oa

OA is an initialism with several meanings across fields; two of the most common are Open Access in scholarly publishing and osteoarthritis, a chronic joint disease.

Open Access (OA) provides unrestricted online access to research outputs, often with reuse rights under licenses such as Creative Commons. Models include Gold OA (articles published in OA journals, sometimes funded by processing charges), Green OA (self-archiving in repositories), Hybrid OA (subscription journals offering OA for individual articles), and Bronze OA (free to read without clear reuse terms). OA aims to widen dissemination, accelerate discovery, and improve public access, while funding, quality control, and the rise of predatory outlets pose challenges. Funder mandates and institutional repositories have driven policy changes in many countries.

Osteoarthritis (OA) is a degenerative joint disease causing pain, stiffness, and reduced mobility. It most commonly affects the knees, hips, hands, and spine. Risk factors include age, obesity, prior joint injury, and genetics. Diagnosis combines clinical assessment with imaging such as X-rays. Management focuses on symptom relief and function: weight loss, exercise, physical therapy, analgesics (acetaminophen, NSAIDs), injections, and, in advanced cases, surgery.

Other uses of OA exist in different domains; meanings depend on context, so the surrounding text should clarify.