72 year old with painful monoarthritis and signs of inflammation. Infection must be excluded.
- Causes:
Inflammation – septic (viral, bacterial, gonococcal), gout, pseudogout, RA (monoarticular), systemic rheumatic disorders ( SLE, still, reactive arthritis, Behcets, bacterial endocarditis, Rheumatic fever etc)
Non Inflammatory – OA, trauma, haemarthrosis, osteonecrosis
2. Pseudogout without superimposed infection
3. Normal synovial fluid contains < 60 to 180 cells per ml, most of which should be mononuclear. Fluid is considered to be “noninflammatory” if it contains < 2000 cells / ml. Finding of > 90% PMNs despite relatively low total leukocyte count should prompt concern about infection or crystal-induced disease. Using a 50000 cutof for leucocytes lacks the sensitivity required to be clinically useful in ruling out infectious arthritis.
4.
| Gout | Pseudogout | |
| History/ Co morbidities | Malignancy
Alcohol Myeloproliferative disorders Medication – diuretics Previous attacks |
Trauma
HyperPTH, Hypothyroidism HypoMg, HypoPO4 Haemochromatosis Usually no previous attacks
|
| Examination | Painful, swollen, inflamed joint
Monoarticular (<5 joints)
|
Painful, swollen, inflamed joint
Gouty tophi Monoarticular is usual |
| Bloods | High Ca
Low Mg, PO4 Low T3/ high PTH |
Uric acid high/ normal |
| Synovial fluid | Uric acid crystals
-ve birefringent – polarised light Larger, needle shaped crystals Blue if parallel to light Yellow if perpendicular |
CapyroPO4 crystals
+ve birefringent Smaller, rhomboid/ needle shaped crystals Yellow if parallel Blue if perpendicular |
| Radiology | Calcifications may be visible | No calcifications
Gouty erosions Sclerotic margins tophi |
| Treatment | Analgesia
Gout treatment Look for cause |
Aspirate joint +/- steroid injection
Analgesia Look for cause |