—50% of sexually active adults with septic arthritis are due to gonococcal infections, while most patients with risk factors for septic arthritis listed below are due to non-gonococcal infections (S. aureus, Streptococci, Gram-negative bacilli)

—more common in women. Less destructive and has better outcome than non-gonococcal arthritis. The synovial fluid Gram stain is only positive in <10%, and culture is often negative in gonococcal arthritis

—osteomyelitis (30%), permanent joint damage, sepsis

—arthritis (location, duration, pain, range of motion, function), adenopathy, fever, rash, oral ulcers, alopecia, Raynaud’s, photosensitivity, sicca, trauma, recent infections, cervical/urethral discharge, sexual encounters, diarrhea, recent travel, past medical history (pre-existing joint disease, gout, rheumatoid arthritis, SLE, IBD, psoriasis, diabetes, IDU), medications (anticoagulants)

—vitals (fever), joint examination (tenderness, swelling, range of motion). Look for nail pitting, onycholysis, tophi, rheumatoid nodules, track marks, psoriasis, keratoconjunctivitis sicca, uveitis, conjunctivitis, episcleritis, murmurs, urethral discharge, and penile ulcers. Examine all joints and pay particular attention to the affected one. Soft tissue injuries (bursitis, tendonitis, muscles) usually have decreased active range of motion but normal passive range of motion, while both active and passive range of motion would be affected in joint diseases. Pelvic examination to inspect the cervix and to look for pelvic inflammatory disease

—patients with monoarthritis have septic arthritis until proven otherwise. Joint infection is a rheumatologic emergency as permanent damage can occur. Presence of crystal does not rule out infection. In up to 75% of patients with septic arthritis, a focus of infection may be found

—for diagnostic and sometimes therapeutic reasons. Absolute contraindication is infection overlying site of injection. Relative contraindications include significant hemostasis defects and bacteremia (NEJM 2006 354:e19)

—NSAIDs/opioids for pain

—empiric (if not at risk for sexually transmitted disease, nafcillin 2 g IV q4h or vancomycin 1 g IV q12h, plus ceftriaxone 2 g IV q24h or cefotaxime 2 g IV q8h. If at risk of sexually transmitted disease, nafcillin 2 g IV q4h for Gram positive organisms on Gram stain; otherwise, give ceftriaxone 2 g IV q24h or cefotaxime 2 g IV q8h if organisms not identifiable yet). Gonococcal (ceftriaxone 1 g IV q24h). Lyme arthritis (amoxicillin 500 mg PO TID, doxycycline 100 mg PO BID, or ceftriaxone 2 g IV daily × 4 weeks). Therapeutic arthrocentesis. Arthroscopic or surgical drainage (if joint inaccessible to needle drainage, organism resistant to antibiotics, or no clinical response in 3–4 days)

—decreased urate excretion and/or increased urate production → uric acid crystals deposited in joints, skin, and kidneys → arthritis, tophi, and renal failure. Gout almost never occurs in pre-menopausal women (estrogen promotes higher urinary fractional excretion of urate)

—surgery, dehydration, fasting, binge eating, binge drinking, exercise, trauma

—may be falsely lowered in an acute attack

—soft tissue swelling, normal joint space, erosions (“punched out” and sclerotic lesions with overhanging edge)

—ALWAYS confirm diagnosis with a synovial fluid tap if possible. Microscopy shows predominantly neutrophilic infiltrate with some intracellular monosodium urate crystals (needle shaped, negative birefringence, i.e. yellow when parallel to plane of polarized light)

—NSAIDs (first line, avoid if renal/hepatic failure; naproxen 375–500 mg PO BID × 3 days, then 250–375 mg PO BID × 4–7 days; sulindac 150–200 mg PO BID × 7–10 days; indomethacin 25–50 mg PO TID × 3 days, then 100 mg PO div BID–QID × 4–7 days; celecoxib 200 mg PO BID × 1 day, then 100 mg PO BID × 6–10 days). Systemic corticosteroids (avoid if joint sepsis not excluded; prednisone 30–60 mg PO daily × 3 days, then ↓ 10–15 mg daily × 3 days until discontinuation, triamcinolone 50 mg IM × 1 dose). Intra–articular corticosteroids (for mono- and oligoarthritis only. Methylprednisolone 40–80 mg intra-articularly once). Colchicine 0.6 mg PO daily-BID during acute attack (avoid the approach of giving colchicine q1h until development of diarrhea). Low dose colchicine regimens (≤1.8 g daily) appear as effective and are better tolerated than higher dose regimens

