Pathophysiology: Chapter 46: Alterations of Musculoskeletal Function in Children

Question 1

Until the skeleton matures and adult stature is reached, where does growth in the length of
bone occur?
a. Epiphyseal line 
b. Physeal plate
c. Epiphyseal cartilage
d. Metaphyseal plate

Answer 1

ANS: B
Until the skeleton matures and adult stature is reached, growth in the length of bone occurs
only at the physeal plate through endochondral ossification.

Question 2

Which skeletal deformity is normal at birth but generally disappears by 21/2 years of age?

a. Genu varum (bowleg)
b. Genu valgum (knock knee)
c. Equinovarus (clubfoot)
d. Pes planus (flat feet)

Answer 2

ANS: A
Genu varum (bowleg) generally resolves itself by 21/2 years of age, whereas genu valgum
(knock knee) maximizes by 5 to 6 years of age. This statement is not true of either
equinovarus or pes planus.

Question 3

The total mass of muscle in the body can be estimated from which serum laboratory test
value?
a. Albumin c. Creatinine
b. Blood urea nitrogen d. Creatine

Answer 3

ANS: C
Of the options available, the total mass of muscle in the body can be estimated from the
amount of creatinine excreted in the urine, because the conversion of creatine to creatinine
only takes place in muscle.

Question 4

What is the most common congenital skeletal defect of the upper extremity?

a. Vestigial tabs c. Rickets
b. Paget disease d. Syndactyly

Answer 4

ANS: D
The most common congenital skeletal defect of the upper extremity is syndactyly, or
webbing of the fingers.

Question 5

What diagnosis is given when the infant’s hip maintains contact with the acetabulum but is
not well seated within the hip joint?
a. Dislocatable hip c. Dislocated hip
b. Subluxated hip d. Subluxable hip

Answer 5

ANS: B
Subluxated hip is the only option used to identify the condition when the hip maintains
contact with the acetabulum but is not well seated within the hip joint.

Question 6

Which sign or symptom is a very late indication of developmental dysplasia of the hip?

a. Asymmetry of the gluteal or thigh folds
b. Leg-length discrepancy
c. Waddling gait
d. Pain

Answer 6

ANS: D
Signs and symptoms of developmental dysplasia of the hip that should be noted include
pain very late in the process. This statement is not true of the other options.

Question 7

Which serum laboratory test is elevated in all forms of osteogenesis imperfecta?

a. Phosphorus c. Alkaline phosphatase
b. Calcium d. Total protein

Answer 7

ANS: C

Of the available options, serum alkaline phosphatase is elevated in all forms of the disease.

Question 8

The failure of bones to ossify, resulting in soft bones and skeletal deformity, characterizes
which disorder?
a. Osteogenesis imperfecta 
b. Rickets 
c. Osteochondrosis
d. Legg-Calvé-Perthes disease

Answer 8

ANS: B
Of the available options, only rickets is a disorder in which growing bone fails to become
mineralized (ossified) and results in soft bones and skeletal deformity.

Question 9

An insufficient dietary intake of which vitamin can lead to rickets in children?

a. C c. B6
b. B12 d. D

Answer 9

ANS: D
Rickets results from either insufficient vitamin D, insensitivity to vitamin D, wasting of
vitamin D by the kidney, or inability to absorb vitamin D and calcium in the gut. Vitamin
D is the only vitamin associated with rickets.

Question 10

In scoliosis, curves in the thoracic spine greater than how many degrees result in decreased
pulmonary function?
a. 40 c. 60
b. 50 d. 80

Answer 10

ANS: D
In scoliosis, curves in the thoracic spine greater than 80 degrees result in decreased
pulmonary function.

Question 11

In osteomyelitis, bacteria gain access to the subperiosteal space in the metaphysis, which is
considered the path of least resistance. What factor makes this route for bacteria the path
of least resistance?
a. Cortex of the bone in this area is porous or mazelike.
b. Blood supply to the metaphysis is easily compromised.
c. Macrophages and lymphocytes have limited access to the subperiosteal space.
d. Bacteria usually spread down the medullary cavity of the bone.

