Rheum - Reactive Arthritis

Question 1

Define Reactive Arthritis

Answer 1

STERILE inflammation in joints FOLLOWING infection especially
• urogenital (e.g. Chlamydia) & gastrointestinal (e.g. Salmonella, Shigella) infections

Question 2

Key points associated with Reactive Arthritis?

Answer 2

Important extra-articular manifestations include:
• Enthesopathy – a disorder relating to the ligament attaching to the bone
• Skin inflammation
• Eye inflammation

ReA may be the first manifestation of HIV or Hep C infection

Commonly affects young adults (with a genetic disposition – e.g. HLA-B27) with an environmental trigger such as a Salmonella infection

Symptoms follow 1-4 weeks after infection (may be mild)

ReA is distinct (sterile) from infection in the joints
• known as SEPTIC arthritis.

Question 3

Is there a biomedical test to check for ReA?

Answer 3

NO as it is ‘seronegative’

Question 4

Musculoskeletal symptoms of ReA?

Answer 4

Arthritis:
 Asymmetrical
 Oligoarthritis – less than 5 joints affected
 Lower limbs more affected

Enthesitis:
 Heel pain – Achilles tendonitis
 Swollen fingers – dactylitis
 Painful feet – metatarsalgia due to plantar fasciitis

Spondylitis:
 Sacroiliitis – inflammation of the sacro-iliac joint
 Spondylitis – inflammation of the spine

Question 5

Extra-articular features of ReA?

Answer 5

Ocular:
 Sterile conjunctivitis

Genito-urinary:
 Sterile urethritis

Skin:
 Circinate balanitis
 Keratoderma blennorrhagicum

Question 6

What was the original description of ReA?

Answer 6

arthritis, urethritis and conjunctivitis following infectious dysentery (Reiter’s syndrome)

Question 7

Compare RA vs. ReA

Answer 7

Onenote!!

Sex Ratio
Age
Arthritis
Enthesopathy
Spondylitis
Urethritis
Skin involvement
Rheumatoid factor
HLA association

Question 8

Compare Spetic A vs. ReA?

Answer 8

Onenote!!

Synovial fluid culture
Antibiotic therapy
Joint Lavage

Question 9

What is one of the biggest things about RA in the comparison table

Answer 9

Note how RA affects the ATLANTO-AXIAL JOINT (

• as this spinal joint contains synovial fluid

Question 10

How is diagnosis achieved for ReA?

Answer 10

3 main ways:

Clinical diagnosis – i.e. asymmetrical arthritis

Investigations of exclusion – i.e. septic arthritis

Other investigations:
• Microbiology:
- Microbial cultures – stool, blood, etc.
- Serology – e.g. HIV, Hep C.

• Immunology:

• RF.
• HLA-B27.

• Synovial fluid examination – only if a single joint is affected.

Question 11

How is ReA treated?

Answer 11

In majority, resolution in 2-6months

NO ROLE for antibiotics

Articular:
• NSAIDs
• Intra-articular corticosteroid therapy

Extra-articular:
• Symptomatic therapy – topical steroids

Refractory disease – non-responsive to treatment:
• Oral glucocorticoids
• Steroid-sparing agents – DMARDs

Question 12

Define Osteoarthritis

Answer 12

Chronic, slowly progressive disorder due to failure of articular cartilage, typically affecting joints of the
 • hand
 • spine 
and 
 • weight-bearing joints

Question 13

What joints does osteoarthritis normally affect?

Answer 13

Joints of the hand
• DIP, PIP, CMC (1st carpometacarpal joint)
• NOT MCP
- Herberden’s nodes - osteophytes at DIP joints
- Bouchard’s nodes – osteophytes at PIP joints
Before (proximal) = Bouchard

Spine

Weight-bearing joints of the lower limbs
• hip/knee, MTP (1st metatarsophalangeal joint)

Question 14

What is osteoarthritis associated with?

Answer 14

o Joint pain
• worse with activity

o Joint crepitus
• creaking sound on movement

o Joint instability

o Joint enlargement
• i.e. Herberden’s nodes.

o Joint stiffness after immobility and limitation of motion.

Question 15

What are radiographic features of osteoarthritis?

Answer 15

o Joint space narrowing

o Subchondral bony sclerosis
• hardening of the bone on the subchondral portion

o Osteophytes
• new bony formations (at joint margins)

o Subchondral cysts

Question 16

Radiographic changes in RA vs. OA?

Answer 16

Onenote!!

Joint space narrowing
• occurs in BOTH due to different reasons
• cartilaginous loss in RA is caused by 2o damage due to synovitis vs. in OA where is it the 1o abnormality

Subchondral sclerosis
Osteophytes
Osteopenia
Bony erosions

Question 17

Pathogenesis of OA?

Answer 17

There is defective and irreversible articular cartilage and damage to the underlying bone

This develops due to (and/or):
• Excessive loading on joints – more apparent in the old
• Abnormal joint components – more apparent in the young

Question 18

What is the most important component of the articular cartilage?

Answer 18

AGGRECAN!

The weight-bearing properties of the articular cartilage depend upon the
• intact collagen scaffold & the high aggrecan content

Aggrecan is made up of
• Chondroitin sulphate & Keratan sulphate
• The GAG chains are important at absorbing water to be used to resist compressive forces.

Question 19

Explain ECM proteoglycans

Answer 19

Proteoglycan – glycoproteins containing 1+ sulphated glycosaminoglycans (GAG) chains

GAGs are repeating polymers of disaccharides and include:
	Chondroitin sulphate.
	Heparan sulphate.
	Keratan sulphate.		
	Dermatan sulphate.		
	Heparin.

Examples:
 Intra-cellular – Serglycin.
 Cell-surface associated – Betaglycan, Syndecan.
 Secreted into ECM – Aggrecan, Decorin, Fibromodulin, Lumican, Biglycan.

Question 20

What in unique about Hyaluronic acid?

Answer 20

Is the ONLY non-sulphated GAG

• and has an important role in maintaining synovial fluid viscosity

Question 21

What is the major proteoglycan in articular cartilage?

Answer 21

Aggrecan

Question 22

Explain the cartilage changes in OA

Answer 22

Reduced proteoglycan
Reduced collagen
Chondrocyte changes
• e.g. apoptosis

Question 23

Explain the bone changes in OA

Answer 23

Changes in sub-articular bone:
• Proliferation of superficial osteoblasts resulting in sclerotic bone
• Focal stress on sclerotic bone  focal superficial necrosis

New bone formation at joint margins (bone spurs):
• Examination can detect these.
• Herberden’s nodes vs Bouchard’s nodes.

Question 24

Management of OA?

Answer 24

o Education.
o Physical therapy.
o Occupational therapy.
o Weight loss (where appropriate) and exercise.
o Analgesia – paracetamol, NSAIDs, intra-articular corticosteroid injections.
o Joint replacements.

Provided the joint is functional, all you have to do is CONTROL the PAIN
• strengthening the muscle around the joint will improve mechanical stability of the joint

Question 25

What are some therapeutic approached for OA, NOT approved in UK?

Answer 25

Glucosamine and chondroitin sulphate supplements
• commonly taken but not approved by NICE

Intra-articular injections of hyaluronic acid
• to increase lubrication in the knee only
• not recommended by NICE

Unlike RA, no DMOADs (Disease-Modifying Osteoarthritis Drugs)
• Future drugs could include – aggrecanase inhibitors, cytokine inhibitors, etc.