CP10-3 Osteoarticular Pathology Flashcards
How is haemopoietic precursors related to age?
Haematopoeitic precursors are inversely proportional to age e.g. 10 year old you have haemopoietic precursors make up 90% of their bone marrow
How does the role of osteoblasts and osteoclasts differ?
Osteoclasts remove old bone and osteoblasts produce new bone
what are the main components of bone?
Proteins and calcium deposits
What percentage of bone proteins are type 1 collagen?
90%
What are the main proteins found in bone?
Type 1 collagen
Cell adhesion proteins
Calcium-binding proteins
Enzymes
Growth factors
Cytokines
Proteins concentrated from serum e.g. IGF
how are osteoblasts and osteoclasts affected by calcitonin and PTH?
Calcitonin causes osteoblasts to produce bone
Parathyroid hormone causes osteoclasts to break down old bone
What are 8 causes of bone disease?
- Defects in nuclear proteins and transcriptase factors e.g. polydactyl
What bone disease is caused by defects in hormones and signal transduction mechanisms?
Dwarfism (achondroplasia and thanatophoria)
What bone diseases are associated with defects in extracellular structural proteins?
Osteogenesis imperfecta with blue sclera
What mutations are associated with defects in extracellular structural proteins of bone?
Mutations in genes which code for alpha-1 and alpha-2 chains of collagen
Mutations of collagen 2, 10 and 11
What bone diseases are associated with defects in folding and degradation of macromolecules?
Mucopolysaccharidosis
Decrease in enzymes which degrade dermatan, heparan and keratan
Cartilage disorders causing short malformed chest wall bones
What is mucopolysaccharidosis?
A lysosome storage disease
What are bone diseases associated with defects in metabolic pathways?
Osteopetrosis
Carbonic a hydrate deficiency
Decreased osteoclasts resorption
What are examples of bone diseases associated with decreases bone mass?
Osteoporosis
What is osteoporosis?
When bone mass peaks in early adulthood and bone loss is accelerated.
What increases risk of developing osteoporosis?
Age
Physical activity
Estrogen withdrawl e.g. menopause
Nutrition
Genetics
What is an example of a bone disease associated with osteoclasts dysfunction?
Paget disease aka osteitis deformans
What are the three phases of Paget’s disease?
1) increased osteoclasts resorption
2) increased hectic bone formation by osteoblasts
3) osteosclerosis
What levels are elevated in patients with Paget’s disease?
Alkaline-phosphatase
Urine hydroxyproline
What are examples of bone diseases associated with abnormal mineral homeostasis?
Rikcetts and osteomalacia
Osteitis fibrosis cystica aka von Recklinghausen’s disease or brown’s tumour due to hyperparathyroidism
Renal osteodystrophy
What causes ricketts and osteo malacia?
Vitamin D deficiency
How does hyperparathyroidism affect the bone?
Causes brown’s tumour
Can cause osteitis fibrosis cystica aka Recklinghausen’s disease
What is renal osteodystrophy?
Any bone disorder which occurs due to chronic renal disease
What are examples of renal osteodystrophy?
Phosphate retention
Hypophosphataemia
Hypocalcaemia
Increased PTH
Increased osteoclasts
Metabolic acidosis as it releases hydroxyapatites from the bone matrix
What words are used to describe fractures?
Complete vs incomplete
Scolded vs open
Communited vs non-communited (splintered)
Displaced vs non-displaced
Pathogenic
Stress fracture
What are the three phases of fracture?
1) Haematoma in minutes to days by PDGF, TGF-beta, FGF
2) soft callus/pro-callus within a week
3) hard callus/bony callus after several weeks
What are 2 complications of fractures?
Pseudarthrosis
Infection especially in open (communicating) fractures
What causes osteonecrosis?
ISCHAEMIA due to:
Trauma
Steroids
Thrombus/embolism
Vessel injury e.g. due to radiation
Increased intra-osseous pressure causing vascular compression
Venous hypertension
What are other names of osteonecrosis?
Avascular necrosis
Aseptic necrosis
What causes osteomyelitis?
Pyogenic causes like staph, e.coli, pseudomonas and klebsiella which are introduced via hematogenous, contiguous or direct implantation.
TB
Syphilis
What is osteomyelitis?
Destruction of bone via inflammation usually due to infection
What occurs in bone in acute osteomyelitis?
An abscess of bone
What are complications of osteomyelitis?
Subperiosteal abscesses
Draining sinus
Joint involvement
What is sequestrum?
Dead bone
What is involucrum?
New bone