—purine-restricted diet (↓ red meats, ↓ seafood, ↑ low-fat dairy products, ↑ fruit and veggies) have limited supportive evidence. Avoidance of beer and sugar-laden beverages is beneficial. Allopurinol 50–300 mg PO daily (first line, xanthine oxidase inhibitor, renal dose adjustment required, urate-lowering therapy generally not started in acute attack; however, continue allopurinol if already on it prior to acute attack). Febuxostat 80 mg PO daily is a newer xanthine oxidase inhibitor that can be used in patients intolerant of allopurinol or in those with mild-to-moderate renal failure. Probenecid 250–1000 mg PO BID (first line, ↓ renal urate reabsorption. Ensure normal renal function). Sulfinpyrazone 50–200 mg PO BID. Colchicine 0.6 mg PO BID × 6 months (for prophylaxis against recurrent attacks only. Do not give colchicine IV)

—consider if patients have frequent attacks (≥3/year, tophaceous deposits, overproduction of uric acid, or continued cyclosporine treatment)

—remember to start colchicine or NSAIDs prior to allopurinol and to overlap therapy to prevent precipitating flare. Allopurinol alone can cause an abrupt decrease in serum uric acid → breakdown and release of synovial urate crystal deposits → inflammation. Aim to decrease serum uric acid level below 362 μmol/L [5.1 mg/dL]. Do not start or stop allopurinol during an acute attack

—associated with normal urate levels and chondrocalcinosis that may be visible radiographically. Crystals appear rhomboid and have positive birefringence (blue when parallel to polarized light, yellow when perpendicular). Risk factors include old age, advanced osteoarthritis, neuropathic joint, gout, hyperparathyroidism, hemochromatosis, diabetes, hypothyroidism, hypomagnesemia, trauma, and symptoms

(BCPC)—crystals appear snowball-like with Alizarin red S stain. Implicated in bursitis, inflammation superimposed on osteoarthritis, and calcinosis cutis in systemic sclerosis and CREST

—develop destructive arthritis and tendonitis from calcium oxalate, monosodium urate, calcium pyrophosphate, and basic calcium phosphate crystals. Amyloidosis may also contribute to arthritis

—T-helper 1 mediated process → proteases produced by synovial cells destroy proteoglycans in the articular cartilage → irreversible damage 6 months to 1 year from disease onset

—age >50, female (3:1), first-degree relative with rheumatoid arthritis, smoking, low level of education

—symmetric polyarthritis with joint pain, swelling, redness, morning stiffness (>1 h), and dysfunction

—only in seropositive patients

—fatigue (40%), fever (low grade), sweats, weight loss, myalgia

—add score of categories A to D, with a score of ≥6/10 classified as definite RA

—increased number of joints involved, presence of rheumatoid nodules, erosions, elevated inflammatory markers and seropositivity all suggest more severe disease

—physical therapy, diet (Ω-3 fatty acids). Joint protection (range of motion exercises, orthotics, splints). NSAIDs (antiinflammatory dose). Intraarticular steroid injections (if severe pain). Patient education

—single agent (methotrexate with folic acid, sulfasalazine, hydroxychloroquine, cyclosporine, gold). Combination triple therapy (methotrexate plus sulfasalazine plus hydroxychloroquine). Selective pyrimidine synthesis inhibitor (leflunomide). TNFα inhibitors (infliximab, etanercept, adalimumab, golimumab). B–cell inhibitor (rituximab, an anti-CD20 monoclonal antibody). T–lymphocyte activation inhibitor (abatacept), IL-6 inhibition (tocilizumab). Surgical intervention

—episodic arthritis with one or more joints being affected sequentially for hours to days, and symptom-free periods in between for days to months. May be anti-CCP positive and occasionally progresses to other rheumatic disorders (RA, SLE). Treatment with hydroxychloroquine can be useful

—a benign self-limited form of sarcoidosis. Tetrad of erythema nodosum, hilar lymphadenopathy, arthritis (ankles and sometimes knees), and fever

—overlap syndrome with clinical features of two or more rheumatologic disorders (RA, SLE, Sjogren’s syndrome, scleroderma, inflammatory myopathies) but does not fit the diagnostic criteria for any specific disorder

—a specific overlap syndrome with clinical features of SLE, scleroderma, polymyositis, and antibodies to RNP. Characteristically, Raynaud’s phenomenon, myositis, and synovitis are present

—typically affects women aged 15–45

—antibody-immune complex deposition in kidneys (glomerulonephritis), autoantibodies against cell surface antigens on hematopoietic progenitor cells (anemia, neutropenia, thrombocytopenia), antiphospholipid antibodies (thrombosis)

Need ≥4 of 11 criteria (each rash counts as one criterion and ANA as a separate criterion) to meet classification criteria. Note that many patients may not ever fulfill four criteria until several years into their disease course

—symmetric non-erosive polyarthritis with joint pain, swelling, redness, morning stiffness (>1 h), and dysfunction. Sens 88%