septic, crystal and reactive arthritis

Question 1

name the causative organisms for septic arthritis

Answer 1

Staphylococcus aureus, Neisseria gonorrhoea, Haemophilus influenzae (children)

Question 2

what symptoms will a person with septic arthritis have

Answer 2

pain, fever, swollen joint, loss of function

Question 3

how do the bacteria reach the joint in septic arthritis

Answer 3

 The haematogenous route
 Direct spread from the metaphysis
 Penetrating trauma/surgery
 Spread from an adjacent soft tissue infection

Question 4

how do you investigate septic arthritis

Answer 4

o Joint aspirate – microbiology for gram stain and culture
o Blood culture
o FBC – leucocytosis

Question 5

describe the pathology in septic arthritis

Answer 5

o Bacterium (haematogenous) settle within the the synovium which may be infalmmed due to trauma or disease
o Proliferation of the bacteria casues an inflammatory response
o Migration of leucocytes to the joint
o Synovium becomes inflamed with fibrin exudation and numerous neutrophil polymorphs
 Produce a variety of degradative enzymes and break down products which can damage the articular cartilage very quickly
 If left unchecked the joint will be permanently damaged
 May develop secondary osteoarthritis

Question 6

give the differential for a hot, swollen, joint

Answer 6

• Septic arthritis
• Crystal artropathy
• Trauma/haemarthrosis
• Early presentation of a polyarthropathy

Question 7

list risk factors for developing septic arthritis

Answer 7

steroid use, RA, biologics, prosthesis, low socio-economic status, IV drug user, alcoholic liver disease

Question 8

how should septic arthritis be treated?

Answer 8

IV antibiotics, analgaesia, splint and drainage is possible.

Question 9

how are gout crystals deposited

Answer 9

they are deposited preferentially in peripheral joints, especially those affected by OA.
They form in superficial layers of cartilage, in subchondral bone and in fibrous peri-articular tissues.
They can be deposited in soft tissue, forming tophi in the subcutaneous tissue

Question 10

name two potential effects of chronic gout

Answer 10

tophi and nephropathy caused by urate deposition in the renal interstitium and collecting tubules

Question 11

what is podagra

Answer 11

where gout affects the first MTP joint (classic site for gout to first present)

Question 12

what crystals will be seen in the aspirate of someone with gout

Answer 12

negatively birefringent needle shaped crystals will be seen on polarised microscopy

Question 13

who would you find higher uric acid levels in ?

Answer 13

older people, obesity, high alcohol consumption, high protein diet, diabetes mellitus

Question 14

how do you treat the symptoms of gout

Answer 14

high dose NSAIDs

Can use colchicine if they cannot tolerate NSAIDs or can use corticosteroids in an acute setting

Question 15

which gout-lowering therapy is commonly used

Answer 15

allopurinol - xanthine oxidase inhibitor.

Question 16

where does pseudogout crystal deposition occur?

Answer 16

in the synovium

Question 17

which crystals would you see in polarised light microscopy in pseudogout?

Answer 17

positively birefringent rhomboid shaped crystals

Question 18

which crystals are deposited in pseudogout?

Answer 18

calcium pyrophosphate crystals

Question 19

what is reactive arthritis ?

Answer 19

sterile synovitis which occurs following an infection elsewhere in the body. It is an auto-immune response

Question 20

which HLA is reactive arthritis associated with?

Answer 20

HLA-B27 (75%)

Question 21

name some trigger organisms for reactive arthritis

Answer 21

salmonella, shigella, yersinia, chlamydia trachomatis

Question 22

which types of disease often trigger reactive arthritis?

Answer 22

urethritis or diarrhoeal disease

Question 23

name some clinical features of reactive arthritis

Answer 23

acute, aymmetrical lower limb arthritis that usually occurs in larger joints. Chlamydia type is more common in men.
Can occur days to weeks post-infection

Question 24

name some associated clinical features of reactive arthritis

Answer 24

 Enthesitis (e.g. plantar fasciitis),
 sacroiliitis,
 spondylitis,
 anterior uveitis,
 conjunctivitis,
 Circinate balanitis: present shallow erosions, geographical in distribution with a flaky edge in the glans of the penis
 keratoderma blenorrhagica (raised brown plaques on soles and palms),
 dactylitis (inflammation of an entire digit)