What is bone remodelling?
Bone remodelling is the coordinated balance between bone formation and bone resorption and is regulated by systemic hormones and local cell mediators.
Which hormones, growth factors and interleukins affect osteoblast activity?
Hormones: - Parathormone - Insulin - Growth Hormone - Oestrogens, androgens - Calcitonin - Bone morphogenic proteins Interleukins and growth factors: - PDGF - FGF - IL-1 - TNF - TGF-ß
Which hormones, growth factors and interleukins affect osteoclast activity?
Hormones: - Parathormone - PTHRP - Thyroxine - Glucocorticoids - Vitamin D Growth factors and interleukins: - Prostaglandins, kinins - GMCSF - MCSF - PDGF - IL-1, IL-3, IL-6 - TNF - TGF-a
Explain the stages of fracture healing.
- Within first few hours haematoma and acute inflammation
- Organisation of haematoma and granulation tissue
- Primary callus response - differentiation of osteo progenitor cells into bone forming cells.
- External bridging callus - bone formation bridges the gap where the fracture site is
- Remodelling several months afterwards. The callus formation is reduced to reshape and streamline the bone to what it was before.
Describe the histological appearance of a callus.
Large osteoblast cells present with pink osteoid.
In what situations is cartilage formed following a fracture instead of bone?
When there is poor blood and oxygen supply e.g. in elderly patients or a distal limb fracture and when there has been incomplete immobilisation.
List 5 local early complications of fractures.
- Infection (compound/open fractures, poor aseptic technique, metal prosthesis)
- Blood loss from haemorrhage (major long bone fracture or multiple fractures)
- Dislocation of joint.
- Skin loss and soft tissue injury.
- Damage to nerves and vessels.
List 5 local delayed complications of fractures.
- Damage to the epiphyseal plates.
- Avascular necrosis of bone.
- Secondary osteoarthritis.
- Delayed union.
- Non-union.
List 8 systemic complications of fractures.
- Cardiac shock and circulatory failure.
- Fat embolus
- DVT or PE
- Respiratory Distress Syndrome
- Pneumonia
- Sepsis
- Bed sores
- DIC
List 11 factors that impair healing of a fracture.
- Age
- Malnutrition
- Diabetes
- Cancer
- Radiotherapy
- Soft tissue injury
- Compound fracture
- Large fracture gap.
- Poor immobilisation
- Infection
- Ischaemia
Describe treatment issues regarding bone infection.
- Poor blood supply
- Inefficient antibiotic uptake into bone
- PREVENTION is important
What is the presentation of acute osteomyelitis.
Septic process - raised WCC, pyrexia, toxaemia.
Seen in young children and babies so differential of ‘crying child’