Answer 11

ANS: A
The subperiosteal space in the metaphysis is the path of least resistance because the cortex
of the bone in this area is porous or mazelike, and the inflammatory response blocks
spread within the bone. This statement is not true of the other options.

Question 12

How do the clinical manifestations and onset of juvenile rheumatoid arthritis (JRA) differ
from those of rheumatoid arthritis (RA) in adults?
a. JRA begins insidiously with systemic signs of inflammation.
b. JRA predominantly affects large joints.
c. JRA has more severe joint pain than adult RA.
d. JRA has a rapid onset of generalized aches as the first symptom.

Answer 12

ANS: B
The onset of JRA is less gradual than it is in adult RA. JRA also differs from the adult
form in that predominantly the large joints are affected in JRA. The remaining options are
not accurate since the statements are true of RA as well.

Question 13

What is the cause of osteochondrosis?

a. Imbalance between calcitonin and parathyroid hormone
b. Nutritional deficiency of calcium and phosphorus
c. Bacterial infection of the bone
d. Vascular impairment and trauma to bone

Answer 13

ANS: D
Of the options available, only vascular impairment and trauma to bone, coupled with an
underlying developmental or genetic predisposition, have been identified as probable
causes of osteochondrosis.

Question 14

Which bones are affected in Legg-Calvé-Perthes disease?
a. Heads of the femur 
b. Distal femurs
c. Heads of the humerus 
d. Distal tibias
.

Answer 14

ANS: A
A recurrent interruption of the blood supply to only the femoral heads presumably
produces Legg-Calvé-Perthes disease, which is a self-limited disease of the hip

Question 15

Which statement is true regarding the pain experienced with Legg-Calvé-Perthes disease?
a. Pain experienced with Legg-Calvé-Perthes disease in the elbows and upper and
lower arms is aggravated by activity and relieved by rest.
b. Pain experienced with Legg-Calvé-Perthes disease in the knees, inner thighs, and
groin is described as a continuous ache and relieved by antiinflammatory drugs.
c. Pain experienced with Legg-Calvé-Perthes disease in the knees, inner thighs, and
groin is aggravated by activity and relieved by rest.
d. Pain experienced with Legg-Calvé-Perthes disease in the elbows and upper and
lower arms is described as a continuous ache and relieved by antiinflammatory
drugs.

Answer 15

ANS: C
The child with Legg-Calvé-Perthes disease often complains of a limp or pain for several
months. The pain is usually referred to the knee, inner thigh, and groin and aggravated by
activity and relieved by rest. This selection is the only option that accurately describes the
pain associated with Legg-Calvé-Perthes disease.

Question 16

Which assessment finding characterizes Osgood-Schlatter disease?

a. Lateral epicondylitis of the elbow
b. Inflammation of the anterior cruciate ligament
c. Bursitis of the subscapular bursa in the glenohumeral joint
d. Tendinitis of the anterior patellar tendon

Answer 16

ANS: D
Tendinitis of the anterior patellar tendon, within which the patella (kneecap) is embedded,
and associated osteochondrosis of the tubercle of the tibia are characteristics of
Osgood-Schlatter disease. This selection is the only option that is associated with
Osgood-Schlatter disease.

Question 17

At birth, the diagnosis of cerebral palsy (CP) may be made based on what factor?

a. Brain trauma during birth
b. Prematurity
c. Major brain malformation
d. Genetic defect

Answer 17

ANS: A
The diagnosis of CP is often made when gross motor milestones are not met by predicted
ages. In some infants, diagnosis is made at birth because the child has an underlying
diagnosis, such as a major brain malformation that is known to be associated with CP.
None of the other options are known triggers for CP.

Question 18

Which muscular dystrophy syndrome develops from an X-linked recessive mode of
inheritance?
a. Duchenne 
b. Facioscapulohumeral
c. Myotonic 
d. Limb girdle

Answer 18

ANS: A
A deletion of a segment of DNA or a single-gene defect on the short arm of the X
chromosome is believed to be the cause of the X-linked inherited type of Duchenne
muscular dystrophy. This statement is not true of the other options.

