Osteoarthritis (OA)
Osteoarthritis is the most common form of arthritis, affecting over 32.5 million U.S. adults. Once described as simple "wear and tear," OA is now understood as a complex whole-joint disease involving cartilage breakdown, subchondral bone remodelling, synovial inflammation, and altered joint mechanics.
OA most commonly affects the knees, hips, hands (especially the DIP and PIP joints and CMC joint at the base of thumb), and spine (cervical and lumbar facet joints). It is less common in the wrists, elbows, and shoulders unless there has been prior trauma. Classic features: pain worsens with activity and improves with rest, morning stiffness lasting less than 30 minutes, joint enlargement from bone spurs (osteophytes), and crepitus (grating sensation).
X-ray findings correlate poorly with symptoms. Many people with severe radiographic OA (complete loss of joint space) have minimal pain, while others with mild X-ray changes have significant disability. Treatment should be guided by symptoms and function, not X-ray appearance alone.
Rheumatoid Arthritis (RA)
RA is an autoimmune inflammatory arthritis affecting approximately 1.5 million Americans. The immune system attacks the synovial membrane lining the joints, causing chronic inflammation that erodes cartilage and bone if not adequately treated. Without disease-modifying therapy, most patients develop progressive joint destruction within 2 years of onset.
Key distinguishing features from OA: symmetric joint involvement (both wrists, both MCPs), morning stiffness lasting more than 60 minutes, systemic features (fatigue, low-grade fever, weight loss), elevated inflammatory markers (CRP, ESR), and positive rheumatoid factor (RF) and/or anti-CCP antibodies.
RA also causes extra-articular manifestations: rheumatoid nodules, sicca syndrome (dry eyes/mouth), serositis, pulmonary fibrosis, and vasculitis in severe disease. People with RA have a 2–3× higher cardiovascular risk due to systemic inflammation — treating the RA aggressively reduces this risk.
There is a "window of opportunity" in early RA — typically the first 3–6 months — when aggressive DMARD therapy can induce sustained remission and prevent irreversible joint damage. Delayed diagnosis and treatment directly worsens long-term outcomes.
Gout
Gout is caused by deposition of monosodium urate crystals in joints and surrounding tissues. It is the most common inflammatory arthritis in men and post-menopausal women. Elevated serum uric acid (hyperuricaemia) is the central driver — though many people with high uric acid never develop gout.
Classic presentation: sudden onset severe pain and swelling in the first metatarsophalangeal joint (base of big toe) — podagra. The joint becomes exquisitely tender (even light touch intolerable), hot, red, and swollen within hours. Attacks typically self-resolve within 7–14 days untreated. Chronic gout leads to formation of tophi (chalky urate deposits) and joint destruction.
Triggers for acute attacks: dietary purines (red meat, shellfish, organ meats), alcohol (especially beer), dehydration, sudden illness or surgery, diuretics, and starting urate-lowering therapy (which mobilises crystals initially).
Diagnosis
| Test | OA | RA | Gout |
|---|---|---|---|
| X-ray | Joint space narrowing; osteophytes; subchondral sclerosis — first-line imaging | Periarticular osteopenia; erosions — often normal early | Punched-out erosions with overhanging edges in chronic gout |
| MRI | Evaluates cartilage, menisci, bone marrow oedema | Early synovitis, erosions before X-ray changes | Urate deposits; rarely needed for diagnosis |
| Ultrasound | Osteophytes; effusion; Baker's cyst | Synovitis (power Doppler); erosions | Double contour sign (urate on cartilage surface) — highly specific |
| Blood tests | ESR/CRP often normal or mildly elevated | ESR, CRP elevated; RF (70% sensitive); anti-CCP (95% specific); CBC, LFTs before DMARD | Serum uric acid (may be normal during acute attack); renal function |
| Joint aspiration | Clear fluid; no crystals; low cell count | Inflammatory fluid; elevated WBC | Gold standard — needle-shaped negatively birefringent crystals under polarised light |
Treating osteoarthritis
- Exercise: The single most evidence-based intervention. Both aerobic (water-based, cycling, walking) and strengthening exercises reduce pain and improve function comparably to analgesics — without side effects. Quadriceps strengthening is particularly important for knee OA.
- Weight loss: Each pound of weight loss reduces knee joint load by 4 pounds. A 10% reduction in body weight produces significant and durable OA symptom improvement.
