One-liner#
Adult/geriatric approach to knee pain (traumatic and atraumatic): identify red flags (fracture, septic joint, extensor mechanism rupture), recognize common patterns (OA, meniscus, patellofemoral), and set an outpatient-first plan.
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 knee with severe pain on any motion
- Suspected fracture/dislocation: significant trauma, gross deformity, or inability to bear weight
- Extensor mechanism rupture: inability to actively extend knee or perform straight-leg raise after injury
- Neurovascular compromise: new numbness/weakness, cool/pale foot, diminished pulses
- “Locked knee” with inability to extend (esp. acute after twisting injury) when severe/persistent
Key history#
- Trauma vs atraumatic; twisting injury; “pop”; ability to bear weight right after injury
- Timing of swelling: immediate (hemarthrosis/ACL fracture) vs delayed (meniscus/synovitis)
- Mechanical symptoms: locking, catching, giving way, instability
- Pain location: medial/lateral joint line, anterior (patellofemoral), posterior (Baker cyst/hamstring)
- Systemic/inflammatory clues: morning stiffness, multiple joints, known gout/pseudogout, recent infection
- Prior surgeries/injections; occupational kneeling; activity level; anticoagulants (hemarthrosis risk)
Focused exam#
- Inspect gait, alignment, swelling/erythema; compare sides
- Palpate joint lines, patellar tendon/quads tendon, pes anserine, popliteal fossa
- Effusion: bulge sign/patellar tap; ROM (extension full?); pain with passive ROM
- Ligaments: Lachman/anterior drawer (ACL), posterior drawer (PCL), varus/valgus stress (LCL/MCL)
- Meniscus: joint line tenderness; Thessaly/McMurray (context-dependent)
- Patellofemoral: patellar grind/crepitus; pain with stairs/squats
- Neurovascular: distal pulses, sensation, strength if significant trauma
Differential (quick pattern recognition)#
Common/likely (outpatient)#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Knee osteoarthritis | “Ache,” “stiff,” “worse with walking/stairs” | Older; gradual; brief morning stiffness | Crepitus, bony enlargement; ROM pain | PT/strengthening, weight optimization, topicals/analgesics; consider injection |
| Degenerative meniscal tear | “Catches,” “sharp when I twist,” intermittent swelling | Middle/older; twisting; stairs; may have giving way | Joint line tenderness; pain with squat/Thessaly | Conservative care first; consider imaging/referral if persistent locking |
| Acute meniscal tear | “Pop,” swelling later, can’t fully straighten” | Twisting sports injury; delayed effusion | Joint line tenderness; pain with McMurray | Conservative vs referral depending on locking/severity |
| Patellofemoral pain | “Pain behind kneecap,” worse stairs/squats” | Anterior pain; worse with sitting (“movie sign”) | Pain with patellar compression; dynamic valgus | Hip/quad strengthening, taping/bracing, activity modification |
| MCL/LCL sprain | “Inside/outside pain after twist” | Valgus/varus stress injury | Pain/laxity with stress test | Brace, RICE, PT; reassess stability |
| Pes anserine bursitis | “Tender inside below knee” | Medial pain below joint line | Focal tenderness over pes | PT, topicals, avoid kneeling/overuse |
| Baker cyst | “Fullness behind knee” | Posterior swelling, tightness | Popliteal fullness; associated OA/meniscus | Treat underlying cause; ultrasound if DVT concern |
Can’t-miss / urgent#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Septic arthritis | “Hot,” “throbbing,” feels sick | Fever/risk factors; severe pain with any motion | Warmth/effusion; pain with passive ROM | ED now; aspiration/labs/IV antibiotics |
| Fracture (tibial plateau/patella/distal femur) | “Severe after fall,” can’t bear weight | Trauma; inability to bear weight | Point tenderness, large effusion | Urgent imaging (Ottawa knee rules can guide) |
| ACL tear with hemarthrosis | “Pop,” immediate swelling, instability | Acute pivot injury | +Lachman/instability | Brace/immobilize as needed; early ortho/PT pathway |
| Quadriceps/patellar tendon rupture | “Knee gave out,” can’t straighten” | Older; sudden pain after jump/fall | Inability straight-leg raise; palpable gap | ED/same-day ortho |
Workup#
- X-ray for trauma when indicated (Ottawa knee rules: age ≥55, isolated patellar tenderness, fibular head tenderness, inability to flex 90°, inability to bear weight immediately and for 4 steps in clinic).
