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msk.osteoarthritis.core.v1PRODUCTION
msk.osteoarthritis.core.v1

Osteoarthritis (knee / hip / hand — clinical dx → management)

rheumatologychronicadultgeriatric
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Encounter flow

12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

OA is a CLINICAL diagnosis in the typical patient (age ≥45, activity-related pain, ≤30 min stiffness, no systemic inflammatory features) — imaging NOT required; Kellgren–Lawrence grade is a structural anchor, not a diagnostic gate (NICE NG226 2022; ACR/AF 2019 Kolasinski PMID 31908163). Scope: knee, hip, hand (incl. erosive hand OA), with/without inflammatory component

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Phenotype scope set and clinical-vs-imaging frame established

Patient inputs (18)

Pre-test probability of OA rises steeply with age (≈10% men / 13% women symptomatic knee OA at ≥60); age ≥50 is an ACR clinical-criteria item (Altman 1986 PMID 3741515)

Obesity is the dominant modifiable risk factor; ≥5–10% weight loss is disease-modifying for knee OA (IDEA Messier JAMA 2013 PMID 24065013)

≤30 min favours OA; >45–60 min is a pivot toward inflammatory arthritis (RA) — drives differential routing (NICE NG226 2022; Altman 1986)

eGFR (CKD-EPI 2021, race-neutral) gates oral NSAID: avoid if eGFR <30; caution 30–59 (ACR/AF 2019; OARSI 2019 PMID 31278997)

Established CVD / HF / uncontrolled HTN → OARSI recommends NOT using oral NSAID; prefer naproxen if any NSAID needed (PRECISION Nissen NEJM 2016 PMID 27959716)

PUD / prior GI bleed → COX-2 selective + PPI co-prescription if an NSAID is required (PRECISION PMID 27959716)

Concurrent anticoagulant/antiplatelet sharply raises NSAID GI bleed risk → prefer topical NSAID or COX-2 + PPI

DIP/1st-CMC/knee/hip favours OA; symmetric MCP/wrist synovitis favours RA; 1st-MTP podagra favours gout — MECE pivot

Fever / weight loss / fatigue argue against primary OA and toward inflammatory, septic, or malignant cause

Acute hot swollen joint + fever = septic arthritis until proven otherwise — STAT arthrocentesis (not an OA pathway)

Function-limiting refractory pain despite optimised conservative therapy is the arthroplasty-referral threshold (Skou NEJM 2015 PMID 26488691)

Weight-bearing radiograph for KL grade ONLY if atypical / pre-surgical / diagnostically uncertain — not required for typical OA (NICE NG226 2022)

Female sex raises hand and knee OA prior; erosive hand OA predominantly peri/postmenopausal women

Kneeling / squatting / heavy-lifting occupations raise knee OA prior; informs counselling

Prior ACL/meniscal or major joint injury raises post-traumatic OA prior 3–4× in that joint

Normal ESR/CRP lowers posterior probability of active inflammatory arthritis; elevated → re-route to RA/crystal workup (not routinely needed to diagnose OA)

Only when inflammatory pattern suspected — positive RF/anti-CCP routes to rheum.rheumatoid-arthritis.core.v1 (not part of typical OA workup)

If a joint effusion is aspirated: OA fluid is non-inflammatory (WBC <2000, no crystals); rules in crystal/septic if positive

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (6)