- Physiotherapy: Gait training, assistive devices, bracing (knee offloading braces in medial compartment OA), and manual therapy.
- Occupational therapy: Joint protection techniques, adaptive equipment, and activity modification.
- Topical treatments: Topical diclofenac (Voltaren gel) has excellent safety profile — high local concentration with minimal systemic absorption. First choice for hand and knee OA.
| Drug | Evidence | Key considerations |
|---|---|---|
| Topical NSAIDs (diclofenac gel) | High — OARSI first-line for knee/hand OA | Excellent safety; minimal systemic absorption; apply 4×/day |
| Paracetamol / acetaminophen | Modest — declining in guidelines | Safer than NSAIDs systemically; less effective than previously thought; hepatotoxic in overdose |
| Oral NSAIDs | Moderate-high for pain relief | GI, renal, and cardiovascular risks; use lowest effective dose for shortest time; PPI gastroprotection |
| Duloxetine | Moderate — approved for chronic musculoskeletal pain | Useful for centrally sensitised OA pain; also treats comorbid depression and anxiety |
| Opioids | Limited role — OARSI recommends against in most cases | Addiction risk; falls risk in elderly; marginal benefit over NSAIDs in OA |
- Corticosteroid injections: Rapid onset pain relief lasting 4–12 weeks. Most useful for acute flares and as a bridge to other interventions. The 2021 OARSI guidelines note uncertainty about repeated injections potentially accelerating cartilage loss — limit to 3–4 per year per joint.
- Hyaluronic acid (viscosupplementation): Evidence is modest and controversial — some meta-analyses show significant pain reduction, others show no benefit over placebo. More commonly used in Europe than in current U.S. guidelines.
- PRP (Platelet-rich plasma): Emerging evidence suggests benefit in knee OA — a 2023 meta-analysis showed significant pain reduction and function improvement vs placebo or hyaluronic acid. Not yet in mainstream guidelines; quality of evidence still limited.
Treating rheumatoid arthritis
The central principle of modern RA management is treat-to-target (T2T) — aiming for clinical remission (or low disease activity in elderly or comorbid patients) using validated disease activity measures (DAS28, CDAI, SDAI), with monthly reassessment and prompt treatment escalation if targets are not met.
| DMARD class | Key drugs | Role in RA | Monitoring |
|---|---|---|---|
| Conventional synthetic DMARDs (csDMARDs) | Methotrexate (anchor drug), Hydroxychloroquine, Sulfasalazine, Leflunomide | First-line — MTX is the anchor drug in most RA therapy. Often combined (triple therapy: MTX+HCQ+SSZ) | LFTs, FBC, renal function; folinic acid supplementation with MTX |
| Biologic DMARDs (bDMARDs) | TNF inhibitors; anti-IL-6; anti-CD20; CTLA4-Ig | Step 2+ when csDMARDs fail or inadequate response; added to or replacing MTX | Infection screening (TB, hepatitis B); FBC; LFTs; annual screening |
| JAK inhibitors (tsDMARDs) | Tofacitinib, Baricitinib, Upadacitinib, Filgotinib | Step 2+ alternative to biologics; oral route; faster onset; post-marketing safety monitoring for CV/malignancy risk | Lipids, FBC, LFTs; infection screening; avoid in high CV/malignancy risk |
Biologics and JAK inhibitors for RA
| Drug | Target | Examples | Route | Notes |
|---|---|---|---|---|
| TNF inhibitors | TNF-α | Etanercept, Adalimumab, Certolizumab, Golimumab, Infliximab | SC or IV | Most widely used class; strong evidence; biosimilars now available dramatically reducing cost |
| IL-6 inhibitors | IL-6 receptor | Tocilizumab, Sarilumab | SC or IV | Effective in TNF-failure; also for cytokine storm; normalises acute phase reactants (CRP becomes unreliable monitoring marker) |
| Anti-CD20 | B cells | Rituximab | IV infusion ×2 (2 weeks apart) | Preferred in seropositive RA; lymphoma; hepatitis B reactivation risk; effect lasts 6–12 months |
| CTLA4-Ig | T cell co-stimulation | Abatacept (Orencia) | SC weekly or IV monthly | Good safety profile; preferred in patients with history of serious infections |
| JAK inhibitors | Intracellular JAK pathways | Tofacitinib (Xeljanz), Baricitinib (Olumiant), Upadacitinib (Rinvoq) | Oral daily tablet | Rapid onset; no injections; FDA added class warning for CV events, malignancy, thrombosis — use with caution in high-risk patients; upadacitinib highly effective but broader safety monitoring required |
Surgical options
Total joint replacement (arthroplasty) is one of the most successful surgical procedures in medicine. Total knee replacement (TKR) achieves excellent pain relief and functional improvement in 90%+ of appropriately selected patients, with 15–20 year implant survival. Total hip replacement (THR) is similarly effective and durable — many surgeons consider it the highest quality-of-life-improving elective surgical procedure available.
