Fetal Skeletal System Abnormalities Flashcards
What is amelia?
absence of one or more limbs
What is acromelia?
foreshortening of the bones of hand and feet
What is rhizomelia?
shortening of the proximal bones of the extremity
What is mesomelia?
shortening of the distal long bones of the extremity
What is micromelia?
shortening of both segments of the extremity
What is phocomelia?
absence of the long bone segments of an extremity so hand/foot arises from the shoulder/hip
What is hemimelia?
absence of a longitudinal segment of a limb (ex: radial aplasia, radial hypoplasia)
What is acheira?
absence of the hands
What is apodia?
absence of a foot or feet
What is acheiropodia?
absence of hands and feet
How many bones does each finger have? name them.
3 bones: proximal, middle, and distal phalanx
-thumb has two bones; proximal and distal phalanx
What is adactyly?
the congenital absence of fingers or toes
What is polydactyly?
more than 5 digits (more than 5 fingers or toes per hand or foot)
What is syndactyly?
- fusion of digits, tissue and or bone
- one of the most common congenital malformations of the limbs
What are the classifications of syndactyly that describe the severity?
- Simple syndactyly: involves soft tissue only and is classified as partial and complete
- Complex syndactyly: involves fusion of soft tissue and bone of adjacent digits
What is clinodactyly?
abnormal curvature of 4th and 5th digits following the angle of the palm of the hand (a radial angulation of a digit-typically involving the 5th finger, but can involve any or all digits)
What is ectrodactyly?
- lobster claw hand (split hand or foot malformation)
- a genetic disorder characterized by the complete or partial absence of some fingers or toes combined w/ clefts in the hands or feet resulting in a claw-like appearance
- may be isolated or may occur as a component of a syndrome w/ other malformations and characteristics
What is hitchhiker’s thumb?
refers to the hyperextension of the distal interphalangeal joint of the thumb. Seen in the diastrophic dysplasia.
What is diastrophic dysplasia?
- a rare disorder characterized by micromelia, talipes, cleft palate, micrognathia, scoliosis, short stature, earlobe deformities, and hand abnormalities.
- inherited in an autosomal recessive pattern, and the mutation has been mapped to the long arm of chromosome 5
What is a sandal gap?
excessive gap between the 1st and 2nd toe
What is a trident hand?
excessive gap between the 3rd and 4th fingers
What is rocker bottom foot (vertical talus)?
a congenital anomaly of the foot characterized by a prominent heel and a convex rounded sole
What is the ideal time for treatment for rocker bottom foot?
after 6 months but before the age of two
What happens if rocker bottom foot is left untreated?
painful skin conditions such as calluses (thick skin) an d possible skin ulcers can develop
What does surgery involve for treating rocker bottom foot?
realigning the bones and inserting pins to keep them in place
What is hammer toe and it’s cause?
- a deformity in which one or more toes bend downward instead of pointing forward
- may be congenital, but usually occurs over time due to wearing ill-fitting shoes, high heels or arthritis
What is hypoplasia of the thumb and great toes?
mild bilateral shortening of the distal phalanges and/or the first metacarpal or metatarsal
What is talipes equinovarus (clubfoot)?
- malformation of the bones of the foot; foot is most often inverted and rotated medially
- affected foot appears rotated internally at the ankle with eccentric between the calcaneus and tarsal bones
- 50% bilateral
- occurs in males more often than females
- associated with spina bifida
What is the cause of talipes?
-majority is idiopathic and an isolated finding
What is associated with talipes equinovarus (clubfoot)?
spina bifida
How is a diagnosis of clubfoot (talipes equinovarus) made?
may be made with a persistent abnormal inversion of the foot perpendicular to the lower leg
What is the best way to evaluate clubfoot in ultrasound?
identifying a sagittal view of the lower leg
How is the sonographic diagnosis of clubfoot made?
can be made when the metatarsals or the bottom of the foot lie in the same plane as the tibia and fibula
-it is important to see the deformity in multiple views with deferent positions of the extremity
What does dysplasia mean?
the abnormal development of a structure
*What is skeletal dysplasia?
term used to describe abnormal growth and density of cartilage and bone
How many types of skeletal dysplasias have been identified?
more than 271
What are the 4 most common skeletal dysplasias?
achondroplasia, achondrogenesis, osteogenesis imperfecta, and thanatophoric dysplasia
What is achondroplasia?
