W28-L7: Bone Pathology Flashcards
What is the role of the osteocyte canaliculae?
Straw through which they gain nutrients
What cells are osteoprogenitor cells?
mesenchymal stem cells which can proliferate and differentiate into osteoblasts
What lineage do osteoclasts come from?
Monocyte lineage
What expresses OPG and RANK-L?
Osteoblasts
What is intramembranous ossification?
Mesenchymal cells differentiate into osteoprogenitor cells
and start producing osteoid
What do osteoblasts secrete to build bone?
Collagen and secretory vesicles containing alklaline phosphatase
What are the various fracture types?
- Complete vs incomplete
- Displaced
- Open vs closed
- Comminuted (2 separate bone fragments)
- Stress
- Pathological
What are the stages of fracture healing?
4 stages which include: 1. inflammatory
2 & 3. Reparative which is soft then hard callus
4. Remodelling phase
What is involved with the inflammatory phase of bone healing?
- Haematoma formation with a framework of fibrin
- Granulation tissue formation
- first few days
What is involved with the soft callus phase of bone healing?
Cartilage formation which holds the fractured ends together but no structural rigidity,
Periosteum repairs itself over the outside
-days to weeks
What is involved with the hard callus phase of bone healing?
soft callus mineralises and becomes hard via endochondral ossification producing a thickened area of woven bone
-weeks to months
What is involved with the remodelling phase of bone healing?
woven bone to lamellar bone
-Months to years
What happens if the ends are closely apposed?
May not need the soft callus at all and healing will be faster
What is union?
to unite the broken ends to allow bone healing to occur as fast as possible
What are some factors that slow healing?
Age, comorbities, medications, nutrition, fracture type, trauma
What is non-union?
A fracture which will not heal, no matter how long you persist with primary management
What is delayed union?
A fracture which is not healing as fast as expected
What is mal-union?
Healing of a bone in an unacceptable position
What is osteomyelitis?
Infection of bone, usually S. aureus, is very serious and can cause sepsis
What is Osteonecrosis?
Fractures can interrupt the blood supply and leave part of the bone ischaemic eg NoF or scaphoid
What is osteoporosis?
Reduced mass of otherwise normal bone
What is Paget’s disease?
Large, overactive osteoclasts so Osteoblasts produce more bone which eventually produces too much
What is osteomalacia?
Vit. D deficiency in adults which causes impaired bone mineralisation
What is Rickets?
Vit. D deficiency in children
What is Hyperparathyroidism?
Increased PTH that causes Increased osteoclastic activity
What are causes of Hyperparathyroidism?
- Primary: parathyroid hyperplasia or tumour
- Secondary: prolonged hypocalcaemia or hyperphosphataemia
What are the types of bony metasises?
Osteolytic and osteosclerotic