Surgery is considered when: (1) pain is severe, persistent, and failing all conservative measures, (2) function is significantly limited, and (3) quality of life is unacceptable. Age is no longer a barrier — outcomes in patients over 80 who are medically fit are generally excellent.
Other procedures include: arthroscopy (now rarely recommended for OA — evidence of benefit poor except for mechanical symptoms), osteotomy (realignment — in younger patients with varus/valgus deformity), and synovectomy (for refractory RA synovitis).
Exercise and lifestyle
For all forms of arthritis, exercise is not optional — it is therapeutic. The outdated advice to rest joints to protect them has been comprehensively overturned by evidence.
- Aerobic exercise: Water aerobics, cycling, swimming, walking — 150 min/week. Low-impact exercise significantly reduces OA pain without accelerating joint damage.
- Strength training: Particularly quadriceps for knee OA. Strong muscles absorb joint forces and reduce stress on cartilage.
- Flexibility and range of motion: Tai chi has particularly strong evidence for knee OA — RCTs show non-inferior to physical therapy for pain and function.
- Weight management: Weight loss is the most effective conservative intervention for knee OA. The IDEA trial showed 10% weight loss reduced knee OA pain by 50%.
- Diet in gout: Reduce red meat, shellfish, organ meats; avoid fructose-sweetened drinks; limit alcohol (especially beer); adequate hydration (2+ litres/day) reduces urate concentration.
Frequently asked questions
Osteoarthritis is a degenerative joint disease caused by cartilage wear — primarily mechanical in origin and associated with age, obesity, and prior joint injury. It typically causes asymmetric pain in weight-bearing joints, morning stiffness lasting less than 30 minutes, and no systemic features. Rheumatoid arthritis is an autoimmune disease where the immune system attacks joint synovium — it causes symmetric inflammatory joint disease (typically hands and wrists), morning stiffness lasting more than 1 hour, fatigue, and systemic features. RA requires disease-modifying therapy to prevent irreversible joint damage.
There is currently no cure for OA or RA. However, RA can be put into sustained clinical remission with modern biologic and JAK inhibitor therapies — meaning no active inflammation or progressive joint damage — in 50%+ of patients using treat-to-target strategies. Gout is effectively curable with adequate urate-lowering therapy: maintaining serum urate below 6 mg/dL dissolves crystals over 1–2 years and eliminates future attacks. OA is managed to control pain and preserve function rather than reverse structural changes.
No — exercise is one of the most evidence-based interventions for all forms of arthritis. Low-impact aerobic exercise and strength training reduce pain, improve function, and slow progression in OA. Multiple RCTs confirm exercise is as effective as NSAIDs for knee OA pain relief. In RA, exercise reduces fatigue, cardiovascular risk, and maintains muscle mass without triggering flares. The key is choosing appropriate low-impact activities and progressing gradually.
- Kolasinski SL, et al. 2019 ACR/AF Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis Rheumatol. 2020;72(2):220–233.
- Fraenkel L, et al. 2021 ACR Guideline for the Treatment of Rheumatoid Arthritis. Arthritis Rheumatol. 2021;73(7):1108–1123.
- FitzGerald JD, et al. 2020 ACR Guideline for the Management of Gout. Arthritis Rheumatol. 2020;72(6):879–895.
- Wang C, et al. Comparative effectiveness of tai chi versus physical therapy for knee osteoarthritis (SPARK trial). Ann Intern Med. 2016;165(2):77–86.
- Messier SP, et al. Exercise and dietary weight loss in overweight and obese older adults with knee OA (IDEA trial). JAMA. 2013;310(12):1263–1273.