-results from decreased endochondral bone formation, which produces short, squat bones
What is the prognosis of achondroplasia?
-depends on the form
What is heterozygous achondroplasia?
- an autosomal dominant (inherited from one parent), has a good survival rate w/ normal intelligence and a normal life span
- health problems may include neurologic complications and rhizomelia
*What is the most common non-lethal skeletal dysplasia?
*heterozygous achondroplasia
What is homozygous achondroplasia?
- inherited from two parents, is considered lethal, with most infants dying shortly after birth from respiratory complications.
- with this form, sonographic findings are more severe and include a narrow thorax
When is rhizomelia typically detected?
-not until after 24 wks gestation, when a notable difference in gestational age measurements between the BPD and femur length is detected
*When are the sonographic features of achondroplasia evident?
-may not be evident until after 22 wks gestation
What are the sonographic findings of achondroplasia?
- macrocrania
- frontal bossing
- flattened nasal bridge
- micromelia (resulting from rhizomelia)
- trident hand
What is achondrogenesis?
-a rare, lethal condition caused by cartilage abnormalities resulting in abnormal bone formation and absent or hypomineralization of the skeletal bones
What are the sonographic findings of achondrogenesis?
- severely shortened limbs (micromelia)
- absent mineralization of the skull, spine, pelvis, and limbs
- macrocephaly and micrognathia
- polyhydramnios
*What is osteogenesis imperfecta?
- a rare disorder of collagen production leading to brittle bones
- commonly known as brittle bone disease, is a group of disorders that results in multiple fractures that can occur in utero
- 4 different types
What do the fractures come from in osteogenesis imperfecta?
-a result of decreased mineralization and poor ossification
How many types of osteogenesis imperfecta and what is the most severe?
- 4 different types
- Type II, a uniformly fatal form of osteogenesis imperfecta, is the most severe type
- Types I, III, and IV are typically diagnosed after birth
What are the sonographic findings of osteogenesis imperfecta?
- demineralization of the skull (recognized by a lack of posterior shadowing), transducer pressure can alter the shape of the skull
- multiple fractures
- bell shaped chest, the thoracic and abdominal circumference will be remarkably dissimilar leading to a bell-shaped chest
*What is thanatophoric (“death bearing”) dysplasia?
- *the most common lethal skeletal dysplasia
- shortened long bones take on a “telephone receiver” shape, as the diaphysis of the long bones will be bowed and have prominent metaphyseal ends
- the thoracic and abdominal circumference will be remarkably dissimilar, leading to a bell-shaped chest
- thorax remarkably narrow, resulting in hypoplasia of lungs, while abdomen appears prominent
- w/ advancing gestation, redundant soft tissue, especially on limbs, can also be noted
What is the best way/view to recognize thanatophoric dysplasia?
a sagittal view of the fetus
What is the prognosis of thanatophoric dysplasia?
fetuses typically die shortly after birth, succumbing most often to respiratory distress as a result of pulmonary hypoplasia
What are the sonographic findings of thanatophoric dysplasia?
- cloverleaf skull and macrocephaly
- hydrocephalus and frontal bossing
- depressed nasal bridge
- bell-shaped chest (narrow thorax)
- extreme micromelia
- polyhydramnios
- redundant soft tissue
What is radial ray defect?
- the partial to complete absence (aplasia) of the radius or underdevelopment (hypoplasia) of the radius
- usually associated with abnormalities of the bones in the wrist and thumb
- radius may be shortened, curved, or absent, often with hand in medial rotation
- associated with trisomy 13, trisomy 18, amniotic band syndrome, Holt Oram syndrome, and VACTERL syndrome
What is Ellen-van Creveld syndrome?
- also known as chondroectodermal dysplasia, is a rare skeletal dysplasia with an increased frequency in the Amish community
- it is inherited in an autosomal recessive pattern
- may present with a narrow thorax, causing pulmonary hypoplasia, and heart defects, the most common of which is atrial septal defect
What is the most common heart defect of the Ellis-van Creveld syndrome?
atrial septal defect
