ACUTE MONOARTHRITISA great advanced discussion today that focused on monoarthritis.
The first step in assessing an "acute joint" is to determine if the process is articular, periarticular or referred.
If it is indeed an acute articular process the differential includes:
Infectious: SEPTIC UNTIL PROVEN OTHERWISE!!!
- a very good general rule, although as we learned today in classic presentations of other diseases, joint tap may be deferred
Crystal Arthropathy: Gout, Pseudogout (CPPD), Hydroxyapatite
Inflammatory
Seropositive arthritis (early RA or SLE)
Seronegative arthritis (psoriatic, Ankylosing spondilitis, IBD, reactive)
Degenerative: Osteoarthritis
- a very good general rule, although as we learned today in classic presentations of other diseases, joint tap may be deferred
Crystal Arthropathy: Gout, Pseudogout (CPPD), Hydroxyapatite
Inflammatory
Seropositive arthritis (early RA or SLE)
Seronegative arthritis (psoriatic, Ankylosing spondilitis, IBD, reactive)
Degenerative: Osteoarthritis
Trauma: Hemarthrosis, joint trauma
Extra-articular: Bursitis, cellulits, ruptured Baker’s cyst, tendonitis, etc…A JAMA rational clinical exam article on septic arthritis is linked here and a CMAJ article on approach to acute monoarthritis is here. Gout is unusual in premenopausal women. An article on acute calcific periarthritis is linked here.
IMAGING
Not always necessary - may be helpful for
1)Trauma
2)Evidence of crystal disease
3)Baseline study (i.e. to follow for development of pathology in future if septic joint, etc.)/to assess for obvious coexisting osteomyelitis.
Antihyperuricemic Treatment
Indications:
Recurrent kidney stones
Gout and renal failure
Tophi
Associate chronic joint changes
Frequent/severe attacks of gout
Options:
Uricosuric agents: - best in uric acid undexcretors (normal urine uric acid with high serum levels). Avoid if renal stones/uric acid nephropathy. Less effective in renal failure.
Xanthine oxidase inhibitor - decrease uric acid synthesis. Good for almost everyone, but need to consider drug interacations and adjusft for comorbidities (renal failure)
- Use minimum dose to achieve effect (follow serum urate levels)
- Azathioprine (Imuran) is mteabolized by xanthine oxidase (decrease Imuran dose by >50% and follow for toxicity)
- Not clear what its role will be vs allopurinol, and ongoing safety monitoring will be important to follow (as with any new med)
CONSIDER prophylaxis with colchicine (0.6 mg up to BID if normal CrCl) when initiating/titrating antihyperuricemic drugs - stop once normouricemic for 6 months.
