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RH26 Rheumatology
Crystal-Induced Arthropathies Toronto Notes 2019
• Knee
• Polyarticular wrist • Hand (MCP)
• Foot (1st MTP)
• Hip
Figure 14. Common sites of involvement of CPPD
• chronicgout
■ conservative
◆ avoid foods with high purine content (e.g. visceral meats, sardines, shellfish, beans, peas) ◆ avoid drugs with hyperuricemic effects (e.g. pyrazinamide, ethambutol, thiazide, alcohol)
■ medical
◆ anti-hyperuricemic drugs (allopurinol and febuxostat): decrease uric acid production by
inhibiting xanthine oxidase
◆ uricosuric drugs (probenecid, sulfinpyrazone): very rarely used in combination with allopurinol
or febuxostat in patients in whom hyperuricemia is not controlled with the latter
■ prophylaxis with lose dose NSAID/colchicine may be required prior to starting antihyperuricemic
drugs
■ in renal disease secondary to hyperuricemia, use low-dose allopurinol and monitor Cr
• indicationsfortreatmentwithantihyperuricemicmedicationsinclude
■ recurrent attacks (more than 2-3/yr), tophi, bone erosions, urate kidney stones ■ perhaps in renal dysfunction with very high urate load (controversial)
Pseudogout (Calcium Pyrophosphate Dihydrate Disease)
Definition
• jointinflammationcausedbycalciumpyrophosphatecrystals
Etiology and Pathophysiology
• acuteinflammatoryarthritisduetophagocytosisofIgG-coatedCPPDcrystalsbyneutrophilsand subsequent release of inflammatory mediators within joint space
• Usuallymonoarticularbutcanbepolyarticular
• slowerinonsetincomparisontogout,lastsupto2-3wkbutisself-limited
Risk Factors
• oldage,advancedOA,neuropathicjoints
• otherassociatedconditions:hyperparathyroidism,hypothyroidism,hypomagnesemia,
hypophosphatasia (low ALP), DM, hemochromatosis
Signs and Symptoms
• affectsknees,wrists,MCPs,hips,shoulders,elbows,ankles,bigtoe,spine
• asymptomaticcrystaldeposition(seenonradiographonly)
• acutecrystalarthritis(self-limitedflaresofacuteinflammatoryarthritisresemblinggout)
• pseudo-OA(progressivejointdegeneration,sometimeswithepisodesofacuteinflammatoryarthritis) • pseudo-RA(symmetricalpolyarticularpatternwithmorningstiffnessandconstitutionalsymptoms) • frequently triggered by dehydration, acute illness, surgery, trauma
Investigations
• mustaspiratejointtoruleoutsepticarthritis,gout
• CPPDcrystals:presentin60%ofpatients,oftenonlyafewcrystals,positivebirefringence(blue)and
rhomboid shaped
• x-raysshowchondrocalcinosisin75%:radiodensitiesinfibrocartilaginousstructures(e.g.knee
menisci) or linear radiodensities in hyaline articular cartilage
Treatment
• jointaspiration,rest,andprotection
• NSAIDs:alsousedformaintenancetherapy • prophylacticcolchicinePO(controversial) • IAororalsteroidstorelieveinflammation
© Linda Colati