian. A radiograph and a bone scan are shown in Figures 23a and 23b. What is the most likely diagnosis?
. Ankylosing spondylitis
. Arthrokatadysis
. Osteomalacia
. Rheumatoid arthritis
. Developmental dysplasia

Correct Answer & Explanation

. Rheumatoid arthritis

Explanation

The radiograph reveals bilateral severe acetabular protrusio. The bone scan and history confirm involvement of multiple joints, including the knees and the hindfoot. Although the first four choices can all cause the acetabular protrusio, the associated multiple joint involvement suggests the diagnosis of rheumatoid arthritis.

Question 1595

Topic: 4. Pediatrics
Duchenne muscular dystrophy is a genetic disorder that is transmitted by which of the following modes of inheritance?
. X-linked
. Autosomal-dominant
. Autosomal-recessive
. Chromosomal duplication
. Chromosomal deletion

Correct Answer & Explanation

. X-linked

Explanation

DISCUSSION: Patients with Duchenne muscular dystrophy show progressive muscular weakness because of the absence of dystrophin and have the clinical picture of progressive muscle weakness. The condition is an X-linked genetic disease.

Question 1596

Topic: 4. Pediatrics
An 18-month-old child sustains a crush amputation of the tip of the index finger. Bone is exposed, but the nail is intact. Management should consist of
. dressing changes and healing by secondary intention.
. a split-thickness skin graft.
. a full-thickness skin graft.
. a thenar flap.
. a V-Y flap.

Correct Answer & Explanation

. dressing changes and healing by secondary intention.

Explanation

DISCUSSION: Children have a much greater capacity to heal soft-tissue injuries than adults. Most crush or avulsion fingertip amputations in children, particularly those younger than age 2 years, can be treated with serial dressing changes, even with bone exposed.

Question 1597

Topic: 4. Pediatrics
An 8-year-old girl sustained a displaced fracture at the base of the femoral neck in a motor vehicle accident. Management should consist of
. closed reduction and spica cast immobilization.
. closed reduction and fixation of the femoral fracture with smooth pins across the physis.
. open reduction and fixation with screws across the fracture and short of the growth plate, and a spica cast.
. skeletal traction in a 90-90 position.
. temporary traction until fixation with a specially ordered pediatric hip screw is possible.

Correct Answer & Explanation

. open reduction and fixation with screws across the fracture and short of the growth plate, and a spica cast.

Explanation

DISCUSSION: Pediatric intracapsular hip fractures are challenging because of the high rates of complications, including osteonecrosis and varus malunion. These patients should be treated as emergencies. Principles of treatment include anatomic reduction with internal fixation. Screw fixation short of the physis is preferred and may need to be supplemented with spica cast immobilization.

Question 1598

Topic: 4. Pediatrics

Figures 10a and 10b are the sagittal and coronal MRI scans of a 5-year-old boy who noticed “clicking” in his right knee. His family denied any trauma, but admitted that the child was active and fell frequently. Birth and developmental history were unremarkable, and specifically negative for other musculoskeletal conditions. On physical examination, there was no warmth, tenderness, or erythema, or effusion. The child had an audible and palpable clunk when the knee was taken from a position of extreme flexion to full extension. There was no anterior, posterior, medial, or lateral instability on examination or medial or lateral joint line tenderness. The child had not been systemically ill. Radiographs were unrevealing. What is the most likely diagnosis? Review Topic

. Discoid lateral meniscus
. Congenital absence of the anterior cruciate ligament
. Torn medial meniscus
. Osteomyelitis of the distal femur

Correct Answer & Explanation

. Discoid lateral meniscus

Explanation

A discoid lateral meniscus is probably the most common cause of a symptomatic clicking or clunking in the knee in a young child. This is a congenital problem that can become symptomatic as soon as a child ambulates, or the condition may remain asymptomatic for several years. The meniscus develops from a cartilaginous anlage and at no point in its development is it discoid. The MRI scans reveal a band of meniscal tissue filling the joint's lateral compartment on both sagittal and coronal images. A medial meniscal tear is usually accompanied by a history of injury and an effusion, which are not present in this child. There is also no joint line tenderness, which makes this diagnosis less likely. Congenital absence of the anterior cruciate ligament may be found in children born with congenital knee hyperextension, which is ruled out in this case by normal history and examination findings. Children with osteomyelitis are often systemically ill. On examination, they may have warmth and tenderness. MRI scans will often show an area of increased signal on T1-weighted images.

Question 1599

Topic: 4. Pediatrics

A 6-month-old child has the deformity seen in Figure 10. There are no other known associated problems. What is the etiology of this condition? Review Topic

. Exposure to teratogens
. Multifactorily inherited
. A defect of the apical ectodermal ridge
. Excess production of fibroblast growth factor
. Inherited as an autosomal dominant

Correct Answer & Explanation

. Exposure to teratogens

Explanation

The radiograph demonstrates a type IV radial clubhand (radial dysplasia) with complete absence of the radius. This is a pre-axial deficiency usually with complete absence of the thumb. The condition is thought to be caused by an injury to the formation of the apical ectodermal ridge early in embryology. It is not an inherited condition unless it is associated with other syndromic problems. It is not known to be associated with specific teratogens. Fibroblast growth factor is involved in angiogenesis, wound healing, and embryonic development, but is not known to be associated with radial clubhand.

Question 1600

Topic: Pediatric Upper Extremity & Spine
A 10-year-old girl sustained a Gartland type III supracondylar fracture after falling off a trampoline 1 hour ago. She has a well-perfused hand but no palpable pulses. The remainder of her examination is otherwise normal. What is the next step in treatment?
. Oblique radiographs
. Arteriogram
. Exploration of the brachial artery at the elbow
. Closed reduction and pinning of the elbow
. Open reduction and internal fixation of the elbow

Correct Answer & Explanation

. Closed reduction and pinning of the elbow

Explanation

Most supracondylar fractures are extension type and a Gartland type III is defined as a fracture that is completely displaced (i.e., no posterior cortical hinge). Treatment consists of closed reduction and pinning. If there is evidence of vascular compromise, the fracture should be reduced and pinned urgently and the limb reevaluated.

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