6 need judgement
  • informationallife_threateningseptic_arthritis_mimic
    Acute hot swollen joint + fever / immunocompromise — septic arthritis until excluded (NOT an OA pathway) (ACR/AF 2019)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereinflammatory_arthritis_pivot
    Morning stiffness >60 min, symmetric MCP/wrist synovitis, elevated ESR/CRP, or positive RF/anti-CCP — re-route to inflammatory-arthritis engine (Altman 1986 PMID 3741515)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereoral_nsaid_contraindicated_by_comorbidity
    eGFR <30 (CKD-EPI 2021), established CVD/HF/uncontrolled HTN, active PUD/recent GI bleed, or concurrent anticoagulant — oral NSAID gated OFF (OARSI 2019 PMID 31278997)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevererefractory_function_limiting_arthroplasty_threshold
    Persistent life-limiting pain/function loss despite optimised core non-pharm + appropriate pharmacotherapy, with concordant KL grade — arthroplasty-referral threshold (Skou NEJM 2015 PMID 26488691)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatecrystal_arthritis_pivot
    Acute monoarticular hot joint, 1st-MTP podagra, or synovial monosodium urate / CPP crystals — crystal arthropathy, not OA (EULAR; ACR 2020 gout)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderaterepeated_ia_glucocorticoid_cartilage_risk
    Scheduled / frequent intra-articular glucocorticoid (e.g. q12wk long-term) — cartilage-volume loss without pain benefit (McAlindon JAMA 2017 PMID 28510679)
    Trigger could not be auto-evaluated — needs clinician judgement.

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RISK_STRATIFICATIONrequiredDrives severity classification
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Recommended regimen

OA core non-pharm → topical NSAID → comorbidity-gated oral NSAID → adjuncts → recommend-against → arthroplasty (ACR/AF 2019; OARSI 2019; NICE NG226 2022)
axis: oa_core_to_pharmacologic_ladderstep 1 - Step 1 — Core non-pharmacologic (FIRST-LINE for ALL phenotypes; never skipped)
Selected step "Step 1 — Core non-pharmacologic (FIRST-LINE for ALL phenotypes; never skipped)" — Every patient with knee, hip, or hand OA at every severity
  • structured patient education & self-management program
    first line
    education_self_management
    triggers: any_oa_phenotype
    ACR/AF 2019 STRONG; OARSI 2019 Core treatment — improves self-efficacy and pain coping (PMID 31908163; 31278997)
  • structured land-based exercise (strengthening + aerobic + ROM)
    first line
    exercise_therapy
    triggers: knee_oa, hip_oa, hand_oa
    ACR/AF 2019 STRONG; OARSI Core. Knee pain SMD −0.49 (95% CI −0.39 to −0.59) ≈ 12/100-pt; function SMD −0.52; benefit sustained 2–6 mo; magnitude comparable to NSAIDs (Fransen Cochrane 2015 PMID 25569281; hip PMID 26405113)
  • dietary weight loss ≥5–10% of body weight
    first line
    weight_management
    triggers: bmi_>=25, knee_oa, hip_oa
    ACR/AF 2019 STRONG for overweight/obese knee/hip OA. Diet+exercise (−11.4% weight) reduced pain & improved function vs exercise alone; 1 kg loss ≈ 4 kg/step less knee load (IDEA Messier JAMA 2013 PMID 24065013)
  • assistive devices / bracing / hand orthoses
    first line
    biomechanical_device
    triggers: knee_malalignment_or_instability, first_cmc_thumb_base_oa, gait_impairment
    ACR/AF 2019 STRONG: cane, tibiofemoral brace (medial knee OA), 1st-CMC hand orthosis; conditional patellofemoral brace (PMID 31908163)

outpatient playbook — drug actions (5)

  1. 1. core non-pharm (education + structured exercise + weight loss + devices)
    exercise ≥2–3×/wk; weight loss ≥5–10% if BMI ≥25 • n/a • ongoing
    trigger: Every OA patient (first-line, all phenotypes)
    Exercise knee pain SMD −0.49 (Fransen Cochrane 2015 PMID 25569281); IDEA weight loss (Messier JAMA 2013 PMID 24065013)
  2. 2. topical diclofenac
    1% gel 2–4 g QID (knee) / thin layer QID (hand) • topical • QID
    trigger: Knee or hand OA, inadequate non-pharm response
    ACR/AF 2019 STRONG (knee); systemic-sparing first-line drug (Derry Cochrane PMID 28497473)
  3. 3. oral NSAID (naproxen / ibuprofen / celecoxib per matrix)
    naproxen 250–500 mg BID OR ibuprofen 400 mg TID OR celecoxib 100–200 mg/day • PO • lowest effective dose, shortest duration
    trigger: Inadequate topical response AND comorbidity matrix permits
    ACR/AF 2019 STRONG; matrix-gated by eGFR/CVD/PUD/anticoagulant (PRECISION Nissen NEJM 2016 PMID 27959716)
  4. 4. duloxetine
    30 mg daily × 1 wk → 60 mg (max 120 mg) • PO • once daily
    trigger: Centralised/multi-joint pain or oral NSAID contraindicated
    ACR/AF 2019 CONDITIONAL (Chappell PMID 20602715)
  5. 5. intra-articular triamcinolone acetonide
    40 mg knee • intra-articular • single, ≥12-wk interval, not scheduled long-term
    trigger: Knee flare/effusion, systemic therapy limited
    ACR/AF 2019 STRONG short-term (Jüni Cochrane 2015 PMID 26490760); cartilage caution (McAlindon JAMA 2017 PMID 28510679)

