Approach to Joint Pain - Diagnostic Framework 1) Chronicity 2) Inflammatory vs Non-Inflammatory 3) Number of Joints Involved 1) Chronicity: • Acute - Think about bacterial infections (bacterial), acute rheumatic fever • Chronic - Think about indolent infections (gonorrhea, Lyme, mycobacterial), RA, crystal disease, spondyloarthropathies, lupus, OA 2. Inflammatory vs. Non-inflammatory: • Inflammatory - AM stiffness, warm, swollen, tender • Non-inflammatory - No AM stiffness, weight-bearing joints, cool à Osteoarthritis typically non-inflammatory! 3. Number of Joints Involved: Monoarticular (1 joint): • Septic joint (bacterial, gonococcal, Lyme), reactive arthritis, gout or pseudogout, OA *Always do arthrocentesis! Send for cell count, culture, look for crystals. • WBC <2k: Noninflammatory • Bloody: Trauma, coagulopathy, tumor • Non-bloody: OA, avascular necrosis, Charcot (DM2, syphilis, alcohol - peripheral neuropathy so trauma and joint destruction lower limbs) • WBC 2-20k: Inflammatory, crystalline disease, seronegative spondyloarthropathies • WBC >20k: Septic joints with bacterial infection, needs washout! • Key point: If that patient had a prosthetic joint that was placed >30d ago = Worry about late prosthetic joint infection. This may be a more indolent presentation with lower WBC cutoff... >10K is concerning as there may be biofilm-forming organisms Oligoarticular (<5 joints): • Spondyloarthropathies, gout, pseudogout, gonorrhea, Lyme, OA. Like in this case, you can also get bacterial seeding of multiple joints if bacteremic. Polyarticular (5+ joints): • Symmetric vs. non-symmetric. • Acute = Viral - parvovirus, HIV, hepatitis, herpes • Chronic = RA, SLE, psoriatic arthritis Crystals: • Rhomboid, blue = pseudogout • Parallel, yellow = gout (memory trick: remember yellow and allopurinol both have a double L!) #Joint #Pain #MSK #rheumatology #approach #workup #differential #diagnosis #arthritis
