Septic Arthritis, Crystal Arthritis and Reactive Arthritis

Question 1

What common categories can joint problems fall into?

Answer 1

Infection
Inflammatory arthropathy
Crystal arthropathy
Degenerative

Question 2

What are the clinical signs of septic arthritis?

Answer 2

Pain
Fever
Swollen Joints
Loss of Function

Question 3

Name the most common causative organisms of septic arthritis?

Answer 3

S.Aureus
Neisseria gonorrhoea
Haemophilus influenzae

Question 4

Name some risk factors for septic arthritis.

Answer 4

Person is on steroids
Rheumatoid arthritis 
High uric acid levels
- older people
- fat people
- high alcohol consumption
- high protein diet
- DM

Question 5

Define septic arthtitis.

Answer 5

Bacterial infection of joint by blood spread or direct inoculation

Question 6

Name 6 routes by which bacteria can reach the joint and cause septic arthritis.

Answer 6

1 - Haematogenous route
2 - Dissemination from osteomyelitis
3 - Spread from adjacent soft tissue infection
4 - Diagnostic or therapeutic measures
5 - Penetrating damage by puncture or trauma

Question 7

What investigations should be done in suspected septic arthritis?

Answer 7

Joint aspirate - microbiology for gram stain and culture
Blood culture - checking for sepsis
FBC - raised WCC in infection
X-Ray - no value expect to rule out fractures

Question 8

What pathological changes occur in the joint in septic arthritis?

Answer 8

The synovium is inflamed with a fibrous exudate and numerous neutrophil polymorphs
- fibrin and neutrophils form pus which then lines the joint capsule
Underlying cartilage gets disrupted (should be pale and smooth)
- becomes rough as a result of the fibrin deposition

Question 9

What is a common secondary complication of septic arthritis?

Answer 9

Osteoarthritis

- severe loss of articular cartilage

Question 10

How is septic arthritis treated?

Answer 10

IV antibiotics

- hip infections are always surgically cleared, as it is the only way to get an aspirate

Question 11

Describe TB septic arthritis.

Answer 11

• blood spread from foci elsewhere in the body
• usually the spine (Potts disease), hip, knee and tubular bones of the hands
• causes granulomatous inflammation within the joints

Question 12

What other specific types of septic arthritis are there?

Answer 12

TB
Lyme disease - borrelia burgdoferi
Brucellosis
Syphilitic arthritis - congenital and acquired

Question 13

Name the two crystal arthropathies.

Answer 13

Gout and pseudogout

Question 14

How are crystal arthropathies caused?

Answer 14

High levels of uric acid
- which precipitate out of the blood and are depositied in joint spaces
Deposition of this urate crystals occur in joints of soft tissue (tophi)
The body has an inflammatory reaction to the crystals

Question 15

Describe acute and chronic gout.

Answer 15

Acute - precipitation in joint stimulates the acute inflammatory process
Chronic - crystals in the joint space and the surrounding soft tissue (tophi formation)

Question 16

What investigations should be done to confirm a diagnosis of gout?

Answer 16

Joint aspirate
- cytology (examined under polarised light)
Serum urate levels
U&Es

Question 17

If gout is present, what do you expect to see on cytology of as aspirate?

Answer 17

Negatively birefringement
- turn blue when aligned across the direction of polarisation
Needle shaped crystals

Question 18

What is primary gout?

Answer 18

Hyperuricaemia due to a genetic predisposition

• e.g. Lesch-Nyhan syndrome
• deficiency of the enzyme uricase means uric acid can’t be broken down into soluble components

Question 19

What is secondary gout?

Answer 19

High uric acid due to a myeloproliferative disorder (PCRV)

• leukaemia treated by chemo
• thiazides
• chronic renal disease

Question 20

What is more common, primary or secondary gout?

Answer 20

Secondary

Question 21

What do the uric acid crystals look like in chronic gout?

Answer 21

Chalky white appearance of crystals in the sub cut tissues

Question 22

How is gout managed?

Answer 22

NSAIDs - high dose to reduce pain and swelling
- alternatives (colchicine and corticosteriods)
For repeat attacks
- allopurinol (a xanthine oxidase inhibitor)
- uricosuric agent (probenecid) - increases uric acid secretion in urine

Question 23

What are the crystals deposited in pseudogout made of?

Answer 23

Calcium pyrophosphate

Question 24

What is the distinctive feature when pseudogout affects the cartilage and extra-articular tissues?

Answer 24

Chondrocalcinosis

Question 25

Name some causes of secondary pseudogout.

Answer 25

Hyperparathyroidism | Haemochromatosis

Question 26

Describe the appearance of pseudogout crystals on polarised light cytology.

Answer 26

Positively birefringent - appear yellow when aligned across the direction of polarisation Rhomboid shaped crystals

Question 27

What is chondrocalcinosis?

Answer 27

Calcification of the surface of the articular cartilage | - thin white line can be seen on X-Ray

Question 28

How can pseudogout be managed?

Answer 28

Aspiration - reduces pain and swelling NSAIDs Colchicine

Question 29

What is reactive arthritis?

Answer 29

Sterile synovitis which occurs in response to another infection

Question 30

What are some of the trigger organisms for reactive arthritis?

Answer 30

Salmonella Shigella Yersinia Chlamydia trachomatis

Question 31

What are the two most common illnesses that precede a reactive arthritis?

Answer 31

Urethritis or a diarrhoeal illness

Question 32

What gene is reactive arthritis most often associated with?

Answer 32

HLA B27 | - found in 75% of reactive arthritis cases

Question 33

What are the clinical features of reactive arthritis?

Answer 33

``` Acute, asymmetrical lower limb arthritis More common in men Enthesitis Sarcoiliitis Spondylitis Anterior uveitis Conjunctivitis Keratoderma blenorrhagica ```

Question 34

How soon after infection does reactive arthritis occur?

Answer 34

Can occur days to weeks post infection

Question 35

Describe keratoderma blenorrhagica.

Answer 35

Keratinised, mucousy skin lesions commonly found on the palms and soles - vesico-pustular waxy lesion with a yellow brown colour

Question 36

What is the management of reactive arthritis?

Answer 36

Treating the triggering infection doesn't alter the course (self-limiting) NSAIDs Intra-articular steroids

Question 37

What is the prognosis for reactive arthritis?

Answer 37

``` Self limiting - lasts up to 6 months May be chronic May be cardiac complications - aortic regurgitation - aortitis - amyloidosis ```

Question 38

What is enteropathic arthritis.

Answer 38

Form of reactive synovitis seen in association with UC and Crohn's disease An asymmetrical lower limb arthritis This is an autoimmune reaction - antibodies cross reacting with the synovium

Question 39

How is enteropathic arthritis treated?

Answer 39

NSAIDs | Treatment of the underlying bowel disease

Question 40

Where does primary osteoarthritis appear?

Answer 40

Multiple joints in the hands

Question 41

What are the precipitating causing of secondary osteoarthritis

Answer 41

``` Fracture Previous sepsis Rheumatoid arthritis Osteonecrosis CDH Steroids Chronic overuse Gout Haemochromatosis Ochronosis Peripheral neuropathy ```

Question 42

What is osteoarthritis?

Answer 42

Degenerative joint disease - commonest form of arthritis - common the middle aged/elderly Seen most in weight-bearing joints (hip and knee)

Question 43

Describe the pathology of osetoarthritis.

Answer 43

Disorder of the articular cartilage - loss of cartilage - friction/wear of exposed subchondral bone causes subcondrosclerosis - reaction nodules of bone form osteophytes - reduced joint space Synovium becomes hyperplastic -> mild inflammation