Chronic Inflammation

Question 1

Define chronic inflammation

Answer 1

A physiological response to injury:
- persistent and lacks resolution when inflamed tissue cannot overcome the effects of the injury
- persists for weeks, months, years with ongoing tissue damage
- characterised by infiltrates of lymphocytes, plasma cells and macrophages

Question 2

What circumstances can result in chronic inflammation?

Answer 2

• acute inflammation which has progressed to chronic inflammation
• initial response to certain viral/fungal infections

Question 3

What cells are involved in chronic inflammation?

Answer 3

• macrophages
• plasma cells (major anti-body producing)
• lymphocytes

Question 4

Describe granulomatous inflammation

Answer 4

• distinctive pattern of chronic inflammation
• predominated by activated macrophages with modified appearances which cluster and giant cells (from fused epithelial macrophages) = fusion forms granulomas which tend to be surrounded by inflammatory cells
• necrosis can occur in infective cases eg. Caseous necrosis in TB

Question 5

List some causes of chronic inflammation

Answer 5

• infection eg. TB
• foreign material eg. Retained suture material from a surgery
• sarcoidosis, Crohn’s disease
• response to tumour eg. HL

Question 6

Describe what occurs in the phases of healing

Answer 6

• formation of blood clot at site of wound
• formation of granulation tissue (starts as fibrin from chronic inflammatory cells, fibroblasts then migrate to area and lay down plug of immature granulation tissue)
• cell proliferation and collagen deposition (maturation occurs)
• scar formation
• wound contraction
• connective tissue remodelling
• recovery of tensile strength

Question 7

What are the 3 phases of fracture healing?

Answer 7

• inflammation
• repair
• remodelling

Question 8

Describe the inflammatory phase of fracture healing

Answer 8

• haematoma forms at site of fracture
• prostaglandins recruit neutrophil polymorphs, macrophages, lymphocytes and fibroblasts to site of injury
• granulation tissue, ingrowth of new vessels, mesenchymal cell migration
• nutrients and O2 are supplied to exposed bone and muscle

Question 9

Describe the repair phase of fracture healing

Answer 9

• fibroblasts lay down stroma to support ingrowing vessels
• collagen matrix is laid down
• osteoid is secreted and mineralised leading to soft callus formation
• callus ossifies in 4-6 weeks forming bridge of woven bone between fracture fragments

Question 10

Describe the remodelling phase of fracture healing

Answer 10

• occurs slowly over months/years
• returns bone to original shape, structure and mechanical strength

Question 11

What factors affect wound healing?

Answer 11

Local:
- type, size and location of wound
- movement with wound
- infection
- presence of foreign/necrotic material
- irradiation
- poor blood supply

Systemic:
- age
- nutrition
- systemic disease eg. Diabetes
- drugs
- smoking