One-liner#
Adult/geriatric approach to a swollen single joint: rapidly separate septic arthritis and fracture/hemarthrosis from gout/pseudogout and non-emergent causes, then choose the right aspiration/imaging pathway.
Quick nav#
- Red flags / send to ED
- Key history
- Focused exam
- Differential (quick pattern recognition)
- Workup
- Initial management
- Management by diagnosis
- Follow-up
- Patient instructions
Red flags / send to ED#
- Suspected septic arthritis: fever/systemic illness plus hot swollen joint with severe pain on any motion
- Suspected fracture/dislocation: major trauma, deformity, inability to bear weight/use the limb
- Suspected hemarthrosis with significant swelling/pain (especially on anticoagulation) or neurovascular compromise
- Rapidly worsening pain/swelling with pain out of proportion (rare: compartment syndrome/necrotizing infection)
- Immunosuppression/IVDU with acute hot swollen joint (lower threshold for ED/urgent aspiration)
Key history#
- Time course: sudden (hours) vs over days; first episode vs recurrent
- Trauma: fall/twist; anticoagulation/bleeding disorders (hemarthrosis)
- Systemic symptoms: fever, chills, malaise
- Prior gout/pseudogout; recent dehydration/diuretics; recent illness or surgery
- Risk for infection: prosthetic joint, immunosuppression, diabetes, skin breaks/cellulitis near joint, IVDU
- Recent GI/GU infection (reactive arthritis), recent tick exposure (regional)
- Location: knee/ankle/first MTP/wrist are common for crystal disease
Focused exam#
- Vitals; fever; overall toxicity
- Inspect: erythema, warmth, swelling distribution; wounds or nearby cellulitis
- Palpate effusion; compare sides; assess bony tenderness (fracture)
- ROM: pain with passive ROM suggests intra-articular process (infection/crystal)
- Stability testing (if trauma) as tolerated
- Neurovascular exam distal to joint
Differential (quick pattern recognition)#
Common/likely (outpatient)#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Gout flare | “Sudden,” “throbbing,” “even a sheet hurts” | Rapid onset; prior episodes; diuretics/dehydration | Hot swollen joint; extreme tenderness | Treat flare if infection unlikely; aspirate if uncertain |
| Pseudogout (CPPD) | “Sudden swollen knee/wrist” | Older; knee/wrist common; may follow illness | Effusion; warmth | Treat flare; aspirate if uncertain |
| Traumatic effusion/sprain | “Twisted it,” swelling after injury | Clear trauma; swelling may be delayed | Effusion; ligament tenderness | X-ray if indicated; brace/rehab |
| OA flare with effusion | “Ache,” “stiff,” worse after activity | Known OA; less dramatic onset | Mild–moderate effusion; ROM limited by pain | Conservative care; consider aspiration if tense/unclear |
| Bursitis (prepatellar/olecranon) | “Soft lump,” “swollen over kneecap/elbow” | Localized swelling over bursa | Fluctuant superficial swelling; joint ROM relatively preserved | Compression/avoid pressure; aspirate selectively |
| Hemarthrosis (anticoagulation) | “Blew up/swollen fast” | On anticoagulant; minor trauma | Large effusion; bruising | Urgent evaluation; consider aspiration/imaging |
Can’t-miss / urgent#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Septic arthritis | “Hot,” “feels sick,” “can’t move it” | Fever/risk factors; rapidly progressive | Severe pain with passive ROM; effusion | ED now; aspiration/cultures + antibiotics per protocol |
| Fracture/dislocation | “Can’t bear weight,” deformity | Trauma; focal bony pain | Bony tenderness/deformity | ED/urgent imaging + immobilize |
| Necrotizing infection/compartment syndrome (rare) | “Pain out of proportion” | Rapid progression; systemic signs | Tense swelling; severe pain | ED now |
Workup#
- Aspirate when:
- The diagnosis is unclear and infection is in the differential, or
- The presentation is atypical for known gout/CPPD, or
- There is a large tense effusion limiting ROM.
- Typical synovial fluid studies (verify local protocol): cell count/diff, crystals, Gram stain/culture (and consider glucose/protein if used locally).
- Do not rely on serum uric acid during an acute flare to rule in/out gout.
- X-ray for trauma, deformity, focal bony tenderness, suspected OA, or to evaluate chondrocalcinosis (CPPD).
- Labs (when indicated): CBC + ESR/CRP for suspected infection/inflammatory disease; blood cultures if septic arthritis suspected.
Synovial fluid interpretation (quick reference)#
| Finding | Normal | Non-inflammatory (OA) | Inflammatory (gout/RA) | Septic |
|---|---|---|---|---|
| WBC count | <200/μL | 200–2,000/μL | 2,000–50,000/μL | >50,000/μL (often >100k) |
| PMN % | <25% | <25% | >50% | >75% |
| Appearance | Clear | Clear/yellow | Cloudy/yellow | Purulent |
| Crystals | None | None | Urate (gout) or CPPD | Usually none |
Key points:
- WBC >50,000 with >75% PMNs: treat as septic until proven otherwise
- Crystal-positive does NOT rule out infection (can coexist)
- Gram stain is only ~50% sensitive for septic arthritis—do not rely on negative Gram stain to exclude infection
Initial management#
- If septic arthritis is possible: prioritize urgent aspiration/ED pathway and antibiotics per local protocol (do not delay).
