CLINICAL PRINTABLE
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A one-page Osteoarthritis clinical reference is on the way.
1 · Recognition / Alarm Features
- OA features: joint pain worsened by activity and relieved by rest (early disease), morning stiffness <30 minutes (vs >60 minutes in inflammatory arthritis), crepitus, bony enlargement, decreased range of motion. Most commonly affects knees, hips, hands (DIP/PIP joints, first CMC), and spine.
- Diagnosis is clinical in most cases. X-ray findings: joint space narrowing, subchondral sclerosis, osteophytes, subchondral cysts. X-ray severity does not correlate well with symptom severity — significant OA on imaging may be asymptomatic, and severe pain may occur with minimal radiographic changes.
- Distinguish OA from inflammatory arthritis: OA — asymmetric, DIP involvement, morning stiffness <30 minutes, normal inflammatory markers. Rheumatoid arthritis — symmetric, MCP/PIP involvement, morning stiffness >60 minutes, elevated ESR/CRP, positive RF/anti-CCP. Psoriatic arthritis — DIP involvement, skin/nail changes, asymmetric.
- Risk factors: age (strongest), obesity (especially knee OA), prior joint injury, repetitive joint loading, female sex, genetic predisposition. Obesity is the most modifiable risk factor — weight loss of 10% reduces knee pain by 50%.
- Acute flare of OA: increased pain, swelling, warmth. May be triggered by overuse, minor trauma, or crystal deposition (CPPD). Joint aspiration if effusion is present — rule out septic arthritis and crystals.
2 · Differential / Secondary Causes
Rheumatoid arthritis (RA)
Symmetric small joint arthritis (MCPs, PIPs, wrists), morning stiffness >60 minutes, elevated ESR/CRP, positive RF and anti-CCP. Refer to rheumatology. DMARDs (methotrexate) are first-line — not NSAIDs alone.
Pseudogout (CPPD)
Acute inflammatory arthritis, most commonly knee. Chondrocalcinosis on X-ray. Positively birefringent rhomboid crystals on joint aspiration. Treat acute flare with NSAIDs, colchicine, or steroids.
Septic arthritis
Fever, systemic toxicity, acute monoarthritis with effusion. Joint aspiration required. Gram stain, culture, cell count. Do not assume OA flare without excluding infection.
Meniscal tear / internal derangement
Knee pain with mechanical symptoms (locking, catching, giving way). Positive McMurray or Thessaly test. MRI for diagnosis. Orthopedic referral for symptomatic tears.
3 · Treatment Pathway
Exercise — most effective intervention
Aerobic exercise (walking, cycling, swimming) and strengthening exercises reduce pain and improve function in knee and hip OA. Effect size comparable to NSAIDs. Land-based and aquatic exercise are both effective. Physical therapy for supervised exercise program. Do not advise rest — activity improves outcomes.
Weight loss
10% weight loss reduces knee pain by ~50% in obese patients. Most effective intervention for knee OA in overweight/obese patients. Combine with exercise for greatest benefit. Refer to structured weight management program.
Topical NSAIDs — first-line pharmacologic therapy
Topical diclofenac (Voltaren gel) for knee and hand OA: effective, minimal systemic absorption, preferred over oral NSAIDs in older adults and patients with GI/cardiovascular/renal risk. Apply to affected joint 3–4 times daily.
Oral NSAIDs and acetaminophen
Oral NSAIDs (ibuprofen, naproxen, celecoxib): effective for OA pain. Use lowest effective dose for shortest duration. Add PPI for GI protection. Avoid in CKD, cardiovascular disease, or GI history. Acetaminophen: modest benefit, safer profile. Maximum 3 g/day (2 g/day in liver disease or heavy alcohol use).
Intra-articular injections
Corticosteroids: rapid pain relief (weeks to months) for acute OA flare or when oral medications are insufficient. Limit to 3–4 injections per year per joint. Hyaluronic acid (viscosupplementation): modest benefit, more controversial — ACR conditionally recommends against for knee OA. Platelet-rich plasma (PRP): insufficient evidence.
Joint replacement — when to refer
Total knee or hip arthroplasty for severe OA with significant functional limitation not responding to conservative management. Refer to orthopedics when: pain is severe and persistent, function is significantly impaired, and conservative treatment has been optimized for ≥3–6 months. Outcomes are excellent — 90% patient satisfaction at 10 years.
4 · Expected Response
- Exercise: pain reduction and functional improvement within 4–8 weeks of consistent exercise. Benefits are sustained with continued activity.
- Topical diclofenac: onset of pain relief within 1–2 weeks. Comparable efficacy to oral NSAIDs for knee and hand OA with fewer systemic side effects.
- Intra-articular corticosteroids: pain relief within 1–2 days, lasting 4–8 weeks. Repeated injections may accelerate cartilage loss — use judiciously.
- Total knee/hip arthroplasty: significant pain reduction and functional improvement in >90% of patients. Full recovery 3–6 months.
5 · Escalation
- Acute joint effusion with fever or systemic toxicity: joint aspiration to exclude septic arthritis before attributing to OA flare.
- Severe OA with significant functional limitation not responding to 3–6 months of optimized conservative management: orthopedic referral for joint replacement evaluation.
- Atypical features (young age, symmetric involvement, elevated inflammatory markers, systemic symptoms): rheumatology referral to exclude inflammatory arthritis.
Apply It · Change One Detail
APPLY IT
A 68-year-old obese woman with bilateral knee pain worsened by activity and morning stiffness lasting 15 minutes. X-ray shows moderate joint space narrowing and osteophytes. She asks for a cortisone shot. Before injecting, optimize conservative management: prescribe topical diclofenac, refer to physical therapy for a structured exercise program, and discuss weight loss (10% weight loss reduces knee pain by 50%). Intra-articular corticosteroids are appropriate for acute flares or when conservative measures are insufficient — not as first-line.
CHANGE ONE DETAIL
Change one detail — the same patient now has severe bilateral knee pain limiting her ability to walk one block, has failed topical NSAIDs, oral NSAIDs, physical therapy, and multiple injections over 2 years. This is the appropriate time for orthopedic referral for total knee arthroplasty evaluation. Conservative management has been optimized — continued escalation of injections without referral delays definitive treatment.
Bottom Line
Exercise and weight loss are the most effective interventions for knee OA — effect size comparable to NSAIDs. Start with topical diclofenac before oral NSAIDs. Refer for joint replacement when conservative management has been optimized and function remains significantly impaired.
EVIDENCE & REFERENCES
- Kolasinski SL, et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis Care Res. 2020;72(2):149-162. doi:10.1002/acr.24131
- Bannuru RR, et al. OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis Cartilage. 2019;27(11):1578-1589. doi:10.1016/j.joca.2019.06.011
- Fransen M, et al. Exercise for osteoarthritis of the knee. Cochrane Database Syst Rev. 2015;1:CD004376. doi:10.1002/14651858.CD004376.pub3