Question 19

Which protein, absent in muscle cells of Duchenne muscular dystrophy, mediates the
anchoring of skeletal muscle fibers to the basement membrane?
a. Syntrophin c. Dystrophin
b. Laminin d. Troponin

Answer 19

ANS: C
Only dystrophin is present in normal muscle cells and absent in Duchenne muscular
dystrophy. Dystrophin mediates anchorage of the actin cytoskeleton of skeletal muscle
fibers to the basement membrane through a membrane glycoprotein complex.

Question 20

What pulmonary complication in children with Duchenne muscular dystrophy contributes
to their death?
a. Infection 
b. Kyphoscoliosis
c. Impaired formation of alveoli 
d. Cancer

Answer 20

ANS: A
Although the life expectancy of boys with Duchenne continues to rise, death usually
occurs from respiratory infection and a compromised respiratory system, with the majority
living into their middle 20s. Some individuals who have chosen ventilatory support live a
decade or more longer. This selection is the only option that is associated with the death
and pulmonary complications experienced by children with this diagnosis.

Question 21

Generally, what is the first symptom of facioscapulohumeral muscular dystrophy?

a. Inability to open the eyes completely
b. Difficulty standing
c. Drooping shoulders
d. Facial pain

Answer 21

ANS: C
As the name implies, clinical manifestations begin with weakness and atrophy of facial
and shoulder girdle (scapulohumeral) muscles. The illness progresses slowly. An inability
to close the eyes completely may be noted in early childhood. The face is expressionless,
and pouting of the lips makes whistling impossible. The first symptoms usually include
drooping of the shoulders with difficulty in raising the arms above the head. The onset of
weakness in the lower limbs is often delayed for 20 to 30 years, and pseudohypertrophy of
muscles is rare.

Question 22

What is the most common malignant bone tumor diagnosed during childhood?

a. Chondrosarcoma c. Ewing Sarcoma
b. Fibrosarcoma d. Osteosarcoma

Answer 22

ANS: D
Of the options available, osteosarcoma is the most common bone tumor that occurs during
childhood; it originates from bone-producing mesenchymal cells.

Question 23

Molecular analysis has demonstrated that osteosarcoma is associated with which gene?

a. TP53 c. myc
b. src d. TSC2

Answer 23

ANS: B

Of the options available, only the oncogene src has been associated with osteosarcoma.

Question 24

Osteosarcoma usually metastasizes to the:

a. Pancreas c. Lungs
b. Liver d. Brain

Answer 24

ANS: C
Osteosarcoma disseminates through the bloodstream, usually to the lung. As many as 25%
of children diagnosed with osteosarcoma exhibit lung metastases at diagnosis. This
statement is not true of any of the other options.

Question 25

A Ewing sarcoma arises from the:

a. Bone marrow
b. Bone-producing mesenchymal cells
c. Metadiaphysis of long bones
d. Embryonal osteocytes

Answer 25

ANS: A
Arising only from bone marrow, Ewing sarcoma can break through the cortex of the bone
to form a soft-tissue mass.

Question 26

Rhabdomyosarcoma can develop in which type of muscle?

a. Cardiac c. Involuntary
b. Smooth d. Striated

Answer 26

ANS: D
Rhabdomyosarcoma can develop anywhere striated muscle is located. This statement is
not true of the other options.

Question 27

Which organism is the primary cause of osteomyelitis in a newborn?

a. Staphylococcus aureus
b. Escherichia coli
c. Group B streptococcus
d. Bacillus anthracis

Answer 27

ANS: A
S. aureus is the primary cause of osteomyelitis in a newborn. Group B streptococcus and
E. coli infections are responsible for some cases, especially those of multiple bone
involvement and in high-risk infants. S. aureus is the responsible microorganism in 80% to
90% of osteomyelitis cases in older children. Bacillus anthracis (anthrax) is not associated
with osteomyelitis.

Question 28

What is the cause of structural scoliosis?

a. Poor posture
b. Vertebral rotation
c. Poor calcium absorption
d. Intrauterine trauma

Answer 28

ANS: B
Structural scoliosis is the curvature of the spine associated with vertebral rotation. No
research data suggest that any of the other options results in structural scoliosis.