- If crystal flare is likely and infection is unlikely: treat with anti-inflammatory therapy based on comorbidities—see medication tables below.
- Protect the joint: relative rest, ice, compression, elevation; consider bracing if traumatic instability suspected.
Anti-inflammatory options for crystal arthritis flares#
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Naproxen | 500 mg BID × 5–7 days | CKD (eGFR <30), GI bleed/ulcer, HF, anticoagulation | Cr if CKD risk | $ | First-line if no NSAID contraindications |
| Indomethacin | 50 mg TID × 2 days, then 25 mg TID × 3 days | Same as naproxen; higher GI/CNS side effects | Same as naproxen | $ | Potent but more side effects; avoid in elderly |
| Colchicine | 1.2 mg, then 0.6 mg 1 hour later (day 1); then 0.6 mg daily–BID | CKD (reduce dose if eGFR <30); hepatic impairment; CYP3A4 inhibitors | GI symptoms (diarrhea); Cr | $$ | Most effective within 24 hours of flare onset; low-dose regimen preferred |
| Prednisone | 30–40 mg daily × 5 days (no taper needed) | Uncontrolled DM, active infection | Blood glucose in diabetics | $ | Use when NSAIDs/colchicine contraindicated; safe in CKD |
| Intra-articular triamcinolone | 10–40 mg depending on joint size | Active infection; overlying cellulitis | Blood glucose in diabetics | $ | Excellent for monoarticular flare; avoids systemic side effects |
Choosing therapy:
- No contraindications: NSAID (naproxen preferred) or colchicine
- CKD/HF/GI risk: Prednisone or intra-articular steroid
- Diabetes: NSAID or colchicine preferred (steroids spike glucose)
- Monoarticular with secure diagnosis: Intra-articular steroid is highly effective
When NOT to treat empirically:
- Fever or systemic illness (aspirate first to rule out infection)
- First presentation without prior gout diagnosis (consider aspiration)
- Prosthetic joint (always aspirate; do not inject without orthopedic guidance)
Management by diagnosis#
Gout flare (likely; infection unlikely)#
- Education: gout can mimic infection; new patterns or systemic symptoms should prompt aspiration/urgent evaluation.
- Treatment: anti-inflammatory flare therapy per patient risk profile (NSAID/colchicine/steroid options; verify local protocol); avoid starting urate-lowering changes mid-flare unless already on therapy.
- Follow-up: 48–72 hours if not improving; earlier if fever, spreading redness, or worsening pain.
Pseudogout (CPPD)#
- Education: common in older adults; often knee or wrist; can recur.
- Treatment: anti-inflammatory therapy; consider aspiration/injection pathway when diagnosis is secure and severe (verify local protocol).
- Follow-up: 3–7 days if not improving.
Traumatic effusion/sprain#
- Education: swelling can lag injury; focus on stability and function.
- Treatment: ice/compression/elevation, brace as indicated, early ROM/rehab once fracture ruled out; image based on location-specific rules.
- Follow-up: 1–2 weeks to reassess stability and ROM.
Suspected septic arthritis#
- Education: joint infection is time-sensitive and can permanently damage the joint.
- Treatment: ED now for aspiration/cultures and antibiotics per protocol; do not treat as gout without ruling out infection when uncertain.
- Follow-up: ED pathway.
Follow-up#
- If diagnosis is uncertain or symptoms are severe: reassess in 24–72 hours (or sooner) and ensure aspiration/imaging path is clear.
- For typical non-emergent flares (OA/bursitis/known crystal): reassess in 1–2 weeks if not improving.
- Escalate urgently for fever, rapidly increasing redness/swelling, inability to move the joint, or new neurovascular symptoms.
Patient instructions#
- Rest the joint for the next 1–2 days, but keep gentle range of motion as tolerated.
- Use ice 10–15 minutes at a time and consider compression/elevation for swelling.
- Use over-the-counter pain options if safe for you.
- Seek urgent care now for fever, rapidly spreading redness, severe pain with any joint movement, or inability to bear weight/use the limb.
Smartphrase snippets#
Gout flare, treating empirically:
Acute monoarticular swelling of [joint] consistent with gout flare. No fever, no systemic symptoms, prior gout history. Infection unlikely. Treating with [NSAID/colchicine/prednisone]. Return precautions for fever, spreading redness, or worsening pain reviewed. Follow-up in 48–72 hours if not improving.
Aspiration performed:
[Joint] aspirated for diagnostic evaluation of acute monoarticular swelling. [X mL] of [cloudy/clear/bloody] fluid obtained. Sent for cell count, crystals, Gram stain, and culture. [If injected: Injected with triamcinolone X mg after aspiration.] Pending results; patient instructed to return immediately for fever or worsening symptoms.
Referred to ED for septic arthritis concern:
Acute hot swollen [joint] with [fever/systemic symptoms/severe pain with passive ROM]. Septic arthritis cannot be excluded. Referred to ED for urgent aspiration, cultures, and IV antibiotics. Patient instructed to go directly to ED.
Related pages#
Complaint pages#
- Polyarthralgia — multiple joint involvement and inflammatory arthritis screening
- Ankle Pain — ankle-specific evaluation including gout
- Knee Pain — knee-specific evaluation and effusion management
Problem pages#
- Gout — comprehensive gout management including flare treatment and urate-lowering therapy
- Osteoarthritis — OA management when effusion is secondary to degenerative disease