There are many reasons for knee protrusion, and the common causes are sports injury, synovitis of the knee joint, tumor and so on.
1. Sports injury: if long-term strenuous exercise will appear around the knee muscle injury, strains, resulting in swelling, commonly in the training of improper preparation activities, as well as the amount of excessive exercise caused by the phenomenon, which caused the knee protruding phenomenon.
2. Synovitis of the knee joint: synovium is a thin and dense layer of connective tissue that secretes lubrication of the joints, which manifests itself as knee protrusion symptoms, as well as pain, swelling, and restriction of joint activities.
3. Tumor: when there is a tumor on the top of the knee joint, there will be knee protrusion, accompanied by knee pain, hard to touch, but can’t move such as osteosarcoma, which needs to be pathologically examined to diagnose.
The protrusion of the knee may also be caused by other reasons, such as the effusion of the knee joint and the appearance of free bodies in the knee joint. Sports injuries need to pay attention to rest, and other pathologies need timely medical treatment and further diagnosis for pathologic examination.