Knee osteoarthritis mainly refers to the local soft tissue in an inflammatory state due to wear and tear of the knee joint, resulting in perichondral bone hyperplasia. The main symptoms of knee osteoarthritis under ultrasound are thinning of the cartilage, uneven cartilage, unsmooth upper and lower edges, as well as a significant bulge at the lower end of the tibia and lower end of the femur. If the joint cavity shows symptoms such as synovial hyperplasia or exudation, there will be hypoechoic and anechoic areas with significant blood flow signals.