Embryology of the Fetal Skeleton:
Majority of musculoskeletal system forms from primitive
mesoderm arising from _____ cells that are embryonic connective
tissue These cells arise from different regions of the
body. Vertebral column and ribs arise from ____
Limbs arise from ___ plate mesoderm
mesenchymal
somites
lateral
Embryology of the Fetal Skeleton:
Formation of head more complex Cranial bones that
form roof and base of skull arise from ______ cells of primitive
mesoderm Facial bones arise from mesenchymal cells arising
from neural crest, which is _____ in origin
mesenchymal
ectodermal
Embryology of the Fetal Skeleton:
Skeleton initially appears as cartilaginous forms that later
undergo ossification Limb development begins ___ or ___ day
after conception with appearance of upper limb buds Lower
extremity development begins __ days later
26th or 27th
2
Embryology of the Fetal Skeleton:
Stages of development for upper and lower extremities are
same Lower extremity development continues to lag behind
upper extremities
...
Embryology of the Fetal Skeleton:
Limbs initially have ____ shape with ridge of thickened
ectoderm at apex of each bud Known as ___ _______ ____
Digital rays begin to differentiate from apical ectodermal ridge
through process of cell death of ridge between digits
paddle
apical ectodermal ridge
Embryology of the Fetal Skeleton:
Fingers distinctly evident by day ___, but still webbed
By ___ week of development, fingers longer Development
of feet and toes essentially complete by ____ week Soles of
feet turned inward at this time
49
eighth
ninth
Abnormalities of the Fetal Skeleton:
Skeletal ____ describes abnormal growth and density of cartilage and bone
______ occurs secondary to skeletal dysplasia and refers to
disproportionately short stature
dysplasia
Dwarfism
Abnormalities of the Fetal Skeleton:
Some skeletal dysplasias incompatible with life
Lethal forms characteristically extremely severe in prenatal
appearance, as with severe ______ Nonlethal skeletal
dysplasias tend to manifest in milder form
micromelia
Sonographic Evaluation of Skeletal Dysplasias:
1. Assess limb _____. All long bones should be measured. Skeletal
dysplasia suspected when limb lengths fall more than ___ standard
deviations below mean
2. Assess bone ____. Thickness, abnormal bowing or curvature,
fractures, and ribbonlike appearance should be noted.
shortening; two
contour
Sonographic Evaluation of Skeletal Dysplasias:
3. Estimate degree of ______. Decreased attenuation of bones with
decreased shadowing suggests ____mineralization. Special attention
should be focused toward assessment of cranium, spine, ribs, and long bones.
4.Evaluate thoracic _______ and ____. Long, narrow chest or
___-shaped chest may be indicative of specific dysplasias.
ossification; hypo
circumference and shape; bell
Sonographic Evaluation of Skeletal Dysplasias:
5. Survey for coexistent hand and foot anomalies, such as ____ and _____.
6. Evaluate face and profile for facial _____, _____ _______,
________, _________, or other facial anomalies that may be associated
with skeletal dysplasias.
talipes; polydactyly
clefts, frontal bossing, micrognathia, hypertelorism
Sonographic Evaluation of Skeletal Dysplasias:
7. Survey for other associated anomalies, such as hydrocephaly,
heart defects, and nonimmune hydrops.
...
Thanatophoric Dysplasia:
Is most common lethal skeletal dysplasia; occurs in 1 in
4,000 to 10,000 births Term thanatophoric comes from
Greek word thanatoos, meaning �____ _______� Two main
subdivisions are types I and II
death personified
What is the most common lethal skeletal dysplasia?
Thanatophoric Dysplasia
Thanatophoric Dyplasia:
Type I characterized by short, ____ femurs and ___ vertebral
bodies Type II characterized by ____, short femurs, flat
vertebral bodies, and _____ skull Most cases are sporadic
occurrences and the result of mutations in fibroblast growth factor
receptor 3 (_____) gene
curved; flat
straight; cloverleaf
FGFR3
Thanatophoric Dysplasia: Sonographic Features
Severe ____ especially of proximal bones (rhizomelia)
_____ deformity occurs as result of premature craniosynostosis
and may be associated with ACC ____ thorax with shortened
ribs
micromelia
Cloverleaf
Narrow
Thanatophoric Dysplasia:
Protuberant abdomen ______ ______(bulging
forehead) ________ (widely spaced eyes) Flat
vertebral bodies (platyspondyly) Severe polyhydramnios
Hydrocephalus Nonimmune hydrops
Frontal bossing
Hypertelorism
Achondroplasia:
Is most common nonlethal skeletal dysplasia; occurs in
2.53 of every 100,000 births
Results from decreased _____ bone formation
Produces short, ___ bones
Most commonly results from spontaneous ____ but can
transmitted in autosomal fashion
endochondral
squat
mutation
What is the most common nonlethal skeletal dysplasia?
