Osteoarthritis and Reactive Arthritis

Question 1

Define reactive arthritis.

Answer 1

Sterile inflammation in joints following infection, especially urogenital and gastrointestinal infections

Question 2

State a urogenital infection that can cause reactive arthritis.

Answer 2

Chlamydia trachomatis

Question 3

Give some examples of gastrointestinal infections that are associated with reactive arthritis.

Answer 3

Shigella
Salmonella
Campylobacter

Question 4

What subset of the population does reactive arthritis tend to occur in?

Answer 4

It occurs mainly in young adults with a genetic predisposition and an environmental trigger

Question 5

How long after the infection does the reactive arthritis tend toappear?

Answer 5

1-4 weeks

Question 6

Describe the features of the arthritis in reactive arthritis.

Answer 6

It is an asymmetrical arthritis that occurs in relatively few joints

Question 7

Reactive arthritis can cause enthesopathy. Which entheses are likely to get affected and what symptoms will that cause?

Answer 7

Achilles tendonitis
Dactylitis
Metatarsalgia (painful feet because of inflammation of the palmar fascia)

Question 8

What is a very common feature of seronegative spondyloarthropathies?

Answer 8

Sacro-iliitis

Question 9

State some extra-articular features of reactive arthritis?

Answer 9

Sterile conjunctivitis
Sterile urethritis
Circinate balanitis
Keratoderma blennorhagicum

Question 10

What is the triad of symptoms that can be used to describereactive arthritis?

Answer 10

Reiter’s syndrome – joint inflammation + urethritis + conjunctivitis

Question 11

Where can you get spondylitis in rheumatoid arthritis?

Answer 11

At the atlanto-axial joint – there is synovium her

Question 12

Describe the main differences between rheumatoid arthritis and reactive arthritis.

Answer 12

Rheumatoid Arthritis vs Reactive Arthritis
Sex Ratio: 
F>M - M>F
Arthritis: 
Symmetrical, Polyarticular, Small&Large Joints - Asymmetrical, Oligoarticular, Large joints
Enthesopathy:
NO - YES
Spondylitis:
NO (Except atlanto-axial joint in cervical spine) - YES
Urethritis:
NO - YES
Skin involvement:
Subcutaneous nodules - K.blennorhagicum, Circinate balanitis
Rheumatoid factor:
YES - NO
HLA association:
HLA-DR4 - HLA-B27

Question 13

What is the main danger in septic arthritis?

Answer 13

The bacteria produce metalloproteinases that can rapidly degrade thearticular cartilage

Question 14

What are the main differences between septic arthritis and reactive arthritis?

Answer 14

Septic arthritis has a positive synovial fluid culture

It is treated with antibiotics and may even require joint lavage

Question 15

Describe the treatment of reactive arthritis.

Answer 15

It usually resolves by itself

NSAIDs to control pain and symptomatic treatment of extra-articular manifestations

Question 16

Define osteoarthritis.

Answer 16

Chronic slowly progressive disorder due to failure of articular cartilage that typically affects the hands (especially those involved in the pinch grip), spine and weight-bearing joints (hips and knees)

Question 17

Which joints are most commonly affected in osteoarthritis?

Answer 17

DIP 
PIP  
First metacarpophalangeal joint  
Spine 
Knees  
Hips  
First metatarsophalangeal joint

Question 18

What are the names given to the osteophytes found on the hand in osteoarthritis?

Answer 18

Bouchard’s Nodes – PIP

Heberden’s Nodes – DIP

Question 19

What are some other associations of osteoarthritis?

Answer 19

Joint pain (worse with activity)  
Joint crepitus  
Joint instability  
Joint enlargement  
Joint stiffness after immobility  
Limitation of motion

Question 20

What are some radiographic features of osteoarthritis?

Answer 20

Joint space narrowing
Osteophytes
Subchondral bony sclerosis
Subchondral cysts

Question 21

Describe the differences between the radiographic features of rheumatoid arthritis and osteoarthritis.

Answer 21

Rheumatoid arthritis also has joint space narrowing but it doesn’t have subchondral sclerosis or osteophytes
There is osteopenia and there are bone erosions in rheumatoid arthritis but not in osteoarthritis

Question 22

What can the osteoarthritis be caused by?

Answer 22

Abnormal cartilage

Abnormal stress

Question 23

What is the most important component of articular cartilage?

Answer 23

Aggrecan

Question 24

What is aggrecan made up of?

Answer 24

Contains glycosaminoglycan side chains:
Chondroitin sulphate – glucuronic acid + N-acetyl galactosamine
Keratan sulphate – galactose + N-acetyl glucosamine
- Neg charge of glycosaminoglycan side chains attracts water keeping cartilage side chains

Question 25

What is a proteoglycan?

Answer 25

Glycoproteins that contain one or more sulphated glycosaminoglycan (GAG) chains

Question 26

What is special about hyaluronic acid?

Answer 26

It is the only non-sulphated GAG

Question 27

What are the disaccharides in hyaluronic acid?

Answer 27

Glucuronic acid

N-acetyl glucosamine

Question 28

How is osteoarthritis managed?

Answer 28

Physiotherapy – strengthening the muscle around the joint improves joint stability
Analgesia – paracetamol, NSAIDs, intra-articular corticosteroid injections
Joint replacement
Weight loss where appropriate

Question 29

Cartilidge and bone changes in osteoarthritis

Answer 29

Cartilage changes in osteoarthritis:

• Reduced proteoglycan
• Reduced collagen
• Chondrocyte changes e.g. apoptosis
• CHANGES ARE OFTEN LOCALISED

Bone changes in osteoarthritis (once cartilage is damaged):

• Changes in denuded sub-articular bone:
• Proliferation of superficial osteoblasts results in production of sclerotic bone e.g. subchondral sclerosis
• Focal stress on sclerotic bone can result in focal superficial necrosis

New bone formation at the joint margins (termed osteophytes)
· Sometimes you can detect osteophytes clinically (‘at the bedside’) and these have names
· Osteophytes at the distal inter-phalangeal joints are called ‘Heberden’s nodes’
· Osteophytes at the proximal inter-phalangeal joints are called ‘Bouchard’s nodes’