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Activity-related knee pain, worse with use / better with rest (ACR/AF 2019; NICE NG226 2022); Groin / lateral hip pain on weight-bearing, reduced internal rotation (ACR/AF 2019); Hand pain + bony enlargement (Heberden DIP / Bouchard PIP / 1st CMC) (ACR/AF 2019).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Osteoarthritis (knee / hip / hand — clinical dx → management)** (msk.osteoarthritis.core.v1).
Phenotype framing: MECE terminal differential — OA vs rheumatoid arthritis (symmetric MCP/wrist synovitis, stiffness >60 min, RF/anti-CCP+, ESR/CRP↑) vs gout/CPPD (acute hot monoarthritis, podagra, synovial crystals) vs psoriatic/reactive arthritis vs septic arthritis vs avascular necrosis vs referred/neuropathic pain vs secondary OA (haemochromatosis, alkaptonuria). Named pivots: morning-stiffness duration, joint distribution, inflammatory markers, constitutional symptoms (Altman 1986 PMID 3741515)
Scope: OA is a CLINICAL diagnosis in the typical patient (age ≥45, activity-related pain, ≤30 min stiffness, no systemic inflammatory features) — imaging NOT required; Kellgren–Lawrence grade is a structural anchor, not a diagnostic gate (NICE NG226 2022; ACR/AF 2019 Kolasinski PMID 31908163). Scope: knee, hip, hand (incl. erosive hand OA), with/without inflammatory component

No severity triggers fired against current inputs.

Plan

Regimen axis: **OA core non-pharm → topical NSAID → comorbidity-gated oral NSAID → adjuncts → recommend-against → arthroplasty (ACR/AF 2019; OARSI 2019; NICE NG226 2022)** — step "Step 1 — Core non-pharmacologic (FIRST-LINE for ALL phenotypes; never skipped)".
1. structured patient education & self-management program (education_self_management, first line) — ACR/AF 2019 STRONG; OARSI 2019 Core treatment — improves self-efficacy and pain coping (PMID 31908163; 31278997)
2. structured land-based exercise (strengthening + aerobic + ROM) (exercise_therapy, first line) — ACR/AF 2019 STRONG; OARSI Core. Knee pain SMD −0.49 (95% CI −0.39 to −0.59) ≈ 12/100-pt; function SMD −0.52; benefit sustained 2–6 mo; magnitude comparable to NSAIDs (Fransen Cochrane 2015 PMID 25569281; hip PMID 26405113)
3. dietary weight loss ≥5–10% of body weight (weight_management, first line) — ACR/AF 2019 STRONG for overweight/obese knee/hip OA. Diet+exercise (−11.4% weight) reduced pain & improved function vs exercise alone; 1 kg loss ≈ 4 kg/step less knee load (IDEA Messier JAMA 2013 PMID 24065013)
4. assistive devices / bracing / hand orthoses (biomechanical_device, first line) — ACR/AF 2019 STRONG: cane, tibiofemoral brace (medial knee OA), 1st-CMC hand orthosis; conditional patellofemoral brace (PMID 31908163)

