LO: Describe normal bone growth, normal fracture healing and abnormal healing

Bone

• Mechanical support
• Transmission of forces generated by muscle
• Protection
• Calcium homeostasis
• Haematopoiesis
• Physis - growth plate
• Epi - above, dia - along, meta - middle
• Woven bone - immature
• Lamellar bone - mature

Bone growth

1. Activation
2. Resorption
3. Reversal
4. Formation
5. Termination
6. Quiescence

Fractures

• Simple
• Compound - fracture pierces skin
• Comminuted - 3 or more pieces
• Displaced - non-continuous bone
• Stress
• Green-stick - partial fracture where bone bends
• Pathological

Normal fracture healing

1. Day 0-1: Haematoma - blood swell
2. Day 1-week 2: Osteoclasts, osteoblasts, fibrin meshwork
3. Week 2-3: Bony callus, endochondrial ossification, hyaline and fibrocartilage
4. Week 3-months: Remodelling (lamellar bone)

Impaired healing

• Inadequate immobilisation
• Extensive trauma
• Avascular necrosis
• Bone loss, irradiated bone, pathological fractures, metabolic bone disease
• Space or tissue between fragments
• Infection
• Intra-articular fracture
• Age
• Drugs

Osteonecrosis

• Ischaemic necrosis of bone/bone marrow
• Fracture, steroids, alcohol, sickle cell anaemia and the bends
• Osteoarthritis and fracture are major complications

Osteomyelitis

• Infection of bone/bone marrow
• Bacterial usually
• Staphylococcus aureus
• Bone pain and systemic signs of infection
• Lytic focus on x-ray with surrounding sclerosis (bright)
• Blood or bone culture