Achondroplasia
Achondroplasia:
_________ achondroplasia, inherited from one parent
Has good survival rate Normal intelligence; Normal life
span Health problems may include neurologic complications
that may require orthopedic or neurologic _____ intervention
Heterozygous
surgical
Achondroplasia:
_________ achondroplasia, inherited from two parents
Considered ____, with sonographic findings more severe
Narrow thorax Most infants die shortly after birth from
respiratory complications
Homozygous
lethal
Achondroplasia: Sonographic Findings
Rhizomelia ____cephaly (large head) Trident
hands (short proximal and middle phalanges) _____ nasal
bridge Frontal bossing Mild ventriculomegaly may be
identified
Macro
Depressed
Achondrogenesis:
Is a rare, ____ skeletal dysplasia occurring in 1 in _____
fetuses Is caused by cartilage abnormalities that result in
abnormal bone formation and hypomineralization
lethal; 40,000
Achondrogenesis:
Two types of achondrogenesis: Type I (____-_____) and Type II
(_____-_____) Type ___ considered more severe; is transmitted
in autosomal-recessive mode Type ___ less severe, more
common; is result of spontaneous mutation
Parenti-Fraccaro; Langer-Saldino
I
II
Achondrogenesis:
Prognosis ___ Lethal abnormality with infants either
being stillborn or dying shortly after birth from pulmonary
_____
Grim
hypoplasia
Achondrogenesis: Sonographic Findings
Severe micromelia Decreased or absent ____ of
spine Macrocephaly (Large head) ___ trunk
Short thorax and short ribs _____ (small chin)
Polyhydramnios Hydrops possibly identified
ossification
Short
Micrognathia
Osteogenesis Imperfecta:
Rare disorder of ____ production leading to: Brittle
bones Manifestations in teeth, skin, ligaments
____ sclera Four classifications, types
I to IV Types I and IV ____ forms; unlikely that diagnosis
made in utero
collagen
Blue
mildest
Osteogenesis Imperfecta:
Types I and IV transmitted in autosomal-dominant fashion
Type III is ____ form transmitted in autosomal-dominant or
autosomal-recessive manner
severe
Osteogenesis Imperfecta:
Type II considered most severe form; ____
outcome Prevalence of 1 to 2 per 100,000 births Is
inherited in autosomal-dominant or recessive fashion or may result
from spontaneous mutation
lethal
Osteogenesis Imperfecta:
Prognosis depends on type Children with types I and
IV may be short and have multiple _____ during childhood
fractures
Osteogenesis Imperfecta:
Has presented with ____ nuchal translucency in first trimester of pregnancy
increased
Osteogenesis Imperfecta Type II: Sonographic Features
Generalized _____ of bones, especially calvarium
Multiple _____ of long bones, ribs, and spine Narrow
thorax Micromelia Sonographic features of
osteogenesis imperfecta type III similar to those of type II, but
less severe
hypomineralization
fractures
Congenital Hypophosphatasia:
Condition that presents with diffuse hypomineralization
of bone caused by ____ ____ deficiency Occurrence rate is
1 per 100,000 births Inherited condition transmitted in
autosomal-recessive manner
alk phos
Congenital Hypophosphatasia:
May have features similar to osteogenesis imperfecta and
achondrogenesis Diagnosis confirmed with alkaline phosphatase
assay, achieved through: Fetal blood sampling
Chorionic villus sampling DNA analysis
...
