Osteoarthritis Flashcards
What are the two most common rheumatoid diseases?
Osteoarthritis
Rheumatoid Arthritis
Osteoarthritis is recognised to be a metabolically active process with two distinct features. What are these?
Degeneration of cartilage.
Reparation of bone - reformation of bone at end of joint.
What is cartilage composed of?
Chondrocytes.
- these synthesise all components of joint cartilage, collagen and proteoglycan matrix.
What is the purpose of synovial fluid?
For lubrication.
What is the purpose of ligaments and tendons?
Joint stability.
Explain the degenerative process (degeneration of cartilage) which leads to osteoarthritis.
Primary enzymes responsible for the degeneration of cartilage are MMPs - matrix metalloproteinases. This is synthesised by chondrocytes and synovial cells - usually at normal levels.
In osteoarthritis, pro-inflammatory cytokine, IL1 stimulate chondrocytes and synovial cells to produce MMPs at higher levels, leading to cartilage destruction and suppresses repair in osteoarthritis.
Also, IL1 induces nitric oxide production and prostaglandin synthesis - further contributes to cartilage degeneration.
Explain the steps which occur after the cartilage degenerates.
The degeneration of cartilage causes structural failure of the cartilage surface with breaks in the collagen fibres allowing uptake of water. Causes cartilage to swell and split. This leads to fissures and fragmentation of cartilage leading to narrowing of joint space.
Underneath cartilage, exposed bone is subject to pressure, microfracture and death of chondrocytes.
Pressure of synovial fluid forces through microfractures into the bone, causing cysts.
Describe the reparative process which occurs in osteoarthritis.
There is increased activity of osteoblasts (cells which build new bone), leading to formation of new bone at periphery of joint. Process called lipping with outgrowths called osteophytes.
What is primary osteoarthritis?
Primary osteoarthritis has no cause.
Can be hereditary if strong family history.
More common in postmenopausal women.
Uncommon in under 45s.
What is secondary osteoarthritis?
Occurs due to trauma and mechanical problems.
Connection between obesity and development of osteoarthritis.
Occupational hazards and repetitive actions.
List 5 features used to diagnose the condition.
No lab tests. Identify typical symptoms. Physical findings. Radiographic changes on X-Ray. ACR Clinical Classification Criteria.
List some clinical features of osteoarthritis.
- Mono or polyarticular pain with characteristic distribution patterns.
- Pain is localised, aggravated by movement and releived by rest.
- Joints stiffen after resting - gelling.
- Tender joints with a loss of full range of movement.
- Unstable joints and sideways movement of knee.
- Bony enlargements with no heat and swelling.
How long does NSAID take to exert effects?
Analgesic effect can take 1 week but analgesia can be felt after administration.
Anti-inflammatory effect can take up to 3 weeks.
If no effect after these times, a different NSAID must be used.
What 6 factors affect NSAID selection?
Pharmacological factors - half life, efficacy.
Concomitant disease - GI infection, CV disease.
Concomitant drugs - methotrexate.
Previously prescribed drugs.
Cost.
Side effects.
What is a topical cream prescribed in addition to core treatments for osteoarthritis? Describe how it works.
Capsaicin 0.025% cream (Brand name: Zacin).
Licensed for symptomatic relief of pain.
Causes analgesia by depleting the sensory neurones of the NT substance, substance P.
