6)Osteoarthritis

Question 1

Primary risk factors

Secondary risk factors

Answer 1

Primary: Obesity (stress on joints), Genetics (gens), Gender (female) & age (>40).
Secondary: Infection (septic arthritis), inflammation (Rheumatoid arthritis), Metabolic disorders (Gout) & congenital disorders (hip dislocations).

Question 2

Signs and symptoms of OA

Answer 2

Pain, stiffness, loss of mobility & bone spurs.

Question 3

Explain briefly the structure and main components of articular (hyaline) cartilage. (4 marks)

Answer 3

Structure: Has dense, extracellular matrix, surrounded by sparsely populated cells.
Components: Made up of water, type 2 collagen & photoglycanes- also has cells called chondrocytes.

Question 4

Explain the main features of a synovial joint (4 marks)

Answer 4

Bone with articular cartilage
has synovial membrane and synovial fluid 
Blood vessel and neurons 
joint capsule
lymphatic drainage

Question 5

Explain briefly what causes bone spurs to form in osteoarthritis. (4 marks)

Answer 5

Cytokines, IL-1, TNF alpha from macrophages stimulate bone cells in the periosteum. Immature bone cells differentiate into osteoblast, which then build bone in the joint- these outgrowths are called osteophytes.

Question 6

Explain what causes impaired cartilage remodelling in OA. (4 marks)

Answer 6

Normally chondrocytes keep cartilage healthy by synthesising new matrix. They also break down old matrix by secreting protease enzymes. If there is too much degradation from wear and tear, chondrocytes cant maintain homeostasis so there is an imbalance of synthetisation and degradation. As a result of this articular cartilage becomes soft, fissured and thin.

Question 7

Explain what occurs in the inflammatory stage of OA in the synovial joint. (4 marks)

Answer 7

Macrophages release pro inflammatory cytokines tnfa and IL-1. These cytokines cause synovial membrane cells to release proteases. Macrophages also release E-selectin which cause T-cells and neutrophils to be released which causes synovial cells to release more protease.

Question 8

Explain how bone spurs form in OA. (4 marks)

Answer 8

Macrophages release pro inflammatory cytokines tnfa and IL-1. These cytokines stimulate bone cells (stem cells) in the periosteum. Immature bone cells differentiate into osteoblasts . Osteoblasts build new tissue in the bone.

Question 9

Describe the functional changes in the synovial joint observed in OA

Answer 9

Joint space narrows due to loss of cartilage.
Articular cartilage thins causing subchondral bone to be exposed.
new bone grows knows as osteophytes (bone spurs) occur. osteoblasts form new bone tissue in the joint