Ch 20 Part 1 Flashcards
Osteonecrosis
bone death; avascular necrosis due to trauma
Osteomyelitis
bone marrow infection
Dysostosis
developmental anomaly of bone
Homeobox gene
structural development during embryonic development (tends to be regionalized)
Klippel-Feil Syndrome
Failure of cervical vertebrae to develop into 7 vertebrae
idiopathic congential fusion of any two cervical vertebrae
What is the name of the deformity that is often associated with Klippel-Feil Syndrome?
Sprengel’s deformtity
What is sprengel’s deformity?
fusion of scapula to the transverse process
What are some other associated findings with dysostosis?
Aplasia, supernumerary digits, and abnormal fusion of bones
What is aplasia?
absent or incomplete development with abnormal function
In association with dysostosis, where does abnormal fusion of bones usually occur?
usually in the digits
Dysplasia
mutations interfere with growth or homestasis (dwarfism)
Dysplasia of bone is termed?
osteodysplasia
Dysplasia of cartilage is termed?
chondrodysplasia
Osteogenesis Imperfecta is also called
Brittle bone disease
What type of collagen is mutated by Osteogenesis Imperfecta?
Type I
What chains of type I collagen are mutated in Osteogenesis Imperfecta?
Alpha 1 and Alpha 2 chains
What happens to the abnormal collagen suffering from Osteogensis Imperfecta?
it leads to premature breakdown
Is Osteogenesis Imperfecta autosomal recessive or dominant?
autosomal dominant
What structres are typically affected by Osteogenesis Imperfecta?
bones, eyes, teeth, inner ear bones (often leads to deafness), skin, and joints
What type of Osetogenesis Imperfecta is lethal in utero?
Type II
When is Type I Osteogenesis Imperfecta diagnosed?
in childhood
What are some common features associated with Type I O.I.?
fractures, etremeity bowing, scoliosis, ligamentous laxity, hearing loss, short stature
What is Zebra Stripe Sign?
it is associated with children who have Type I O.I. who have been treated with bisphosphonates and appears on X-ray in a zebra stripe fashion
What is the most common form of dwarfism?
Achondroplasia
A decrease in growth plate expansion is referred to as
Achondroplasia
What mutation leads to achondroplasia?
Fibroblast growth factor receptor (FGFR3)
What does the mutation of FGFR3 cause?
decreased cartilage synthesis and inhibited epiphyseal chondrocytes
About what percentage of Achondroplasia is caused by an autosomal dominant mutation of FGFR3?
25%
List some physical features associated with achondroplasia
short proxial extremities, lower extremity bowing, frontal bossing, midface hypoplasia
To be considered a dwarf, you must be this height or shorter?
4’10” (147cm)
Describe the spinal features of Achondroplasia
bullet vertebrae, hyperlordosis or kyphosis at birth, scoliosis, and spinal stenosis
What parts of the vertebral column become stenotic with achondroplasia?
foramen magnum and spinal canal
What can spinal stenosis of achondroplasia lead to?
possible brain compression or cardiovascular abnormalities (may be lethal)
Describe Thanatophoric dwarfism?
Fatal: extremely small thorax and short long bones
perinatal respiratory failure
What else can OsteoPETROSIS be called?
marble bone disease or Albers-Schonberg disease
What is the main identifier of Osteopetrosis?
decreased osteoclast-mediated bone resoprtion
In other words, excessive over-mineralization of bone leads to brittleness
What is the other main feature of osteopetrosis?
skeletal sclerosis (“stone-like” bone) which leads to increases in fractures
Foraminal stenosis of ostepetrosis can lead to?
cranial nerve palsies
What does the medullary cavity fill with in osteopetrosis?
deranged hematopoiesis
What can deranged hematopoiesis of osteopetrosis lead to?
hepatosplenomegaly, recurrent infections, and anemia
What is the treatment for osteopetrosis?
stem cell replacement
List some typical X-ray features associated with osteopetrosis?
bright white appearance due to overly dense bone, lacking medulla in long bones, and Erlenmeyer flask deformity
What do fractures of osteopetrosis look like on X-ray?
“chalk-stick fracture”
What type of bone is most impacted by osteoporosis?
trabecular bone (cancelous spongy)
What are some common bones affected by osteoporosis?
vertebral bodies, femoral neck, calcaneus
A decrease in bone density leads to an increase in
porosity
What T-score determines a major fracture risk?
2.5 SD and above
What is primary Senile osteoporosis?
age-related osteoporosis
What is the other form of primary osteoporsis?
Postmenopausal
A decrease in growth factor equals a decrease in osteoblast ativity, with normal osteoclast activity describes what?
Senile osteoporosis
Around what age does bone loss of .5% each year begin?
mid 20’s
A decrease in estrogens accelerating bone loss describes
Postmenopausal osteoporosis
What are the three factors that determine peak bone mass?
physical activity, genetic factors, and nutrition
Describe how one may maximize bone desnity in young adulthood.
Diet, regular exercise (resistance training, athletics), Ca+ and Vit. D supplementation
List some common risk factors for osteoporosis
Increased age, sedentary lifestyle, family history, malnutrition, and malsbsorption
What are some common fractures typically associated with osteoporosis?
vertebral compression fractures,and femoral neck fractures
A vertebral compression fracture as a result from osteoporosis in the thoracolumbar region leaves one at risk for
pneumonia
A femoral neck fracture as a result of osteoporosis leaves one at risk for
pulmonary emboli
What is the preferred method for diagnosing osteoporosis?
DEXA scan, or bone density scan
What is the required bone percentage loss to have osteoporosis?
30-40% bone loss
List some ways one can prevent osteoporosis
physical activity prior to age 30, Ca+ and Vit. D supplementation, and pharmacological agents
Bone in Paget’s Disease appears to have a _____ appearance
“shaggy”
In short, describe how Paget’s disease affects bone
regional osteoclast activity
excessive bone formation which leads to disorganized lamellar bone with greater bone mass, but is weakened
How is Paget’s disease diagnosed?
serum testing to determine if alkaline phosphatase levels are eleavted (byproduct of osteoblast activity)
Bone in Paget’s disease is said to be in this pattern
mosaic or “jigsaw” pattern
In Idiopathic Paget’s disease, what antigens are attached on osteoclasts?
Paramyxoviridae
What percentage of Idiopathic Paget’s diease is asymptomatic?
70-90%
How is Idiopathic Paget’s Disease diagnosed?
through incidental X-ray findings
What is the MC (most common) feature of Idiotpathic Paget’s disease?
neck and back pain
What is an “ivory vertebra sign”?
On x-ray findings a vertebral body appears very white in comparison to the others
What three ailments is an “ivory vertebra sign” indicative of?
Paget’s disease, metastatic cancer, and lymphoma
