Bone pathology Flashcards
What is periosteum? Give its functions
- Membranous tissues that covers the surfaces of bones
- Supplies blood to bones through small blood vessels
- Gives them sensory stim via nerves
- Grows and repairs bone by producing new bone cells
Describe the histology of compact bone
Periosteum as outer layer
- Circumferential lamellae lies behind
- Inbetween interstitial lamellae is osteons
- Osteons contains concentric lamella and at the centre of the osteons is the blood vessels
- Blood vessels can be found within central canals (vertical) or can be found within perforating canals (horizontal)
- Osteocytes are present in the lacunae (resorption or bone)
What is the difference between cortical and cancellous bone?
Cortical forms the outer layer of the skeleton and is dense
Cancellous occurs between the cortices and is spongy or trabecular
What special tests can be done at specialist level to test the bone biochemistry (asess bone remodelling)?
- Blood calcium
- Osteoblast or Osteoclast activity
- Parathryoid hormone
- Vit D assays
What is Osteogenesis imperfecta and how does it clinically present?
- Type 1 collagen defect
- Inherited and there are 4 main types
Clin features
- Weak bones , multiple fractures
- Can be ass with dentinogenesis imperfecta
What is Achondroplasia?
- Autosomal dominant developmental abnorm
- Poor endochondrl ossification
- Dwarfism
What is Osteopetrosis?
- Abnormal bone growth and high bone density (stone bone)
- Lack of osteoclst activity so failure to resorb
- lead to marrow obliteration
What is Fibrous dysplasia ?
- Uncommon gene defect in which bone is replaced by fibrous tissue mainly seen during active growth period
- May present as slow growing asymptomatic bony swelling under 20yrs
Can monostotic (single bone) or Polyostotic (many bones)
Give the radiological features of Fibrous dysplasia
- Variable appearances and can be describes as ‘ ground glass’ ‘orange peel’ ‘ fingerprint whorl’
- Margins tend to blend into adjacent bone
- Bone maintains approximate shape initially
- Becomes more radiopaque as lesion matures
Give the histology of Active Fibrous Dysplasia
- ‘Fibro osseous’
- Fibrous replacement of bone so contains cellular fibrous tissue where bone should be
What is rarefying osteitis ?
- Localised loss of bone in response to inflammation
- Aleays occurs secondary to another form of pathology most likely apical perio, periapicla granuloma or periapical abscess
What is Sclerosing osteitis?
- Localised increase in bone density in response to low grade inflammation
- Most common around apex of tooth with necrotic pulp - -ve sensibility testing
- May lead to external rr if chronic
What is Idiopathic osteosclerosis?
- Localised increase in bone density of unknown cause
- AKA dense bone island
- No bony expansion , no effect adjacent teeth, always aympt , premolar molar region
What is alveolar osteitis?
- AKA dry socket
- Severe pain , loss of clot and bony sequestrum after extraction
Give the aetiology of bone necrosis. (Why might it occur)
Osteomyelitis (rare endogenous infection)
- Acute or Chronic
Avascular necrosis
- Age related ischaemia
- Anti resorptive medication
Irradiation
- ORN
