Knee cysts are fluid-filled sacs that can develop around the knee joint. They often occur due to conditions like arthritis or injury, leading to swelling and discomfort. The most common type is the Baker's cyst, which forms behind the knee and can cause tightness or pain. These cysts may not always require treatment, especially if they are small and painless. However, if they cause significant discomfort or limit movement, options like aspiration (draining the fluid) or surgery may be considered. Regular monitoring by a healthcare professional is essential for managing symptoms effectively.