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Osteoarthritis

** Osteoarthritis is a common, progressive degenerative joint disease characterized by the breakdown of cartilage and underlying bone, leading to pain, stiffness, and functional limitation. **CONTENT:** ## Overview Osteoarthritis (OA) is the most prevalent form of arthritis worldwide and a leading cause of disability. It results from the gradual loss of articular cartilage—the smooth, lubricated tissue that allows bones to glide past one another—combined with changes in the subchondral bone, synovium, ligaments, and surrounding muscles. The disease typically manifests as **joint pain**, **stiffness**, and **reduced range of motion**, symptoms that develop slowly over years and may fluctuate with activity and weather. While any synovial joint can be affected, the **distal interphalangeal joints** of the fingers, the **first carpometacarpal joint** at the base of the thumb, the **knees**, **hips**, and the **cervical and lumbar spine** are most frequently involved. Risk factors are multifactorial. **Age** is the strongest predictor, with prevalence rising sharply after age 50. **Genetic predisposition**, **obesity**, **joint injury**, and **mechanical overload** (e.g., repetitive occupational tasks) also increase susceptibility. Unlike inflammatory arthritides such as rheumatoid arthritis, OA is primarily a **mechanical wear‑and‑tear** process; systemic organs are not directly affected. Nonetheless, the chronic pain and functional loss can profoundly impair quality of life, limiting work, recreation, and independence. Individuals experiencing persistent joint pain, swelling, or difficulty performing daily activities should seek evaluation by a health‑care professional, as early diagnosis and tailored management can slow progression and improve outcomes. ## History/Background The recognition of osteoarthritis dates back to antiquity, with Hippocrates describing “hardening of the joints” in the 5th century BC. The term “osteo‑arthritis” was coined in the 19th century by French physician **Jean‑Louis Armand de Quatrefages**, who distinguished it from inflammatory arthritis based on its degenerative nature. Radiographic imaging, introduced in the early 1900s, allowed clinicians to visualize joint space narrowing, osteophyte formation, and subchondral sclerosis—hallmarks that still define modern diagnostic criteria. In the 1950s, the **Kellgren–Lawrence grading system** standardized radiographic assessment, facilitating epidemiologic studies. The late 20th century saw a shift from viewing OA as an inevitable consequence of aging to recognizing modifiable risk factors such as obesity and joint injury, prompting public‑health initiatives aimed at prevention and early intervention. ## Key Information - **Epidemiology:** Approximately **240 million** people worldwide have activity‑limiting OA, making it the fourth leading cause of global disability. Prevalence is higher in women after menopause and in populations with high body‑mass index. - **Pathophysiology:** Cartilage degradation is driven by an imbalance between anabolic (building) and catabolic (breakdown) processes, mediated by inflammatory cytokines (e.g., IL‑1β, TNF‑α), matrix‑degrading enzymes (MMPs, ADAMTS), and mechanical stress. Subchondral bone responds with sclerosis and cyst formation, while the synovium may develop low‑grade inflammation. - **Clinical Presentation:** Classic symptoms include **pain worsened by use and relieved by rest**, **morning stiffness lasting <30 minutes**, and **crepitus** (a grinding sensation). Advanced disease may present with joint swelling, deformity, and, when the spine is involved, radicular pain, weakness, or numbness in the limbs. - **Diagnosis:** Diagnosis relies on a combination of history, physical examination, and imaging. Plain radiographs remain first‑line, revealing joint space loss, osteophytes, and subchondral changes. MRI can detect early cartilage loss and soft‑tissue involvement. Laboratory tests are generally normal but are useful to exclude inflammatory arthritides. - **Management:** There is no cure; treatment focuses on symptom relief, functional preservation, and slowing progression. Core strategies include **weight management**, **exercise therapy** (strengthening, aerobic, and flexibility), **patient education**, and **pharmacologic options** such as acetaminophen, NSAIDs, and intra‑articular corticosteroids or hyaluronic acid. For end‑stage disease, **joint replacement surgery** (total knee or hip arthroplasty) offers substantial pain relief and functional gain. **When to seek professional care:** Persistent joint pain that interferes with sleep, daily activities, or work, sudden swelling, or new neurological symptoms (e.g., numbness, weakness) warrant prompt medical evaluation. ## Significance Osteoarthritis imposes a massive socioeconomic burden through health‑care costs, lost productivity, and the need for long‑term disability support. Its impact extends beyond the individual, affecting families and health systems, especially as global populations age. Understanding OA has driven advances in biomechanics, tissue engineering, and regenerative medicine, including research into **stem‑cell therapies**, **disease‑modifying osteoarthritis drugs (DMOADs)**, and **biomarker development** for early detection. Public‑health campaigns emphasizing weight control, joint‑protective ergonomics, and regular physical activity have demonstrated measurable reductions in incidence and severity. Moreover, the disease serves as a model for studying chronic, low‑grade inflammation and its interplay with metabolic health, informing broader strategies for age‑related musculoskeletal disorders. **INFOBOX:** - Name: Osteoarthritis - Type: Degenerative joint disease (non‑inflammatory arthritis) - Date: Recognized as distinct clinical entity in the 19th century; modern diagnostic criteria established mid‑20th century - Location: Primarily affects synovial joints—hands, knees, hips, spine - Known For: Leading cause of disability worldwide; hallmark cartilage degeneration and osteophyte formation **TAGS:** osteoarthritis, degenerative joint disease, cartilage degeneration, musculoskeletal health, chronic pain, disability, joint replacement, public health