Swelling above the knee may be caused by trauma, bursitis, tumors and so on. 1. Trauma: If you are usually hit by external forces or undergo strenuous exercise, it may lead to soft tissue injury, and the symptoms of swollen and bulging above the knee will appear. 2. Bursitis: clinically, bursitis can occur due to aseptic inflammation around the bursa, which may lead to oozing of tissue fluid, and this symptom will appear. 3. Tumor: clinically, after the appearance of osteosarcoma, osteochondroma, bone cyst and other neoplastic diseases, due to the increasing size of the tumor may compress the knee, and this symptom will also appear. Normally, you need to observe the symptoms more, and if there is any obvious discomfort, it is better to consult the doctor in time.