Crystal Arthropathies and Septic Arthritis (R6) Flashcards
List the 2 main cystal related arthropathies (Incl the composition of each)
- Gouty arthropathy ➞ monosodium urate (MSU)
- Calcium pyrophosphate dihydrate disease (CPPD) ie. Pseudogout
What is gout?
An inflammatory and destructive arthritis which results from the deposition of urate crystals from extracellular fluids
(Urate is the final degradation product of purine metabolism)
Typical presentation of gout?
A single acute hot, swollen and painful joint
Compare acute gout vs gouty arthritis in terms of:
- presentation and onset
- resolutions yes/no?
- physical impairments
- affected joints
What defines hyperuricemia (gout)?
Serum urate > 6.8 mg/dl
List 3 groups of people who are at an increased risk of gout
- Boys with unusual enzymatic defects
- Men after puberty
- Women after menopause
Explain the pathway of gout development
Explain how drugs act in this pathway for treatment
List 4 risk factors for gout
- Male
- Obesity
- High purine diet (e.g. meat and seafood)
- Alcohol
- Diuretics
- Existing cardiovascular or kidney disease
- Family history
List 3 joints which tend to be affected in gout?
- Base of the big toe (MTP joint)
- Wrists
- Base of thumb (CMC joint)
Can also affects large joints like the knee and ankle
Clinical sign indicative of gout?
Gouty tophi
Subcutaneous deposits of uric acid in the hands (DIP), elbows and ears
How is gout diagnosed?
- Clinically History, Exam, CRP and ESR
- Joint aspiration (polarized Light Microscopy) = gold standard
List 4 findings on microscopy of fluid aspiration in gout
- No bacterial growth (excl septic arthritis)
- Needle shaped crystals
- Negatively birefringent of polarised light
- Monosodium urate crystals
How is gout managed during an acute flare?
- NSAIDs (eg. ibuprofen) are first-line
- Colchicine second-line
- Steroids can be considered third-line
Gout Prophylaxis?
- Allopurinol (xanthine oxidase inhibitor) → reduces uric acid
- Lifestyle changes → wt loss, hydration, and minimising alcohol
Should allopurinol prophylaxis be initiated during or after an acute flare of gout?
Initiated after acute attack is settled
Once treatment of allopurinol has been started then it can be continued during an acute attack
List 4 findings on X-ray indicative of gout.
- Space between the joint is maintained
- Lytic lesions
- Punched out erosions
- Erosions can have sclerotic borders with overhanging edges
What is calcium pyrophosphate crystal deposition disease?
Precipitation of calcium pyrophosphate dihydrate (CPPD) crystals in connective tissues
Short term for CPPD is Pyrophosphate arthropathy
List the 4 clinical presentations of CPPD
- Asymptomatic CPPD
- Pseudogout ➞ acute CPP
- Pseudo - RA ➞ chronic CPP
- Pseudo-OA ➞ OA with CPPD
What age group and sex does CPPD most commonly affect?
Older adults ➞ increasingly common in both men and women with advancing age
What is Pseudogout?
Calcium pyrophosphate crystals are deposited in the joint causing joint problems
Also known as chondrocalcinosis
List 4 risk factors for pseudogout
- Advanced age
- Injury or previous joint surgery
- Hyperparathyroidism
- Haemochromatosis
- Hypomagnesaemia
- Hypophosphataemia
Typical presentation of pseudogout?
An older adult with a hot, swollen, stiff, painful knee
Can affect the shoulders, wrists and hips and can be asymptomatic
How is pseudogout diagnosed?
Joint aspiration of synovial fluid
Clinically tends to be milder in presentation than gout or septic arthritis
List 4 findings on microscopy of fluid aspiration in psuedogout
- No bacterial growth
- Calcium pyrophosphate crystals
- Rhomboid shaped crystals
- Positive birefringent of polarised light
What is the classic pathognomonic X-ray change seen in pseudogout?
Chondrocalcinosis - diganostic
Thin white line in the middle of the joint space caused by the calcium deposition
List 4 other X-ray changes which may be seen in pseudogout
Similar to OA
- loss of joint space
- osteophytes
- subarticular sclerosis
- subchondral cysts
Management of Pseudogout?
Usually self-resolve but symptomatic management involves:
- NSAIDs
- Colchicine
- Joint aspiration
- Steroid injections
- Oral steroids
Joint washout (arthrocentesis) is an option in severe cases
List 4 ways CPPD crystals differ from MSU crystals
I. More difficult to detect
II. Smaller (0.5 to 10 microns)
III. Weakly positively birefringent or not birefringent
IV. More polymorphic with rod-shaped and cuboid crystals in addition to the usual rhomboidal form
What is Septic Arthritis?
Infection inside a joint
Medical emergency, as infection can destroy the joint and cause serious systemic illness
In what age group is Septic Arthritis most common?
Children under 4 years
List 4 risk factors for Septic Arthritis
- Joint replacement
- RA
- CKD
- Immunosuppression
How does septic arthritis present?
- Hot, red, swollen and painful joint
- Refusing to weight bear
- Stiffness and reduced range of motion
- Systemic symptoms ie. fever, lethargy and sepsis
Most common joint(s) affected by septic arthritis in
- Adults
- Children
Usually only affects a single joint
- knee
- hip, knee or ankle
Most common causative organism in septic arthritis?
Staphylococcus aureus
Others incl:
- Neisseria gonorrhoea
- Group A strep (Strep pyogenes)
- Haemophilus influenza
- E. coli.
According to the BNF how long should antibiotic treatment of septic arthritis continue for?
6-12 weeks
List 4 important ddx for septic arthritis
- Transient sinovitis
- Perthes disease
- Slipped upper femoral epiphysis
- Juvenile idiopathic arthritis
Investigations for Septic Arthritis
- Joint aspiration for gram staining, crystal microscopy, culture and antibiotic sensitivities
- Bloods: high WCC, ESR/CRP
- Blood cultures
- X-ray of joint
What criteria is used to diagnose Septic Arthritis in children?
Explain
The Kocher criteria
- fever >38.5 degrees C
- non-weight bearing
- raised ESR
- raised WCC
Management of Septic Arthritis
- IV antibiotics
- Consider joint washout under GA in severe cases
- Physiotherapy after acute infection resolves
List 3 complications of Septic Arthritis
- Osteomyelitis
- Arthritis
- Ankylosis fusion
Antibiotics for septic arthritis:
- First line
- If penicillin-allergic
- MRSA suspected
- Gonococcal arthritis or Gram-negative infection suspected
- Flucloxacillin
- Clindamycin
- Vancomycin
- Cefotaxime
How is septic arthritis most commonly spread?
Hematogenous spread
Eg. spread from abscesses