- X-ray (weight-bearing if possible) for suspected OA when it will change management (baseline severity, injection/surgical planning).
- Aspiration:
- Diagnostic: when hot swollen joint and infection vs crystal is in the differential.
- Therapeutic: tense effusion limiting ROM.
- Typical studies (verify local protocol): cell count/diff, crystals, Gram stain/culture.
- Labs (CBC, ESR/CRP) only when infection/inflammatory arthritis suspected (do not delay aspiration/ED pathway if septic arthritis is suspected).
- MRI is rarely first-line in primary care; consider if persistent mechanical locking, suspected internal derangement not improving with conservative care, or pre-op planning.
Initial management#
- Relative rest from provoking activities; ice for acute swelling; compression and elevation as tolerated.
- Analgesics/topicals as appropriate (verify local protocol/formulary)—see medication tables below.
- Consider a short period of bracing for instability/pain with ambulation (hinged brace for collateral ligament sprain; patellar sleeve/taping for patellofemoral pain).
- Early PT or home strengthening program for OA/patellofemoral/most meniscal patterns.
Analgesic options for knee pain#
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Diclofenac gel 1% | Apply 4 g to knee QID; max 16 g/day per joint | Avoid on broken skin; caution if systemic NSAID contraindications | Minimal systemic absorption | $$ | First-line for knee OA; lower GI/renal risk than oral NSAIDs |
| Acetaminophen | 650–1000 mg q6–8h; max 3 g/day (2 g/day if liver disease) | Severe hepatic impairment; chronic alcohol use | LFTs if prolonged use | $ | Safe adjunct; limited efficacy alone for OA |
| Ibuprofen | 400–600 mg q6–8h with food; max 2400 mg/day | CKD (eGFR <30), GI bleed/ulcer, uncontrolled HTN, HF, anticoagulation | Cr, BP if prolonged use | $ | Effective; limit to 7–10 days if possible |
| Naproxen | 250–500 mg q12h; max 1000 mg/day | Same as ibuprofen | Same as ibuprofen | $ | Convenient BID dosing |
| Meloxicam | 7.5–15 mg daily | Same as ibuprofen | Same as ibuprofen | $ | Once-daily; COX-2 preferential (slightly lower GI risk) |
| Capsaicin cream 0.025–0.075% | Apply TID–QID to affected area | Avoid on broken skin, mucous membranes | Local burning (improves with use) | $ | Takes 2–4 weeks for effect; useful adjunct for OA |
When NOT to use oral NSAIDs:
- CKD stage 4–5 (eGFR <30)
- Active GI bleeding or high ulcer risk without PPI
- Uncontrolled hypertension or decompensated HF
- On anticoagulation (increased bleeding risk)
- Elderly with multiple risk factors—prefer topical
Management by diagnosis#
Knee osteoarthritis#
Education: Strength and weight optimization often matter more than imaging findings; flare-ups are common.
Treatment:
- PT (quad/hip strengthening), activity pacing, and step-count goals that are sustainable
- Topical NSAID first-line; consider oral NSAID if needed and safe (see tables above)
- Consider injection pathway when conservative measures fail and pain blocks rehab
Intra-articular injection options (verify local protocol)#
| Agent | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Triamcinolone 40 mg | 40 mg in 1–2 mL; may dilute with lidocaine | Active infection; uncontrolled DM (will spike glucose); anticoagulation (relative) | Blood glucose in diabetics × 1–2 weeks | $ | Provides 4–12 weeks relief; limit to 3–4 injections/year per joint |
| Methylprednisolone 40–80 mg | 40–80 mg in 1–2 mL | Same as triamcinolone | Same as triamcinolone | $ | Similar efficacy to triamcinolone |
| Hyaluronic acid (viscosupplementation) | Per product (single vs series) | Active infection; known allergy to avian products (some formulations) | None specific | $$$$ | Mixed evidence; consider if steroid contraindicated or failed; often requires prior auth |
When NOT to inject:
- Suspected septic joint (aspirate first, do not inject steroid)
- Overlying cellulitis or skin breakdown
- Uncontrolled diabetes without close glucose monitoring plan
- More than 3–4 steroid injections per joint per year
Adjunctive options for chronic OA pain#
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Duloxetine | 30 mg daily × 1 week, then 60 mg daily | Hepatic impairment; concurrent MAOIs; uncontrolled glaucoma | BP, mood; avoid abrupt discontinuation | $$ | FDA-approved for chronic MSK pain; consider if NSAIDs contraindicated or comorbid depression/anxiety |
Follow-up: 6–12 weeks; earlier if rapid decline or new swelling/instability.
