Pre-Patellar Bursitis or Fracture: Do you experience pain when performing any activity? Is the kneecap warm, tender, and swollen? These could be due to a fracture or bruise of the kneecap, if you have fallen hard on that affected knee. Or else, it could be a symptom of pre-patellar disease, which is caused due to the irritation of the bursa, which is a small fluid-filled sac located in front of the kneecap.