Lectures Flashcards by Andrew Gvozdanovic

What percent of acutely swollen/painful joints are down to septic arthritis?

10%

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What percentage of those with septic arthritis will develop permanent damage?

50%

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What is the mortality of septic arthritis?

10-16%

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What are the four hallmarks of septic arthritis?

Biofilm - protecting the microbe
Acute synovitis with proliferative hyperplasia
Cartilage degradation by bacterial and leucocyte proteases/cytokines/pressure phenomenon
Subchondral bone loss

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What are the three ways in which septic arthritis may develop?

Haematogenous (50%)
Direct - osteomyelitis
Implantation - trauma, arthrocentesis, intra-articular injection and orthopaedic surgery

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What are the main causative agents of septic arthritis in infants?

G -ve bacilli

H. Influenzae

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What are the main causative agents of septic arthritis in children?

S. Aureus

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What are the main causative agents of septic arthritis in adults?

S. Aureus

Group A β-haemolytic streptococci

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What are the main causative agents of septic arthritis in the elderly?

G -ve bacilli

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What are the main causative agents of septic arthritis in those with a prosthetic joint?

Early - coagulase negative staph

Late - staph and strep

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What percentage of TB infections lead to TB mono arthritis?

1% of TB infections cause/lead to TB monoarthritis

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How might you diagnose a TB monoarthritis?

Positive skin test - evidence for
Abnormal CXR - evidence for
Synovial biopsy and culture - diagnosis

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Which joints may be affected by a tuberculous monoarthritis?

Weight bearing joints - knee/hip/wrist

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What is the patient profile of a gonococcal arthritis?

Young
Sexually active
Female

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What is the initial presentation of a gonococcal arthritis?

Migratory polyarthralgia
Tenosynovitis
Dermatitis

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What percentage of gonococcal infection arthritis are polyarticular?

40-70% of gonococcal bacterial arthritis cases are polyarticular

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What is is the percentage recovery of bacteria in a gonococcal arthritis?

<10% blood

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What is the response of a gonococcal arthritis to antibiotics?

Within a few days there is an excellent outcome

What is the patient profile for a non-gonoccal bacterial arthritis?

Newborn/elderly
Compromised host
RA host

What is the initial presentation of a non-gonococcal bacterial arthritis?

Single, hot, swollen and painful joint

What percentage of non-bacterial gonococcal arthritis are polyarticular?

10-20%

What percentage of bacterial recovery is found in non-gonococcal bacterial arthritis?

> 90% synovial fluid

50% blood

What response does non-gonococcal bacterial arthritis have to antibiotics?

Takes weeks
Joint drainage must be adequate
Outcome often poor

What are the steps of managing septic arthritis?

Immediate synovial fluid aspiration
Blood culture
Swab and culture nasopharynx/rectum
GU culture
Imaging

What tests are performed on the fluid aspiration of septic arthritis?

Gram stain - 50% NGSA and 25% GSA Culture - 90% for NGSA and 50% for GSA PCR for gonococcal DNA

What will you see on each modality of imaging used in septic arthritis?

XR - effusion, juxta-articular osteoporosis and erosion CT - effusion; use diagnostically for hip/shoulder aspiration MRI - Soft tissue oedema and abscesses

How do you manage septic arthritis?

ABx against staph/strep - pen or fluclox (modified based on culture and serology) IV ABx for 2-4wks Join drainage - FNA or open Early joint mobilisation to prevent contractors Removal of any prosthetic

How would you summarise septic arthritis?

An acute rheumatological emergency characterised by a single, hot, swollen joint. Must be immediately aspirated for gram stain and culture. Treat with ABx, drain and mobilisation.

What is a DDx for septic arthritis?

Flare up of systemic joint disease Gout/pseudogout Seronegative arthritis (reactive/psoriatic/IBD arthritis) Sarcoidosis Vasculitis

What is the cause of gout?

An inflammatory response to monosodium urate monohydrate crystals developing into secondary hyperuricaemia

What is the epidemiology of gout?

Prevalence 8.4/1000 8x M>F Rare in children and pre-menopausal women

What is the typical age of onset of gout?

40-50y in men | >60 women

How do you define (quantitatively) hyperuricaemia?

>6mg/dl or >360umol/l

What is the relationship between RA and gout?

Inverse

How can hyperuricaemia be classified?

Underexcretion - 90% | Overproduction - 10%

What are the many many causes of hyperuricaemia?

``` Idiopathic/genetic Chronic renal failure Drugs and cytotoxic drugs Blood causes Psoriasis ```

What drugs are known to cause hyperuricaemia?

CANT LEAP ``` Cyclosporin/cytotoxic (tumour lysis syndrome) Alcohol Nicotinic acid Thiazides Lasic Ethambutol Aspirin - low dose Pyranzinamide ```

Which blood disorders are known to cause hyperuricaemia?

``` Polycythaemia Leukaemia Pernicious anaemia Chronic haemolytic anaemia Lymphoproliferative disorders ```

Which joint is most commonly affected by an acute gouty episode?

``` 1st MTPJ (podagra) in 50% Other lower limb joints ```

Other than the lower limb joints where else might gout present itself?

Non-articular deposition in the olecranon bursa and achilles tendon

Is gout generally mono or polyarticular?

Gout is monoarticular in 90% of cases

When might gout progress to to a polyarticular pathology?

In females with a myelo/lymphoproliferative disorder

What is the onset of gout?

Gout tends to have a rapid onset of pain, swelling and erythema