Osteoarthritis

Question 1

What ate the risk factors for osteoarthritis?

Answer 1

• Genetic predisposition – rare mutations in collagen types II, IX, XI, GDF-5 (not well understood yet)
• Anatomic factors – Improper alignment leads to movement in directions the joint is not designed to do, which increases friction and wear and tear of the joint
• Joint injury (from sports, surgery etc)
• Obesity – increases load on weight-bearing joints/metabolic OA related to obesity
• Aging – changes in ECM (e.g. thinning, dec hydration, inc brittleness)
• Gender (M<50yo, W>70yo)

Question 2

What is the pathophysiology behind osteoarthritis?

Answer 2

• Articular cartilage damage takes place – chondrocytes repair damage – aberrant chondrocyte function results in more breakdown, leading to cartilage loss and chondrocyte apoptosis
• When the damage worsens to the level of physical damage, DAMPs are released – macrophages recognise using PRRs, stimulated to release inflammatory cytokines (IL-1β, IL-8, TNF, chemokines)
• DAMPs also stimulate the complement pathway – leads to synovitis (chondrocytes activated to induce inflammation), which makes the synovial space smaller as a result
• Subchondral bones also rub against each other, becoming denser, smooth, more brittle and stiffer, with dec weight bearing ability – development of sclerosis, microfractures and osteophytes to compensate

Question 3

What are the clinical features of osteoarthritis?

Answer 3

Pain
→ Insidious onset – slow progression over years
→ Worse with joint use, relieved by rest
→ Most severe over joint line

Swelling – from joint effusion (transient)

Erythema & warmth

Morning stiffness <30min

Limited joint movement

Functional limitation/instability

Asymmetric monoarticular or oligoarticular involvement – typically hand, knee, hip (all weight-bearing)

Possible crepitus on motion, reduced range of movement, enlargement of bone

Question 4

What are the possible lab findings in osteoarthritis?

Answer 4

Erythrocyte sedimentation rate (ESR) < 20mm/h

Question 5

In which patient groups can clinical diagnosis be made without imaging?

Answer 5

→ ≥45yo
→ Activity-related joint pain (in one or a few joints)
→ Morning stiffness <30mins

Question 6

In which patient groups should additional testing for osteoarthritis be done?

Answer 6

Younger individuals (<45yo)

Presence of atypical symptoms that suggest alternative/additional diagnosis
→ Hx of recent trauma
→ Rapidly worsening symptoms or deformity
→ Concerns of infection or malignancy – e.g. unusual sites, marked pain at rest, unintended weight loss, constitutional symptoms

Question 7

What non-pharm strategies are strongly recommended for osteoarthritis?

Answer 7

• exercise (low-impact)
• weight loss
• Tai Chi
• use of cane/walking stick
• use of braces/orthosis

Question 8

What non-pharm strategies should be avoided for osteoarthritis?

Answer 8

• TENS
• Iontophoresis
• Massage
• Modified shoes
• Weighted insoles
• Vibration therapy

Question 9

What pharm strategies should be used for osteoarthritis?

Answer 9

Oral NSAIDs

Topical NSAIDs for knee
→ Topical not usually used for hands as it is easily removed during daily activities
→ Topical not used for hip as the topical formulation cannot penetrate so far

Intraarticular steroids for knee, hip

Alternatives - not so ideal:
- Paracetamol
- Tramadol
- Duloxetine
- Chondroitin
- Topical capsaicin

Question 10

How should topical NSAIDs be used?

Answer 10

Do not use TOP NSAIDs for open wounds, skin conditions

Possible skin reactions, photosensitivity

Question 11

When should surgical treatment be used for osteoarthritis?

Answer 11

→ QoL substantially affected
→ Non-surgical Tx is ineffective/unsuitable