Question: what is the knot on my knee?
Answer: A bursa is a small sac of fluid that cushions a joint and helps it move easily. Bursitis of the kneecap is inflammation of the bursa found between the front of the kneecap and the skin. Kneeling for a long time can cause kneecap bursitis, which can develop into an egg-shaped bump on the front of the kneecap.