Congenital Hypophosphatasia:
Lethal disorder Death usually occurs shortly after
birth as result of _______ complications
respiratory
Congenital Hypophosphatasia: Sonographic Features
Diffuse hypomineralization of bones Moderate to
severe micromelia Extremities that may be bowed, fractured,
or ___ Poorly ossified _____ with well-visualized brain
structures Small thoracic cavity
absent
cranium
Diastrophic Dysplasia:
Very rare disorder characterized by:
Micromelia _____ (clubbed feet) Cleft
palate ______ (small chin) Scoliosis
Short stature Earlobe deformities Hand
abnormalities
Inherited in autosomal-recessive pattern
Talipes
Micrognathia
Diastrophic Dysplasia:
Micromelia Talipes Fixed ____ thumb
(hitchhiker thumb) Scoliosis Talipes
(clubfoot) Micrognathia (small chin) Cleft
palate
abducted
Camptomelic Dysplasia:
Camptomelic dysplasia is known as ___ bone. Is a
group of _____ (lethal or non lethal?) skeletal dysplasias
characterized by bowing of long bones This ____ (rare or
common?), short-limbed dysplasia occurs in 1 per 150,000
births. Most cases occur as spontaneous mutation
Also inherited in autosomal-recessive pattern
bent
lethal
rare
Camptomelic Dysplasia:
Lethal anomaly Most infants die in neonatal period
because of pulmonary _____ Infants surviving neonatal
period usually die within first year of life
hypoplasia
Camptomelic Dysplasia:
Bowing of long bones with ____ extremities affected most
severely Small thorax Hypoplastic fibulas &
scapulae Hypertelorism (wide set eyes) Cleft
palate Micrognathia (small chin) Talipes (club
feet) Hydrocephalus Polyhydramnios
Hydronephrosis
lower
Roberts' Syndrome:
Rare condition characterized by _____ and ____ anomalies
Autosomal-recessive disorder Also known as _______
syndrome May present with associated chromosomal
abnormalities
phocomelia; facial
pseudothalidomide
Roberts' Syndrome:
Prognosis ___ Stillbirth and infant mortality
common Survivors are growth-restricted and have severe mental
retardation
poor
Roberts' Syndrome: Sonographic Findings
Phocomelia, with upper extremities more severely affected
_____ cleft lip and palate ______ (wide set eyes)
______ (small head) Cardiovascular, renal, and GI
anomalies may be identified
Bilateral
Hypertelorism
Short-rib Polydactyly Syndrome:
____ skeletal dysplasia characterized by short ribs, short
limbs, and polydactyly Prevalence of 1 in 200,000
births Four primary types defined Is inherited in
autosomal-recessive manner Lethal; Most infants die shortly
after birth as a result of pulmonary hypoplasia.
Lethal
Short-rib Polydactyly Syndrome:
Type I, or Saldino-Noonan syndrome Type II, or
Majewski syndrome Type III, or Naumoff syndrome
Type IV, or Beemer-Langer dysplasia
...
Short-rib Polydactyly Syndrome: Sonographic Findings
Narrow thorax with short ribs Polydactyly
Micromelia Midline facial cleft Anomalies of
CNS, cardiovascular, and GI Polyhydramnios may be
identified.
...
Jeune's Syndrome:
Is known as _______ _____ ________
Is a skeletal dysplasia characterized by very narrow
thorax Prevalence is 1 in 100,000 to 130,000 births
Is inherited in autosomal-recessive manner
asphyxiating thoracic dysplasia
Jeune's Syndrome:
Two types have been described Has a range of
severity Most severe form results in death because of
pulmonary hypoplasia, caused by narrow thorax
...
Jeune's Syndrome: Sonographic Findings
Small thorax Rhizomelia Renal dysplasia
Polydactyly (less common)
...
Ellis-van Creveld Syndrome:
Is also known as _________ dysplasia Prevalence is 1
in 60,000 births Increased frequency in _____ community
estimated to be up to 1 in 5000 births Is inherited in
autosomal-recessive pattern
chondroectodermal
Amish
Ellis-van Creveld Syndrome:
May present with: Narrow thorax, causing pulmonary
hypoplasia Heart defects, the most common of which is
____ ____ defect (ASD) Approximately ____
will die during infancy from cardiorespiratory complications
atrial septal defect
one half
Ellis-van Creveld Syndrome:
Other features identified include: Abnormal ____
Hypoplastic nails ___ hair
Survivors have normal intellect and ____ stature.
teeth
Thin
short
Ellis-van Creveld Syndrome:
Limb shortening Narrow thorax
Polydactyly Heart defects (50%)
...