Setting playbook (outpatient) — Confirm OA clinically (no over-imaging), exclude inflammatory/crystal/septic mimics, deliver core non-pharm to every patient, layer comorbidity-appropriate pharmacotherapy, and refer for arthroplasty only when conservative therapy fails (ACR/AF 2019; OARSI 2019 PMID 31278997; NICE NG226 2022)
5. core non-pharm (education + structured exercise + weight loss + devices) exercise ≥2–3×/wk; weight loss ≥5–10% if BMI ≥25 n/a ongoing — Every OA patient (first-line, all phenotypes) (Exercise knee pain SMD −0.49 (Fransen Cochrane 2015 PMID 25569281); IDEA weight loss (Messier JAMA 2013 PMID 24065013))
6. topical diclofenac 1% gel 2–4 g QID (knee) / thin layer QID (hand) topical QID — Knee or hand OA, inadequate non-pharm response (ACR/AF 2019 STRONG (knee); systemic-sparing first-line drug (Derry Cochrane PMID 28497473))
7. oral NSAID (naproxen / ibuprofen / celecoxib per matrix) naproxen 250–500 mg BID OR ibuprofen 400 mg TID OR celecoxib 100–200 mg/day PO lowest effective dose, shortest duration — Inadequate topical response AND comorbidity matrix permits (ACR/AF 2019 STRONG; matrix-gated by eGFR/CVD/PUD/anticoagulant (PRECISION Nissen NEJM 2016 PMID 27959716))
8. duloxetine 30 mg daily × 1 wk → 60 mg (max 120 mg) PO once daily — Centralised/multi-joint pain or oral NSAID contraindicated (ACR/AF 2019 CONDITIONAL (Chappell PMID 20602715))
9. intra-articular triamcinolone acetonide 40 mg knee intra-articular single, ≥12-wk interval, not scheduled long-term — Knee flare/effusion, systemic therapy limited (ACR/AF 2019 STRONG short-term (Jüni Cochrane 2015 PMID 26490760); cartilage caution (McAlindon JAMA 2017 PMID 28510679))

Non-pharmacologic actions:
- Structured land-based exercise referral (physiotherapy / supervised program) (Fransen Cochrane 2015 PMID 25569281)
- Dietary weight-management referral if BMI ≥25 (IDEA Messier JAMA 2013 PMID 24065013)
- Cane / tibiofemoral knee brace / 1st-CMC hand orthosis as indicated (ACR/AF 2019)
- Counsel AGAINST glucosamine/chondroitin, hyaluronic acid, opioids (ACR/AF 2019 strong against)
- Orthopaedic referral for arthroplasty when conservative therapy exhausted + function-limiting (Skou NEJM 2015 PMID 26488691)

AVOID / contraindication checks:
- Matrix:oral_NSAID|eGFR<30(CKD EPI 2021)=>AVOID_all_oral_NSAID_use_topical_or_duloxetine (ACR/AF 2019; OARSI 2019 PMID 31278997)
- Matrix:oral_NSAID|eGFR_30_59=>use_lowest_dose_shortest_duration_monitor_eGFR_and_BP (ACR/AF 2019)
- Matrix:oral_NSAID|established_CVD_or_HF_or_uncontrolled_HTN=>OARSI_not_recommended;if_unavoidable_prefer_naproxen_lowest_dose (PRECISION Nissen NEJM 2016 PMID 27959716; OARSI PMID 31278997)
- Matrix:oral_NSAID|PUD_or_prior_GI_bleed=>use_COX2_selective(celecoxib)+PPI_or_avoid (PRECISION PMID 27959716)
- Matrix:oral_NSAID|concurrent_anticoagulant_or_antiplatelet=>prefer_topical_NSAID;if_oral_required_COX2+PPI (ACR/AF 2019)
- Matrix:topical_NSAID|any_comorbidity=>preferred_systemic_sparing_first_line_knee_hand (ACR/AF 2019; OARSI Level 1A)
- Matrix:IA_glucocorticoid|repeated_scheduled_use=>interval_cap_>=12wk_NOT_long_term_scheduled (cartilage loss — McAlindon JAMA 2017 PMID 28510679)
- Matrix:acetaminophen|hepatic_impairment_or_elderly=>cap_<=2000mg_day (ACR/AF 2019)
- Matrix:duloxetine|hepatic_impairment_or_uncontrolled_HTN_or_MAOI=>avoid;monitor_LFT_BP (ACR/AF 2019 conditional)
- Opioids recommend against deprescribe (ACR/AF 2019 strong against; OARSI Level 5 PMID 31278997)
- Glucosamine chondroitin hyaluronic recommend against (ACR/AF 2019 strong against; GAIT PMID 16495392; Rutjes PMID 22868835)