Meniscal symptoms (degenerative or minor traumatic)#
- Education: many tears improve without surgery; focus on strength and function.
- Treatment:
- PT with gradual loading; avoid deep squats/twisting early while symptoms are flared.
- Analgesics/topicals as appropriate.
- Consider referral if persistent true locking, recurrent significant effusions, or failure to improve with conservative care.
- Follow-up: 4–6 weeks.
Ligament sprain (MCL/LCL) / instability#
- Education: expect gradual improvement; protect from high-risk pivoting.
- Treatment:
- Hinged brace when needed, early ROM, and PT for stabilization/proprioception.
- Assess ACL/PCL if significant instability or hemarthrosis.
- Consider ortho referral for high-grade sprains, persistent instability, or high-demand athletes.
- Follow-up: 1–2 weeks if unstable; otherwise 4–6 weeks.
Suspected gout/pseudogout (crystal arthritis)#
Education: Can mimic infection; diagnosis often requires aspiration when uncertain.
Treatment:
- If diagnosis is secure and infection unlikely, treat flare with anti-inflammatory therapy per patient risk profile
- If diagnosis is uncertain or high-risk features are present, prioritize aspiration/ED pathway over empiric treatment
- Evaluate urate management and triggers as indicated once acute flare resolves
Acute gout flare treatment#
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Naproxen | 500 mg BID × 5–7 days | CKD, GI bleed, 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; concurrent CYP3A4 inhibitors | GI symptoms (diarrhea); Cr | $$ | Most effective if started within 24 hours of flare; 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 | 40 mg (knee) | Active infection; overlying cellulitis | Blood glucose in diabetics | $ | Excellent option for monoarticular gout; avoids systemic side effects |
When NOT to start urate-lowering therapy:
- During acute flare (can worsen/prolong flare)—wait 2–4 weeks after flare resolves
- Without discussing long-term commitment with patient
Follow-up: 1–2 weeks; urgent escalation if fever or rapidly worsening pain/swelling.
Follow-up#
- Reassess in 1–2 weeks for traumatic injuries with instability or significant effusion.
- Reassess in 4–6 weeks for most atraumatic patterns starting PT/home program.
- Urgent return for fever/hot swollen knee, inability to bear weight after injury, new numbness/weakness, or inability to extend the knee.
Patient instructions#
- Use ice 10–15 minutes at a time for swelling, plus compression and elevation as tolerated.
- Avoid painful twisting/deep squats initially; prioritize gentle range of motion and walking as tolerated.
- Consider over-the-counter pain options if safe for you.
- Seek urgent care for fever with a hot/swollen knee, new inability to bear weight after injury, or inability to straighten the knee.
Smartphrase snippets#
Knee OA, conservative management:
Knee pain consistent with osteoarthritis; no red flags. Plan: topical NSAID, PT referral for quad/hip strengthening, activity pacing. Discussed weight optimization if applicable. Will consider injection if conservative measures fail. Return precautions reviewed.
Meniscal symptoms, conservative trial:
Knee pain with mechanical symptoms suggestive of meniscal pathology; no locking or significant instability. Plan: conservative management with PT, activity modification, and analgesics. Will reassess in 4–6 weeks; consider imaging/referral if persistent locking or failure to improve.
Acute gout flare:
Acute monoarticular knee swelling consistent with gout flare; infection ruled out by [aspiration/clinical presentation]. Treating with [agent] × [duration]. Discussed triggers and will address urate-lowering therapy once flare resolves. Return precautions for fever or worsening reviewed.
Related pages#
Complaint pages#
- Hip pain — hip pathology that may refer to knee
- Ankle pain — lower extremity evaluation
- Monoarticular swelling — acute joint swelling differential
- Polyarthralgia — multiple joint involvement
- Falls/Injury evaluation — trauma assessment
Problem pages#
- Osteoarthritis — comprehensive OA management including knee-specific considerations
- Gout — urate-lowering therapy and chronic gout management
- Osteoporosis — fracture risk assessment and bone health
Coding/billing notes (optional)#
- Document trauma mechanism, weight-bearing status, effusion, ROM, ligament testing, and infection screening to support imaging/aspiration/referral decisions.