fetal musculoskeletal pt1 Flashcards
When can most of the fetal bones be imaged?
15-16 wks
What is the name for the arms and legs (including long bones)?
Appendicular skeleton (extremely long bones, metacarpals, metatarsals, phalanges can all be seen and are well ossified by 2nd trimester)
What bones are not ossified until after birth and therefore cannot be seen?
carpals
(exception, is calcaneus which ossifies by 5th and 6th month)important in seeing Club Foot deformity
The scapulae and clavicles can be seen. What does the clavicular length roughly correlate with?
gestational age of fetus
Name the upper extremity bones?
humerus, radius (thumb side), ulna(pinky side)
Name the lower extremity bones?
femur (measured as part of 4 biometrics), tibia (medial and larger), fibula (could remove to lose weight :)
What is the name for the cranium, face, spine, and pelvis?
axial skeleton
What are the facial bones?
orbits, maxilla (upper jaw), mandible (lower jaw), osseous nasal septum
When can the iliac ossification centers be seen? What about the ischial ossification centers?
early second trimester, about 20 weeks
What are the two classification methods that exist for skeletal disorders?
one accounts for gene and protein defects, the other is based upon embryonic pattern of limb abnormalities
Can environmental factors alter embryologic differentiation causing limb malformations?
Yes, exposure to drugs, hormones, viral infections, radiation, and hyperglycemia in the mother
What are the 3 distinct characteristics of lethal dysplasias?
Severe micromelia, severely hypoplastic thorax, and the identification of a Specific Feature of the lethal dysplasia.
When a long bone measures more than 4 standard deviations below the mean? FL/AC less than .16 helps define the degree of shortness as severe.
Severe micromelia
When the thorax is severely hyperplastic, the lungs can’t develop? (no survival) Thoracic circumference less than the 5th percentile for gestational age.
Severely hypoplastic thorax
What is an example of a Specific Feature of lethal dysplasia?
multiple fractures in utero indicate osteogenesis imperfecta type II (lethal form)
Most common lethal dysplasia? Three leaf clover skull.
Thanatophoric dysplasia
A rare lethal form of short limbed dyplasia with a lack of vertebral ossification-(KEY)?
AchondroGenesis
Which type of AchondroGenesis is more severe? (20% of all cases)
Type 1
Which type of AchondroGensis is less severe and autosomal dominant? (80% of all cases)
Type 2
What type of Osteogenesis imperfecta is the lethal form?
Type 2 is lethal
Lethal dysplasia with Abnormally fragile bones, fractures in utero, bones look really thick, disorder of production of collagen
Osteogenesis imperfecta type II
Lethal dysplasia with Rare bone demineralization-(KEY) disorder due to low levels of serum and tissue alkaline phosphatase
Congenital hypophosphatasia
Lethal dysplasia with bent/bowed bones (most commonly tibia and femur) sometimes referred to as “telephone receiver” deformities
Camptimelic dysplasia
Lethal short limb dysplasia characterized by rhizomelia dwarfism
Homozygous dominant achondroplastic dwarfism
Lethyl dysplasia characterized by polydactyly (many digits)
Short rib polydactyly syndrome
In all of these lethal syndromes they are similar in that they all have what?
short extremities, and small thoracies (BUT there is one particular feature in each to guide us to which disease it is)
LETHAL DYSPLASIA
- ) Thanatophoric dysplasia/dwarfism
- ) AchondroGenesis
- )Osteogenesis imperfecta type II
- )Congenital hypophosphatasia
- )Camptimelic dysplasia
- )Homozygous dominant achondroplastic dwarfism
- )Short rib polydactyly syndrome
THE ONE DEFINING FEATURE
- ) most common/ 3 leaf clover skull (Kleeblattshcadel)
- ) lack of vertebral ossification
- ) fractures in utero/bones look thick
- ) bone demineralization
- )bent/bowed bones/ telephone receiver
- ) rhizomelia dwarfism
- ) polydactyly (many digits)