Caudal Regression Syndrome/ Sirenomelia:
Includes range of malformations of ___ end of neural tube
Sirenomelia is anomaly in which there is ____ of lower
extremities
caudal
fusion
CRS/ Sirenomelia:
Sirenomelia had been considered an extreme form of CRS but is
currently thought to be separate disorder. Overall
incidence of CRS unknown Incidence of sirenomelia reported
to be 1 in 60,000 births, with ____ prevalence of 2.7 to 1
male
CRS/ Sirenomelia:
Vascular hypoperfusion is thought to be a causative factor in
sirenomelia, with a ____ umbilical artery commonly associated that
may divert blood flow to the caudal end
Is associated with monozygotic twinning and ____ use
single
cocaine
CRS/ Sirenomelia Sonographic Findings:
____ agenesis Talipes Abnormal lumbar
vertebrae, pelvic abnormalities, contractures, or decreased movement
of lower extremities
Sacral
Sirenomelia Sonographic Findings:
Variable ____ of lower extremities Bilateral ____
agenesis Oligohydramnios ____ umbilical artery
fusion
renal
Single
VACTERL association is group of anomalies that may
occur together
Vertebral defects
Anal atresia
Cardiac anomalies
Tracheoesophageal fistula
Renal anomalies
Limb dysplasia
...
VACTERL:
For VACTERL association to be considered, ___ features
must be identified Single umbilical artery may be
identified When VACTERL association seen with accompanying
_____, condition termed VACTERL-H syndrome
VACTERL association with concurrent sirenomelia has been
reported
three
hydrocephalus
Postural Anomalies:
Normal development of fetus requires movement
Multiple events can cause _____ in fetal movement
Oligohydramnios Multiple gestations
Congenital uterine anomalies
decrease
Postural Anomalies:
Decreased movement may be due to abnormality of fetal ____,
connective tissue, or musculature These conditions not only
decrease fetal movement but also may result in abnormal contractures
and postural deformities.
nerves
Arthrogryposis Multiplex Congenita:
Condition marked by severe contractures of extremities because
of abnormal innervation and disorders of ____ and connective
tissue Represents group of disorders that may be inherited or
sporadic
muscles
Arthrogryposis Multiplex Congenita:
Rigid extremities ___ arms Hyperextension of
knees ____ hands Talipes (club feet)
Flexed
Clenched
Arthrogryposis Multiplex Congenita:
Polyhydramnios or oligohydramnios may accompany this
condition, as can anomalies of CNS Other associated defects
include facial and renal anomalies Fetal ____ have also
been noted.
seizures
Pena-Shokeir Syndrome:
Is characterized by: Abnormal joint contractures
____ abnormalities Polyhydramnios
IUGR Pulmonary hypoplasia
Facial
Pena-Shokeir Syndrome:
Inherited in autosomal-recessive manner or sporadic
occurrence Pena-Shokeir syndrome and trisomy___ have similar
features, so karyotyping should be offered.
18
Pena-Shokeir Syndrome: Sonographic Findings
Limb abnormalities (contractures, clinched hands, talipes,
____-____ feet) Facial abnormalities (micrognathia and
cleft palate) Polyhydramnios and hydrops may be
identified.
rocker-bottom
Miscellaneous Limb Abnormalities:
Hand and foot abnormalities may occur with skeletal
dysplasias, either as part of chromosomal syndrome or as an isolated
event.
Amputation defects may be identified as total or partial
absence and may be associated with ______ ____syndrome.
Congenital absence of one or more extremities (amelia) may be
observed prenatally.
Amniotic band syndrome
Misc. Limb Abnormalities:
Radial ray defects include hypoplasia or aplasia of ____ and
____ Are associated with chromosomal anomalies, such as
trisomies __ and __ and VACTERL association
radius and thumb
13 and 18
Misc. Limb Abnormalities:
Numerous syndromes have presented with absent or hypoplastic
radius and thumb Holt-Oram syndrome
Thrombocytopenia with absent radii (TAR) syndrome
Ulnar ray anomalies can occur.
...
Club Foot:
Clubfoot, also known as ____, describes deformities of foot
and ankle Occurs in approximately 1 to 3 in 1000 live
births ____ predominance; half of cases of clubfoot _____
(uni or bi?)
talipes
Male; unilateral
Rocker-bottom Foot:
Rocker-bottom foot characterized by prominent ___ and convex
sole Is associated with multiple syndromes and chromosomal
anomalies, especially trisomy __
heel
18