The chief symptoms of knee arthritis are pain, stiffness, and loss of function. Arthritis can make your knees ache much of the time, and cause intense, throbbing pain if you have a flare-up.Flare-ups usually happen in response to a trigger. There are two primary triggers for a flare-up of knee arthritis. One is a change in the weather, typically when barometric pressure falls, leading to wet and cold weather. The other is doing more physical activity than usual or changing the types of activities you do.Along with pain and stiffness, your knees are likely to feel hot and tender and might swell. They might also become twisted or distorted. Stiffness is usually worse after a period of inactivity but eases as you move about.Having knee arthritis makes it hard to kneel because of the pain, and it can be a major problem getting up from a kneeling position because your knees get weaker as the arthritis worsens.