Monitoring

Regimen monitoring:
- WOMAC pain function at baseline and response (ACR/AF 2019; MCII pain Likert ~3.94 McAlindon JAMA 2017 PMID 28510679)
- eGFR BP GI symptoms on oral NSAID (ACR/AF 2019; OARSI 2019 PMID 31278997)
- IA glucocorticoid interval cap >=12wk no scheduled long term (McAlindon JAMA 2017 PMID 28510679)
- weight and exercise adherence each visit (IDEA Messier JAMA 2013 PMID 24065013)
- LFT on duloxetine; deprescribe ineffective analgesics especially opioids (ACR/AF 2019)

Setting (outpatient) monitoring:
- WOMAC pain/function trajectory + exercise/weight adherence each visit (ACR/AF 2019)
- eGFR, BP, GI symptoms while on oral NSAID (OARSI 2019 PMID 31278997)
- IA glucocorticoid interval cap ≥12 wk, no scheduled long-term (McAlindon JAMA 2017 PMID 28510679)
- LFT on duloxetine; periodic deprescribing review of ineffective analgesics (ACR/AF 2019)

Follow-up plan: Chronic self-management with periodic reassessment; deprescribe analgesics that lack benefit (especially opioids — ACR/AF 2019 against); maintain exercise + weight; re-refer to orthopaedics if progressive functional decline; revisit surgical timing using shared decision-making (benefit vs serious-AE trade-off — Skou NEJM 2015 PMID 26488691)
- Close-out criterion: Long-term self-management + deprescribing + surgical-timing plan booked

Monitoring phase: Track pain/function trajectory (WOMAC), exercise & weight-loss adherence; on oral NSAID surveil renal function (eGFR), BP, and GI symptoms; cap intra-articular glucocorticoid frequency (effect decays by 13–26 wk, repeated scheduled injection → cartilage loss — McAlindon JAMA 2017 PMID 28510679); reassess weight (1 kg loss reduces knee load ~4 kg/step) (ACR/AF 2019; OARSI 2019 PMID 31278997)

Disposition

Current setting: outpatient — Confirm OA clinically (no over-imaging), exclude inflammatory/crystal/septic mimics, deliver core non-pharm to every patient, layer comorbidity-appropriate pharmacotherapy, and refer for arthroplasty only when conservative therapy fails (ACR/AF 2019; OARSI 2019 PMID 31278997; NICE NG226 2022)

Disposition criteria:
- Continue outpatient self-management if controlled on core non-pharm ± appropriate pharmacotherapy (ACR/AF 2019)
- Refer to orthopaedics for arthroplasty if conservative therapy exhausted + life-limiting (Skou NEJM 2015 PMID 26488691)
- Admit only for a complication (septic joint, post-injection sepsis, surgical pathway)

Escalation triggers (move to higher acuity):
- Acute hot swollen joint + fever → ED arthrocentesis (septic arthritis — NOT OA) (ACR/AF 2019)
- Inflammatory pattern (stiffness >60 min, symmetric synovitis, ESR/CRP↑, constitutional) → rheumatology / RA engine (Altman 1986 PMID 3741515)
- True mechanical locking / acute injury → orthopaedics / knee-pain engine
- Refractory function-limiting disease despite optimised conservative therapy → orthopaedic arthroplasty referral (Skou NEJM 2015 PMID 26488691)

Patient Action Plan

**Osteoarthritis self-management plan**
Personalised values: affected_joints, exercise_program, weight_target, analgesic_plan, comorbid_CKD_CVD_PUD.

