骨关节炎（英语：osteoarthritis，缩写为OA）是一种以关节软骨退行性变和继发性骨质增生为特性的慢性关节疾病。多见于中老年人，女性多于男性。好发于负重较大的膝关节、髋关节、腰骶部脊柱关节（Lumbosacral joint）及第一蹠趾关节（First MIP joints）等部位，以及手部的远程指间关节（DIP joints）、近端指间关节（PIP joints）。该病亦称为骨关节病、退行性关节炎、增生行关节炎、退化性关节炎、骨性关节炎等。随着人口的老化以及肥胖比率上升，骨关节炎的盛行率将会提高。

Osteoarthritis (OA) is a type of joint disease that results from breakdown of joint cartilage and underlying bone. The most common symptoms are joint pain and stiffness. Initially, symptoms may occur only following exercise, but over time may become constant. Other symptoms may include joint swelling, decreased range of motion, and when the back is affected weakness or numbness of the arms and legs. The most commonly involved joints are those near the ends of the fingers, at the base of the thumb, neck, lower back, knee, and hips. Joints on one side of the body are often more affected than those on the other. Usually the symptoms come on over years. It can affect work and normal daily activities. Unlike other types of arthritis, only the joints are typically affected.