DISEASES

Question 1

most common disease of the growth plate

autosomal dominant

gene FGFR3, chrom 4

due to disorganized growth plate with premature sealing of the growth plate

Answer 1

achondroplasia

Question 2

a subtype of achondroplasia:

shortened proximal extremities with normally sized trunk

bowing of legs

lordotic posture

no change in longevity, intelligence or reproductive status

Answer 2

heterozygous achondroplasia

Question 3

deficiency in the synthesis of type I collagen

mutation in gene for coding alpha 1/alpha 2 chains

bone fragility and multiple fractures

joint, eyes, ears, skin and teeth, abnormal dentition, hearing loss, blue sclerae

Answer 3

osteogenesis imperfecta (brittle bone disease)

Question 4

decreased skeletal mass

primary(most common) and secondary types (diesase, diet, neoplasia, endocrine, drugs like heparin)

peak bone mass

additional risk factors:
genetic factors
physical activity
diet
hormonal status

bone loss most conspicuous in parts of skeleton containing abundant trabecular bone like femoral neck and vertebral bodies

***trabeculae thin and widely separated

Answer 4

osteoporosis

Question 5

lysosomal storage diseases

Answer 5

mucopolysaccharidoses

Question 6

aka marble bone disease due to deficient osteoclastic activity, both autosomal dominant and recessive forms

deposition of thickened, heavily mineralized bone

anemia, thrombocytopenia and neutropenia

bones lack medullary canals
erlenmeyer flask appearance

treated with bone marrow transplant

Answer 6

osteopetrosis

Question 7

increased osteoclastic activity and bone resorption followed by exuberant bone formation with overall increased bone mass

three phases
1st-osteoclastic activity and bone loss
2nd-mixed osteoclastic and osteoblastic proliferation
3rd-late osteosclerotic phase

mosaic pattern of cement lines

multifocal and solitary
spine, skull and pelvic bones affected
asymptomatic with pain

Answer 7

pagets disease of bone

Question 8

due to vitamin D deficiency or disturbance in metabolism

defective mineralization of bone with increase in unmineralized osteoid, referred to as rickets in children

rachitic rosary
bowing of legs

Answer 8

osteomalacia

Question 9

entire skeleton affected by increased bone resorption

decreased bone mass leading to fractures, skeletal deformities, and joint pain

primary(hyperplasia or adenoma) and secondary types(compensatory hypersecretion of PTH)

affects cortical bone most, cutting cone, brown tumor

not a true neoplasm and predisposes to pathologic fracture

Answer 9

hyperparathyroidism

Question 10

due to chronic renal disease, esp those on dialysis

multifactorial

• osteopenia
• osteomalacia
• secondary hyperparathyroidism
• growth retardation

acidosis leads to increase in RANK/RANKL pathway

Answer 10

renal osteodystrophy

Question 11

aka avascular necrosis

d/t:
vascular interruption
vessel injury
thrombosis or embolism
venous hypertension
increased intraosseous pressure
idiopathic

2 types of infarcts
subchondral
medullary

dead bone surrounded by necrotic adipocytes
***creeping substitution

Answer 11

osteonecrosis

Question 12

infection of the bone and marrow

most common etiologic agents are the pyogenic bacteria like staph aureus and myco tuberculosis

pyogenic OM caused by staph aureus as most common w/ salmonella too, assoc with sickle cell disease

chronic OM

• sequestrum
• involucrum
• draining sinuses
• pathologic fx

note**:brodie abcess and potts disease

Answer 12

osteomyelitis