First, degenerative osteoarthritis. As people age, the knee joint degenerates, which can lead to cartilage damage, meniscal tears and secondary synovitis, resulting in pain on both sides of the knee joint, along with knee swelling and limited joint movement. X-rays, CT and MRI are needed to confirm the diagnosis and treatment. Second, synovitis, when synovitis causes pain in the knee joint, there will also be pain on both sides of the knee joint, often accompanied by severe swelling and fluid accumulation in the knee joint. It requires medication for synovitis and aspiration of the joint cavity to cure it. Third, meniscal damage, when the knee has bilateral meniscal tears or congenital meniscal developmental abnormalities, such as disc meniscus, there will be bilateral pain on both sides of the knee joint, and an MRI should be performed to further confirm the diagnosis and treatment.