-
Achondroplasia
- defect in cartilage growth
- FGFR3 point mutation (Chr. 4)
- autosomal dominant
- usually spontaneous mutation
-
Osteogenesis imperfecta
- impaired collagen type I synthesis
- osteoblast defect
- type II disease fatal early in life
-
Mucopolysaccharidosis
- lysosomal storage disorder
- buildup of SO32- in various cell types (GAG's)
- cause hepatosplenomegaly and skeletal deformities
- Type I = Hurler's (gargoylism) = a-L-iduronidase deficiency
- Type II = Hunter's = iduronate-2-sulfatase deficiency
-
Osteoporosis
- loss of bone mass
- difficulty bearing weight => fractures
- vertebral compression fractures => kyphosis
- 1o - age and menopause related
- 2o - hypercorticism, hyperparathyroidism, malnutrition
- estrogen and exercise important
-
Osteopetrosis (Albers-Schonberg)
- increased bone density
- osteoclast defect
- bone fractures easily despite increased density
- impaired hematopoeisis due to reduced marrow space => anemia
- cranial nerve compression from narrowed foramina
- AR = fatal
- AD = less severe
-
Paget's Disease (osteitis deformans)
- abnormal bone remodeling
- 3 stages: osteolytic, mixed, late phases
- (resorption, resorption + deposition => mosaic, deposition)
- possibly caused by paramyxovirus
- 85% polyostotic
- high blood alkaline phosphatase and urine hydroxyproline
-
Osteomalacia/Rickets
- soft bones due to poor matrix calcification
- Vit D deficiency
- adults = osteomalacia
- children = rickets
-
Rickets deformities
- pigeon chest
- late fontanelle closure
- rachitic rosary (string-of-beads appearance of ribs)
- Harrison groove - depression along diaphragm
- craniotabes - thin and soft parietal + occipital bones
-
Osteitis fibrosa cystica (von Recklinghausen)
- widespread osteolytic lesions
- giant cell granulomas (brown tumors) - multinucleated osteoclasts
- caused by hyperparathyroidism
- high alkaline phosphatase
-
Renal osteodystrophy
- osteomalacia secondary to renal disease
- renal failure => phosphate retention => hypocalcemia => increased PTH (2o hyperparathyroidism) => increased osteoclast activity
- renal failure => low vitamin D => low Ca2+ absorption => see above
- metabolic acidosis, Fe + Al deposits in bone
-
Serum analysis results:
normal Ca2+
normal PO33-
normal/low alkaline phosphatase
Which metabolic bone disease is most likely?
osteoporosis
-
Serum analysis results:
increased Ca2+
decreased PO33-
increased alkaline phosphatase
Which metabolic bone disease is most likely?
osteitis fibrosa cystica (von Recklingheusen)
-
Serum analysis results:
normal/low Ca2+
variable PO33-
normal/high alkaline phosphatase
Which metabolic bone disease is most likely?
osteomalacia/rickets
-
Serum analysis results:
normal Ca2+
normal PO33-
very high alkaline phosphatase
Which metabolic bone disease is most likely?
Paget disease (osteitis deformans)
-
Tuberculous osteomyelitis
- secondary to Tb infection located elsewhere
- vertebral bodies (usually T and L) = Pott's disease
-
Pyogenic osteomyelitis
- S. aureus most common
- can result in bone necrosis
- involucrum (bone sleeve) can form around necrotic area
- Brodie abscess = wall of granulation tissue formed
- group B Strep and E. coli in newborns
- Salmonella in sickle-cell patients
- Pseudomonas in IV drug users
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