**Stable — controlled on self-management** (green):
Triggers:
- Pain manageable with exercise + topical NSAID PRN
- Maintaining or losing weight (if overweight)
- Function preserved for daily activities
Actions:
- Keep doing your exercise program — it is as effective as anti-inflammatory tablets and the benefit fades if you stop (Fransen Cochrane 2015)
- Continue weight management — every kilogram lost takes ~4 kg of load off the knee per step (IDEA Messier JAMA 2013)
- Use topical anti-inflammatory gel as needed rather than tablets when possible (ACR/AF 2019)
- Do NOT spend money on glucosamine, chondroitin, or hyaluronic acid injections — high-quality trials show no real benefit (ACR/AF 2019; GAIT)

**Flare or rising symptoms** (yellow):
Triggers:
- Increased joint pain / swelling limiting usual activity
- Needing pain medication most days
- Exercise becoming difficult
Actions:
- Keep moving within comfort — short-term relative rest is fine but avoid deconditioning (ACR/AF 2019)
- Optimise topical NSAID; only add an oral NSAID at the lowest dose if your kidney/heart/stomach history allows (discuss first) (OARSI 2019)
- Ask about a single intra-articular steroid injection for a knee flare — short-term help, not a repeated long-term plan (Jüni Cochrane 2015; McAlindon JAMA 2017)
- Contact your clinician to review the plan and exclude another cause
Contact provider when:
- Pain not improving within 2–4 weeks of optimised therapy
- New joint swelling or a single very painful joint
- Side effects from medication (stomach pain, swelling, BP rise)

**Possible non-OA emergency or surgical threshold** (red):
Triggers:
- Hot, swollen, very painful joint with fever (possible joint infection)
- Joint locking / giving way / unable to bear weight
- Severe constant pain that stops you sleeping or walking despite full treatment
Actions:
- A hot swollen joint with fever — seek urgent medical care now (this is NOT osteoarthritis until infection is excluded)
- Joint locking or sudden inability to bear weight — urgent assessment for a mechanical problem
- Discuss orthopaedic referral for joint replacement if pain is life-limiting despite full conservative treatment (Skou NEJM 2015)
Contact provider when:
- Always seek emergency care for fever + a hot swollen joint (ACR/AF 2019)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Acute hot swollen joint + fever / immunocompromise — septic arthritis until excluded (NOT an OA pathway) (ACR/AF 2019)
- [SEVERE] Morning stiffness >60 min, symmetric MCP/wrist synovitis, elevated ESR/CRP, or positive RF/anti-CCP — re-route to inflammatory-arthritis engine (Altman 1986 PMID 3741515)
- [SEVERE] eGFR <30 (CKD-EPI 2021), established CVD/HF/uncontrolled HTN, active PUD/recent GI bleed, or concurrent anticoagulant — oral NSAID gated OFF (OARSI 2019 PMID 31278997)

Citations

- 2019 ACR/Arthritis Foundation OA Guideline (Kolasinski, Arthritis Rheumatol/Arthritis Care Res 2020) + OARSI 2019 (Bannuru, Osteoarthritis Cartilage) + NICE NG226 2022 + AAOS 2021 (knee) [PMID:31908163](https://pubmed.ncbi.nlm.nih.gov/31908163/)
- Cited evidence (PMID 31908149) [PMID:31908149](https://pubmed.ncbi.nlm.nih.gov/31908149/)
- Cited evidence (PMID 31278997) [PMID:31278997](https://pubmed.ncbi.nlm.nih.gov/31278997/)
- Cited evidence (PMID 3741515) [PMID:3741515](https://pubmed.ncbi.nlm.nih.gov/3741515/)
- Cited evidence (PMID 25569281) [PMID:25569281](https://pubmed.ncbi.nlm.nih.gov/25569281/)

Last reconciled with current guidelines: 2026-05-22.
References
  • 2019 ACR/Arthritis Foundation OA Guideline (Kolasinski, Arthritis Rheumatol/Arthritis Care Res 2020) + OARSI 2019 (Bannuru, Osteoarthritis Cartilage) + NICE NG226 2022 + AAOS 2021 (knee) — PMID:31908163
  • Cited evidence (PMID 31908149) — PMID:31908149
  • Cited evidence (PMID 31278997) — PMID:31278997
  • Cited evidence (PMID 3741515) — PMID:3741515
  • Cited evidence (PMID 25569281) — PMID:25569281