For patients with painful symptoms when bending the knee, it is mainly seen in the following diseases: i. It is seen in patients with degeneration of the knee joint and osteoarthritis, which leads to an increase in pressure inside the knee joint. When the knee is flexed, the pressure inside the knee joint is further increased, resulting in significant pain in the knee joint. When the knee joint is flexed, the increased bone around the knee joint will also stimulate the surrounding soft tissues and the degenerated cartilage inside the knee joint, resulting in abnormal friction, which will aggravate the pain in the knee joint. Second, in patients with posterior meniscal horn injury of the knee, thus squeezing the injured posterior meniscal horn when flexing the knee joint, this condition will also have significant pain symptoms when the knee is bent.