Ch. 20 - Congenital bone/cartilage diseases Flashcards
Musculoskeletal system (MSK) is also known as what?
The locomotor system
Tissues involved in the musculoskeletal system?
osseous, muscular, connective
The musculoskeletal system integrates with what other system?
The nervous system
Congenital disorders?
Dystosis Dysplasia osteogenesis imperfect (O.I.) achondroplasia osteopetrosis
What is dysostosis?
Developmental anomaly of bone
Dysostosis includes what features?
Abnormal mesenchymal migration
Defective ossification of fetal cartilage
Dysostosis can either be ______ or part of a _____?
Sporadic (isolated)
syndromes
Dysostosis contains what kind of gene alterations?
homeobox gene alterations
The homeobox gene deals with what?
Structural development during embryologic development
This condition shows: 1) aplasia, 2) supernumary digits, and 3) abnormal fusion of bones.
dysostosis
Mutations that interfere with growth or homeostasis (dwarfism). (condition)
dysplasia
Dysplasia in bone called:
osteodysplasia
Dysplasia in cartilage called:
chondrodysplasia
Dysplasia in this context is ____ pre-cancerous?
NOT
A type of dysostosis that shows Sprengel’s Deformity, is idiopathic, and has congenital fusion of any 2 cervical vertebrae
Klippel -Feil syndrome
What is the MC congenital malformation of the limbs?
syndactyly
What is the ratio of live births showing syndactyly?
1:2000-3000 live births
Two features of digits that show up in dysostosis?
Syndactyly and
polydactyly
Osteogenesis imperfect (O.I.) is also known as what?
Brittle bone disease
O.I. has mutations of what?
Type 1 collagen (alpha1 or alpha2 chains)
The type of mutations in O.I. of collagen type 1 is _____ dominant.
autosomal dominant
Abnormal collagen in O.I. leads to what?
Premature breakdown
Abnormal extracellular matrix in O.I. affects what areas?
Eyes, inner ear bones, skin, joins, teeth
Type I O.I. life expectancy
Normal lifespan
Type II O.I. life expectancy
Lethal in uteral
Type II O.I. causes what to happen in utero?
Cerebral hemorrhage,
Respiratory failure.
When is type I O.I. diagnosed?
In childhood
What are common things associated with type 1 O.I.
Fractures, extremity bowing, scoliosis, ligamentous laxity (dislocations), hearing loss, short stature
Children with O.I. who have been treated with biophosphates (cyclical) show what sign on radiography?
Zebra stripe sign
What is the MC form of dwarfism?
Achondroplasia
How does achondroplasia lead to dwarfism?
Decreased cartilage synthesis leads to deceased growth plate expansion.
What inhibits the epiphyseal (growth plate) chondrocytes?
FGFR3 (Fibroblast growth factor receptor) mutation
What is the percentage of spontaneous achondroplasia?
75%
What is the percentage of autosomal dominant achondroplasia?
25%
What are some feature of those with achondroplasia?
Short proximal extremities, lower extremity bowing, frontal bossing,
mid-face hypoplasia (low nasal bridging)
The lollipop kids on “The WIzard of Oz” are which kind of dwarfism?
hypopituitary dwarfism
What are some other causes of dwarfism?
Turner syndrome
Hypothyroidism
Malnutrition
O.I.
What is the incidence of achondroplasia?
1:10,000
What are some features of the spinal column in achondroplasia?
hyperlordosis and kyphosis at birth
Bullet vertebrae
Scoliosis
Spinal stenosis
What other types of stenosis can occur in achondroplasia?
foramen magnum stenosis
Spinal canal stenosis
What can cause death in achondroplasia?
Brain stem compression
What else can be lethal with achondroplasia?
Cardiovascular abnormalities
What is the fatal type of dwarfism?
thanatophoric dwarfism
What is the incidence of thanatophoric dwarfism?
1 : 20,000 births
What happens in thanatophoric dwarfism?
Extremely small thorax and shortened long bones that lead to perinatal respiratory failure.
What is osteopetrosis?
A group of rare genetic disorders that decrease osteoclast-mediated bone reabsorption.
Osteopetrosis creates what?
Skeletal sclerosis or “stone-like” bone
Skeletal sclerosis in osteopetrosis can lead to what?
Increased fractures.
Besides increase fractures what other things happen with osteopetrosis?
formainal stenosis –> cranial nerve palsied
medullary cavity fills –> deranged hematopoies
In osteopetrosis, when the medullary cavity fills it also can lead to what?
hepatosplenomegaly Recurrent infections (anemia)
What is the treatment for osteopetrosis?
Stem cell replacement
What are some features on x-ray of osteopetrosis?
White bone because of no medulla and
Erlenmeyer flask deformity
