Osteoarthritis
Osteoarthritis is a whole-joint disease -- not simply "wear and tear" -- affecting an estimated 302 million people worldwide, per 2025 Lancet data and the ACR/AF 2019 guideline.
Symptoms
Joint pain that worsens with activity and improves with rest, morning stiffness lasting less than 30 minutes, and gradually reduced range of motion, most often in the knees, hips, and hands.
Causes and risk
Age, obesity, prior joint injury, repetitive joint stress, and genetics all contribute; it involves inflammatory and metabolic processes beyond simple mechanical wear.
How it is evaluated
Osteoarthritis is a clinical diagnosis based on history and exam. Imaging is reserved for atypical, refractory, or rapidly progressive presentations -- a normal x-ray does not rule it out.
Treatment
Exercise, weight loss, and topical or oral NSAIDs carry strong recommendations from the ACR/AF 2019 guideline, along with intra-articular corticosteroid injections for flares. The OARSI 2019 stepwise algorithm is broadly consistent, though ACR and OARSI diverge on supplements like glucosamine and chondroitin, which ACR does not recommend.
When to seek care
A joint that is hot, red, significantly swollen, and accompanied by fever is not typical osteoarthritis and needs urgent evaluation to rule out joint infection. Inability to bear weight after trauma, or a sense of joint instability, also warrants prompt evaluation.