Patients with pain in the lateral right knee can have several causes: First, injury to the meniscus: If there is a tear in the lateral meniscus, it can lead to pain in the lateral space of the knee, which can be accompanied by significant pressure pain, as well as localized popping and interlocking symptoms, at which point an MRI of the knee should be examined for diagnosis and treatment. Second, ligament inflammation: If there is chronic inflammation of the ligaments, pain at the lateral ligaments of the knee can occur, and relevant investigations and x-rays should be taken to rule out other diseases. Third, meniscal cysts: When meniscal cysts are large, they can cause pain on the anterior side of the lateral gap of the knee, and the cysts can be palpated when the knee is flexed or straightened, and early MRI examinations should be performed and surgery should be performed if necessary. Fourth, tumor: If there is a tumor growing in the bone on the lateral side of the knee, it can also cause pain and can be accompanied by percussion pain, which should be diagnosed and treated by CT and MRI.