Osteoarthritis

Question 1

Define OA

Answer 1

progressive deterioration of cartilage and bone due to failed repair of joint damage caused by stresses on the joint

Question 2

Causes of OA

Answer 2

1. Primary (idiopathic)
   - most common
   - unknown

2 Secondary

• post traumatic/mechanical
• post inflammatory/infectious
• scoliosis
• endocrine disorders (acromegaly etc)
• metabolic disorders (gout)
• neuropathic (Charcot joints)
• avascular necrosis

Question 3

Pathophysiology of OA

Answer 3

• deterioration of articular cartilage due to local biomechanical factors and release of proteolytic
and collagenolytic enzymes
ƒƒ- cartilage catabolism > synthesis
ƒƒ- loss of proteoglycans and water exposes underlying bone
• abnormal local bone metabolism further damages joint
• altered joint function and damage
• synovitis is secondary to cartilage damage; therefore, may see small effusions in OA

Question 4

Risk factors of OA

Answer 4

genetic predisposition, advanced age, obesity (for knee OA), female, trauma

Question 5

Px of OA

Answer 5

• localized to affected joints (not a systemic disease)

* pain is often insidious, gradually progressive, with intermittent flares and remissions

Question 6

Describe joint involvement in OA

Answer 6

• asymmetric
• hand
- ƒƒDIP (Heberden’s nodes = osteophytes -> enlargement of joints)
ƒƒ- PIP (Bouchard’s nodes)
ƒƒ- CMC (usually thumb squaring)
- ƒƒ1st MCP (other MCPs are usually spared)
• Hip
• Knee
• 1st MTP
• L-spine (L4-L5, L5-S1)
• C-spine (C5, 6)
• Uncommon: ankle, shoulder, elbow, MCP, rest of wrist

Question 7

What are the 4 radiographic hallmarks of OA?

Answer 7

• Joint space narrowing
• Subchondral sclerosis
• Subchondral cysts
• Osteophytes

Question 8

Rx of OA

Answer 8

no treatment alters the natural history of OA

Conservative

• weight loss if overweight
• physio
• occupational therapy; aids, splints, walker, cane

Pharm

• NSAIDs, glucosamine +/- chondroitin
• corticosteroid/hyaluronic acid joint infections
• topical capsaicin, NSAID

Surgical:
- joint debridement, osteotomy, total/partial joint replacement, fusion