Approach to a Single Painful Joint OW! It hurts!

Monoarticular Causes A. Septic (bacteria, fungus, parasite) ACK!!! B. Trauma (meniscus, ligament, overuse, fracture, hemarthrosis) C. Crystal ( gout, pseudogout ) D. Neuropathy (Charcot ) E. AVN (ischemia) F. RA G. Lyme disease H. Paget’s disease (osteitis deformans) I. Neoplasms (osteoid osteoma, villonodular synovitis )

History Onset? Trauma? Circumstances. Joint probs b4? (OA? Knee replacement?) Where? Migratory? Multiple? Extraarticular sympts? Sex/Drugs/Rock and Roll?

Physical Inspection (SEADS) Palpation (milking, patellar tap) ROM Other joints Rest of body

Labs and Tests Synovial Fluid CBC ESR ANA RF X ray bilat joints

Management of the BIG 4

Things to Remember Septic arthritis is a medical emergency: two potential complications are sepsis and osteomyelitis. Always rule out septic arthritis. Always tap a monoarthritis and send the synovial fluid for cell count, Gram stain, fluid culture, and crystals.

The case of Mr. R 82 yr old M w/PMHx of OA, A fib. Fever, malaise, swollen painful R knee x 1/52, cannot weight bear currently. No travel. Was found on the floor, says he “fell but couldn’t get up”. At baseline, pt has dementia but is physically active. O/E: hr 80ireg ireg, temp 37.9, pt is confused, ROM of R knee degress with pain. R knee is swollen, red, tender. No obvious deformity. Lab: wbc is 14.8, uric acid 450uL (N: ), INR 9 (Pt gets BW done regularly.)

What could we do? Tell pt that they must go to the hospital. Sepsis? Monitor vitals. X ray both knees. obtain BW and blood cultures Urine culture and swabs if gonococcal cause suspected Tap the joint (to obtain fluid and to relieve pain). Treat empirically with IVAbx until C+S comes back.

Empiric Abx Treatment

What did I see done ? CT head: N X ray knees and CXR: N BW repeated: same Blood and urine cultures obtained. IV Vanco + Ceftriaxone (?) Morphine for pain. Warfarin stopped. Tap was not done due to INR. Dx: Hemarthrosis due to INR, R/O Septic Art.

Lesson learned You should ALWAYS tap and obtain synovial fluid (no matter the INR). In this case < 50,000c/uL, G stain -, all cultures -, intracellular CPPD crystals identified on microscopy. Dx: Acute Pseudogout. IVAbx stopped and corticosteroids injected into knee. D/C with PT referral.

References Cibere, J., “Acute Monoarthritis”, CMAJ, May 30, 2000; 162(11) Moses,S.,“Monoarticular Arthritis”, Family Practice Notebook.com, August 26, 2003 The Washington Manual of Medical Therapeutics, chap. 24 The Merck Manual 17th ed, chap 5, 13, 21 Sanford Guide to Antimicrobial Therapy